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Article

Effect of Simulated Grazing on Morphological Plasticity and Resource Allocation of Aeluropus lagopoides

by
Basharat A. Dar
,
Abdulaziz M. Assaeed
,
Saud L. Al-Rowaily
,
Abdullah A. Al-Doss
,
Muhammad M. Habib
,
Jahangir A. Malik
and
Ahmed M. Abd-ElGawad
*
Production Department, College of Food & Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(1), 144; https://doi.org/10.3390/agronomy14010144
Submission received: 22 November 2023 / Revised: 30 December 2023 / Accepted: 3 January 2024 / Published: 8 January 2024
(This article belongs to the Special Issue Advances in Grassland Ecology and Grass Phenotypic Plasticity)
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Abstract

:
Aeluropus lagopoides, a dominant palatable species in various sabkha and coastal regions of Saudi Arabia, can withstand harsh saline environments through phenotypic plasticity. When subjected to grazing, how A. lagopoides adapt phenotypically is currently unknown. There is a breakage in the chain of study on the spatial and temporal expansion strategy of A. lagopoides plants when subjected to different grazing stresses in different saline soil habitats. A grazing experiment was conducted to investigate the phenotypic plasticity and resource allocation pattern response of A. lagopoides in different saline soils. Individual A. lagopoides rhizomes from five saline regions were grown and exposed to varied grazing treatments in the form of clipping, viz; light, moderate, and heavy grazing, as compared to a grazing exclusion control. Our results showed that heavy grazing/clipping significantly decreased the shoot system and above-ground biomass in high-saline region plants in the early season. Plant length, root length, root and shoot biomass, the number of stolons, average stolon length, leaf area, and SLA of A. lagopiodes responded significantly to grazing intensities. A. lagopoides from the Qareenah, Qaseem, and Jizan regions were more tolerant to light grazing than A. lagopoides from the Salwa and Jouf regions. Light grazing showed significantly good re-growth, especially during the late season. Light grazing decreased the synthesis of chlorophyll content. Also, A. lagopiodes reduced the risk caused by reactive oxygen species via the increased accumulation of proline content. Overall, plants adapted to different morphological and physiological strategies to tolerate different levels of grazing intensities by adapting their morphological attributes. Though heavy grazing damages the plant, light and moderate grazing can be allowed to maintain the productivity and economic benefits of sabka habitats where soil conditions are moderately saline.

1. Introduction

Many arid rangelands of the globe have undergone severe degradation, resulting in low vegetation cover and increased soil erosion [1]. Overgrazing by livestock could be attributed to rangeland degradation [2]. Among various rangeland habitats, sabkhas are mostly marginal nonproductive zones scarce of vegetation. Besides having stressful conditions, the overgrazing of palatable species aggravates the condition of biological species [3]. Some palatable species have disappeared, and others are on the verge of extinction. Overgrazing led to a considerable deficit in forage, accentuating the desertification phenomenon [3]. Halophytic plants are widely distributed, and are especially abundant in arid and semi-arid regions. Several palatable halophytes and other salt-resistant plants grow in semi-arid saline habitats like wetlands, swamps, degraded soils, coastal zones, and sabkhas [4,5]. Besides being a potential source of fuel, wood, pulp, and fiber, halophytes also can be used in land reclamation, dune stabilization, and landscaping. The potential usage of halophytic plants probably lies in their alternative utilization as forage and fodder [6]. Aeluropus lagopoides is a perennial halophytic grass distributed globally, mainly in the ecoregions of high salinity and semi-desert climates [7]. In Saudi Arabia, it is found in various coastal and inland sabkhas [8] and grows in certain vegetation areas in the wetland wadi Qareenah, Riyadh, salt marsh Sabkha of Qaseem, and Jouf. It also inhabits the coastal regions of Salwa and Jizan region [9,10].
A. lagopoides exhibits adaptive phenotypic features such as efficient seed germination, gradual vegetative growth, stolon-based propagation, epicuticle wax production, salt-secreting glands, small waxy leaflets, and strong root architecture, which helps the plant to survive in both coastal and inland stressful saline habitats, especially during summers [11]. Owing to its structural modification and adaptation, this plant can withstand saline environments uninhabitable to many other plant species [12]. In inland and coastal sabkha habitats of Saudi Arabia, A. lagopoides is used as a source of forage where other palatable plants are scarce [13]. Its low sodium content, high total digestible nutrients, and tolerance to salinity make it a good fodder candidate for saline agriculture [14].
Second to wildfire, heavy grazing is the most frequent large-scale disturbance leading to vegetation structure alterations and reduced productivity [15]. This phenomenon affects the morphology and functional traits of the plants [16]. However, proper grazing management has been found to have a positive effect on grasses, such as increasing tillering, enhanced photosynthesis, and growth recovery [17], resulting in equal-compensatory or over-compensatory growth [18]. On the contrary, excessive grazing can decrease plants’ shoot system regrowth, leading to under-compensatory growth [18]. The overall impact of one or several grazing events may have a positive, negative, or neutral effect on the overall growth of the plants, depending upon the habitat resource availability, frequency, and intensity of the defoliation [19]. Plants frequently subjected to defoliation may show distinct morphological and physiological parameters via the mechanism of adaptive plasticity [20,21].
Frequent defoliation improved the grazing resistance of Bouteloua curtipendula via increased tiller production with lower mass [22]. Removal of above-ground biomass by herbivores can cause a negative shift in the root–shoot ratio due to energy investment in leaf production after defoliation [23]. Ungrazed tillers of Leymus chinensis exhibited phenotypic plasticity in response to the defoliation of neighboring shoots in grasses with the clonal reproduction system [24]. However, Bryant et al. [25] found that rhizomatous populations of Schedonorus arundinaceus were more plastic in response to defoliation than non-rhizomatous ones. During grazing, large herbivores directly decrease plant height and trigger grazing intensity-dependent plastic responses [26]. Plants can undergo dwarfing with increasing grazing intensity, and above-ground biomass decreases as a result [27]. According to meristem allocation models, after grazing or clipping, the compensatory regeneration capability of the plants is related to the number of intact meristems and the activation of dormant buds [28]. Heavy clipping or grazing can directly lead to a reduction in forage biomass [29,30].
The phenotypic plasticity of plant tolerance to herbivory is a common trait that is often viewed as a fitness response to damage [31]. Attributes that confer tolerance to grazing include the availability and activation of dormant meristems, as well as the extent and composition of bud banks [32], reallocation of stored carbohydrates and nutrients [33], increased photosynthetic activity of basal leaves escaping from defoliation [34], and increased relative growth rate [35]. The internode length, branching intensity, and biomass allocation responded significantly to grazing intensities in palatable plants [36]. These traits influence plant fitness by shifting the allocation of resources within plants [31].
As the season changes, plants undergo developmental changes between active and dormant phenological phases, resulting in a significant difference in the metabolic physiology of plants [37]. Plants differ in their ability to recover from grazing between seasons [38] and this may influence their regrowth, thereby significantly altering the ecosystem’s functioning [39]. In response to seasonal grazing, plants can adjust their morphological and physiological traits and improve the stress resistance and regrowth capacity of forage vegetation [40], while various disturbances, including overgrazing, can negatively affect productivity by reducing plant biomass and cover [41,42]. Reduced plant cover can decrease soil’s water infiltration capacity, resulting in increased runoff, soil erosion, and carbon losses due to reduced plant biomass. However, due to a limited number of palatable species in the sabkhas of Saudi Arabia, one of the few, A. lagopoides, undergoes intense grazing. This plant forms a specific zonation of different halophytic vegetation corresponding to the soil salinity and adapts itself to the varied saline environment by modifying its morphology through phenotypic plasticity [10,43]. Besides being palatable, this plant has other economic importance [44]. It is a sand stabilizer plant and may have the capacity to tolerate or resist grazing by implementing plant-ecological strategies. This plant is under intense grazing stress because of the presence of limited palatable species in saline regions, and there is every possibility that this type of habitat can lead to soil erosion and destabilization. In addition, soil salinization and patch dispersal are increased by various factors, including climate, geography, grazing, and others [45]. Therefore, understanding grazing levels for the sustainable management of saline ecosystems is crucial. However, most of the studies have failed to quantify and predict the associational effects when plants face biotic and abiotic stresses in heterogeneous environments and have overlooked the spatial strategies adopted by these halophytic species. Therefore, the present study aimed to investigate the phenotypic strategies adapted by A. lagopoides under different grazing levels over time in stressful environments. We addressed the following questions: (i) What is the extent of grazing tolerance adapted by a specific region of A. lagopoides? (ii) How do plants’ functional traits change over time in response to various grazing intensities?

2. Materials and Methods

2.1. Field Plant Samples Collection

Five locations were targeted to collect mother fruiting A. lagopoides that represented the coastal and inland salt-affected lands. A. lagopoides plants were randomly uprooted along with the soil rhizosphere from 5 different saline regions of Saudi Arabia viz; (1) inland sabkha Qareenah, Riyadh, (2) inland sabkha Al-Aushazia, Qaseem, (3) inland sabkha in Domat Aljandal, Jouf, (4) Coastal lowland sabkha, Salwa, and (5) Coastal Sabkha, Jizan. These saline regions are different eco-regions with a geographical distance of more than 200 km from each other. This species is a dominant one and grows both sexually and asexually in these ecological zones. Since it is among the few palatable species, especially during the summer season, this species is exposed to intense grazing. The excavated plants were immediately transferred to plastic pots and labeled for their region before being transferred to the Shade House Experimental Station, College of Agriculture and Food Sciences, King Saud University, Riyadh, Saudi Arabia. We targeted these regions based on our previous work on that plant, which survives well in saline areas [10]. This plant is considered a very promising foraging plant with high palatability and nutritive value, particularly in summer when other annual forage species are almost absent.

2.2. Establishment of Pot Experiment for Simulated Grazing

Before starting the simulated grazing experiment, a preliminary trial was conducted to assess the viability of A. lagopoides seed, but the seeds failed to germinate. Therefore, we opted for rhizome propagation as a vegetative propagation method. A greenhouse pot experiment was set up to assess the impact of grazing on morphological plasticity and biomass allocation in A. lagopoides collected from various regions of Saudi Arabia. The duly established plants of A. lagopoides from different regions were used for this grazing experiment. The excavated plants were allowed to establish to full maturity and produced enough rhizomes. This stage took four months, during which the soil conditions were maintained to enable the excavated plants to be established and flourish according to the plants’ specific region characteristics (Table 1).
Each region-wise rhizome was separately transplanted into plastic pots filled with soil collected from the corresponding regions where the mother plant samples were uprooted for rhizome generation. The rhizomes were transplanted at 2 cm depth, at which they were totally covered with soil. The rhizomes were allowed to grow and establish themselves for 45 days till full vegetative maturity was reached. Five grazing intensities were established to study the effect of grazing on morphological plasticity and biomass allocation of plants: (1) Ungrazed (UG) as a control, (2) light grazing (L, 25% clipping), (3) moderate grazing (M, 50% clipping), (4) heavy grazing (H, 75% clipping) and (5) complete grazing (100% clipping). Each grazing intensity was artificially applied (via clipping) to full-grown rhizomes of A. lagopoides. The treatments were replicated three times. All experimental units, i.e., pots, were irrigated as and when needed to prevent drought stress. As needed, during the whole period of the experiments, the electrical conductivity (EC) and pH levels of the pot soil were routinely tested with an EDT NE287 Micro Conductivity Meter and an EDT FE 257 Micro pH Meter (Hanna instruments, Woonsocket, RL, USA), respectively, to ensure that both these soil parameters were maintained at levels consistent with the soil’s region of origin (Table 1). However, upon complete grazing (100% clipping), the plants from each region could not regrow and died, so this treatment was omitted from the experiment.

2.3. Measurement of Morphological Parameters

The experiment’s measurements were taken twice (early and late season). For the early season, the whole shoot system morphological attributes (shoot length, average stolon length, number of tillers per plant, number of leaves per plant, and number of stolons per plant) were measured after 75 days of grazing. As for the late season, both shoot system and root system attributes were calculated along with the biomass allocation after 240 days. The experiment was finally terminated by excavating the plants from pots for biomass allocation measurement to assess adaptive plasticity upon grazing. Each individual’s leaf area was measured using the WinDIAS system (Delta-T Devices Ltd., Cambridge, UK). The Specific Leaf Area (SLA) was determined as the leaf area ratio to leaf dry mass. At the same time, the leaf dry matter content (LDMC) was measured as the ratio of leaf dry mass to saturated leaf fresh mass [45]. The biomass resource allocation, root mass fraction, shoot mass fraction, and their ratio were calculated to assess the effect of grazing on the plastic response over time of A. lagopoides of different regions [46].

2.4. Estimation of Chlorophyll and Proline Contents

The chlorophylls (a, b, and a + b) and proline content were measured in A. lagopoides of different treatments and regions for the late season. Measurements for chlorophyll and proline content were deferred to the late season because cutting any part of the plant material would have disrupted the grazing treatment, and the plants were allowed to grow at the same levels of grazing intensities for late-season morphological measurement. At the end of the late season, morphological measurements for both shoot and root systems were taken. The chlorophyll a, chlorophyll b, and total chlorophyll (a + b) were measured using the Lichtenthaler and Wellburn method [47]. About 500 mg of the young fresh leaves was extracted using acetone, and the required chlorophyll contents were determined on absorbance measurements at 663 and 645 nm using a UV-VIS spectrophotometer (SHIMADZU, Kyoto, Japan, UV1800).
Proline content (µg/g FW) of the plant materials was determined by homogenizing 0.1 g of the young fresh leaves with mortar and pestle in 10 mL of sulfosalicylic acid (3%). The homogenate was centrifuged at 5000 rpm for 10 min (Benchtop Centrifuge-5810R, Eppendorf, Hamburg, Germany), and 2 mL of supernatant was extracted in a separate test tube. The 2 mL extract was incubated with 2 mL of glacial acetic acid and ninhydrin each for 1 h in a boiling water bath at 94 °C to 100 °C followed by ice shock. Next, 4 mL of toluene was added, and after mixing for 20 s, chromophore was collected in a separate tube. The proline content was determined via an absorbance measurement at 520 nm using a UV–VIS spectrophotometer (SHIMADZU, Kyoto, Japan, UV1800).

2.5. Statistical Analysis of the Data

The experiment was based on a three-factor design (region, season, and grazing intensity statistically analyzed based on a factorial design consisting of the region as the main factor, the season as a sub-factor, and the grazing levels as a sub-sub-factor with three replicates [48] using Statistix 8.1 for ANOVA and the PC SAS software, version 9.1.3 (SAS Institute, Cary, NC, USA, 2002–2003) for mean separation using HSD/Duncan’s test (p < 0.5 and p < 0.01) for significant mean. The measurement for biomass allocation was taken at the end of the late season, i.e., at the termination of the experiment. However, the biomass allocation and chlorophyll and proline content data were analyzed based on factorial design analysis with region as the main factor and grazing as the sub-factor. Treatment means upon significance were separated using LSD/Duncan (p = 0.01, p = 0.01).

3. Results

At the end of the experiment, both region and grazing over time and their interaction significantly affected all shoot and root morphological characteristics as well as resource allocation of A. lagopodies, except for specific leaf area (SLA) which showed no significance for grazing, and the effect was region-specific as well (Table 2 and Table 3).

3.1. Effect of Grazing over Time on Shoot Morphological Traits

Generally, A. lagopoides plants during the late season showed more growth on almost all shoot morphological parameters than in the early season, corresponding to their respective grazing intensities, resulting in over-compensatory growth (Figure 1). A. lagopoides from the Qaseem region showed significantly more vegetative growth for shoot length (L = 57.33 cm), no. of stolons/plant (UG = 7), No. of leaves (UG = 7.4 × 102 leaves M = 4.5 × 102), and average stolon length (H = 70.89 and UG = 69.31 cm, respectively) for the late season compared to the plants of other regions. However, A. lagopoides from the Qareenah region showed more growth for No. of tiller/Plant (UG = 57 nos. and L = 48 nos.) followed by Qaseem (UG = 44 nos.) for the late-season grazing.

3.2. Grazing Effects on Leaf Morphological Traits

For all studied leaf parameters, A. lagopoides plants from Jizan region showed more growth than other regions (Figure 2). Overall, no big difference was observed between ungrazed and light grazing treatments in all the regions. However, the growth was greater for both ungrazed (UG) and light grazing (L) clipping for the late season compared to the early season. In contrast, A. lagopodies from the Jouf Region had the most diminished growth (Figure 2). The leaf dry weight (LDW) of A. lagopoides from the Jizan region for light grazing during the late season showed significantly higher growth than for the ungrazed one, while the Leaf Area (LA) for ungrazed and light grazing (UG = 4.60 cm2 and L = 4.10 cm2) for the early season showed a larger area compared to their corresponding grazing intensities (UG = 4.50 cm2 and L = 3.91 cm2) for late-season growth. The Salwa region obtained the highest value of Specific Leaf Area (SLA = 2.10 cm2/mg) compared to other regions.

3.3. Effect of Grazing over Time Chlorophyll and Proline Content of A. lagopoides

The photosynthetic pigment contents of the leaf are shown in Figure 3. The results indicated that contents differed significantly among the grazing intensities (p < 0.05) and the location of the plant as well (Table 3).
The Chl a, Chl b, and Tot Chl contents were higher by a significant amount in ungrazed plants and were at their lowest in heavy grazing plants from each location. Overall, the Jizan region has the highest Chl a (15.18), Chl b (12.38), and Tot Chl contents (12.39) than other regions, followed by Qaseem. The lowest pigment values were found in the Jouf region from their corresponding grazing intensities. For each location, the pigment contents of light grazing plants were significantly lower than the moderate- and heavy-grazing plants. Similarly, grazing intensities significantly affected the proline content in leaves of A. lagopoides, which increased with the increase in grazing intensity, and the effect was region-specific (Figure 3). The proline content was highest in A. lagopoides plants of the Salwa region (21.76) followed by the Qareenah region (19.24) under heavy grazing and was at its lowest in the Jizan region when the plants were ungrazed. However, the leaves of A. lagopoides had significantly higher proline content when subjected to heavy grazing followed by moderate grazing compared to ungrazed and lightly grazed plants in each region.

3.4. Morphological Traits under Different Grazing Intensities at the Termination of Experiment

Biomass patterns and their allocation towards shoot and root systems showed significant effects of grazing treatments (p < 0.01) (Table 3). Overall, A. lagopoides plant performance at the end of light grazing showed values close to ungrazed treatments for most of the morphological parameters and responded region-wise (Table 3 and Figure 4).
Shoot length and root length decreased with the increase in the intensity of the grazing intensity except in the plants of A. lagopoides from the Qaseem region, in which the shoot length (57.33 cm) and root length (58.50 cm) under light grazing treatments were significantly higher at the end of the late season than the ungrazed plants from the same regions. Grazing intensities significantly decreased the dry shoot weight and root dry weight of A. lagopoides from all regions. A. lagopoides from the Qareenah region under light grazing showed a higher shoot dry weight (26.14 g), followed by the plants of the Qaseem region at the same grazing level (SDW = 22.95 g) after control. Similarly, under light grazing, the plant’s root dry weight (4.68 g) for the Jizan region was significantly higher, followed by Qaseem (4.33), compared to ungrazed plants of other regions.

3.5. Comparisons of Shoot, Leaf, and Root Biomass Fractions of A. lagopoides under Different Grazing Intensities at the Termination of Experiment

Grazing treatments significantly affected the biomass patterns and their allocation toward shoot, root, and leaf systems at the termination of the experiment (p < 0.05, Figure 5). The significance is region-dependent as well. Regarding shoot mass fraction, light grazing compensated the entire shoot biomass of A. lagopoides at the harvest stage in all the regions (Figure 5A). However, the lowest shoot mass fraction was found on A. lagopiodes subjected to ungrazed treatment in the Salwa and the Jouf regions (0/40 g/g each). Regarding root mass fraction, leaf mass fraction, and root shoot ratio, A. lagopiodes in the Jizan region showed significantly higher results in response to all grazing treatments except the ungrazed one, which was highest in the Salwa and the Jouf regions (0.60 g/g) (Figure 5B–D). In the Jizan region, the root allocation, leaf allocation, and root/shoot ratio were highest after heavy grazing, followed by light grazing treatment. The Qareenah and Qaseem region had the lowest root and leaf mass allocation as well as root/shoot ratio after all the grazing treatments (Figure 5B–D).

4. Discussion

In response to environmental heterogeneity and stress, rhizomatous plants exhibit a variety of adaptations, including changes in morphological plasticity, physiological integration, and resource allocation between functioning organs [49]. In this study, we investigated the tolerance level and phenotypic adaptation of A. lagopoides growing in saline regions against grazing. Our study indicated that A. lagopoides from different regions exhibit notable phenotypic plasticity in various morphological traits, such as plant height, number of tillers, number of leaves, number of stolons, and mean stolon length, in response to grazing. This morphological plasticity was region-dependent and could have been affected by the saline–alkali properties of the soil.
Grazing directly affects vegetation growth, plant biomass, and dry matter distribution based on the grazing intensities and season [50]. In the present study, morphological parameters of A. lagopoides plants from all regions were able to withstand light and moderate grazing in the late season compared to the early season. During the late season, stimulation of plant height was observed during light and moderate grazing, while the number of tillers was observed to be stimulated by light grazing. Similar stimulation of plant size and tiller number functions was observed in other grass species [26]. Also, new tillers are produced continually but at different rates depending on the season. The steady decrease in shoot length of A. lagopoides with increasing grazing intensity during the early season developed it into a more dwarf-like phenotype, which may be a grazing avoidance strategy to protect the plants.
As the main shoot system was clipped/grazed at different intensities, the leaves of A. lagopoides were significantly influenced by the intensity of grazing and the duration of growth after the grazing. The number of leaves in ungrazed and moderately grazed A. lagopoides plants was significantly higher from the Qareenah region, followed by Qaseem region plants. Production of new leaves in A. lagopoides plants from the Qaseem region under moderate grazing was higher than light and heavy grazing from the same region, which means its response is flexible. This flexible response to the production of new leaves may involve variable patterns of resource allocation and activation of dormant buds [51].
The number of stolons per plant and the average stolon length of A. lagopoides from the Qaseem and Jizan regions were significantly higher under ungrazed and light grazing intensity. Stolon numbers decreased with the increase in grazing intensity and were region- and season-dependent. However, the average stolon length seems to have strong genetic programming and is not modulated by grazing intensities and post-grazing factors [52]. During grazing, the main shoot system is consumed by herbivores and significantly influences the plants’ leaves. Thus, SLA, an indicator of leaf function, represents the plant’s ability to acquire and use the plant’s resources for its different uses [53]. In the Jizan and Qareenah regions, A. lagopoides grown under heavy grazing had the highest SLA, which means that A. lagopoides can grow new leaves faster than can occur during light and moderate grazing. The response was more flexible during the early grazing season when the plant was under grazing stress.
In this study, the chlorophyll synthesis of A. lagopoides grown from all regions in all grazing intensities was significantly lower than in control (ungrazed). Among regions, A. lagopoides from Jizan showed significantly higher chlorophyll synthesis than other regions in their corresponding grazing intensities. This may be due to higher leaf fresh weight, leaf mass, and leaf area, which absorbs and utilizes more solar energy. However, our results show that light grazing inhibits chlorophyll synthesis or may increase the activity of chlorophyll-degrading enzymes more than moderate and heavy grazing intensities, which agrees with photosynthetic and physiological responses of Leymus chinensis to different levels of grazing intensity [20]. However, Chl b can be converted into Chl a via the chlorophyll cycle, which gives plants the ability to optimally adapt to changing stressful conditions [54]. When decreasing the reactive oxygen species (ROS) level, the balance among the activity of different antioxidant enzymes is crucial [55]. Different grazing intensities induce ROS generation in plants, and the antioxidant enzyme production is not sufficient to mitigate the negative influence of ROS. Thus, proline acts as ROS scavenger under different stresses [56]. Therefore, the increased accumulation of proline in grazed plants would have increased the osmotic potential to protect the cells of the plants in saline environments [57,58]. Biomass allocation in the placement of resource-acquiring structures (shoot and roots) was also a kind of phenotypic plasticity.
Compared to ungrazed plants, grazing significantly decreased the shoot length and photosynthetic capacity of the grazed plant. This ultimately led to under-compensatory growth [59]. Light grazing, however, had no significant effect on the majority of shoot morphological traits in the low-saline regions of Qareenah and Qaseem and on leaf morphological traits in Jizan. The same trend was observed for biomass accumulation. A similar trend was also reported in the study of the grazing effect on Bromus ircutensis and Psammochloa villosa [60]. The grazing of A. lagopoides in the highly saline Salwa region did not lead to high compensatory growth because high salinity levels in the soil led to a decrease in water potential, reduced root activity, and caused a physiological drought [61].
The above- and below-ground biomass and its allocation pattern in A. lagopoides responded differently to different grazing intensities. A. lagopoides from the Qareenah, Qaseem, and Jizan regions have the highest adaptive plasticity to light and moderate grazing compared to other regions. This reflects species’ different ecological responses to heterogeneous environments. This compensatory growth may have been stimulated by light and moderate grazing by promoting the growth of tillers, increasing the bud number, and thus increasing the photosynthetic rate of A. lagopoides in these low-saline regions [24].
To improve grazing resistance, plants may adopt strategies of avoidance (escape from grazers) and tolerance (regrowth capacity after defoliation) [62,63]. Biomass allocation response to grazing intensities depends on the clipping intensity, the source location of the plant, and the post-grazing duration. Severe grazing intensity promotes significant changes in both the above- and below-ground biomass of forage plants was partially accepted. In this study, all grazing intensities except heavy grazing treatments significantly increased the above-ground shoot biomass and decreased the root biomass of A. lagopiodes in all regions. However, among the various regions, A. lagopiodes from Qareenah and Qaseem had more shoot mass fraction in their respective grazing intensities. In comparison, the Jouf and the Jizan regions had more root mass fraction. Grazing is widely considered to be a factor of environmental degradation [64], leading to pasture productivity losses [65], associated with lowering root biomass with increasing defoliation [66]. The leaf mass fraction was positively correlated with root biomass and was high in the Jouf and Jizan regions.
Compared to the Qareenah and Qaseem regions, A. lagopiodes were less affected by light and moderate grazing in the Salwa, Jouf, and Jizan regions. To adapt to grazing pressure, plants’ root/shoot ratio is modified to enable the plants to capture resources in the best possible way [67]. In this study, light and moderate grazing increased the root/shoot ratio, indicating that grazing changes the above- and below-ground biomass allocation. When plants’ grazing pressure is decreased, they allocate more biomass to support root growth. However, in the Qareenah and Qaseem regions, there was no difference in either above- and below-ground biomass experiencing different grazing intensities. The same results were also found in the steppe, where no difference was found in ungrazed and grazed grassland [68].

5. Conclusions

Our study suggests that maintaining and modifying morphological characteristics are the main integration strategies employed by the A. lagopodies plant to tolerate or resist grazing. In low-saline regions, A. lagopoides can maintain plant functional traits when exposed to light and moderate grazing, which promotes compensatory growth in contrast to high-saline regions. In addition to anthropogenic disturbance (grazing), saline–alkali heterogeneity in the soil was also a driving factor promoting temporal growth of this plant. For future research, the focus should be on the biomass distribution model of this plant in field experiments, to explore the morphological, photosynthetic characteristics, and growth strategy of A. lagopoides under trampling, mowing, and soil saline–alkali heterogeneity environments, so as to provide an effective reference for the rational utilization of palatable species of salt marsh habitats.

Author Contributions

Conceptualization, A.M.A., A.M.A.-E. and B.A.D.; formal analysis, B.A.D., A.M.A.-E., J.A.M. and A.M.A.; investigation, B.A.D., A.M.A., A.M.A.-E., A.A.A.-D., S.L.A.-R. and A.M.A.; writing—original draft preparation, B.A.D., A.M.A.-E. and A.M.A.; writing—review and editing, B.A.D., A.M.A., S.L.A.-R., A.A.A.-D., M.M.H., J.A.M. and A.M.A.-E.; visualization, B.A.D. and A.M.A.-E. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by The Researchers Supporting Project number (RSPD2024R676) King Saud University, Riyadh, Saudi Arabia.

Data Availability Statement

Data are contained within the article.

Acknowledgments

The authors extend their appreciation to The Researchers Supporting Project number (RSPD2024R676) King Saud University, Riyadh, Saudi Arabia.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Le Houerou, H. An overview of vegetation and land degradation in world arid lands. In Degradation and Restoration of Arid Lands; Dregne, H.E., Ed.; International Center for Semi Arid Land Studies: Lubbock, TX, USA, 1992; pp. 127–163. [Google Scholar]
  2. Al-Tabini, R.; Al-Khalidi, K.; Al-Shudiefat, M. Livestock, medicinal plants and rangeland viability in Jordan’s Badia: Through the lens of traditional and local knowledge. Pastor. Res. Policy Pract. 2012, 2, 2041–7136. [Google Scholar] [CrossRef]
  3. Aidoud, A.; Le Floch, E.; Le Houérou, H.N. The arid steppe rangelands of Northern Africa. Sci. Et Chang. Planétaires/Sécheresse 2006, 17, 19–30. [Google Scholar]
  4. Squires, V.R. Overview of problems and prospects for utilizing halophytes as a resource for livestock and for rehabilitation of degraded lands. In Halophytes as A Resource for Livestock and for Rehabilitation of Degraded Lands; Springer: Berlin/Heidelberg, Germany, 1994; pp. 1–6. [Google Scholar]
  5. Zahran, M.A.; Murphy, K.J.; Mashaly, I.A.; Khedr, A.A. On the ecology of some halophytes and psammophytes in the Mediterranean coast of Egypt. Verhandlungen-Ges. Fur Okologie 1996, 25, 133–146. [Google Scholar]
  6. Loconsole, D.; Cristiano, G.; De Lucia, B. Glassworts: From wild salt marsh species to sustainable edible crops. Agriculture 2019, 9, 14. [Google Scholar] [CrossRef]
  7. Breckle, S.-W. Salinity, halophytes and salt affected natural ecosystems. In Salinity: Environment-Plants-Molecules; Springer: Dordrecht, The Netherlands, 2002; pp. 53–77. [Google Scholar]
  8. Basahi, R.A. Plant diversity of the coastal regions of Gulf of Aqaba, Saudi Arabia. Annu. Res. Rev. Biol. 2018, 26, 1–11. [Google Scholar] [CrossRef]
  9. Abd-ElGawad, A.M.; Assaeed, A.M.; Al-Rowaily, S.L.; Dar, B.M.; Malik, J.A. Moisture and salinity drive the vegetation composition of Wadi Hargan, Riyadh, Saudi Arabia. Diversity 2021, 13, 587. [Google Scholar] [CrossRef]
  10. Dar, B.A.; Assaeed, A.M.; Al-Rowaily, S.L.; Al-Doss, A.A.; Abd-ElGawad, A.M. Vegetation composition of the halophytic grass Aeluropus lagopoides communities within coastal and inland sabkhas of Saudi Arabia. Plants 2022, 11, 666. [Google Scholar] [CrossRef]
  11. Mohsenzadeh, S.; Malboobi, M.; Razavi, K.; Farrahi-Aschtiani, S. Physiological and molecular responses of Aeluropus lagopoides (Poaceae) to water deficit. Environ. Exp. Bot. 2006, 56, 314–322. [Google Scholar] [CrossRef]
  12. Kumar, A.; Kumar, A.; Lata, C.; Kumar, S. Eco-physiological responses of Aeluropus lagopoides (grass halophyte) and Suaeda nudiflora (non-grass halophyte) under individual and interactive sodic and salt stress. South Afr. J. Bot. 2016, 105, 36–44. [Google Scholar] [CrossRef]
  13. Chaudhary, S.A.; Le Houerou, H.N. The rangelands of the Arabian Peninsula. Sci. Chang. Planétaires/Sécheresse 2006, 17, 179–194. [Google Scholar]
  14. Torbatinezhad, N.; Maghsoodlowrad, H.; Gharahbash, A. Nutritive value of Aeluropus littoralis and Aeluropus logopoides in sheep. J. Agric. Sci. Nat. Resour. 2000, 7, 31–45. [Google Scholar]
  15. Huntly, N. Herbivores and the dynamics of communities and ecosystems. Annu. Rev. Ecol. Syst. 1991, 22, 477–503. [Google Scholar] [CrossRef]
  16. Briske, D. Strategies of plant survival in grazed systems: A functional interpretation. In The Ecology and Management of Grazing Systems; Hodgson, J., Illius, A.W., Eds.; CAB International: Wallingford, UK, 1996; pp. 37–67. [Google Scholar]
  17. Zheng, C.C.; Wang, Y.J.; Sun, H.; Wang, X.Y.; Gao, Y.Z. Effects of clipping on nitrogen allocation strategy and compensatory growth of Leymus chinensis under saline-alkali conditions. J. Appl. Ecol. 2017, 28, 2222–2230. [Google Scholar]
  18. Ma, H.; Zheng, C.; Gao, Y.; Baskin, C.C.; Sun, H.; Yang, H. Moderate clipping stimulates over-compensatory growth of Leymus chinensis under saline-alkali stress through high allocation of biomass and nitrogen to shoots. Plant Growth Regul. 2020, 92, 95–106. [Google Scholar] [CrossRef]
  19. Noy-Meir, I. Compensating growth of grazed plants and its relevance to the use of rangelands. Ecol. Appl. 1993, 3, 32–34. [Google Scholar] [CrossRef] [PubMed]
  20. Liu, M.; Gong, J.; Yang, B.; Ding, Y.; Zhang, Z.; Wang, B.; Zhu, C.; Hou, X. Differences in the photosynthetic and physiological responses of Leymus chinensis to different levels of grazing intensity. BMC Plant Biol. 2019, 19, 558. [Google Scholar] [CrossRef]
  21. De Ryck, S.; Reheul, D.; De Riek, J.; De Keyser, E.; De Cauwer, B. Genetic and morphological variation of Belgian Cyperus esculentus L. clonal populations and their significance for integrated management. Agronomy 2023, 13, 572. [Google Scholar] [CrossRef]
  22. Smith, S.E. Variation in response to defoliation between populations of Bouteloua curtipendula var. caespitosa (Poaceae) with different livestock grazing histories. Am. J. Bot. 1998, 85, 1266–1272. [Google Scholar]
  23. Kuijper, D.; Dubbeld, J.; Bakker, J. Competition between two grass species with and without grazing over a productivity gradient. Plant Ecol. 2005, 179, 237–246. [Google Scholar] [CrossRef]
  24. Wang, D.; Du, J.; Zhang, B.; Ba, L.; Hodgkinson, K.C. Grazing intensity and phenotypic plasticity in the clonal grass Leymus chinensis. Rangel. Ecol. Manag. 2017, 70, 740–747. [Google Scholar] [CrossRef]
  25. Bryant, R.H.; Matthew, C.; Hodgson, J. Growth strategy of rhizomatous and non-rhizomatous tall fescue populations in response to defoliation. Agriculture 2015, 5, 791–805. [Google Scholar] [CrossRef]
  26. Diaz, S.; Lavorel, S.; McIntyre, S.; Falczuk, V.; Casanoves, F.; Milchunas, D.G.; Skarpe, C.; Rusch, G.; Sternberg, M.; NOY-MEIR, I. Plant trait responses to grazing—A global synthesis. Glob. Chang. Biol. 2007, 13, 313–341. [Google Scholar] [CrossRef]
  27. Li, J.; Wang, Z.; Ren, H.; Jin, Y.; Han, M.; Wang, S.; Han, G. Plastic response of individual functional traits in Stipa breviflora to long-term grazing in a desert steppe. Acta Bot. Boreali Occident. Sin. Yangling 2017, 37, 1854–1863. [Google Scholar]
  28. Huhta, A.-P.; Lennartsson, T.; Tuomi, J.; Rautio, P.; Laine, K. Tolerance of Gentianella campestris in relation to damage intensity: An interplay between apical dominance and herbivory. Evol. Ecol. 2000, 14, 373–392. [Google Scholar] [CrossRef]
  29. Sun, J.; Zhan, T.; Liu, M.; Zhang, Z.; Wang, Y.; Liu, S.; Wu, G.-L.; Liu, G.; Tsunekawa, A. Verification of the biomass transfer hypothesis under moderate grazing across the Tibetan plateau: A meta-analysis. Plant Soil 2021, 458, 139–150. [Google Scholar] [CrossRef]
  30. Ilmarinen, K.; Mikola, J.; Vestberg, M. Do interactions with soil organisms mediate grass responses to defoliation? Soil Biol. Biochem. 2008, 40, 894–905. [Google Scholar] [CrossRef]
  31. Simms, E.L. Defining tolerance as a norm of reaction. Evol. Ecol. 2000, 14, 563–570. [Google Scholar] [CrossRef]
  32. Wang, L.; Gan, Y.; Wiesmeier, M.; Zhao, G.; Zhang, R.; Han, G.; Siddique, K.H.; Hou, F. Grazing exclusion—An effective approach for naturally restoring degraded grasslands in Northern China. Land Degrad. Dev. 2018, 29, 4439–4456. [Google Scholar] [CrossRef]
  33. Li, X.-L.; Liu, Z.-Y.; Ren, W.-B.; Yong, D.; Lei, J.; Guo, F.-H.; Hou, X.-Y. Linking nutrient strategies with plant size along a grazing gradient: Evidence from Leymus chinensis in a natural pasture. J. Integr. Agric. 2016, 15, 1132–1144. [Google Scholar] [CrossRef]
  34. Hodgkinson, K. Influence of partial defoliation on photosynthesis, photorespiration and transpiration by lucerne leaves of different ages. Funct. Plant Biol. 1974, 1, 561–578. [Google Scholar] [CrossRef]
  35. Tiffin, P. Mechanisms of tolerance to herbivore damage: What do we know? Evol. Ecol. 2000, 14, 523–536. [Google Scholar] [CrossRef]
  36. Li, X.; Png, G.K.; Li, Y.; Jimoh, S.O.; Ding, Y.; Li, F.; Sun, S. Leaf plasticity contributes to plant anti-herbivore defenses and indicates selective foraging: Implications for sustainable grazing. Ecol. Indic. 2021, 122, 107273. [Google Scholar] [CrossRef]
  37. Maurya, J.P.; Bhalerao, R.P. Photoperiod-and temperature-mediated control of growth cessation and dormancy in trees: A molecular perspective. Ann. Bot. 2017, 120, 351–360. [Google Scholar] [CrossRef]
  38. Li, S.L.; Yu, F.H.; Werger, M.J.; Dong, M.; Ramula, S.; Zuidema, P.A. Understanding the effects of a new grazing policy: The impact of seasonal grazing on shrub demography in the Inner Mongolian steppe. J. Appl. Ecol. 2013, 50, 1377–1386. [Google Scholar] [CrossRef]
  39. Leffler, A.J.; Beard, K.H.; Kelsey, K.C.; Choi, R.T.; Schmutz, J.A.; Welker, J.M. Delayed herbivory by migratory geese increases summer-long CO2 uptake in coastal western Alaska. Glob. Chang. Biol. 2019, 25, 277–289. [Google Scholar] [CrossRef] [PubMed]
  40. Song, L.; Pan, Y.; Gong, J.; Li, X.; Liu, M.; Yang, B.; Zhang, Z.; Baoyin, T. Physiology of Leymus chinensis under seasonal grazing: Implications for the development of sustainable grazing in a temperate grassland of Inner Mongolia. J. Environ. Manag. 2020, 271, 110984. [Google Scholar] [CrossRef]
  41. Freitag, M.; Kamp, J.; Dara, A.; Kuemmerle, T.; Sidorova, T.V.; Stirnemann, I.A.; Velbert, F.; Hölzel, N. Post-soviet shifts in grazing and fire regimes changed the functional plant community composition on the Eurasian steppe. Glob. Chang. Biol. 2021, 27, 388–401. [Google Scholar] [CrossRef]
  42. Qi, Q.; Zhang, D.; Zhang, M.; Tong, S.; Wang, W.; An, Y. Spatial distribution of soil organic carbon and total nitrogen in disturbed Carex tussock wetland. Ecol. Indic. 2021, 120, 106930. [Google Scholar] [CrossRef]
  43. Assaeed, A.M.; Dar, B.A.; Al-Doss, A.A.; Al-Rowaily, S.L.; Malik, J.A.; Abd-ElGawad, A.M. Phenotypic plasticity strategy of Aeluropus lagopoides grass in response to heterogenous saline habitats. Biology 2023, 12, 553. [Google Scholar] [CrossRef]
  44. Phondani, P.C.; Bhatt, A.; Elsarrag, E.; Alhorr, Y.M.; El-Keblawy, A. Criteria and indicator approach of global sustainability assessment system for sustainable landscaping using native plants in Qatar. Ecol. Indic. 2016, 69, 381–389. [Google Scholar] [CrossRef]
  45. Vile, D.; Garnier, E.; Shipley, B.; Laurent, G.; Navas, M.-L.; Roumet, C.; Lavorel, S.; Díaz, S.; Hodgson, J.G.; Lloret, F. Specific leaf area and dry matter content estimate thickness in laminar leaves. Ann. Bot. 2005, 96, 1129–1136. [Google Scholar] [CrossRef] [PubMed]
  46. Perez-Harguindeguy, N.; Diaz, S.; Garnier, E.; Lavorel, S.; Poorter, H.; Jaureguiberry, P.; Bret-Harte, M.; Cornwell, W.; Craine, J.; Gurvich, D. New handbook for standardised measurement of plant functional traits worldwide. Aust. J. Bot. 2013, 61, 167–234. [Google Scholar] [CrossRef]
  47. Lichtenthaler, H.K.; Wellburn, A.R. Determinations of total carotenoids and chlorophylls a and b of leaf extracts in different solvents. Biochem. Soc. Trans. 1983, 603, 591–592. [Google Scholar] [CrossRef]
  48. Steel, R.G.D.; Torrie, J.H. Principal and Procedure of Statistics: A Biochemical Approach, 3rd ed.; Mcgraco-Hill book Company: New York, NY, USA, 1986. [Google Scholar]
  49. Cahill, J.F., Jr.; McNickle, G.G.; Haag, J.J.; Lamb, E.G.; Nyanumba, S.M.; St. Clair, C.C. Plants integrate information about nutrients and neighbors. Science 2010, 328, 1657. [Google Scholar] [CrossRef]
  50. Chai, J.; Yu, X.; Xu, C.; Xiao, H.; Zhang, J.; Yang, H.; Pan, T.J.A.S.E. Effects of yak and Tibetan sheep trampling on soil properties in the northeastern Qinghai-Tibetan Plateau. J. Appl. Soil Ecol. 2019, 144, 147–154. [Google Scholar] [CrossRef]
  51. Tuomi, J.; Nilsson, P.; Astrom, M. Plant compensatory responses: Bud dormancy as an adaptation to herbivory. Ecology 1994, 75, 1429–1436. [Google Scholar] [CrossRef]
  52. Mocelin, N.G.; Schmitt, D.; Zanini, G.D.; Camacho, P.A.G.; Sbrissia, A.F. Grazing management targets for tangolagrass pastures. Agriculture 2022, 12, 279. [Google Scholar] [CrossRef]
  53. Hoque, M.A.; Okuma, E.; Banu, M.N.A.; Nakamura, Y.; Shimoishi, Y.; Murata, Y. Exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine by increasing antioxidant enzyme activities. J. Plant Physiol. 2007, 164, 553–561. [Google Scholar] [CrossRef]
  54. Qian, L.; Qi, S.; Cao, F.; Zhang, J.; Zhao, F.; Li, C.; Wang, C. Toxic effects of boscalid on the growth, photosynthesis, antioxidant system and metabolism of Chlorella vulgaris. Environ. Pollut. 2018, 242, 171–181. [Google Scholar] [CrossRef]
  55. Chen, Y.; Hung, Y.-C.; Chen, M.; Lin, M.; Lin, H. Enhanced storability of blueberries by acidic electrolyzed oxidizing water application may be mediated by regulating ROS metabolism. Food Chem. 2019, 270, 229–235. [Google Scholar] [CrossRef]
  56. Kavi Kishor, P.B.; Sreenivasulu, N. Is proline accumulation per se correlated with stress tolerance or is proline homeostasis a more critical issue? Plant Cell Environ. 2014, 37, 300–311. [Google Scholar] [CrossRef]
  57. Mohammadi, H.; Ghorbanpour, M.; Brestic, M. Exogenous putrescine changes redox regulations and essential oil constituents in field-grown Thymus vulgaris L. under well-watered and drought stress conditions. Ind. Crops Prod. 2018, 122, 119–132. [Google Scholar] [CrossRef]
  58. Kurepin, L.V.; Ivanov, A.G.; Zaman, M.; Pharis, R.P.; Allakhverdiev, S.I.; Hurry, V.; Huener, N. Stress-related hormones and glycinebetaine interplay in protection of photosynthesis under abiotic stress conditions. Photosynth. Res. 2015, 126, 221–235. [Google Scholar] [CrossRef]
  59. Qu, L.; Liu, J.; Yang, J.; Bai, L.; Huang, Y.; Lu, N.; Yu, H.; Wang, Z.; Li, Z. Soil saline-alkali heterogeneity is an important factor driving the spatial expansion of clonal plant in grassland. Front. Environ. Sci. 2023, 10, 2750. [Google Scholar] [CrossRef]
  60. Liu, H.-D.; Yu, F.-H.; He, W.-M.; Chu, Y.; Dong, M. Clonal integration improves compensatory growth in heavily grazed ramet populations of two inland-dune grasses. Flora 2009, 204, 298–305. [Google Scholar] [CrossRef]
  61. Mahlooji, M.; Seyed Sharifi, R.; Razmjoo, J.; Sabzalian, M.; Sedghi, M. Effect of salt stress on photosynthesis and physiological parameters of three contrasting barley genotypes. Photosynthetica 2018, 56, 549–556. [Google Scholar] [CrossRef]
  62. Cingolani, A.M.; Posse, G.; Collantes, M.B. Plant functional traits, herbivore selectivity and response to sheep grazing in Patagonian steppe grasslands. Appl. Ecol. 2005, 42, 50–59. [Google Scholar] [CrossRef]
  63. Rusch, G.; Skarpe, C.; Halley, D. Plant traits link hypothesis about resource-use and response to herbivory. Basic Appl. Ecol. 2009, 10, 466–474. [Google Scholar] [CrossRef]
  64. Cai, Y.; Yan, Y.; Xu, D.; Xu, X.; Wang, C.; Wang, X.; Chen, J.; Xin, X.; Eldridge, D.J. The fertile island effect collapses under extreme overgrazing: Evidence from a shrub-encroached grassland. Plant Soil 2020, 448, 201–212. [Google Scholar] [CrossRef]
  65. Fedrigo, J.K.; Ataide, P.F.; Filho, J.A.; Oliveira, L.V.; Jaurena, M.; Laca, E.A.; Overbeck, G.E.; Nabinger, C. Temporary grazing exclusion promotes rapid recovery of species richness and productivity in a long-term overgrazed Campos grassland. Restor. Ecol. 2018, 26, 677–685. [Google Scholar] [CrossRef]
  66. Gao, Y.Z.; Giese, M.; Lin, S.; Sattelmacher, B.; Zhao, Y.; Brueck, H. Belowground net primary productivity and biomass allocation of a grassland in Inner Mongolia is affected by grazing intensity. Plant Soil 2008, 307, 41–50. [Google Scholar] [CrossRef]
  67. Wang, L.; Niu, K.; Yang, Y.; Zhou, P. Patterns of above-and belowground biomass allocation in China’s grasslands: Evidence from individual-level observations. Sci. China Life Sci. 2010, 53, 851–857. [Google Scholar] [CrossRef] [PubMed]
  68. Liang, Y.; Han, G.; Zhou, H.; Zhao, M.; Snyman, H.A.; Shan, D.; Havstad, K.M. Grazing intensity on vegetation dynamics of a typical steppe in northeast Inner Mongolia. Rangel. Ecol. Manag. 2009, 62, 328–336. [Google Scholar] [CrossRef]
Agronomy 14 00144 g001
Figure 1. Various traits of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed L: light grazing; M: medium grazing; H: heavy grazing). Values are means ± standard error (n = 3). Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test, p < 0.01 **, p < 0.05 *). Capital letters indicate significance by region, while small letters indicate significance by season and an asterisk indicates significance by grazing intensity.
Figure 1. Various traits of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed L: light grazing; M: medium grazing; H: heavy grazing). Values are means ± standard error (n = 3). Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test, p < 0.01 **, p < 0.05 *). Capital letters indicate significance by region, while small letters indicate significance by season and an asterisk indicates significance by grazing intensity.
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Figure 2. Leaf fresh weight (LFW), leaf dry weight (LDW), leaf area (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed L: light grazing; M: medium grazing; H: heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test, p < 0.01 **, p < 0.05 *). Capital letters indicate significance by region, while small letters indicate significance by season and an asterisk indicates significance by grazing intensity.
Figure 2. Leaf fresh weight (LFW), leaf dry weight (LDW), leaf area (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed L: light grazing; M: medium grazing; H: heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test, p < 0.01 **, p < 0.05 *). Capital letters indicate significance by region, while small letters indicate significance by season and an asterisk indicates significance by grazing intensity.
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Figure 3. The chlorophyll a, chlorophyll b, and proline content in leaves of A. lagopoides plants of different regions with different grazing intensities (ungrazed, light, medium, and heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test, p < 0.05). Capital letters indicate significance by region, while small letters indicate significance by grazing intensities.
Figure 3. The chlorophyll a, chlorophyll b, and proline content in leaves of A. lagopoides plants of different regions with different grazing intensities (ungrazed, light, medium, and heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test, p < 0.05). Capital letters indicate significance by region, while small letters indicate significance by grazing intensities.
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Figure 4. Shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, and root dry weight of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed L: light grazing, M: medium grazing, H: heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test). Capital letters indicate significance by region, while small letters indicate significance by grazing intensity.
Figure 4. Shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, and root dry weight of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed L: light grazing, M: medium grazing, H: heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test). Capital letters indicate significance by region, while small letters indicate significance by grazing intensity.
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Figure 5. Shoot mass fraction (A), root mass fraction (B), leaf mass fraction (C), and root/shoot ratio (D) based on dry matter of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed LG: light, MG: medium; HG: heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test). Capital letters indicate significance by region, while small letters indicate significance by grazing intensity.
Figure 5. Shoot mass fraction (A), root mass fraction (B), leaf mass fraction (C), and root/shoot ratio (D) based on dry matter of A. lagopoides plants from different regions grown with different grazing intensities (UG: ungrazed LG: light, MG: medium; HG: heavy grazing). Values are means ± standard error. Values of a parameter labeled with different letters differ significantly between grazing intensities (ANOVA followed by LSD test). Capital letters indicate significance by region, while small letters indicate significance by grazing intensity.
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Table 1. pH and EC of the soil collected from different saline regions of Saudi Arabia.
Table 1. pH and EC of the soil collected from different saline regions of Saudi Arabia.
RegionpHEC (dS·m−1)
Qareenah8.32 ± 0.1811.37 ± 1.03
Qaseem8.30 ± 0.1410.28 ± 1.87
Salwa8.49 ± 0.6131.35 ± 4.41
Jouf8.14 ± 0.118.78 ± 1.43
Jizan8.04 ± 0.223.58 ± 1.76
Table 2. Analysis of variance (factorial design) of morphological parameters in A. lagopoides of different regions grown under four grazing levels during early and late season.
Table 2. Analysis of variance (factorial design) of morphological parameters in A. lagopoides of different regions grown under four grazing levels during early and late season.
Source of VariationDFSSMSF-Valuep-ValueSSMSF-Valuep-Value
Shoot length (cm)Number of Tillers per Plant (no.)
Region (R)415,162.73790.67269.79<0.0001 ***5788.61447.15134.62<0.0001 ***
Season (S)18167.78167.67581.3<0.0001 ***4416.54416.53410.84<0.0001 ***
Grazing (G)37079.92359.98167.96<0.0001 ***4029.21343.06124.94<0.0001 ***
R × S43131.2782.7955.71<0.0001 ***3514.1878.5181.72<0.0001 ***
R × G122861.8238.4916.97<0.0001 ***563.646.974.37<0.0001 ***
S × G3427.5142.4910.14<0.0001 ***383.1127.6911.88<0.0001 ***
R × S × G121239.7103.317.35<0.0001 ***743.461.955.76<0.0001 ***
Error80112414.05 86010.75
Number of Stolons (no.)Average Stolon Length (cm)
Region (R)4204.16751.0417133.15<0.0001 ***21,5285381.9147.75<0.0001 ***
Season (S)150.750.7132.26<0.0001 ***11,57011,570.3317.65<0.0001 ***
Grazing (G)3137.36745.7889119.45<0.0001 ***6661.82220.660.96<0.0001 ***
R × S44.6331.15833.020.022 *2098.1524.514.4<0.0001 ***
R × G1275.9676.330616.51<0.0001 ***2613.3217.85.98<0.0001 ***
S × G312.4334.144410.81<0.0001 ***345.4115.13.160.0291 *
R × S × G1210.5670.88062.30.014 *3402.9283.67.79<0.0001 ***
Error8030.6670.383 291436.4
Specific Leaf Area (cm2)Leaf Dry Matter Content
Region (R)413.95953.4898821.03<0.0001 ***18.8534.71331.390.2453 ns
Season (S)10.0010.000960.010.9395 ns58.18658.185617.140.0001 ***
Grazing (G)30.46440.154780.930.4289 ns14.7074.90241.440.2361 ns
R × S40.75830.189571.140.3428 ns30.127.53012.220.0743 *
R × G122.2440.1871.130.351 ns60.1515.01251.480.1504 ns
S × G30.78210.260711.570.2029 ns22.3627.4542.20.0949 *
R × S × G123.41770.284811.720.0786 *47.7633.98031.170.3168 ns
Error8013.27740.16597 271.513.398
*** p < 0.001, * p < 0.05, ns: non-significant at p < 0.05.
Table 3. Analysis of variance (factorial design) of morphological parameters in A. lagopoides of different regions grown under four levels of grazing.
Table 3. Analysis of variance (factorial design) of morphological parameters in A. lagopoides of different regions grown under four levels of grazing.
Variation SourceDFSSMSF-Valuep-ValueSSMSF-Valuep-Value
Shoot length (cm)Root length (cm)
Region (R)411,814.602953.60169.73<0.0001 ***2657.60664.4029.33<0.0001 ***
Grazing (G)32497.20832.39158.60<0.0001 ***2475.92825.3034.48<0.0001 ***
R × G12814.8067.9012.940.0001 ***1598.67133.225.57<0.0001 ***
Error40331.808.29 331.88.29
Shoot dry weight (g)Root dry weight (g)
Region (R)43443.46860.86137.98<0.0001 ***76.1019.0217.220.0005 ***
Grazing (G)31439.88479.95129.14<0.0001 ***448.99149.6650.66<0.0001 ***
R × G12731.3560.9416.40<0.0001 ***215.0817.926.07<0.0001 ***
Error40197.134.92 98.462.46
Shoot mass (g)Root mass (g)
Region (R)40.490.1244.14<0.0001 **0.48600.1244.14<0.0001 ***
Grazing (G)33.020.0811.75<0.0001 ***0.25000.0811.75<0.0001 ***
R × G1212.040.045.590.0001 ***0.47500.045.590.0001 ***
Error400.230.01 0.020.01
Leaf mass (g)Chlorophyll a (µg/gFW)
Region (R)40.100.0327.410.0001 ***141.9235.48164.10<0.0001 ***
Grazing (G)30.030.018.420.0003 ***139.1746.39160.20<0.0001 ***
R × G120.080.015.530.0001 ***557.4446.45164.92<0.0001 ***
Error400.030.01 1.030.03
Chlorophyll b (µg/g FW)Total chlorophyll (µg/g FW)
Region (R)4107.9126.97510.28<0.0001 ***493.33123.32937.94<0.0001 ***
Grazing (G)344.8914.96296.17<0.0001 ***341.79113.93866.45<0.0001 ***
R × G12227.8918.99375.85<0.0001 ***1473.08122.75933.57<0.0001 ***
Error401.960.05 5.260.13
Proline (µg/g FW)Root/shoot ratio
Region (R)4303.9275.97189.50<0.0001 ***2.180.5447.63<0.0001 ***
Grazing (G)3233.7277.90156.90<0.0001 ***1.910.6415.66<0.0001 ***
R × G12578.5648.2197.14<0.0001 ***3.400.287.00<0.0001 ***
Error401.860.05 1.370.03
*** p < 0.001, ** p < 0.01, Chl a: chlorophyll a; Chl b: chlorophyll b; Tot Chl: total chlorophyll.
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Dar, B.A.; Assaeed, A.M.; Al-Rowaily, S.L.; Al-Doss, A.A.; Habib, M.M.; Malik, J.A.; Abd-ElGawad, A.M. Effect of Simulated Grazing on Morphological Plasticity and Resource Allocation of Aeluropus lagopoides. Agronomy 2024, 14, 144. https://doi.org/10.3390/agronomy14010144

AMA Style

Dar BA, Assaeed AM, Al-Rowaily SL, Al-Doss AA, Habib MM, Malik JA, Abd-ElGawad AM. Effect of Simulated Grazing on Morphological Plasticity and Resource Allocation of Aeluropus lagopoides. Agronomy. 2024; 14(1):144. https://doi.org/10.3390/agronomy14010144

Chicago/Turabian Style

Dar, Basharat A., Abdulaziz M. Assaeed, Saud L. Al-Rowaily, Abdullah A. Al-Doss, Muhammad M. Habib, Jahangir A. Malik, and Ahmed M. Abd-ElGawad. 2024. "Effect of Simulated Grazing on Morphological Plasticity and Resource Allocation of Aeluropus lagopoides" Agronomy 14, no. 1: 144. https://doi.org/10.3390/agronomy14010144

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