Responses Of Grasses Research Articles

Post‐fire grazing by feral ungulates significantly reduces perennial grass cover in north Australian mesic savannas

AbstractSince the late 1800s, north Australian savannas have experienced a fundamental shift in grazing pressure, moving from an assemblage of native macropods to introduced ungulates. In contrast to macropods, ungulates have hard hooves, are greater in size and exhibit bulk feeding strategies, resulting in a greater impact on perennial grass cover. However, the response of perennial grasses to ungulate grazing may vary depending on rainfall, soil fertility and fire, as well as ungulate density and feeding behaviour. Interactions between grazing, drought and fire are of particular interest, as climate change is predicted to increase rainfall variability and fire frequency across northern Australia. In this study, we tested for interactions between grazing and drought, as well as fire and grazing, on two vegetation zones surrounding waterholes, through a 5 years fencing exclusion experiment. Despite drought conditions occurring over 2 years of the study, no interaction between grazing and drought was detected. This is most likely due to the relatively low ungulate density present during the study (~1 ungulate/km2). In contrast, after fire was introduced to the study sites, significantly more perennial grass cover was recorded at fenced sites relative to unfenced sites. Due to the study design the cause of change cannot be directly inferred. However, when the potential drivers are considered further (rainfall, soil properties, fire and changes in ungulate density), an interaction between grazing and fire is the most probable cause. Wetland vegetation showed a stronger response to fencing than the surrounding savanna, with this result most likely due to differences in ungulate feeding behaviour between the two vegetation zones. Our findings are important, as fire and ungulate grazing are both widespread across Australia's savannas and reduced perennial grass cover has been linked to increased cat predation on rapidly declining small, native mammal populations.

Comparative behavioral responses of grass carp (Ctenopharyngodon idella), bighead carp (Hypophthalmichthys nobilis), and silver carp (H. molitrix) to free amino acids in water.

Control and elimination of invasive fishes, like carps (Order Cypriniformes), may be possible by using chemical stimuli to congregate them for removal. To this end, we tested behavioral responses of grass (Ctenopharyngodon idella), bighead (Hypophthalmichthys nobilis), and silver carp (H. molitrix) to L-alanine, L-arginine, L-glutamic acid, and L-aspartic acid. In grass carp, the first three amino acids have been shown to be beneficial for growth, and all four produce a strong olfactory response in this species. This study used pairs of conspecific fish in a video-recorded, sound-insulated, clear acrylic, tube-shaped tank; during trials, an amino acid stimulus was delivered at one end of that tank. Changes in space use, velocity, and acceleration across all amino acids differed significantly among species. Changes in space use by grass carp indicated avoidance of only two amino acids, L-alanine and L-aspartic acid. There was no evidence for attraction to amino acids for grass or silver carp. For bighead carp, change in spatial use on exposure to amino acids indicated attraction across the four amino acids. This attraction was enhanced by lowered velocity. Our results suggested that olfactory sensitivity does not directly translate to behavioral responses. Other sensory cues, for example tactile, visual, and/or taste, may mediate the selective foraging of grass carp. Amino acids may serve as a better olfactory attractant for bighead carp compared to grass or silver carp.

Distinct morphophysiological responses of the native C4 grasses Axonopus siccus and Eragrostis polytricha to shading

Light, an important abiotic factor that shapes plant growth, is explored here in its impact on two native C4 grasses of campo rupestre, an important and unique montane ecoregion in Brazil that occurs across the biomes Cerrado, Atlantic Forest and Caatinga. Axonopus siccus and Eragrostis polytricha seedlings were subjected to two light conditions: (i) artificial shading and (ii) full sun. The evaluations included growth, nutrition, photosynthesis, leaf anatomy, and metabolism. Shading influenced most of the growth parameters of E. polytricha but left A. siccus morphology almost unchanged. The parameters of leaf anatomy, nutrient content, and chlorophyll a fluorescence exhibited consistent patterns between species. In particular, A. siccus showed higher Amax and light compensation point in shaded conditions, while E. polytricha revealed distinctive changes in carbon metabolism (soluble sugars, sucrose, and starch content), explaining its increased shade growth. These findings underscore various light stress responses in these native C4 grasses.

Evaluation of Germination and Early Seedling Growth of Different Grasses Irrigated with Treated Mine Water

Coal mining is known to have negative impacts on the environment, necessitating land rehabilitation after mining activities. Amongst the problems associated with coal mining is the accumulation of acid mine drainage characterized by large amounts of heavy metals and high acidity. The impact of these environmental problems on the ecosystem around mining areas underscores a need to devise strategies that will ensure sustainable restoration of the ecosystem integrity to ensure environmental protection. Of these, treatment of acid mine drainage using calcium sulfate dihydrate, which is subsequently used for irrigation during phytoremediation, holds great promise for restoration of open-cast mines. However, although grasses are used for rehabilitation of coal mined areas, the impacts of treated mine water on the germination, seedling emergence, and plant growth of grasses are not well known. The aim of the study was to evaluate the germination and early seedling growth responses of different forage grasses to treated mine water. Seven forage grass species were selected, with four species represented by two varieties while others were represented by one variety, totaling 11 forage grasses. For each plant entry, 100 seeds were placed in J.R. Petri’s dishes lined with Whatman No. 2 filter paper and watered with distilled and mine water to assess germination. For the seedling establishment experiment, only five species were studied, in which twenty seeds per species were sown in pots containing mine soil and irrigated using distilled and treated mine water. The final germination percentage (FGP), germination rate index (GRI), corrected germination rate index (CGRI), and T50 were determined for the germination trail and total biomass was assessed for the seedling growth trail. The highest FGP for all grasses was attained under controlled conditions, using distilled water, ranging from 38–94%. All grasses germinated when watered using treated mine water and had a FGP ranging from 20–91%. Relative to distilled water, GRI and CGRI were highest only for L. multiflorum cv AgriBoost when seeds were watered using the treated mine water. All grasses watered with treated mine water produced high biomass for the first two weeks, after which biomass production started to decline. Two grasses, Eragrostis curvula cv Ermelo and Lolium multiflorum cv Archie, showed tolerance to treated mine water irrespective of its high electrical conductivity (557 mS∙m−1). Therefore, these grasses could be used in the rehabilitation of coal-mined areas irrigated with treated mine water.

Analyzing and predicting the response of the signal grass seed crop to plant nitrogen status

Nitrogen (N) deficiency has detrimental effects on productivity and the profit of producers in areas where signal grass [Urochloa decumbens (Stapf) R.D. Webster (syn. Brachiaria decumbens Stapf.)] cv. Basilisk is grown for seed production. The objective of this paper was to clarify the effects of indicators of signal grass plant N status on seed yield (SY), SY components, yield formation, seed quality, panicle growth parameters, and remobilization of vegetative N on seed growth. Germinable pure SY, harvest index (HI), and N harvest index (NHI) were also measured. Different rates of N fertilizer application (0, 50, 100, and 150 kg ha−1) were applied after the cleaning cut to both the first crop (October - January) and the second crop (February - May) in 2010–2011 and 2011–2012, on a sandy loam soil representative of soils used for seed production in Brazil. Although the N nutrition index (NNI) increased at key developmental stages, the highest values were near to 0.85. This suggests that all crops were maintained under N-limiting conditions. In N-limited crops, a strong relationship was detected between NNI and accumulated N deficit throughout the study period with relative SY. A low NNI after the cleaning cut was found to restrict fertile tiller number (FTN), spikelets per panicle, and spikelet density m−2 measured at anthesis. In all crops, at harvest, NNI at anthesis increased germinable pure SY, FTN, number of seeds per panicle, HI, NHI, and amount of remobilized N to seeds, but not thousand seed weight (TSW), seed germination, panicle dry matter (DM) accumulation rate, and individual seed growth rate. Regression analyses suggested that the NNI, accumulated N deficit, aboveground plant biomass (AGPB), and N content were better associated with relative SY than with plant N concentration (PNC). The study shows that the NNI quantifies the intensity and duration of N deficiency in signal grass and should be considered in research studies and for application in seed production fields to improve N fertilization recommendations.

Responses in species diversity in the Hulunbuir grassland to phosphorus addition under nitrogen-limiting and non-limiting conditions.

The phenomenon of nitrogen deposition resulting in species loss in terrestrial ecosystems has been demonstrated in several experiments. Nitrogen (N) and phosphorus (P), as major nutrients required for plant growth, exhibit ecological stoichiometric coupling in many ecosystems. The increased availability of nitrogen can exacerbate the ecological effects of phosphorus. To reveal the ecological effects of phosphorus under nitrogen-limiting and non-limiting conditions, we conducted a controlled N-P interaction experiment over 5 years in the Hulunbuir meadow steppe, where two nitrogen addition levels were implemented: 0g N·m-2·a-1 (nitrogen-limiting condition) and 10g N·m-2·a-1 (nitrogen-non-limiting condition), together with six levels of phosphorus addition (0, 2, 4, 6, 8, and 10g P·m-2·a-1). The results showed that nitrogen addition (under nitrogen-non-limiting conditions) significantly decreased species diversity in the steppe community, which was exacerbated under phosphorus addition. Under nitrogen-limiting conditions, phosphorus addition had no marked impact on species diversity compared to the control; however, there were substantial differences between different levels of phosphorus addition, exhibiting a unimodal change. Under both experimental nitrogen conditions, the addition of 6g P·m-2·a-1 was the threshold for affecting the community species diversity. Nitrogen addition reduced the relative biomass of legumes, bunch grasses, and forbs, but substantially increased the relative biomass of rhizomatous grasses. In contrast, phosphorus addition only markedly affected the relative biomass of forbs and rhizomatous grasses, with the former showing a unimodal pattern of first increasing and then decreasing with increasing phosphorus addition level, and the latter exhibiting the opposite pattern. The different responses of rhizomatous grasses and other functional groups to nitrogen and phosphorus addition were observed to have a regulatory effect on the changes in grassland community structure. Phosphorus addition may increase the risk of nitrogen deposition-induced species loss. Both nitrogen and phosphorus addition lead to soil acidification and an increase in the dominance of the already-dominant species, and the consequent species loss in the forb functional group represents the main mechanism for the reduction in community species diversity.

Comparative transcriptome analyses reveal regulatory network and hub genes of aluminum response in roots of elephant grass (Cenchrus purpureus)

Aluminum (Al) toxicity severely restricts the growth and productivity of elephant grass in acidic soils around the world. However, the molecular mechanisms of Al response have not been investigated in elephant grass. In this study, we conducted phenotype, physiology, and transcriptome analysis of elephant grass roots in response to Al stress. Phenotypic analysis revealed that a low concentration of Al stress improved root growth while higher Al concentrations inhibit root growth. Al stress significantly increased the citrate (CA) content in roots, while the expression levels of genes related to citrate synthesis were substantially changed. The multidrug and toxic compound extrusion (MATE) family were identified as hub genes in the co-expression network of Al response in elephant grass roots. Phylogenetic analysis showed that hub genes CpMATE93 and CpMATE158 belonged to the same clade as other MATE genes reported to be involved in citrate transport. Additionally, overexpression of CpMATE93 conferred Al resistance in yeast cells. These results provide a theoretical basis for further studies of molecular mechanisms in the elephant grass response to Al stress and could help breeders develop elite cultivars with Al tolerance.

Insights on phytoremediation of chromium from tannery wastewater contaminated soil

The study was conducted to evaluate the phytoremediation response of Arundo donax and vetiver grasses irrigated by different levels (0%, 10%, 25%, 50%, 75%, and 100%) of treated tannery wastewater. After 60 days, matured plants were harvested, sorted into root, leaf, stem and shoot, dried and digested using standard procedures and analyzed for Cr(VI) and total Cr using atomic absorption and UV-Visible spectrophotometer, respectively. Corresponding results revealed height growth of Arundo donax and vetiver grasses was greatly affected by the irrigation level of tannery wastewater. Roots of vetiver grasses accumulate the highest amount of Cr(VI) (2.76 mg/kg) compared to the shoots Cr(VI) 1.72 mg/kg. Lowering concentration of tannery wastewater used for irrigation to 10% boosted the accumulation capacity (3.99 mg/kg) of the root of Arundo donax grasses for Cr(VI). The translocation values (TF > 1) demonstrated favourability of Arundo donax grasses for phytoextraction of Cr(VI) to plant tissues above ground level. However, the bioaccumulation values (BAF > 1) of the root of vetiver grasses proved suitability for the phytostabilisation of Cr(VI). Arundo donax and vetiver grasses have demonstrated a substantial reduction in Cr contamination of soils from tanneries, and therefore, phytoremediation is potentially feasible for the decontamination of Cr-polluted environments.

Neighbour effects on plant biomass and its allocation for forbs growing in heterogeneous soils

Abstract Focal plants are considerably affected by their neighbouring plants, especially when growing in heterogeneous soils. A previous study on grasses demonstrated that soil heterogeneity and species composition affected plant biomass and above- and belowground allocation patterns. We now tested whether these findings were similar for forbs. Three forb species (i.e. Spartina anglica, Limonium bicolor and Suaeda glauca) were grown in pots with three levels of soil heterogeneity, created by alternatively filling resource-rich and resource-poor substrates using small, medium or large patch sizes. Species compositions were created by growing these forbs either in monocultures or in mixtures. Results showed that patch size × species composition significantly impacted shoot biomass, root biomass and total biomass of forbs at different scales. Specifically, at the pot scale, shoot biomass, root biomass and total biomass increased with increasing patch size. At the substrate scale, shoot biomass and total biomass were higher at the large patch size than at the medium patch size, both in resource-rich and resource-poor substrates. Finally, at the community scale, monocultures had more shoot biomass, root biomass and total biomass than those in the two- or three-species mixtures. These results differ from earlier findings on the responses of grasses, where shoot biomass and total biomass decreased with patch size, and more shoot biomass and total biomass were found in resource-rich than resource-poor substrates. To further elucidate the effects of soil heterogeneity on the interactions between neighbour plants, we advise to conduct longer-term experiments featuring a variety of functional groups.

Genetic response of a perennial grass to warm and wet environments interacts and is associated with trait means as well as plasticity.

Potential for rapid evolution is an important mechanism allowing species to adapt to changing climatic conditions. Although such a potential has been largely studied in various short-lived organisms, to what extent we can observe similar patterns in long-lived plant species, which often dominate natural systems, is largely unexplored. We explored potential for rapid evolution in Festuca rubra, long-lived grass with extensive clonal growth dominating in alpine grasslands. We used field sowing experiment simulating expected climate change in our model region. Specifically, we exposed seeds from 5 independent seed sources to novel climatic conditions by shifting them along a natural climatic grid and explored genetic profiles of established seedling after 3 years. Data on genetic profiles of plants selected under different novel conditions indicate that different climate shifts select significantly different pools of genotypes from common seed pools. Increasing soil moisture was more important selective pressure than increasing temperature or interaction of the two climatic factors. This can indicate negative genetic interaction in response to the combined effects, or that the effects of different climates are interactive rather than additive. The selected alleles were found in genomic regions likely affecting function of specific genes or their expression. Many of these were also linked to morphological traits (mainly to trait plasticity) suggesting these changes may have a consequence for plant performance. Overall, these data indicate that even long-lived plant species may experience strong selection by climate, and their populations thus have the potential to rapidly adapt to these novel conditions.

Growth response of vetiver grass (Chrysopogon zizanioides (L.) Roberty) to chemical amendments in assisted phytoremediation of contaminated mined soil

Growth response of vetiver grass (Chrysopogon zizanioides (L.) Roberty) to chemical amendments in assisted phytoremediation of contaminated mined soil

Phenotypic plasticity variations in Phragmites australis under different plant–plant interactions influenced by salinity

Abstract Coastal wetland ecosystems are increasingly threatened by escalating salinity levels, subjecting plants to salinity stress coupled with interactions in the community. Abiotic factors can disrupt the balance between competition and facilitation among plant species. Investigating the effects of different neighboring species and trait plasticity could extend the stress gradient hypothesis and enhance understanding of vegetation distribution and diversity in salt marshes. We conducted a greenhouse experiment and investigated the plastic response of wetland grass Phragmites australis to seven neighboring plants of three functional types (conspecifics, graminoids and forbs) under soil salinity (0 and 10 g/L). Plant height, base diameter, density, leaf thickness, specific leaf area and total and part biomasses were measured. Additionally, the relative interaction index (based on biomass) and the relative distance plasticity index (RDPI) were calculated. Salinity significantly reduced the biomass, height, density and diameter of P. australis. The functional types of neighboring plants also significantly affected these growth parameters. The influence of graminoids on P. australis was negative under 0 g/L, but this negative effect shifted to positive facilitation under 10 g/L. The facilitation effect of forbs was amplified under salinity, both supporting the stress gradient hypothesis. The growth traits of P. australis had a plastic response to salinity and competition, such as increasing belowground biomass to obtain more water and resources. The RDPI was higher under salt conditions than in competitive conditions. The plant–plant interaction response to stress varies with plant functional types and trait plasticity.

Оценка эффективности смесей фестулолиума с люцерной в лесостепи Приобья (Западная Сибирь)

The results of the research of festulolium and alfalfa in a joint herbage with different methods of sowing and doses of mineral nitrogen conducted in the forest-steppe of Western Siberia in the period from 2020–2023 are presented. The growth and development of crops in the initial period of life, winter hardiness, productivity and economic feasibility of cultivation were taken into account both in favorable 2019–2021 (HTC = 1.0...1.29) and in unfavorable 2022–2023 (HTC = 0.6...0.99). A high response of perennial grasses was achieved in sowing festulolium one row + alfalfa three rows — 38.13 t/ha of green mass, which corresponds to a single-species alfalfa crop. Sowing with a mixture of seeds is 21% less productive. A positive effect was obtained from optimizing the level of cenosis and foliage of alfalfa by 56%, which was confirmed by an average correlation (r = 0.58). The energy efficiency coefficient (CEE) had maximum values of 9.8–11.7 and was characterized as high, the profitability of cultivating mixtures was 407–465%. A positive effect was obtained when N30 was introduced into the sowing of festulolium one row + alfalfa three rows — 21–36% to 37.41 t/ha of green mass. In comparison with the unfavorable background, the share of festulolium in the yield of mixtures increased to 58–71%, alfalfa decreased to 29–42%. CEE = 4.9–5.6 (the value is from medium to high), the profitability of cultivating mixtures is 325–378%. The application of mineral nitrogen N60 to joint crops of festulolium and alfalfa increases the collection of green mass compared with single-species sowing of festulolium by 10–20%, to 34.74–37.93 t/ha of green mass due to the maximum proportion of cereals in mixtures — 62–80% with its responsiveness to fertilization. CEE = 4.5–4.9 (average value), the profitability of cultivating mixtures is 323–365%.

Physiological Responses of C4 Perennial Bioenergy Grasses to Climate Change: Causes, Consequences, and Constraints.

C4 perennial bioenergy grasses are an economically and ecologically important group whose responses to climate change will be important to the future bioeconomy. These grasses are highly productive and frequently possess large geographic ranges and broad environmental tolerances, which may contribute to the evolution of ecotypes that differ in physiological acclimation capacity and the evolution of distinct functional strategies. C4 perennial bioenergy grasses are predicted to thrive under climate change-C4 photosynthesis likely evolved to enhance photosynthetic efficiency under stressful conditions of low [CO2], high temperature, and drought-although few studies have examined how these species will respond to combined stresses or to extremes of temperature and precipitation. Important targets for C4 perennial bioenergy production in a changing world, such as sustainability and resilience, can benefit from combining knowledge of C4 physiology with recent advances in crop improvement, especially genomic selection.

Nitrogen rather than water availability limits aboveground primary productivity in an arid ecosystem: Substantial differences between grasses and shrubs

AbstractChanges in water and nitrogen availability can affect the structure and function of arid ecosystems. How these resources affect aboveground primary productivity (ANPP) remains far from clear. We examined the N and water limitation of ANPP from the species to the community level and the response of ANPP to annual precipitation in a Patagonian steppe. We conducted a 7‐year field experiment with water addition (+W), nitrogen addition (+N) and +NW. Destructive methods for grasses and allometric relationships for shrubs were used to assess ANPP and vegetation indices (NDVI and MSAVI2) to estimate community ANPP. An increase in ANPP of one grass species (Papposstipa humilis) and a decrease of the grass Poa ligularis under +N were observed. Some shrub species exhibited mortality under nitrogen addition. Nitrogen exerted a positive effect on grass ANPP and amplified the sensitivity of grass ANPP to annual precipitation. However, +N had not effects on the shrub ANPP and shrub ANPP‐precipitation relationship. Water addition by itself had no effect on ANPP for either shrubs or grasses. However, shrubs responded positively to an unusually wet year regardless of treatment and were also more sensitive to changes in annual precipitation than grasses. Total ANPP increased significantly in +N relative to the C and +W but without changes in the sensitivity to annual precipitation. The results suggest that the responses of grasses and shrubs to water inputs are driven by soil moisture redistribution and rooting depth and that grass and community ANPP are more limited by N than by water.

Nutritional, Physiological, and Enzymatic Responses of Native Grasses from the Pampa Biome Cultivated Under Excess Zinc

Nutritional, Physiological, and Enzymatic Responses of Native Grasses from the Pampa Biome Cultivated Under Excess Zinc

Will trees or grasses profit from changing rainfall regimes in savannas?

Increasing rainfall variability is widely expected under future climate change scenarios. How will savanna trees and grasses be affected by growing season dry spells and altered seasonality and how tightly coupled are tree-grass phenologies with rainfall? We measured tree and grass responses to growing season dry spells and dry season rainfall. We also tested whether the phenologies of 17 deciduous woody species and the Soil Adjusted Vegetation Index of grasses were related to rainfall between 2019 and 2023. Tree and grass growth was significantly reduced during growing season dry spells. Tree growth was strongly related to growing season soil water potentials and limited to the wet season. Grasses can rapidly recover after growing season dry spells and grass evapotranspiration was significantly related to soil water potentials in both the wet and dry seasons. Tree leaf flushing commenced before the rainfall onset date with little subsequent leaf flushing. Grasses grew when moisture became available regardless of season. Our findings suggest that increased dry spell length and frequency in the growing season may slow down tree growth in some savannas, which together with longer growing seasons may allow grasses an advantage over C3 plants that are advantaged by rising CO2 levels.

Water productivity and growth parameters of Fawn-tall fescue and Tekapo-orchard grass under deficit irrigation in arid zones.

This study aimed to determine the drought stress response of Fawn-tall fescue and Tekapo-orchard grass and investigate a drought stress resistance marker. Grass genotypes were grown under four Irrigation treatments I1 equivalent to 0.3 standard crop evapotranspiration (ETc), I2 equivalent to 0.65 ETc, I3 equivalent to 0.75 ETc, and I4 equivalent to 1.2 ETc. Plant height, fresh weight, dry weight were measured and the Water productivity (WP) were calculated. The results showed a reduction in the growth of both grass genotypes as the drought stress increased as indicated by the shorter plants and reduction in fresh and dry weight. However, the WP results showed that the Fawn-tall fescue endured the drought stress better than the Tekapo-orchard grass as indicated by the constant values of the plant WP across the tested irrigation treatments. The results was confirmed by the amplification of dehydrin genes where Fawn-tall fescue was found to be homozygous for dehydrin genes.

A highly sensitive and flexible capacitive pressure sensor based on an ionic hydrogel dielectric layer with a lateral-bending microstructure

The lateral-bending microstructure was inspired by the deformation response of grass under pressure, which exhibits localized deformation under slight compressive loads.

BRS Paiaguás e BRS Piatã: potencial para uso sob irrigação em ambiente semiárido

ABSTRACT This work aimed to evaluate the physiological parameters, the biomass flow, and the productive characteristics of the grasses BRS Piatã and BRS Paiaguás at different levels of water supply in the semi-arid region. The experiment was carried out in the dry season, in Sobral, Ceará State, Brazil. The following irrigation depths were used: 30, 60, 90, and 120% of ETo. The experiment was carried out in pots with a capacity of 7.5 dm3 at field level, using a 0-0.2m layer of argisol soil as substrate. As a result, the photosynthetic rate was not affected in the largest water treatments. In the biomass flow, the responses of grasses to treatments 90 and 120% of ETo were similar for the variables number of live leaves and phyllochron. Regarding the productive characteristics, pseudo-culm biomass was effective only in the treatment of 120% of ETo, while, for the efficiency of water use, in treatments 60 and 90% of ETo, the difference was effective. In conclusion, in the treatments of 60 and 90% of the ETo, it was possible to maintain good morphological characteristics of the grasses and to increase the biomass production during the dry season in the semi-arid region.