Reproductive height determines the loss of clonal grasses with nitrogen enrichment in a temperate grassland

Tall clonal grasses commonly display competitive advantages with nitrogen(N)enrichment.However,it is currently unknown whether the height is derived from the vegetative or reproductive module.Moreover,it is unclear whether the height of the vegetative or reproductive system regulates the probability of extinction and colonization,and determines species diversity.In this study,the impacts on clonal grasses were studied in a field experiment employing two frequencies(twice a year vs.monthly)crossing with nine N addition rates in a temperate grassland,China.We found that the N addition decreased species frequency and increased extinction probability,but did not change the species colonization probability.A low frequency of N addition decreased species frequency and colonization probability,but increased extinction probability.Moreover,we found that species reproductive height was the best index to predict the extinction probability of clonal grasses in N-enriched conditions.The low frequency of N addition may overestimate the negative effect from N deposition on clonal grass diversity,suggesting that a higher frequency of N addition is more suitable in assessing the ecological effects of N deposition.Overall,this study illustrates that reproductive height was associated with the clonal species extinction probability under N-enriched environment.

Sporting Usefulness Potential of Nine Local Taxa of Grasses for Lawns in the Agro-Ecological Zone with Bimodal Rainfall in Cameroon

The Cameroonian flora has a very high biodiversity that remains largely unexplored. It contains many grasses that can be used for sports lawns, but are currently underutilized. In order to contribute to the improvement of the quality of sports lawns, nine local grass taxa from the agro-ecological zone with bimodal rainfall in Cameroon were evaluated for their potential for sporting use in natural lawns. The method of the Study and Control Group for Varieties and Seeds was used to evaluate the sports lawn characteristics of the taxa. The resistance to trampling and pulling, the density of the lawn, and the aesthetic appearance, which are factors in calculating the sports index, were monitored at two sites, including the experimental space at the University of Yaounde 1 in the Center region and Kagnol 2 in the East region, from January 2017 to January 2020. The monthly lawn characteristic data allowed for the differentiation between the means and the determination of the sports index of the taxa compared to commercialized lawn varieties. The sports index of the evaluated taxa varied: Cynodon dactylon (6.989), Eleusine indica (6.338), Sporobolus natalensis (6.301), Cynodon cf Cynodon dactylon (6.257), Eragrostis tremula (5.939), Sporobolus pyramidalis (5.583), Agrostis rupestris (5.335), Axonopus compressus (4.991), and Digitaria sp. (4.544). These results show that these grass taxa have potential for sporting use in lawn mixtures at different levels of sports disciplines.

Plant growth and soil microbial community structure of legumes and grasses grown in monoculture or mixture

A greenhouse pot experiment was conducted to investigate the in?uence of soil moisture content on plant growth and the rhizosphere microbial community structure of four plant species (white clover, alfalfa, sudan grass, tall fescue), grown individually or in a mixture. The soil moisture content was adjusted to 55% or 80% water holding capacity (WHC). The results indicated that the total plant biomass of one pot was lower at 55% WHC. At a given soil moisture, the total plant biomass of white clover and tall ...

Isolation and Identification of Bacterial Endophytes from Grasses along the Oregon Coast

Bacterial endophytes have been shown to improve abiotic and biotic stress responses in plants. Plants growing under harsh conditions along the Oregon Coast could contain bacterial endophytes that improve persistence and growth of grasses in this environment. Thirty-four plants consisting of eight different species were collected along the Oregon coast from four different sites. Bacterial endophytes were isolated from root crown, stem and leaf tissues. A portion of the 16S rRNA ITS regions of each isolate was amplified, sequenced, and used to perform a BLAST search against the nucleotide database collection at National Center for Biotechnology Information. One-hundred and thirty-three different bacterial isolates, ninety-four of which were unique, representing thirty-six different taxonomic groups were found. Over 50% of the total bacteria isolates were in just five taxonomic groups. Pseudomonads were the most predominant bacteria isolated, making up 20.3% of the total isolates, followed by Curtobacterium and Microbacterium, each at 8.2%, Bacillus at 7.5% and Xanthomomas at 6%. Forty-seven percent (17 of 36) of the taxonomic groups contained only a single isolate. Fourteen bacterial isolates from five taxonomic groups, nine of which were from the genus Pseudomonas, were found to have 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, an enzyme associated with improving plant growth under stress. These newly discovered bacterial endophytes will be a valuable biological resource to develop approaches to increase the yield and adaptability of grasses and other crops grown in diverse environments and to meet the challenges associated with an unpredictable climate.

Root proliferation in native perennial grasses of arid Patagonia,Argentina

Pappophorum vaginatum is the most abundant C4 perennial grass desirable to livestock in rangelands of northeastern Patagonia, Argentina. We hypothesized that （1） defoliation reduce net primary productivity, and root length density and weight in the native species, and （2） root net primary productivity, and root length density and weight, are greater in P. vaginatum than in the other, less desirable, native species （i.e., Aristida spegazzinfi, A. subulata and Sporobolus cryptandrus）. Plants of all species were either exposed or not to a severe defoliation twice a year during two growing seasons. Root proliferation was measured using the cylinder method. Cylindrical, iron structures, wrapped up using nylon mesh, were buried diagonally from the periphery to the center on individual plants. These structures, initially filled with soil without any organic residue, were dug up from the soil on 25 April 2008, after two successive defoliations in mid-spring 2007. During the second growing season （2008-2009）, cylinders were destructively harvested on 4 April 2009, after one or two defoliations in mid- and/or late-spring, respectively. Roots grown into the cylinders were obtained after washing the soil manually. Defoliation during two successive years did reduce the study variables only after plants of all species were defoliated twice, which supported the first hypothesis. The greater root net primary productivity, root length den- sity and weight in P. vaginatum than in the other native species, in support of the second hypothesis, could help to explain its greater abundance in rangelands of Argentina.

Soil Depth and Changes in Dry Mass and Competitive Intensity of Two C₄Grasses

The presence of grassland biomes and species cannot be predicted by examining bottom up causes such as precipitation and temperature. Top down causes including herbivory and fire seem to be major controlling aspects with other factors secondary. We examined soil depth and competitive ability of two North American C4 grasses in a greenhouse experiment. Changes in dry mass were determined and competitive intensity was calculated for both species. Species were grown separately or together in pots 30, 90, or 180 cm deep. When grown in monoculture, Schizachyrium scoparium total and belowground dry mass increased from the 30 to 90 cm depth, with no further significant increase from 90 to 180 cm. Aboveground dry mass did not increase significantly with depth. Total dry mass of Buchloe dactyloides increased significantly with depth when grown in monoculture. Aboveground dry mass increased from 30 to 90 cm depth but not from 90 to 180 cm. Belowground dry mass of B. dactyloides did not increase significantly with depth. In 180 cm pots, 53% of S. scoparium root dry mass was in the top 30 cm;74% of B. dactyloides root dry mass was in the top 30 cm. Roots of B. dactyloides were not found deeper than 90 cm. Aboveground dry mass of S. scoparium was not different in mixture or monoculture at any depth. Buchloe dactyloides aboveground dry mass in mixture was significantly lower than monoculture at the 30 cm depth, but not at 90 or 180 cm. The greatest competitive intensity was in the shallow soil pots. Soil depth could partially explain mosaics found in C4 grasslands where both species were found together with S. scoparium on deeper soils and B. dactyloides on shallower soils.

Effects of Rooting Agents on Growth and Photosynthetic Traits of Sudan Grasses

[Objective] To investigate the effects of rooting agents on the growth and photosynthetic traits of Sudan grasses. [ Method] The responses of the growth and some photosynthetic traits of Sudan grasses to three NK II rooting agents were determined according to the randomized complete block design. [ Result] Compared to control treatment, the Sudan grass treated by NK 11-298 showed higher chlorophyll a and carotenoid contents, higher chlorophyll fluorescence parameter values （ PSII quantum efficiency： ФPSII; photochemical quenching： qP; and electron transport rate： ETR）, higher maximum photosynthetic rate （Pmax） and respiration rate （ Rd）, and the highest biomass accumulation. The chlorophyU fluorescence parameter values of Sudan grasses treated by NK 11-888 and NK 11-16 were higher than those of control treatment （ P 〈 0.05）, and other indexes had no significant difference. [ Conclusion] The rooting agents should be selected carefully according to their practice aims because of sensibility of Sudan grass to rooting agents.

Ornamental Grasses in Kew Gardens

Definition and ornamental characteristics of ornamental grasses,as well as a general background of Kew Gardens were introduced,with an emphasis of species and landscaping modes of ornamental grasses in Kew Gardens.

Observations of Spring Hard Freeze Injury to C₄Perennial Grasses Native to the Great Plains, USA

The native prairies of the Great Plains USA are dominated by perennial C4 grasses like switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii). Spring hard freeze injury to C4 perennial grasses is rare but information is lacking in the literature. Our objective was to document effects of spring hard freeze damage to C4 perennial grasses native to the Great Plains USA. On 2 May at 24:00 pm, air temperature near Mead, Nebraska was below freezing and remained below freezing until 8:00 am on 3 May, with a minimum air temperature of -2.8°C. Based on 50-year of weather data for this site, a minimum threshold temperature of 0°C on or after 3 May occurred 16 times, but a minimum threshold temperature of -2.8°C on or after 3 May occurred only twice. Grass tillers were visually evaluated to determine extent of freeze damage. The terminal 3- to 5-cm of the leaf lamina was blackened 4-d after freezing and had complete browning, rolling, and desiccation 14-d after freezing. Tiller survival was not negatively affected by the freezing temperatures in May 2004. As the growing season progressed, all agronomic and livestock responses were within normal ranges for these C4 grasses. This is the first field report of multiple C4 prairie grass species responses to a spring hard freeze following significant spring growth. Plant recovery to this late-spring hard freeze demonstrates the ecological resilience of these C4 prairie grasses. These rare spring hard freezes had short-term impacts on C4 grasses but did not negatively impact agronomic performance for forage or bioenergy later in the growing season.

Cattle-Breeding Valley Plains and C4 Spontaneous Grasses in North Patagonia

The climate of North Patagonia (Argentina) is semiarid and the region periodically suffers severe droughts that may lastseveral years, decreasing forage offer and consequently cow livestock and productivity. In most of the cattle fields extensive grazing isusually continuous through the year-long. The absence of pasture rotational schemata affects rangeland health changing thecomposition of plants communities in detriment of the valuable species. When under a severe drought, the appreciated forageLeptochloa crinita (= Trichloris crinita) stopped reproduction and the population became scarce, a grazing schedule was designed in acattle farm to avoid foraging during spring and summer in a paddock located in the valley plains, where the species was disappearing.Besides L. crinita populations, the sympatric presence of the Poaceae Aristida mendocina, Distichlis spicata and Distichlis scoparia isexpected, each one in slightly different patches within the same area. The forage value differs between species but all of them are eatenby bovines. For ten years the plant communities were studied with the aims of determining the incidence of the patches on the paddockcarrying capacity in early autumn and estimating the contribution of the four C4 species to bovine diet by microhistology. Free ofgrazing during its growing period, L. crinite enhanced the area of its patches and the biomass production of its good quality forage andwas consumed preferently. A. mendocina is not prized by cattle but contributed to the diet at the end of the foraging period. Distichlisspp. is important component of the cows’ diet, especially in dry years. Management actions to preserve a valuable species may haveside effects involving other community members.

Ecological Study of Two Grasses: <i>Cenchrus ciliaris</i>and <i>Digitaria commutate</i>Endangered Autochthonous of the Dry Zone of Tunisia

The Saharian ecosystems present an important intensity of rising sensitization to: Erosion, and desertification whose impacts are irreversible. On the one hand, the weakness of the yield and the poverty of soil lead to a limited biodiversity. In addition to these difficulties, hydra is the main cause of the rarification of certain pastoral species such as Cenchrus ciliaris and Digitaria commutata. The ecological study underlines a distribution of these species which are very dependent on water resources in the dry regions of Tunisia. The bioclimatic (temperature, pluviometry) variations lead to modifications to these species from one area to another which are translated through several parameters. Concerning the number of bundles, the difference is important. The national park of Bouhedma records the highest number, compared with Bni khdach, Jerba, Khanguit aicha and Matmata respectively. The variation inter-site of study also is considerable by the study of the morphological parameters (height, number and length of leaves by bundle, number of ear) whose bundles of the national park Bouhedma occupy the first class.

Prediction of the Distribution of Perennial Cultivated Grasses in the Northwest Sichuan Plateau, China under Climate Change

In order to determine the threshold and potential distribution of climatic conditions for perennial cultivated grasses in the Northwest plateau of Sichuan, China, the niche model is used to simulate the main climatic factors affecting the distribution of perennial cultivated grasses, and to predict the current and future climate change prospects. The results show that: 1) Wet index, accumulated temperature, isothermal, and annual average temperature range are the four major climatic factors affecting the distribution of perennial cultivated grasses in the Northwest Sichuan Plateau. 2) Model training and prediction data can be achieved well under the appropriate range of major climatic factors. 3) Under the background of climate warming, from now to 2080, the potential distribution of perennial cultivated grasses in the Northwest plateau of Sichuan, China will increase. The study aims to provide scientific decision-making basis for maintaining grassland ecosystem stability and promoting desertification management and even industrial restructuring of agriculture and animal husbandry.

Application Research of Water-saving and Drought-resistant Landscape Plants:A Case Study of Inner Mongolia Drought-resistant Mongolian Grasses

Construction of "water-saving landscape architecture" is a crucial content of building "conservation-minded society'',an important approach of ensuring the sustainable development of landscaping industry.It targets at exploring a reasonable means of using the nature,so as to improve ecological conditions and environment,save resources and energies,and promote the harmonious coexistence of man and nature.Landscape plant is a significant component of landscape architecture,it is a key section to choose proper drought-resistant plant species for the landscape construction.

Soil compaction and arbuscular mycorrhizae affect seedling growth of three grasses

Soil compaction is a limitation to establishment of native forest species on reclaimed surfacemined lands in Appalachia. Previously, non-native forage species such as tall fescue (Schedonorus arundinaceus(Schreb.) Dumort., nom. cons.) have been planted because they easily established on reclaimed mine soil. There is now interest in establishing robust native prairie species to enhance biodiversity and provide greater potential for root activity in the compacted soil. We conducted a 10-week glasshouse study comparing growth of “Pete” eastern gamagrass (Tripsacum dactyloidesL.), “Bison” big bluestem (Andropogon gerardiiVitman), and “Jesup MaxQ” tall fescue at soil bulk densities (BD) of 1.0, 1.3, and 1.5 g·cm-3. We also examined effects of arbuscular-mycorrhizal fungi (AMF) on plant growthin relation to compaction. Sources of AMF were a reclaimed surface coal mine soil and a native tallgrass prairie soil. Shoot and root biomass of tall fescue and big bluestem were reduced at 1.5 BD while eastern gamagrass growth was not affected. Growth ofbig bluestem and eastern gamagrass was greaterwith AMF than without, butsimilar between AMF sources. Tall fescue growthwas not enhanced by AMF. Overall, tall fescue biomass was 3 times greater than eastern gamagrass and 6 times greater than big bluestem when comparing only AMF-colonized grasses. Eastern gamagrass and big bluestem are both slower to establish than tall fescue. Eastern gamagrass appears to be more tolerant of compaction, while big bluestem appears somewhat less tolerant.

Epichloë − a lifeline for temperate grasses under combined drought and insect pressure

Fungal Epichloëendophytes form symbiotic associations with many temperate grasses,such as Lolium and Festuca,giving their host grasses an ecological advantage.The importance of specific Epichloëendophytes in providing varying levels of protection against invertebrate pests has been well documented.Similarly,but with fewer studies,the benefits of Epichloëto host grasses in drought events has been shown.Endophyte-infected grasses show an improved persistence against herbivore insect attack as well as resilience under drought.However,there are relatively few studies that investigate the interaction between drought and insect pressure,and yet it is these combined pressures that can prove detrimental for a ryegrass or fescue crop.This review examines the current state of knowledge on the effects of Epichloëon the interactions of insects and drought in temperate grasses.

Effects of inclusion of purple prairie clover (Dalea purpurea Vent.)with native coolseason grasses on in vitro fermentation and in situ digestibility of mixed forages

Background:Incorporation of legume species into native North American pastures is considered an effective method to increase native pasture productivity and improve the nutritive value of forage.This study evaluated the effects of inclusion of purple prairie clover(PPC,Dalea purpurea Vent.),a native legume forage,with native coolseason grasses on the in vitro fermentation and in situ digestibility of mixed forages.Methods:Whole plant PPC and mixtures of cool-season grasses were harvested when the PPC reached the vegetative(VEG),full flower(FL)and seedpod(SP)stages,and were combined in ratios(DM basis)of 0:100,25:75,50:50,75:25 and 100:0 at each maturity.In vitro ruminal incubations using these mixtures were conducted for 48 h to determine gas production(GP),in vitro DM disappearance(IVDMD),total volatile fatty acids(VFA)and ammonia-N production.Mixtures of forages harvested when the PPC reached the FL stage and 50:50 mixture of forages harvested at VEG,FL and SP stages were incubated in the rumen of three heifers for 0,2,6,12,24,48,72 and 96 h to determine in situ degradabilities of DM,neutral detergent fibre(aNDF)and crude protein(CP).Results:Contents of aNDF and ADF increased(P<0.01),while CP decreased(P<0.001)as PPC matured.Concentrations of extractable condensed tannins in PPC ranked as FL>VEG>SP(P<0.05).Regardless of PPC proportions in the mixture,GP decreased(P<0.05)with increasing PPC maturity.Increasing PPC proportions linearly increased(P<0.001)GP,IVDMD and total VFA at VEG,but linearly decreased(P<0.001)them at SP.Irrespective of PPC maturity,ammonia-N production linearly increased(P<0.01)with increasing proportions of PPC and the concentration was higher(P<0.05)at VEG than at FL and SP stages.Increasing proportion of PPC at either maturity linearly increased(P<0.001)molar percentage of acetate(A)and branched-chain VFA,but linearly decreased(P<0.001)molar percentage of propionate(P),resulting in a linearly increase(P<0.001)in the A:P ratio.Increasing FL PPC in the mixture linearly and quadratically(P<0.01)increased a(soluble fraction),but linearly and quadratically decreased(P<0.01)b(potentially degradable fraction)for DM and aNDF,resulting in linear(P<0.05)and quadratic(P<0.01)increases in DM and aNDF maximum potential degradabilities(a+b).Effective degradabilities of DM and aNDF were also linearly and quadratically increased(P<0.05),and CP was quadratically increased(P<0.05)with increasing FL PPC,with the greatest effective degradability being observed with ratios between 50:50 and 75:25.Ruminal maximum potential degradabilities of DM and aNDF decreased(P<0.001)as the forage matured.Effective degradability of DM ranked as VEG>FL>SP(P<0.001),whereas the effective degradability of aNDF was similar between VEG and FL and both were greater(P<0.01)than SP.Conclusions:Inclusion of vegetative PPC in a mixed forage diet resulted in the greatest digestibility and incorporation of PPC before seedpod stage with native grasses had a positive effect on ruminal fermentation.Effects of PPC on ruminal digestion depend on both the stage of maturity and its proportion in mixed legume-grass pastures.Pastures containing 50%of PPC in full flower stage would likely provide the greatest quality diet to grazing ruminants subject to potential animal selectivity.

Isolation and Identification of Fungal Endophytes from Grasses along the Oregon Coast

Fungal endophytes have been shown to improve abiotic and biotic stress response in plants. Grasses growing along the Oregon coast are exposed to harsh conditions and may harbor endophytes that enable them to survive and grow under these conditions. Endophytic fungi were isolated from thirty-four grass plants representing eight different grass species at four different locations along the Oregon coast. The ITS-1, 5.8S, and ITS-2 regions of each isolate were amplified, sequenced, and used to perform a BLAST search against the nucleotide database collection at National Center for Biotechnology Information. One-hundred-eleven different fungal isolates were classified into thirtynine genera with two isolates that did not show a match greater than 95%. These endophytes will be investigated to determine their potential for improving the adaptability of grasses and other crop plants to grow in diverse environments where they are subjected to multiple biotic and abiotic stresses.

Early Forage Biomass and Sward Structures of Native Warm-Season Grasses Established at Different Seedling Densities

Effects of transplanted seedling density and species on sward structure of native warm-season grass (NWSG) stands were compared in a randomized complete block design. About 6-week-old NWSG (big bluestem (BB, Andropogon gerardii Vitman), eastern gamagrass (GG, Tripsacum dactyloides L.), indiangrass [IG, Sorghastrum nutans (L.) Nash] and switchgrass (SG, Panicum virgatum) seedlings were transplanted in 45-cm wide rows on clean-tilled seedbeds. Within-row spacing was 30, 25, or, 20 cm giving 10, 12, and 15 plants m-2 as low, medium, and high seedling density, respectively. During establishment, the stands were allowed uninterrupted first year growth without fertilizers or irrigation but when necessary, tall-growing broadleaf weeds were mechanically removed. In the following spring, all dead standing biomass was mowed down to allow emerging tillers access to sunlight. During the second year after planting, early-spring basal diameters, row-length intercepted by the NWSG crowns, mid-summer sward heights, and percentage bare ground were determined. From the second June after planting, and for two consecutive years, plots were harvested twice year-1 to assess forage biomass. Data showed that, unlike species, seedling density had no effect on the assessed parameters. Cumulative forage biomass, in kg DM ha-1, was the least for GG (4901) at low and the most (18,245) for SG at high seedling density during the second year. Corresponding values for the third year were 4500 and 7799 kg DM ha-1. Basal diameters ranged from 18 cm (BB) to 24 cm (IG) while percent row intercepts were from 6 (GG) to 46 (IG) with sward heights measuring 41 cm (IG) to 54 cm (GG). In each stand, percent ground cover by the NWSGs, and at every seedling density, averaged 60.5. Transplanting at ≥10 plant m-2 resulted in harvest-ready stands by the second year of establishment. And while close spacing favored the NWSGs against weeds, data showed that an initial plant density of >10 plants m-2 may not result in increased forage production worthy the additional establishment cost. Data on response to fertility management and forage quality attributes are necessary for more reliable practical recommendations.

Effect of Varying Temperature Regime on Phyllochron in Four Warm-Season Pasture Grasses

Using accumulated temperature measures to predict plant development may provide guidance on timing of management practices to minimize competition between warm and cool-season components of mixed pastures. However, temperature and plant development relationships for warm-season pasture grasses common in the southern Great Plains of the USA have not been extensively studied. Under controlled environment conditions, base temperature (Tbase) values were determined for Big bluestem (Andropogon gerardii Vitman), Indiangrass (Sorghastrum nutans, (L.) Nash), Little bluestem (Schizachyrium scoparium (Michx) Nash) and, Sideoats grama (Bouteloua curtipendula (Michx) Torr). Measures of the accumulated temperature requirement for the phyllochron (leaf appearance interval) were made under a range of temperature regimes for these same species. Mean Tbase was 8.1&degC and differences among species were not significant (P > 0.05). Within temperature regimes mainstem leaf appearance was closely and linearly related to accumulated temperature above Tbase. Increase of 7.5&degC in night temperature increased phyllochron by a mean of 43%, but similar increase in day temperature only increased phyllochron by 16%. Phyllochron increased by 6.4&degC leaf-1 for each 1&degC increase in daily mean temperature within the range of 15.0&degC to 22.5&degC. If accumulated temperature measures are to monitor reliably the development of warm-season grasses, allowance must be made for changes in phyllochron as the growing season progresses.

Leaf gas exchange characteristics,biomass partitioning,and water use efficiencies of two C4 African grasses under simulated drought

Background:Few studies have evaluated the effect of drought on the morphophysiological characteristics of African C_(4) grasses.We investigated how drought affects leaf gas exchange characteristics,biomass partitioning,and water use efficiencies of Enteropogon macrostachyus and Cenchrus ciliaris.Methods:The grasses were grown in a controlled environment under optimum conditions,that is,70%of the maximum water‐holding capacity(WHC)for the first 40 days.Thereafter,half of the columns were maintained under optimum or drought conditions(30%of maximum WHC)for another 20 days.Results:Under optimum conditions,C.ciliaris showed a significantly higher photosynthetic rate,stomatal conductance,and transpiration rate than E.macrostachyus.Drought decreased the photosynthetic rate,stomatal conductance and transpiration rate only in C.ciliaris.The net photosynthetic rate,stomatal conductance,and leaf transpiration of E.macrostachyus did not differ significantly under optimum and drought conditions.E.macrostachyus showed an increase in its water use efficiencies under drought to a greater extent than C.ciliaris.Conclusions:Our results demonstrate that C.ciliaris is more sensitive to drought than E.macrostachyus.The decrease in the intercellular CO_(2) concentration and the increase in stomatal limitation with drought in C.ciliaris and E.macrostachyus suggest that stomatal limitation plays the dominant role in photosynthesis of the studied African C_(4) grasses.