Grassland Science最新文献

Our study area, Ejina, is located in the southern Gobi Desert, Inner Mongolia, China, where the annual precipitation is <50 mm and the annual potential evaporation is >3,600 mm. The Heihe River flows from the Qilian Range through the study area, and the desert landscape along the river includes oases formed by forests and grasslands. We established a survey area of approximately 1.5 ha in grassland facing a seasonal swamp, a branch of the Heihe River. We posed the following questions in this desert grassland: (1) how do soil water content (SWC) and salinity change with distance from the riverbank? (2) How do vegetation, aboveground biomass, and species richness change with distance from the riverbank? (3) How much can be supplied to grazing animals, and how many animals can be grazed? Our results indicated that (1) the SWC is high within 20 m of the riverbank and low beyond 20 m, the standing biomass is positively correlated with SWC, but there was no evidence of a correlation between salinity and distance to water; the electrical conductivity was high both inland and adjacent to the riparian swamp. (2) Vegetation could be classified to six classes, following a gradient from the riverbank (swamp margin) to the dry inland area beyond 20 m from the riverbank. Species richness and aboveground biomass were highly correlated. Classification result led us to recommend that generalist species tolerant of the distinct moisture gradient in the site be used in restoration efforts. (3) Per-hectare aboveground biomass was 478.93 dry weight (dw) kg, 321.2 ha of equivalent grassland would be required to graze 100 goats annually.

Drought is a major factor limiting plant growth. Plants cope with stress via morphophysiological responses. Rhizosphere-related bacteria, fungi and other microorganisms can help plants cope with drought via various mechanisms. We conducted a pot experiment on Cyperus esculentus wherein we subjected it to various drought levels and analyzed the functional traits of its aboveground and belowground organs. High-throughput sequencing was used to study the structure and diversity of the microbial community in the rhizosphere. Drought stress substantially lowered the densities of the leaves, stems, roots and seeds relative to the untreated control. Drought stress inhibited the growth and reduced the yield of C. esculentus. The leaves and seeds have higher water content and are more sensitive to drought stress than the roots. With the aggravation of drought stress, the plant height of C. esculentus decreased significantly, the root:shoot ratio increased and the specific leaf weight had no significant difference. Change in shoot height was the most evident response of C. esculentus to drought stress. Plants under drought stress reduced their leaf area and assumed a specific leaf weight to maintain photosynthetic performance. Rhizosphere fungi were more sensitive to drought stress than rhizosphere bacteria. Drought stress increased the relative abundances of Bacteroidetes, Verrucomicrobia, Patescibacteria, Actinobacteria and Nitrospirae. Drought-stressed C. esculentus maintained their photosynthetic performance by reducing shoot height and leaf area while assuming a stable specific leaf weight. Drought stress exerted a significantly stronger negative impact on rhizosphere fungi than rhizosphere bacteria. The results clarified the response strategies of functional traits and rhizosphere microorganisms of C. esculentus to drought stress.

The performance of seven Urochloa grass genotypes (three worldwide cultivars cv. Basilisk, cv. Piata, cv. Xaraes and four landrace cv. Adamaoua1, cv. Adamaoua2, cv. North1 and cv. North2) subjected to two cutting regimes (mid-June cut and mid-July cut) was evaluated for regrowth characteristics, seed yields, seed quality and herbage production in 2020 and 2021 cropping seasons at Wakwa, Ngaoundere, Cameroon. This divergence in harvesting practices raises concerns regarding the effectiveness and efficiency of forage utilization, as well as the potential impact on livestock productivity and sustainable farming systems. A split plot design with five replications and a 1-year-old sward was used for the study. In both years, genotypes were significantly different for plant height and tiller numbers at 12 weeks after cutting (P ≤ 0.007). In 2020, the dry matter yield (DMY) ranged between 8.78 t/ha (cv. Piata) and 12.75 t/ha (cv. Xaraes) for June cut regrowth and between 7.69 t/ha (cv. Piata) and 10.26 t/ha (cv. Xaraes) for July cut regrowth. In 2021, DMY ranged between 6.06 t/ha (Adamaoua2) and 13.95 t/ha (cv. Xaraes) for the June cut and between 6.55 t/ha (cv. Adamaoua2) and 10.47 t/ha (cv. Basilisk) for the July cut. For flowering behavior and seed yields, Basilisk flowered earliest while cv. Xaraes flowered latest. In 2020, seed yields were 74.80 kg/ha and 107.72 kg/ha for June cut and July cut regrowth, respectively, whereas in 2021, seed yields were 331 kg/ha and 431 kg/ha for June cut and July cut regrowth, respectively. cv. Adamaoua1 produced the highest seed yield in both years. The cutting regimes evaluated in this study were indifferent for DMY and seed yield.

Bahiagrass (Paspalum notatum Flügge) is a warm-season grass where high lignin content limits its forage quality, negatively affecting animal performance. To create a new breeding method by genome editing, isolation and characterization of lignin biosynthesis genes and identification of their molecular relationships are essential. The caffeic acid O-methyltransferase (COMT) and cinnamyl alcohol dehydrogenase (CAD) cDNA clones were isolated from bahiagrass, and their protein sequences showed high similarity to other C4 monocot species through phylogenetic analysis. Gene expression analysis of phenylalanine ammonia-lyase (PAL), COMT and CAD, involved in crucial stages of lignin biosynthesis and lignin content, was conducted at different plant developmental stages. The highest gene expression levels of these genes were observed in the vegetative (V) and early reproductive stages, while the lignin content increased until the middle reproductive stage and remained constant thereafter. Additionally, to further understand the molecular relationships in lignin biosynthesis, the effect of CAD downregulation was analyzed in transgenic bahiagrass lines introduced with sorghum CAD antisense and RNAi vector obtained from a previous report. This led to a reduced lignin content and affected the expression of PAL and COMT working upstream of CAD. In the V stage, PAL expression was lower in transgenic lines compared to wild type (WT), while COMT expression showed no significant differences. However, PAL and COMT expression of transgenic lines in the middle reproductive stage (R2) was significantly higher than in the WT. These findings suggest that the downregulation of CAD gene expression affects PAL and COMT expression and induces a feedback system in the R2 stage. Lignin content influenced the phenotype of the transgenic plants with significantly reduced lignin, exhibiting a dwarf phenotype with shorter plant heights. The findings of this study can be applied to genome editing for the development of practical new breeding materials with improved digestibility in bahiagrass.

The purpose of this study was to evaluate different methodologies used in the field in order to find the one that could most effectively relate to the morphophysiological condition of Brachiaria decumbens cv. Basilisk (syn. Urochloa decumbens cv. Basilisk Stapf R.D. Webster). Two light interception frequencies (LI, 85% and 95%) and two defoliation intensities were adopted as targets for the residual leaf area index (RLAI 1.3 and 1.8). The treatments consisted of evaluating different methods of measuring the canopy height (CH) through its ability to correlate with the morphophysiological variables of species B. decumbens cv. Basilisk. High correlations between the methods CH, compressed height (CHe), weighted height 1 (WH₁) and weighted height 8 (WH₈) were observed mainly with the variables total forage biomass (TFB) and leaf area index (LAI) in both residual and pre-grazing conditions. The path analysis showed degrees of multicollinearity, which determined the use of the “k” constants in order to correct the distortions of the diagonal elements of the correlation matrix X'X. Path analysis provided direct cause/effect indexes on TFB using LAI = 0.1435, photosynthesis (A) = −0.1061, CH = 0.1616, CHe = 0.0913, WH₁ = 0.1386 and WH₈ = 0.0575; on LAI using CH = 0.2404, CHe = 0.2164, WH₁ = 0.2307 and WH₈ = 0.2183; and on photosynthesis rate (A) using LAI = 0.2895, CH = 0.0203, CHe = −0.1170, WH₁ = 0.0352 and WH₈ = 0.0937. Similarity was observed between intercepts and slope coefficients for TFB prediction using CH, CHe, WH₁ and WH₈, providing mean values of 1069.57 and 204.06, respectively. Methods CH and WH₁ presented a significant correlation with most morphophysiological variables and can be used to quantify TFB and LAI, while CH and WH₈ can be used only for TFB.

The intensity of grazing on palatable species can vary depending on the neighboring plants in plant communities. We aimed to search for species whose biomass can have a positive effect on palatable plants near them in a grassland under grazing pressure by sika deer. We selected Iris sanguinea Hornem. as an indicator species of ease of being grazed because it is a palatable and past dominant species before the increase in deer density. We estimated the effects of the biomass of neighboring plant species, soil water content, and distance from the forest edge on the height of I. sanguinea. The height was remarkably and positively affected by the biomass of four graminoid species with larger biomass and slightly positively affected by the biomass of a toxic species. This study suggests that the biomass of less-palatable species may have an important influence on the size of palatable species under grazing pressure by deer.

Salt stress is one of the main environmental factors affecting plant growth. Photosynthesis, which provides the energy needed for plant growth and development, will be severely restricted under salt stress. Strigolactones (SLs), a class of carotenoid-derived phytohormone, play an important role in regulating plant growth and responding to multiple biotic and abiotic stresses. In this study, we investigated the role of rac-GR24 (a synthetic SLs analog) in the amelioration of salt stress in the photosynthesis of alfalfa. These results showed that rac-GR24 treatment could increase the content of soluble sugar and soluble protein, increase superoxide dismutase, catalase, and peroxidase activity and reduce the content of malondialdehyde in alfalfa leaves, thus relieving the damage caused by salt stress in alfalfa leaves. Moreover, rac-GR24 treatment could also regulate the K⁺/Na⁺ homeostasis, improved stomatal conductance and increased chlorophyll content, which improved the photosynthesis limited by salt stress. The expression levels of selected gene for photosynthesis and antioxidants were consistent with the physiological performance. Our study indicated that rac-GR24 could alleviate the negative effects on photosynthesis of alfalfa under salt stress.

Accurate determination of the weed ratio in artificial meadows is critical for efficient pasture renovation. Reed canary grass (Phalaris arundinacea L., RCG) is treated as a troublesome grass in the Hokkaido region of Japan because of its low feed quality and poor palatability in dairy farming. In the present study, we examined a method of identifying the dominant area of RCG in timothy (Phleum pretense L.) meadows by applying the Canny method to unmanned aerial vehicle (UAV)-based digital surface model (DSM) images. Comparing the actual RCG patches observed in a field survey (50 m quadrats × 4 places) with the predicted patches, the pixel-based recall and F value were 0.90 and 0.83, respectively. These results demonstrated that the area of RCG can be detected using a simple method without supervised data or deep learning. This study is expected to be utilized in a wide variety of applications using relative height differences.

Grazing management frequently relies on forage availability as an indicator of performance. However, canopy structure and composition can play an important role in foraging behavior and intake in native grasslands. Here, we aim to (1) assess the effect of grazing management on herbage biomass, tussock cover, average canopy and inter-tussock canopy height, and to (2) study the effect of these canopy structure components on short-term intake rate (STIR) and patch selectivity of beef cattle, in a native grassland in the Campos region in southern Brazil. Ten 1000 m² experimental units were built in five paddocks (two per paddock) managed with different herbage allowance (HA) treatments: four fixed year-round HA (1 to 4 kg dry matter [DM]/kg live weight [LW]) and one variable HA (2 and 3 kg DM/kg LW during spring and the rest of the year, respectively). The experimental units were grazed individually with four heifers during 45 min, in two grazing cycles. Before each grazing session, we assessed the total herbage mass, average and inter-tussock canopy height, and tussock cover. During the 45-min grazing sessions, we evaluated the STIR (g DM/kg LW^0.75/min) and grazing time in tussock and inter-tussock strata. Increasing the HA increased the total herbage mass, canopy height and tussock cover. The STIR was maximized with herbage mass of 2200 kg DM/ha and a tussock cover of ~7%, canopy structures related with moderate grazing intensities (i.e., 2 and 3 kg DM/kg LW), which increased the selection opportunity by herbivores. Canopy structures associated with heavy (1 kg DM/kg LW) and lenient grazing intensity (4 kg DM/kg LW) determined linear decreases of 50% in STIR.

Corn production for concentrated feed is increasing in Japan, and cultivation techniques are necessary to obtain higher yields. To expand the corn production for concentrated feed in the Kanto region of Japan, corn varieties based on their earliness was evaluated. Changes in ear yield and moisture content were compared among 12 commercial varieties, which were divided into three groups based on their relative maturity (RM): extremely early (RM 95–100), early (RM 113–115) and medium (RM 125). The varieties were sown at three different times (late April, middle May and late May) for three cultivation years. Our experiment found that the ear dry weights of both early and medium groups were higher than that of the extremely early group. Ear moisture of the extremely early group decreased rapidly and reached 35% as a standard for harvesting time we defined, at 60 days after silking, while that of the early group reached 35% at 70 days after silking, and that of the medium group did not reach 35% during the experimental period. Late sowing decreased ear dry weight and delayed ear moisture decreasing. The extremely early group had the advantage of early harvesting at 60 days after silking, and the early group obtained a higher yield than the extremely early group at the harvesting at 70 days after silking. These results suggest that extremely early and early groups are suitable for corn production for concentrated feed in the Kanto region.