Grassland Science最新文献

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.

The sustainable supply of whole crop maize (WCM, Zea mays L.), as the domestic high-quality forage source, is causing great concern among the related parties in the Republic of Korea. Many new cultivars were introduced or developed in recent decades. This study was conducted to construct the WCM weather-crop yield prediction model considering cultivar maturity as well as to evaluate the effects of local climatic factors on yield. Data on the nationwide adaptability tests of WCM cultivars and the meteorological data were collected and merged into a dataset (n = 386, 22 years) after data cleansing. Three climatic variables, including the accumulation values of growing degree days, precipitation, and sunshine hours from seeding to harvesting, were generated. Then, the dataset was split into two sub datasets considering cultivar maturity. Subsequently, the models, including the three climatic variables and the cultivated location, were constructed for both sub datasets. The finesses and accuracy of the models were confirmed by residual diagnostics and 3-fold cross-validation. The accumulated temperature, sunshine time, and precipitation were found to significantly affect the WCM yield variance, while the precipitation factor caused stresses to the yield, which indicates water management is important for WCM cultivation.

Ticktrefoil (Desmodium) species from the USDA, ARS, Plant Genetic Resources Conservation Unit (PGRCU) germplasm collection in Griffin, GA, were evaluated for their potential livestock nutraceutical (nutritional + pharmaceutical) value in a field small plot study at the Fort Valley State University (FVSU) Agricultural Research Station, Fort Valley, GA. Horse marmalade (Desmodium discolor Vogel), greenleaf ticktrefoil (Desmodium intortum [Mill.] Urb.), panicledleaf ticktrefoil (Desmodium paniculatum [L.] DC.), Hawaii ticktrefoil (Desmodium sandwicense E. May) and twisted ticktrefoil (Desmodium tortuosum [Sw.] DC.) were established in a greenhouse and transplanted to field plots, with plant material from each species harvested, freeze-dried, ground and analyzed for nutrient content and bioactivity. Crude protein (CP) levels in D. discolor and D. tortuosum averaged 233 g/kg, whereas CP in D. intortum, D. paniculatum and D. sandwicense ranged from 99 to 157 g/kg. The Desmodium species had in vitro true digestibility values of 755 to 878 g/kg. There were no detectable condensed tannins in D. discolor and D. tortuosum, whereas D. intortum, D. paniculatum and D. sandwicense averaged 88, 89 and 73 g/kg total condensed tannin, respectively. There were species differences in flavonoid content (p < .01), with the highest delphinidin and cyanidin concentrations in D. sandwicense and D. paniculatum, respectively. There were no detectable levels of delphinidin or cyanidin for D. discolor or D. tortuosum. Quercitin and kaempferol concentrations were highest in D. intortum and D. paniculatum, respectively, whereas D. discolor and D. tortuosum had the lowest values. The highest protein precipitable phenolics and total phenolic concentrations were for D. paniculatum. Desmodium species have potential as nutraceutical forage for livestock and warrant further investigation.

In Japan, additional potassium fertilization is used as a countermeasure for radiocesium-contaminated grasslands in the Tohoku and North Kanto regions. A 2-year pot experiment was conducted to assess the efficacy of using tall fescue (Festuca arundinacea Schreb.), a low-cesium-absorption grass species, to replace orchardgrass (Dactylis glomerata L.), the most common forage grass species in these regions, to reduce potassium fertilization and improve the forage mineral balance. The treatments were a combination of two grass species (tall fescue and orchardgrass) and two potassium application rates (0 [K0] and three times the conventional amount [K3]) with four replications. The grass species and potassium application rate had significant (p < .001) effects on plant cesium-137 concentrations. The results of the generalized linear mixed-model analysis indicated that when tall fescue replaced orchardgrass, cesium-137 in the forage grass was reduced to 34% and that the K3 treatment reduced cesium-137 to 46% relative to the K0 treatment. The difference in cesium-137 concentration between the two grass species increased as the soil exchangeable K₂O content decreased. The equations for estimating the cesium-137 concentration (y [g/kg]) from the exchangeable K₂O content (x [g/kg]) were obtained as y = 63.7e^–2.095x for tall fescue and y = 185.5e^–3.327x for orchardgrass. These equations indicate that tall fescue cultivation can reduce the risk of elevated radioactive Cs in the grass by reducing potassium fertilizer to approximately half that of orchardgrass. There were no differences in the response of plant potassium concentrations or the potassium/(calcium + magnesium) equivalent ratio to soil exchangeable K₂O content among the grass species. However, the mineral balance of forage can be improved by reducing potassium fertilizer applications for cesium-137 remediation. Tall fescue has good potential to remediate contaminated grasslands as it reduces additional potassium fertilization and improves the mineral balance of forage.

Clarifying the relationship between plant and soil characteristics under different establishment years of artificial grassland can improve the adaptive management ability of alpine grassland, which is of great significance to the sustainable development of alpine grassland ecosystems. This study used field quadrat surveys and indoor analyses to determine the plant community and soil nutrient characteristics of artificial grasslands with different establishment years and analyzed the characteristic differences and internal relations under different establishment years combined with correlation analysis and redundancy analysis. The results showed that the vegetation coverage decreased significantly (p < .05) after the establishment of 5 years, the biomass of artificial grassland decreased with the increase in establishment years and the species diversity index showed a “V-shaped” change. With the increase in establishment years, the total nutrients of the artificial grassland increased, and the available nutrients decreased. The results of correlation analysis and redundancy analysis showed that soil nutrients in the 0–30 cm soil layer were intrinsically correlated with biomass and soil pH, soil water content and soil bulk density were significantly correlated with plant community changes during the establishment of artificial grassland. This study will help to clarify the changes in plant and soil characteristics of artificial grassland with different establishment years and provide a scientific and theoretical basis for restoring degraded alpine grassland.

The negative impacts of sika deer (Cervus nippon) on Japanese serows (Capricornis crispus) are a subject of concern in the mountainous regions of Japan. To develop a methodology to collect information with regard to the abundance and habitat selection of sympatric large mammals using drones (unmanned aerial vehicles; UAVs) equipped with thermal infrared and red-green-blue (RGB) sensors, surveys were conducted at night and in the early morning in a high mountainous habitat. Despite the similar size and shape in thermal infrared images for sika deer and Japanese serows, species identification based on body color using RGB images was possible during the period from dawn to early morning. The UAV surveys also revealed the large abundance of deer (>40 deer/km²) and suggested different habitat selection between deer and serows in the alpine grassland. Our results were the first snapshots of sympathetic deer and serow distribution. UAV surveys using both thermal infrared and RGB sensors in early morning could be useful for research and monitoring of large mammals in open areas, such as grasslands, marshlands, high mountains, farmlands and drylands.