Journal of Agronomy and Crop Science最新文献

The cover image is based on the Original Article Warm-season turfgrass species genotype-by-environment interaction for turfgrass quality under drought by Beatriz Tome Gouveia et al., https://doi.org/10.1111/jac.12681.

One of the biggest challenges the turfgrass industry is currently facing is limitations of available water for irrigation of turfgrass areas. Efforts on breeding for drought resistance have increased over the past several years across the United States. Thus, the objectives of this study were to evaluate the performance of bermudagrass (Cynodon spp. Rich.), St. Augustinegrass (Stenotaphrum secundatum (Walter) Kuntze), seashore paspalum (Paspalum vaginatum Swartz) and zoysiagrass (Zoysia spp. Willd.) breeding lines from five different breeding programs under drought and estimate genetic parameters in order to increase selection efficiency for drought resistance improvement in these breeding programs. The germplasm sources were bermudagrass from Oklahoma State University and University of Georgia (UGA); St. Augustinegrass from North Carolina State University, Texas A&M University System (TAMUS) and University of Florida (UF); zoysiagrass from UF and TAMUS; seashore paspalum from UGA. Field trials were conducted from 2016 to 2019 at research facilities in Citra, FL and Dallas, TX. The response variables evaluated were per cent living ground cover (%GC), and turfgrass quality under normal or non-drought (TQND) and drought conditions (TQD). The genetic variance was significant for TQND and TQD in bermudagrass, TQD in St. Augustinegrass and all traits in zoysiagrass. The heritability estimates were higher for TQD than for TQND in bermudagrass and St. Augustinegrass. Genetic correlation estimates showed that indirect selection can be effective to select drought-resistant genotypes. Several genotypes performed better than all commercial cultivars in both St. Augustinegrass and zoysiagrass.

The yield traits and physiological responses of three wheat genotypes were studied when subjected to heat and combined heat and drought stress at anthesis under either aCO₂ (400 ppm) or eCO₂ (800 ppm) in a greenhouse. The heat treatment was 7-days at day/night 35/28°C, and the combined heat and drought was withholding irrigation from the heat-stressed plants until the photosynthetic rate reached <5 μmol m⁻² s⁻¹. The LM62 genotype had higher photosynthetic rate compared with LM19, though no significant difference in grain yield was found. eCO₂ increased photosynthesis at 35°C and significantly lowered the electron transport rate at high intercellular CO₂ concentrations. Maximum velocity of Rubisco carboxylation (V_cmax) and the maximum velocity of RuBP regeneration in leaves (J_max) increased in 35°C compared with 25°C, though when normalized to 25°C both V_cmax and J_max decreased in the heat-stressed plants, indicating that an inhibition had occurred. The maximum photochemical efficiency of photosystem II (F_v/F_m) decreased under heat, which correlated with the yield loss caused by the stress. F_v/F_m also decreased under combined heat and drought, though it did not related to the declined yield. A small leaf area prolonged the drying period of Gladius, and it was the genotype with the lowest decrease in yield because of stress. It is concluded that the effects of heat and combined heat and drought stress on the gas exchange and photosynthetic capacity on leaf area basis are not directly linked to the yield performance among wheat genotypes, while the morphological characteristics of the plants are important determinants of grain yield in response to those abiotic stresses.

Pasture persistence is a key determinant of the economic and environmental performance of pastoral animal production systems. Large and deep root systems that help resist summer water stress have been proposed as a relevant trait for vegetative persistence of perennial temperate forage species growing in subtropical climates or under future climatically challenging scenarios. In a previous study [Jauregui et al., 2017. Persistence of tall fescue in a subtropical environment: Tiller survival over summer in response to flowering control and nitrogen supply. Grass and Forage Science 72, 454–466] we have shown that nitrogen fertilization and grazing management aimed at ‘control flowering’ increased the survival of tall fescue tillers during harsh summers in Uruguay (lat. 32°S). Here we assessed: (i) to what extent tiller survival is mediated by root system size in spring and (ii) what consequences tiller survival entails for root mass, depth and morphology the following autumn. In two field experiments, significant increases in tiller survival in response to nitrogen fertilization and grazing management (+60% and +80% in 2011/12 and 2012/13, respectively) were not related to concomitant effects on the size or depth of the root system in spring (p > .10). Even when six-fold within-treatment variation in root mass was observed, within-treatment variation in summer tiller survival was little affected (<15%, p = .08). In turn, differences in tiller survival over summer affected little root system characteristics the following autumn. Therefore, we found scant support for the hypothesis that large and deep root systems contribute to survival of tall fescue tillers in this subtropical humid climate. Except for soils with less than 30 mm of plant available water holding capacity, summer water deficits did not induce severe tiller mortality in tall fescue in this climate.

In the context of climate change, high temperature is one of the main abiotic stresses hampering durum wheat production. Through the characterization of an international panel of 271 genotypes, this study investigates the effects of heat stress on quality traits and identifies which glutenins (Glu-1, Glu-2 and Glu-3 loci) alleles are the most important to obtain high gluten strength under optimal and high temperature conditions. In parallel with the wide variability observed in the panel, the genotype and environmental effects, including their interaction, showed highly significant effect on test weight, thousand kernel weight, grain protein content (GPC), sodium dodecyl sulphate sedimentation volume (SDSS) and SDSS index. Only one genotype maintained test weight and thousand kernel weight under heat-stress conditions whereas for GPC, SDSS and SDSS index, most genotypes increased values. All Glu loci had significant effects on grain protein content (with the exception of Glu-B2), SDSS and SDSS Index. None of the Glu loci interacted with the environment or years under study. Among the identified alleles, Glu-A1b, Glu-B1an, Glu-B1a, Glu-B2a, Glu-A3a.x, Glu-A3d, Glu-B3a and Glu-B3ax (including the LMW-2 pattern) were associated with high values for SDSS and SDSS Index. Genotypes identified in this study, with good performances under optimal and high temperature growing conditions, could be useful for breeding programs. The non-interaction of the Glu loci with the environment facilitates the introgression of desired alleles regardless of high growing temperatures.

Wheat yield and nitrogen use efficiency (NUE) have improved simultaneously with the genetic development of wheat varieties. However, wheat selection is carried out routinely in N-rich field conditions, with breeding progress limited under low soil available nitrogen. Thus, we performed a 2-year field investigation using eight milestone winter wheat varieties released between 1947 and 2017 in the Huang-Huai-Hai region of China with two N applications—normal (CK; 220 kg N ha⁻¹) and reduced (RN; 110 kg N ha⁻¹)—in Shaanxi, China, to examine changes in wheat yield, NUE, water use efficiency (WUE) and root biomass. Our findings revealed average annual yield increases of 49.615 kg ha⁻¹ and 36.905 kg ha⁻¹ under CK and RN, respectively. Notably, the NUE trend mirrored yield, increasing with the release year of wheat varieties, with average annual increases in NUE of 0.192 and 0.336 kg kg⁻¹ under CK and RN, respectively. In the RN treatment, N uptake efficiency (UPE) increased with year of release, while N utilization efficiency (UTE) had no significant relationship. In the CK treatment, UTE increased with year of release, while UPE had no significant relationship. Across the 2-year experiment, surface root biomass (0–20 cm layer) increased with year of release under CK but had no relationship under RN, while deep root biomass (20–200 cm layer) decreased with year of release under CK and increased under RN. The roots of modern wheat varieties responded better to soil nitrogen levels and produced higher yields, NUE and WUE than earlier varieties by adjusting root biomass distribution in soil.

The unique nature and environment of the Vietnamese Mekong Delta as well as its agricultural production and its traditional lifestyle are endangered by a rising sea level and increasing salinization of the ground and surface water. This paper aims at the assessment of Vietnamese people's information on and attitudes towards these problems as well as their respective convictions and beliefs. Imbedded in an online survey with 2000 completed interviews we also conducted a Contingent Valuation study with which we want to assess people's willingness to contribute personally and financially to saving the Mekong Delta as an indication of the benefits they would expect from such a project. We interviewed three different groups of respondents, one of which lives directly in the Mekong Delta, a second lives outside the Delta, but close to it, that is in Ho Chi Minh City, and the third group lives far away from the Delta in Hanoi. With these three subsamples of respondents we wanted to capture not only the use benefits but also the nonuse benefits accruing from such a project. In the course of the interviews, we found that the Mekong Delta is of great interest and importance to all interviewees, no matter in which part of Vietnam they live. They were mostly well informed on the problems there and had strong opinions on the causes of these problems as well as on suitable strategies to fight them. In our Contingent Valuation study, we assessed the willingness of people at the different study sites to contribute financially to a hypothetical project for the preservation of the Mekong Delta and the socio-economic, attitudinal and psychological determinants of this willingness. Besides these empirical findings, we also obtained valuable insights regarding various methodological aspects of Contingent Valuation studies.

Increasing sea level rise and subsequent salinization in mega deltas, such as the Vietnamese Mekong Delta (VMD), pose a risk to rice (Oryza sativa L.) production during the dry season. This study investigated the salinity resistance of a selection of common rice genotypes from the VMD along with an international check, IR64. The 20 rice varieties were grown hydroponically for 5 weeks in a greenhouse and then exposed to three levels of NaCl concentration (0 mM, 50 mM and 100 mM) over a period of 2 weeks to determine their susceptibility to salinity. Rice plants were scored and SPAD (leaf greenness) and PRI (photochemical reflectance index) were measured on the youngest fully developed leaf on the main tiller. After harvesting the 7-week-old plants, biomass and ion (K⁺, Cl⁻, Na⁺) content were determined by organ across all tillers. Averaged over all varieties, both at 50 mM and 100 mM NaCl, there was a significant reduction in plant biomass, 39% and 52% respectively. However, the effect of the NaCl treatments and the uptake of Cl⁻ and Na⁺ were significantly different between varieties (p < .0001). Using biomass and ion content as part of a multivariate analysis, varieties were classified according to their susceptibility to salinity and their predominant strategy towards managing ion accumulation. The grouped varieties were further characterized by patterns in Cl⁻ and Na⁺ partitioning and nondestructive parameters such as SPAD and PRI.

The aim of this study was to determine the drought tolerance of four different genotypes, including two wheat varieties (Ceyhan 99 and Sagittario) and two wheat lines (Zdeb101 and Zdeb102), and create irrigation schedules. This study was performed with treatments applied at three irrigation levels (S100: treatment where the entire water need of the plant was met, S50: 50% of the water provided in the S100 treatment, S0: Rainfed), with four genotypes and four replications in a split-plot design in Kahramanmaras East Mediterranean Transitional Zone Agricultural Research Institute in 2019 and 2020. The Ceyhan 99 and Sagittario varieties, which are widely cultivated in the region and the Zeb101 and Zdeb102 lines that are candidates for varieties were used in the study. In the study, 217.1 and 213.77 mm of water was given to S100, 108.54 and 106.88 mm of water was given to S50, and no irrigation was provided to S0 in 2019 and 2020, respectively. The effects of different irrigation levels on yield, water use efficiency (WUE), irrigation water use efficiency (IWUE), protein content and wet gluten content were investigated. At the end of this study, seasonal evapotranspiration (ET), irrigation water and yield decreased from S100 to S0. WUE, IWUE and yield response factor (Ky) values showed different trends in both years. There was no significant difference in yield between the varieties. However, in the stress susceptibility index (SSI) analyses of the genotypes, it was found that the most drought-tolerant genotypes were Zdeb102 (0.50) and Ceyhan 99 (0.54). The highest protein content and wet gluten content were found as 11.38% and 22.24% in the Sagittario variety, respectively. It is recommended that Zdeb102 and Ceyhan 99 be cultivated in regions such as Kahramanmaras which have semi-arid climate characteristics in the Mediterranean.

The literature describes the belowground and aboveground phenology of potato to be linearly related. Bud formation is synchronous with tuber initiation and flowering with tuber filling. Many agronomic and breeding studies on potato use non-destructive aboveground phenology to assess belowground development. No information is currently available on the influence of water deficit on the synchrony of above- and belowground development in potato. Five contrasting potato genotypes were subjected to four irrigation treatments on two different soil types. The irrigation treatments were as follows: fully watered, early drought, intermediate drought, and late drought. In 5-day intervals after withholding water, detailed belowground and aboveground development was recorded. Results showed that the synchrony between aboveground and belowground development is strongly influenced by both water deficit and development stage at drought initiation. Under early drought, the aboveground development was hastened and belowground development was delayed. The opposite was found in later development stages. The earlier the drought was initiated, the longer the tuber filling phase was, while the bulking phase was shortened. We concluded that under terminal drought conditions aboveground development and belowground development need to be evaluated separately and cannot follow the standard evaluation system that uses aboveground phenology as a proxy for tuber formation belowground development rates.