Journal of Agronomy and Crop Science最新文献

Pulse production is decreased when grown on waterlogged soil in rice-based cropping. This study evaluated four pulse crops—grass pea, field pea, cowpea and lentil—to find out their responses to waterlogging (WL) stress at emergence and vegetative stages. The treatment levels at emergence were drained control, 4-, 7- and 10-day WL, while in the vegetative stage they were drained control, 6-, 10- and 14-day WL. In the emergence stage, %emergence was significantly reduced as WL duration increased. After 10-day WL, emergence was reduced to 65% for grass pea, 30% for field pea, 5% for lentil and 7% for cowpea. At the vegetative stage, in both the WL and recovery phases, the WL treatment reduced plant height, tap root length, shoot and root dry mass compared to those in drained control with a significant difference in crops. In recovery as compared to the WL phase at 14-day WL, the chlorophyll content was increased 15% in cowpea and 14% in grass pea but decreased in field pea (26%) and lentil (35%). Similarly, in the recovery phase at 14-day WL, shoot relative growth rates (RGRs) of cowpea, grass pea, field pea and lentil were 20, 66, 10 and 5 mg plant⁻¹ d⁻¹; which were 66%, 70%, 8% and 14% of drained control, respectively. The RGR of root at 14-day WL was also higher in cowpea and grass pea with the rate of 13.8 and 16 mg⁻¹ plant⁻¹ d⁻¹, respectively; in sharp contrast to a reduction of −4.3 mg⁻¹ plant⁻¹ d⁻¹ in field pea and −3.9 mg⁻¹ plant⁻¹ d⁻¹ for lentil than drained control. Furthermore, the higher number of adventitious roots was found in cowpea (14) and grass (9) pea than in field pea (6) and lentil (4). Comparison between growth stages, grass pea was tolerant to WL in both stages. Cowpea was WL sensitive at emergence, but tolerant to vegetative stage. Field pea was moderately tolerant to emergence but was sensitive at vegetative stage. Lentil was sensitive at WL at both stages. These novel insights will allow the fitting of winter pulses to various cropping systems according to the perceived risk of WL at various growth stages.

The identification of soybean genotypes tolerant to soil compaction makes it possible to reduce productivity loss under stress conditions. Added to this, the prior selection of these genotypes will result in greater assertiveness in the positioning of cultivars in the field. Thus, the objective was to evaluate the susceptibility of soybean genotypes to compaction in greenhouse and field conditions; verify which characteristics of seedlings under high resistance to root penetration are correlated with crop production in compacted soil; and to validate the substrate mechanical impedance method for evaluating the susceptibility of plant genotypes to soil compaction. Seeds of 20 genotypes were sown in a substrate mechanical impedance system under controlled conditions. The characteristics evaluated were total root length, total root surface area, mean root diameter, total root volume, taproot length, shoot length, root dry matter and seedling shoot dry matter. In the field experiment, half of the planting area was compacted, constituting two treatments, soil with and without compaction. The percentage of seedling emergence, initial plant height, stem diameter, number of nodes, internode length, number of lateral branches, shoot dry matter, final plant height, absolute and relative growth rate, number of pods, weight of 100 seeds and grain yield. In addition, the number of days between soybean sowing until plant flowering and grain harvest was recorded according to genotype and soil compaction level. In a controlled environment, genotypes tolerant to soil compaction show greater plasticity of root characteristics and smaller alterations in the shoot of seedlings. In the field, these genotypes show smaller reductions in growth rate, height, number of pods and grain yield. The shoot dry matter and the root dry matter of soybean seedlings in a mechanical impedance system present a positive and negative correlation, respectively, with soybean yield in compacted soil, indicating that the genetically determined susceptibility to soil compaction stress was similar throughout ontogenesis. The substrate mechanical impedance system used to evaluate the performance of soybean seedlings under stress, facilitates the decision-making in breeding programs focused on identifying genotypes expressing soil compaction tolerance.

Increased food, feed, and biofuel demands of the future will require a greater reliance upon crop production systems in arid and semi-arid regions around the world. Diminishing freshwater resources and hotter and drier climatic conditions will also necessitate the use of highly drought tolerant and water-use efficient crops. Cactus pear (Opuntia ficus-indica) is a low-water input, climate-resilient crop capable of high biomass production due to its use of crassulacean acid metabolism (CAM). Cactus pear produces both food and forage/fodder, a wide variety of high-value byproducts, and serves as a bioenergy feedstock for biogas or bioethanol production. Here, we evaluated the biomass productivity of 14 Opuntia spp. accessions from the National Arid Land Plant Genetic Resources Unit (NALPGRU) in Parlier, CA under semi-arid conditions with a planting density of 6667 plants ha⁻¹ over a 3-year period to identify high-yielding biomass producers. Mean annual cladode fresh weight (CFW) (73.7 Mg ha⁻¹ year⁻¹), cladode dry weight (CDW) (5.2 Mg ha⁻¹ year⁻¹), and cladode count (CC) (10.5 cladodes plant⁻¹) increased by 2.9-, 2.8-, and 2.8-fold in year 3 compared with year 1. PARL 845, hybrid no. 46 (O. ficus-indica × O. lindheimerii), showed the highest annual mean CFW (152.8 Mg ha⁻¹ year⁻¹), CDW (13.3 Mg ha⁻¹ year⁻¹), CC (22.1 cladodes plant⁻¹), and dry matter content (DMC, 11.2%) among all accessions tested. Non-hybrid accessions PARL 242 (O. cochenillifera), PARL 582 (Opuntia sp.), and PARL 584 (Opuntia sp.) showed 100% cladode establishment rates and CDW productivity of >6 Mg ha⁻¹ year⁻¹. Such biomass productivity results indicate that cactus pear displays great potential as a crop with many uses with lower water inputs than conventional crops for arid and semi-arid environments.

Cotton (Gossypium hirsutum L.) cultivars exhibit varying responses to heat stress. To investigate the heat resistance of various cotton and establish an index system for evaluating their heat resistance, 21 cotton cultivars were selected and subjected to two temperature regimes (CK, average temperature 28°C, 32/24°C; HT, average temperature 38°C, 42/34°C). The results showed that under high temperatures, different changes occurred in individual indexes of cotton, reflecting the differences in heat resistance in cotton cultivars. A total of 21 cotton cultivars could be classified into four types: heat-tolerant, moderate heat-tolerant, moderate heat-sensitive and heat-sensitive cultivars by multivariate statistical analysis. Moreover, the indexes of net photosynthetic rate (P_n), leaf superoxide dismutase activity (LSOD), the maximum photochemical quantum yield (F_v/F_m), the actual photochemical quantum yield (Φ_PSII), leaf malondialdehyde content (LMDA), leaf catalase activity (LCAT), dry matter weight of shoot (SDW) and root malondialdehyde content (RMDA) were determined to be useful for evaluating the cotton heat tolerance by stepwise regression analysis. The pot experiment showed that the reduction of boll number, boll weight and seed cotton yield was more remarkable under HT in the heat-sensitive cultivar CCRI-92 than in the heat-resistant cultivar CCRI-69, which further verified the screening results. In conclusion, the heat-sensitive cultivars CCRI-92 and heat-resistant cultivar CCRI-69 which are identified by seedling experiment could serve as ideal experimental materials for studying heat resistance in cotton. The physiological indices such as P_n, LSOD, F_v/F_m, Φ_PSII, LMDA, LCAT, SDW and RMDA be employed for assessing the heat tolerance in cotton.

The greenhouse effect caused by global warming was becoming more and more obvious, resulting in increased frequency of high temperature and high humidity, which significantly affected maize productivity. However, it was poorly understood how the interactions of high temperature and high humidity affected leaf senescence, photosynthetic performance and yield of summer maize. Three stress treatments including (a) high temperature stress (T), (b) waterlogging stress (W) and (c) complex stress (T-W) were set at the third leaf stage (V3), the sixth leaf stage (V6) and the tasselling stage (VT) in 2019–2020 to explore the influence mechanism of complex stress. Each stress treatment period lasted 6 days. Non-stressed plants served as control. Yield, antioxidant enzyme activity, photosynthetic characteristics, and dry matter accumulation were determined. Our study found that the activity of antioxidant enzymes was significantly decreased, while malonyldialdehyde (MDA) accumulation was increased under each stress treatment. As a result, the photosynthetic characteristics were impaired, manifested in a significant decrease in net photosynthetic rate (Pn), enzyme activities of phosphoenolpyruvate carboxylase (PEPCase) and ribulose diphosphate carboxylase (RUBPCase). The decrease in photosynthetic intensity affected by each stress treatment led to a significant decrease in total dry matter accumulation and grain yield. The most significant effects of waterlogging and combined stresses on yield occurred at the V3 stage, followed by the V6 and VT stages. However, the most significant effects of high temperature occurred at the VT stage, followed by the V6 and V3 stages. Moreover, the compound stress exacerbated damage to leaf senescence and photosynthetic properties of summer maize compared to the single stress of high temperature or waterlogging.

Reproductive failure in cotton caused by drought has been reported to be closely associated with alterations in pistil fertility; however, the mechanism of the effect of drought on pistil fertility in cotton is less studied. We hypothesized that drought would inhibit the ovule formation to alter pistil potential fertility. To address this hypothesis, we conducted a water deficit induction experiment with a cotton cultivar, Dexiamian 1. Results showed that drought damaged the cytological structure of the developing ovules. This resulted in a lower ovule number, finally leading to lower cottonseed number and boll weight. And the decreased ovule number was closely related to the reactive oxygen species (ROS) accumulation in pistil during ovule development. Further analysis of antioxidant metabolism found that in the enzymatic antioxidant system, drought decreased the activities of superoxide dismutase (SOD) and catalase (CAT), resulting in the accumulation of superoxide anion ($��{O_2}^{�•�-�}�$) and hydrogen peroxide (H₂O₂). Regarding the non-enzymatic antioxidant system, the elevated glutathione reductase gene (GhGR) expression under drought promoted the glutathione (GSH) accumulation; however, the decreased dehydroascorbate reductase gene (GhDHAR2) expression under drought inhibited the conversion of GSH to ascorbic acid (AsA). Although the increased monodehydroascorbate reductase gene (GhMDHAR) expression under drought promoted AsA accumulation, drought-induced reduced ascorbate peroxidase gene (GhAPX) expression inhibited the reduction of H₂O₂ by AsA, which ultimately led to higher AsA content and H₂O₂ content. We conclude that drought impedes the ovule formation by disturbing pistil's antioxidant metabolic homeostasis to destruct the cytological structure of the developing ovules.

Enhancing Nitrogen Use Efficiency (NUE) is extremely important towards mitigating climate change, especially in wheat where the NUE is less than 50%. Hence, optimizing grain yield under reduced application of nitrogenous fertilizer is a significant challenge. To address this challenge, a comprehensive study was conducted to investigate various agronomic traits and morphological, biochemical and molecular parameters related to NUE. This study explored their interrelationships and effects on grain yield, providing novel insights that were not previously reported. A set of 278 diverse wheat genotypes were assessed, encompassing eight NUE-related field traits. All traits' values were reduced under stressed N (ranging from 7.5% to 77.5%) except Nitrogen Utilization Efficiency (NUtE) and NUE. Data analysis showed a significant positive correlation between grain yield and all other NUE-related traits (r² value ranged from .23 to 1.00), highlighting their relevance in comprehending the biological NUE of wheat plants. Principal component analysis (PCA) also revealed that N at head and N at harvest were more connected with gain yield, NUE and biomass under the optimum N condition, but less connected with gain yield and NUE under the stressed N condition. To complement the field data, representative genotypes were further subjected to a hydroponics experiment under absolute N control to study the different morphological parameters, photosynthetic pigments and the performance of essential N- and C-metabolizing enzymes at the seedling stage. N stress had a detrimental impact on the majority of the parameters (−0.84% to −79.8%). Nitrite reductase (NiR), glutamate dehydrogenase (GDH) and isocitrate dehydrogenase (ICDH) enzymes as well as root length (RL), root fresh weight (RFW) and CS transcript, were positively affected by 5.9%–35.6%. The correlation analysis highlighted the substantial influence of four key N-metabolizing enzymes, namely nitrate reductase (NR), glutamine synthetase (GS), glutamate oxo-glutarate aminotransferase (GOGAT), and GDH on grain yield. Additionally, this study highlighted the direct and indirect associations between seedling parameters and field traits, where shoot and root length were found to be most significant for N acquisition, especially under N stress. In conclusion, these findings offer valuable insights into the intricate network of traits and parameters influencing wheat grain yield under varying N regimes.

Elevated atmospheric CO₂ concentration (e[CO₂]) and varied nitrogen (N) fertilization levels may mediate the different responses of C₄ crops to progressive soil drought. In this study, the effects of reduced N (N1, 0.8 g pot⁻¹) and adequate N (N2, 1.6 g pot⁻¹) supply on leaf physiology, plant growth and water use efficiency (WUE) of maize (C₄ crop) exposed to progressive soil drought grown at ambient CO₂ (a[CO₂], 400 ppm) and elevated CO₂ (e[CO₂], 800 ppm) concentration were investigated. The results indicated that compared with a[CO₂], net photosynthetic rate (A_n) and leaf water potential (Ψ_l) at e[CO₂] were maintained in maize leaves, while stomatal conductance (g_s), transpiration rate and leaf hydraulic conductance were decreased, leading to enhanced WUE from stomatal to leaf scale. Despite A_n and Ψ_l of e[CO₂] plants were more sensitive to progressive soil drought under both N fertilization levels, e[CO₂] would increase leaf ABA concentration ([ABA]_leaf) but decline the g_s response to [ABA]_leaf under N1 supply. e[CO₂] coupled with N1 fertilization was conducive to enlarging leaf area, promoting specific leaf area, root and total dry mass, whereas reduced stomatal aperture and plant water use under progressive drought stress, contributing to an improvement in plant WUE, implying a better modulation of maize leaf stomata and water status under reduced N supply combined with e[CO₂] responding to progressive soil drought. These findings in the current study would provide valuable advice for N management on maize (C₄) crop efficient water use in a drier and CO₂-enriched environment.

Durum wheat (Triticum durum Desf.) is a fundamental staple food for the countries of the Mediterranean basin. Climate change is predicted to cause a trend of increasing drought severity in this region in the near future, necessitating the improvement of durum wheat's resilience to drought stress. Using polyethylene glycol to simulate water scarcity, early vigour parameters in germinating seeds are quickly, easily and affordably assessed. Many screenings, however, only consider the seedling stage; consequently, genotypes identified as promising for cultivation in drought scenarios, may not show such features if drought appears in later phenological phases, as happens in Mediterranean climatic areas, generally prone to terminal drought. The correlation between drought stress resistance during the seedling stage (early vigour) and later stages in the life cycle is elusive due to the lack of scientific efforts. Here we used polyethylene glycol screening to classify fifty-five tetraploid wheat accessions into three clusters (susceptible, medium resistant and highly resistant to drought), based on morpho-physiological traits. These accessions included durum wheat cultivars and landraces, as well as ancestors like durum emmer wheat and wild emmer wheat. The results of the screenings were combined with subsequent pot experiments using nine randomly selected accessions, imposing terminal drought, and evaluating their performance. Principal component analysis was performed on data for net photosynthesis, stomatal conductance, transpiration and grain yield. Notably, the genotypes that performed best in the pot experiments were also those that performed well in the screening. Highly resistant candidates had in fact higher physiological and performance parameters than susceptible candidates. In summary, polyethylene glycol screening of germinating seeds resulted to be suitable to predictively evaluate drought resistance in tetraploid wheat accessions under terminal drought conditions, typical of Mediterranean climate zones. The reported data, thus evidence of how this inexpensive and simple method might be efficiently applied for large-scale phenotyping.

Increased frequency and severity of chilling damage events pose potential risks to crop performance and productivity due to climate change. Accurate and real-time access to chilling damage is important for crop growth and yield stability based on field's actual environment. To precisely identify regional chilling events and evaluate the impacts on crops, this study presents a model to estimate field air temperature in view of field crop situations. Land surface temperature, enhanced vegetation index, solar-induced chlorophyll fluorescence and solar declination were involved in the model. With field simultaneous continuous monitoring and multisource fused remote sensing data, the model was calibrated and validated in Jiefangzha Irrigation Area (JIA) and Changchun City (CC) in North China, accompanied by the determination coefficient ≥0.756, root mean square error ≤0.782°C, relative error ≤0.041 and consistency index ≥0.902. Meanwhile, sensitivities of the model factors were determined through path analysis, where the factors performed according to the order solar-induced chlorophyll fluorescence >solar declination >land surface temperature > enhanced vegetation index. Using the validated model, chilling damage to maize was further detected in JIA and CC from 2010 to 2020. Results showed that the severity of chilling damage was greater in CC than in JIA, along with the sterile-type occurring three events in JIA and seven in CC, while the delayed-type only twice in JIA in 2012 and 2016, but five times in CC in 2013, 2014, 2016, 2017 and 2019, respectively, being consistent with local statistics. In response to chilling damage, enhanced vegetation index and solar-induced chlorophyll fluorescence demonstrated the negative chilling effects on greenness and light use efficiency for fluorescence. Serious yield losses were caused, with yield-reducing by 5.00% (Dehui, 2013), 19.00% (Jiutai, 2014), 21.65% (Suburban district, 2016), 8.83% (Shuangyang, 2017) and 2.19% (Jiutai, 2019) in CC. The linear relationship between yield and growing degree days was a bit weakened by chilling damage, with the determination coefficient varying from 0.614 to 0.531. The increasing rate of yield with growing degree days decreased from 20.365 kg/(°C·d) in non-chilling damage years to 9.670 kg/(°C·d) in chilling damage years. These findings indicate that the presented model is especially adaptive for agricultural field environments, enabling rapid precision detection of chilling damage on crops at regional scales. It will provide references for gauging the impact of chilling damage on crops, finding efficient solutions to the stress and ensuring sustainable development of agriculture.