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Extreme weather events threaten food security, yet global assessments of crop waterlogging are rare. Here, we make three important contributions to the literature. First, we develop a paradigm that distils common stress patterns across environments, genotypes and climate horizons. Second, we embed improved process-based understanding into a contemporary farming systems model to discern changes in global crop waterlogging under future climates. Third, we elicit viable systems adaptations to waterlogging. Using projections from 27 global circulation models, we show that yield penalties caused by waterlogging increased from 3–11% historically to 10–20% by 2080. Altering sowing time and adopting waterlogging tolerant genotypes reduced yield penalties by up to 18%, while earlier sowing of winter genotypes alleviated waterlogging risk by 8%. We show that future stress patterns caused by waterlogging are likely to be similar to those occurring historically, suggesting that adaptations for future climates could be successfully designed using current stress patterns.

Cropping of rice and wheat (Triticum aestivum L.) in rotation contiguously in the same field is a fundamental pillar of double-cropping systems in southern China. Yields of such cropping systems are increasingly challenged as climate change (CC) drives increases in autumnal rainfall, delaying rice harvesting and subsequent sowing of wheat. Here, our purpose was to identify prospective traits of wheat crops enabling adaptation to later sowing and successively truncated growing seasons caused by CC. To identify traits that maintained or improved yields, we constructed 4,096 hypothetical genotypes underpinned by step-wise variations in parameters regulating phenology, growth and yield components. We then assimilated biophysical response surfaces through genotype (G) by environment (E) by management (M) analyses (G×E×M) using six locations spread across the breadth of southern China. We showed that later sowing reduced cumulative radiation interception, cumulative thermal time and crop capture of growing season rainfall. The culmination of these factors shortened crop duration and decreased biomass accumulation and retranslocation after anthesis, reducing grain number and penalising yields. Genotypes that had greater radiation use efficiency, longer juvenile phases and greater grain filling rates were more effective in alleviating yield losses with delayed sowing. However, not even the highest yielding genotype × management combination could entirely alleviate yield losses with delayed sowing. Our results suggest that CC and increasingly frequent extreme climatic events may reduce wheat yields in such cropping systems in the absence of other adaptation.

Ratoon rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested crop (main crop). The yield formation of ratoon rice crops is dependent on the panicles that regenerated from the stubble of the main crop. The regeneration ability is an index that is used to evaluate the germination quantity of regenerated buds. The source-sink relationship was closely related with regeneration ability of ratoon crop. However, the influence of source-sink regulation on the regeneration ability of ratoon rice has rarely been studied. Field experiments were conducted to examine the effects of source-sink regulation through leaf-cutting and spikelet-thinning on the regeneration rate of ratoon crop in central China in 2017 and 2018. The treatments included three leaf-cutting and two spikelet-thinning treatments, which were conducted at the full heading stage of the main crop. Spikelet-thinning increased the regeneration rate of ratoon crop by 20.9% in 2017 and 32.5% in 2018 as compared with the treatments with no spikelet-thinning. However, leaf-cutting decreased the regeneration rate of ratoon crop by 28.9% in 2017 and 7.6% in 2018 compared with the treatments with no leaf-cutting. The effects of spikelet-thinning on the regeneration rate were decreased as the number of cutting leaves increased. The negative effects of leaf-cutting on the regeneration rate were reversed by the treatment of thinning one half of spikelets. The regulatory effects of leaf-cutting and spikelet-thinning on regeneration rate were associated with the changes in the ratio of grain number to green leaf area, stubble dry weight and non-structural carbohydrates content in the stubble.

Ustiloxin A (UA) and ustiloxin B (UB), two major mycotoxins produced by the pathogen of rice false smut (RFS) during rice cultivation, have attracted increasing attentions due to their potential health risks. However, limited data are available about their occurrence and fate in paddy fields and contamination profiles in rice. In this study, a field study was performed to investigate the occurrence and translocation of UA and UB in RFS-occurred paddies. For the first time to our knowledge, we reported a ubiquitous occurrence of the two ustiloxins in the paddy water (range: 0.01-3.46 μg/L for UA and0.02-1.15 μg/L for UB) and brown rice (range: 0.09-154.08 μg/kg for UA and0.09-23.57 μg/kg for UB). A significant positive correlation was observed between ustiloxin levels in paddy water and brown rice (r

Unmanned aerial vehicles-collected (UAVs) digital red–green–blue (RGB) images provided a cost-effective method for precision agriculture applications regarding yield prediction. This study aims to fully explore the potential of UAV-collected RGB images in yield prediction of winter wheat by comparing it to multi-source observations, including thermal, structure, volumetric metrics, and ground-observed leaf area index (LAI) and chlorophyll content under the same level or across different levels of nitrogen fertilization. Color indices are vegetation indices calculated by the vegetation reflectance at visible bands (i.e., red, green, and blue) derived from RGB images. The results showed that some of the color indices collected at the jointing, flowering, and early maturity stages had high correlation (R2 = 0.76–0.93) with wheat grain yield. They gave the highest prediction power (R2 = 0.92–0.93) under four levels of nitrogen fertilization at the flowering stage. In contrast, the other measurements including canopy temperature, volumetric metrics, and ground-observed chlorophyll content showed lower correlation (R2 = 0.52–0.85) to grain yield. In addition, thermal information as well as volumetric metrics generally had little contribution to the improvement of grain yield prediction when combining them with color indices derived from digital images. Especially, LAI had inferior performance to color indices in grain yield prediction within the same level of nitrogen fertilization at the flowering stage (R2 = 0.00–0.40 and R2 = 0.55–0.68), and color indices provided slightly better prediction of yield than LAI at the flowering stage (R2 = 0.93, RMSE = 32.18 g/m2 and R2 = 0.89, RMSE = 39.82 g/m2) under all levels of nitrogen fertilization. This study highlights the capabilities of color indices in wheat yield prediction across genotypes, which also indicates the potential of precision agriculture application using many other flexible, affordable, and easy-to-handle devices such as mobile phones and near surface digital cameras in the future.

Ustiloxins, a group of bioactive metabolites produced by the pathogen of rice false smut (RFS), have emerged as ubiquitous contaminants in RFS-occurred paddy fields and could accumulate in rice. Nevertheless, the prevalence of ustiloxins in rice and exposure risks of humans are limited. In this study, concentrations of ustiloxin A (UA) and ustiloxins B (UB), which are two predominant ustiloxins, were measured in 240 rice samples from China and 72 rice samples from 12 other counties. The detection rates (DRs) of UA and UB were 82.1% and 49.3%, respectively, and their concentrations in rice ranged from below detection limit (LOD: 0.22 μg/kg) to 85.96 μg/kg dw. Furthermore, for the first time, we reported the occurrence of UA (DR = 22.8%) in urine collected from residues of Enshi city, China. Urinary UA were significantly correlated with the activities of alanine aminotransferase in male, and this male-biased hepatotoxicity was further confirmed in mice exposure experiment. This study for the first time reported the widespread geographical distribution of ustiloxins in rice, as well as emphasized the occurrence of internal exposure and potential health risk in humans.

Climate change (CC) in central China will change seasonal patterns of agricultural production through increasingly frequent extreme climatic events (ECEs). Breeding climate-resilient wheat (Triticum aestivum L.) genotypes may mitigate adverse effects of ECEs on crop productivity. To reveal crop traits conducive to long-term yield improvement in the target population of environments, we created 8,192 virtual genotypes with contrasting but realistic ranges of phenology, productivity and waterlogging tolerance. Using these virtual genotypes, we conducted a genotype (G) by environment (E) by management (M) factorial analysis (G×E×M) using locations distributed across the entire cereal cropping zone in mid-China. The G×E×M invoked locally-specific sowing dates under future climates that were premised on shared socioeconomic pathways SSP5-8.5, with a time horizon centred on 2080. Across the simulated adaptation landscape, productivity was primarily driven by yield components and phenology (average grain yield increase of 6-69% across sites with optimal combinations of these traits). When incident solar radiation was not limiting carbon assimilation, ideotypes with higher grain yields were characterised by earlier flowering, higher radiation-use efficiency and larger maximum kernel size. At sites with limited solar radiation, crops required longer growing periods to realise genetic yield potential, although higher radiation-use efficiency and larger maximum kernel size were again prospective traits enabling higher rates of yield gains. By 2080, extreme waterlogging stress in some regions of mid-China will impact substantially on productivity, with yield penalties of up to 1,010 kg ha

Developing energy-saving and high-efficiency crop managements is required for food and energy security. Huang-Huai-Hai Plain produces more than 60% of the wheat in China. However, no published studies have investigated the energy budget of wheat production in this area. Using an input-output energy analysis from 2012 to 2014, we assessed energy flow of various managements. The average energy input and output ranged from 37.5 to 57.4 and 170.9–263.9 GJ ha−1, respectively. Compared with rainfed wheat (W1), irrigated wheat presented significantly higher energy inputs and outputs. Compared with farmers' practices (W2), optimized management based on soil water content (SWC) at depths of 0–20 (W3) and 0–40 cm (W4) reduced energy use; however, this reduction did not occur at soil depths of 0–60 cm (W5). Among four irrigated managements, W4 produced the highest energy output with the lowest energy input. Moreover, W4 presented the highest net energy, energy use efficiency, and energy productivity, which were 8.2%, 15.6%, and 14.9% higher than those presented by W2, respectively. The lowest specific energy in W4 indicated that the energy consumed to produce 1 kg of wheat can be substantially reduced via efficient water management. SWC-based water management had a significant positive effect on energy-related factors without sacrificing crop productivity.

Water-saving irrigation techniques are critical for winter wheat (Triticum aestivum L.) development in the Huang-Huai-Hai Plain of China and assist in coping with increasingly serious water shortages. A micro-sprinkling irrigation experiment was conducted from 2010 to 2012 to investigate how soil water distribution, photosynthesis, drymass accumulation, and grain yield responded to different sprinkling angles. Five treatments were designed: Rainfed, W35, W50, W65, and W80. The Rainfed treatment consisted of no irrigation throughout the growing season. The W35 to W80 treatments involved irrigation applied through micro-sprinkling hoses with sprinkling angles of 35°, 50°, 65°, and 80°, respectively. Micro-sprinkling irrigation could regulate soil water content to the target level of previous designs. After irrigation, distribution of soil water across the four inter-rows was the most uniform in W80. Following the intermediate stage of grain filling, when increasing sprinkling angle from 35° to 80°, the mean actual photochemical efficiency, maximum quantum yield of the PSII, flag leaf photosynthetic rate, and canopy apparent photosynthetic rate (CAP) significantly increased. A high sprinkling angle is favorable in improving the grain-filling rate as well as lengthening its duration. At maturity, the W80 treatment produced the highest dry matter (DM) in the stem plus sheath and the highest grain weight and total DM, leading to the highest 1000-grain weight, grain yield, and water-use efficiency (WUE). Overall, the optimum sprinkling angle of the micro-sprinkling hose for supplemental irrigation (SI) of winter wheat after jointing is 80°, and the benefits are hypothesized to arise from an increased uniformity of soil water conditions.

Ratoon rice, which refers to the production of a second rice crop from the stubble after the harvest of the main crop, is considered a green and resource-efficient rice production system. This review was undertaken to comprehensively evaluate the performance of ratoon rice in comparison with other rice cropping systems regarding the grain yield, grain quality, economics, and sustainability. In addition, the morphology and physiological bases associated with the performance of ratoon rice was also reviewed. With good crop management, ratoon rice gives a yield equivalent to 60% that of the main crop but with a 50% reduction in resources and labor input. Moreover, rice ratooning improves the grain quality, increases the profits for farmers, and decreases greenhouse gas emissions. Several agronomic practices for tiller-bud regeneration, such as nutrient and water management at the harvest of the main crop, establishment of the main crop, stubble cutting height and the variety selection and integrated technologies for the control of diseases and insects, were suggested to strongly affect the performance of ratoon rice. However, constraints, including low and unstable yield of ratoon crop, lodging, and lack of suitable cultivars and specialized rice harvester for the ratoon rice system, have limited the wide scale adoption of ratoon rice. Meanwhile, the mechanisms underlying the specific management strategies for ratoon rice need to be deeply studied.

Background The middle and lower reaches of the Yangtze River plain produce the second highest amount of wheat in China; however, waterlogging is an important environmental factor that substantially affects the yield production of wheat (Triticum aestivum L.) in this region. Methods In this study, seven treatments were implemented, including no waterlogging and exogenous 6-benzylaminopurine (6-BA) as a control (CK); waterlogging at booting (BW), anthesis (AW) and 15 days after anthesis (DAA, FW); and spraying 6-BA before waterlogging at booting (BW-6BA), anthesis (AW-6BA) and 15 DAA (FW-6BA), to determine the ability of 6-BA to alleviate the harmful impact of waterlogging on aboveground biomass production and grain yield. The widely cultivated wheat cultivar “Zhengmai 9023” was used. Results The results showed that more than 190.0 mm of rainfall, which accounted for approximately 45.0% of the precipitation over the whole wheat growing season, was distributed after the booting stage (April and May). In all waterlogged treatments, the photosynthetic rate, aboveground biomass and grain yield decreased, but the differences between the CK and the FW treatment were not significant. The grain yield decreased by 18.38%, 41.79% and 5.67% in the BW, AW and FW treatments, respectively. Spraying 6-BA before waterlogging enhanced the root activities after anthesis and then decreased the malondialdehyde concentrations of the flag leaves and the third leaf, increased the photosynthetic rate of the flag leaves and enhanced aboveground biomass and grain yield. Among the increments between the treatments, the increments between the BW and BW-6BA treatments were the largest, but between the FW and FW-6BA were smallest. In comparison to the other waterlogging treatments, the grain yields from the FW and FW-6BA treatments were significantly higher because of the higher kernel numbers per spike. The results indicated that waterlogging after the booting stage restrained the dry matter production of winter wheat, but spraying 6-BA before waterlogging slowed the plant senescence rate and reduced grain yield loss.

Background Increasing rice yield and its stability are important to achieving the sustainability of rice production. Rice yields have increased substantially in China during recent decades, but information on the trend in yield stability has been limited. In this study, the trends in rice yield and rice yield stability from 1949 to 2015 were analysed in China's rice production. Results The results showed that rice yields for all 16 provinces presented an increasing trend during the study period. The national annual rice yield gain was 86.0 kg ha-1 during the last six decades, varying from 48.4 to 106.0 kg ha-1 in different provinces and exhibiting linear, bilinear, or trilinear relationships. Remarkably, the annual yield increase was smaller in provinces dominated by double rice cropping systems than in the other provinces. Notably, rice yield stagnations have occurred in recent years at provincial and national levels. Absolute residuals over time showed slight increases in four of 16 provinces, indicating a reduction in yield stability in these four provinces. However, the relative yield residuals exhibited a clear trend towards increased yield stability for all 16 provinces. The rice yields of newer cultivars planted with improved crop management practices were consistently higher and more stable than with cultivars from the beginning of the study period. Conclusion This study revealed that rice yield in China has increased substantially, accompanied by improved stability over the last six decades. Given the spatial difference, this study emphasizes the priority of orienting long-term on-farm studies to investigate yield stability. © 2020 Society of Chemical Industry.

Tillage is an important management tool for tackling and promoting water conservation and improving crop yield in northern China, where winter wheat production is frequently threatened by drought. Although plowing (P) and rotary tillage (R) practices are widespread in the region, only few studies have focused on subsoiling. Three practices, namely P, R, and RS (rotary tillage every year and subsoiling interval of 2 years), were evaluated under field conditions over a period of 7 years. The average soil water consumption from RS increased by 24.6% and 69.0% compared to that from P and R, respectively, from sowing to jointing in the 40–100 cm soil layer, and increased by 54.2% and 81.6% compared to that from P and R, respectively, from jointing to maturity in the 80–180 cm soil layer. The net photosynthesis rate and stomatal conductance of flag leaf from RS treatment from 20 days after anthesis (DAA) to 30 DAA were significantly higher than those from P and R, which is likely the reason for the higher dry matter accumulation at maturity in RS than that in P and R. The 4-year average of grain yield and water use efficiency from RS increased by 22.7% and 37.0%, respectively, compared to that from P and by 7.7% and 11.9%, respectively, compared to that from R. Thus, RS is the best method for increasing grain yield and water use efficiency of winter wheat in northern China.

Water shortage threatens agricultural sustainability in the Huang-Huai-Hai Plain of China. Thus, we investigated the effect of supplemental irrigation (SI) on the root growth, soil water variation, and grain yield of winter wheat in this region by measuring the moisture content in different soil layers. Prior to SI, the soil water content (SWC) at given soil depths was monitored to calculate amount of irritation water that can rehydrate the soil to target SWC. The SWC before SI was monitored to depths of 20, 40, and 60 cm in treatments of W20, W40, and W60, respectively. Rainfed treatment with no irrigation as the control (W0). The mean root weight density (RWD), triphenyl tetrazolium chloride reduction activity (TTC reduction activity), soluble protein (SP) concentrations as well as catalase (CAT), and superoxide dismutase (SOD) activities in W40 and W60 treatments were significantly higher than those in W20. The RWD in 60–100 cm soil layers and the root activity, SP concentrations, CAT and SOD activities in 40–60 cm soil layers in W40 treatment were significantly higher than those in W20 and W60. W40 treatment is characterized by higher SWC in the upper soil layers but lower SWC in the 60–100-cm soil layers during grain filling. The soil water consumption (SWU) in the 60–100 cm soil layers from anthesis after SI to maturity was the highest in W40. The grain yield, water use efficiency (WUE), and irrigation water productivity were the highest in W40, with corresponding mean values of 9169 kg ha−1, 20.8 kg ha−1 mm−1, and 35.5 kg ha−1 mm−1. The RWD, root activities, SP concentrations, CAT and SOD activities, and SWU were strongly positively correlated with grain yield and WUE. Therefore, the optimum soil layer for SI of winter wheat after jointing is 0–40 cm.

Water shortage threatens agricultural sustainability in China, effective water-saving technologies urgently need to be developed. In this study, five treatments were conducted: rainfed (W0), a local supplemental irrigation (SI) practice (W1), and three treatments in which soil water content was tested prior to SI, specifically at 0–20 (W2), 0–40 (W3) and 0–60 cm (W4) soil layers. Soil water consumption in W3 had no differ with W2 but was higher than W1 and W4. Crop evapotranspiration in W1, W3 and W4 treatments were higher than that in W2. W3 treatment had higher leaf area index than W1 and W4 at later grain filling stages. The mean photosynthetically active radiation capture ratio in W3, especially at 20, 40 and 60 cm plant heights, were significantly higher than those in W1, W2 and W4. The chlorophyll content index, actual photosynthetic activities, catalase and superoxide dismutase activities of flag leaves from W3 were the highest after the middle grain filling stages. W3 treatment obtained the highest grain yield (9169 kg ha−1) and water use efficiency (20.8 kg ha−1 mm−1) in the two seasons. These benefits likely accrued through created a suitable soil moisture environment in W3 treatment.

A shortage of water threatens agricultural sustainability in the Huang-Huai-Hai Plain of China. Effective water-saving technologies need to be developed urgently. The experiment reported here, conducted between 2010 and 2012, aimed to determine how the length of the micro-sprinkling hose delivering supplemental irrigation affected photosynthetsis, dry matter (DM) accumulation, grain filling, and yield of winter wheat. Four treatments were compared: rainfed (W0) and irrigated with micro-sprinkling hoses with lengths of 40 m (W40), 60 m (W60), and 80 m (W80). The relative soil water content in the 0–140 cm soil horizon (RSWC) did not differ between 0 and 40 m from the proximal border of irrigated plots either in W40 or W60, and no differences in RSWC were observed across four inter-rows, spaced 22.9 cm apart, from the micro-sprinkling hoses in W40. However, RSWC decreased significantly with increasing distance from the proximal border in W80. There were no differences in mean actual photochemical efficiency (ΦPSII), maximum quantum yield of the PSII ( F v/ F m), flag leaf photosynthetic rate ( P n) or canopy apparent photosynthetic rate (CAP) 20 days after anthesis (DAA) between plants from W40 and W60, but all were greater in plants from W40 and W60 than in plants from W80. The ΦPSII, Fv/Fm, Pn, and CAP in plants from W80, but not W40, decreased significantly with increasing distance from the proximal border from 20 DAA. The total DM and the harvest index of plants from W40 were greater than those of plants from W60 and W80. The grain filling rate in the middle and later filling stages, 1000-grain weight, grain yield and water use efficiency became less as the length of micro-sprinkling hose was increased from 40 m to 80 m. In this study, the optimum length of micro-sprinkling hoses for irrigating wheat after jointing was 40 m to 60 m. The results indicate the importance of uniformity of irrigation water distribution in increasing the productivity of winter wheat.

The development of water-saving irrigation techniques is required for future food and ecological security in the Huang-Huai-Hai Plain of China, which suffers from severe water shortage. Field experiments were performed over two years (2010/2012) with the high-yielding winter wheat cultivar Jimai22 to examine the effects of supplemental irrigation (SI) with micro-sprinkling hoses on water distribution in soil and grain yield of winter wheat. Five irrigation treatments were tested: rainfed (T0), and irrigated with micro-sprinkling hoses with minimum sprinkling angles (i.e. the angle between the tangent of the initial water jet and the horizontal) of 35° (T1), 50° (T2), 65° (T3) and 80° (T4). The SI brought soil water content in the 0–140 cm profile to 75% field capacity (FC) at jointing and 70% FC at anthesis in 2010/2011, and 70% FC at both jointing and anthesis in 2011/2012. The distribution uniformity of irrigation water (Cμ) in soil after irrigation at jointing and anthesis was increased by increasing sprinkling angle from 35° to 80°. The increase in the soil water content in the 0–40 cm soil layer of the inter-rows decreased significantly with increasing distance from the micro-sprinkling hose in T1, T2 and T3, but there was no significant difference between inter-rows in T4. As sprinkling angle was increased from 35° to 80°, the amount of SI required (CIR), soil water consumption (ΔW) and crop evapotranspiration (ETc) decreased. The grain filling rate at the later filling stage, 1000-kernel weight, dry matter accumulation (DM), grain yield, and agronomic water use efficiency (AWUE) were significantly higher in T4 than in T1, T2 and T3. The CIR, ΔW and ETc had significant, negative, linear relationships with Cμ. However, DM, grain yield, and AWUE had significant, positive, linear relationships with Cμ with mean correlation coefficients of 0.60, 0.91 and 0.91, respectively. In this study, the optimum sprinkling angle of micro-sprinkling hoses for irrigating wheat after jointing was 80°.