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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

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.

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.

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

The fraction of absorbed photosynthetically active radiation (fAPAR) is a critical biophysical parameter for crop growth monitoring and yield estimation. Remote sensing provides an efficient way for measuring fAPAR over large areas, compared with the time-consuming and labor-intensive field measurements. However, the optical remote sensing signals usually saturate over dense vegetation (e.g., Leaf Area Index (LAI) > 5 or fAPAR > 0.7), limiting the performance of optical remote sensing in modeling fAPAR. Multi-source remote sensing data fusion has proven to be a feasible method to overcome the saturation problem of optical remote sensing in vegetation monitoring, but little is known about the performance of optical, structural and thermal features fusion for modeling winter wheat fAPAR. Also, the modeling powers of optical, structural, and thermal features for fAPAR estimation have seldom been compared. To fill in these knowledge gaps, the very high spatial resolution RGB-optical and thermal imagery collected by Unmanned Aircraft Vehicle (UAV) were used to quantify the powers of RGB-derived vegetation indices (VIs), Structural Indices (SIs, crop height/canopy cover), and Canopy Temperature (CT) and their combinations in modeling winter wheat fAPAR in this study. The modeling powers of different remote sensing features were compared with the commonly used hyperspectral vegetation indices (HVIs) from field spectrometer measurements. Results showed that (1) multi-source data fusion that integrates optical, structural, and thermal features provided the best model in winter wheat fAPAR mapping (R2 = 0.907 and RMSE = 0.041) ; (2) the RGB imagery-derived optical (i.e., RGB VIs) and structural features (i.e., RGB SIs) were important preditors for winter wheat fAPAR modeling, and their combination can steadily improve the modeling accuracy (~2% improvement in R2 compared to optical-only model); (3) the thermal feature alone performed the worst among all experiments, but it still can complement other types of remote sensing features (i.e., RGB VIs&SIs) and further improve the modeling accuracy within the framework of data fusion (~3% improvement in R2 compared to optical-only model). In general, this study indicates that the framework of multi-source remote sensing data fusion can provide more accurate, efficient measurements of winter wheat fAPAR for crop management in precision agriculture, which can help improve resource utilization efficiency (e.g., determine where and when to apply nitrogen fertilizer) and ensure food security in the face of climate change.

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.

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°.