Shun-Li Zhou

Expression of chemosensory proteins in hairs on wings of Locusta migratoria (Orthoptera: Acrididae)

The hairs on the wings of Locusta migratoria were observed and mapped using light microscopy, as well as by scanning and transmission electron microscopy. Based on their ultrastructure, we can distinguish four main types of hairs on the wings of adult L. migratoria, viz, short, medium and long hairs, and sensilla chaetica. The long hairs are located only on the ventral surface of the hindwing, whereas the other three types are present both on the dorsal and ventral surfaces of forewing and hindwing in both sexes. Medium hairs and sensilla chaetica are significantly more abundant on the dorsal surface of forewings in both females and males, than on the ventral surface, whereas the opposite was observed for short hairs (P < 0.01). No significant difference between males and females was observed in the density of any type of hairs (P > 0.1). Several dendritic branches, enveloped by a dendrite sheath, are situated in the lymph cavity of sensilla chaetica. Instead, no dendritic structure was observed in the cavity of the other three types of hairs. Immunocytochemical localization of chemosensory proteins (CSPs) was performed on ultrathin sections of hairs on wings. The antiserum against chemosensory proteins from L. migratoria (LmigCSP‐II) strongly labelled sensilla chaetica, with gold granules only found in the outer sensillum lymph. In addition, the epidermal cell membrane of the wing was stained by the antiserum against LmigCSP‐II. The other three types of hairs were never labelled. The results indicate that the wings might involve in contact chemoreception process.

Contribution of ear photosynthesis to grain yield under rainfed and irrigation conditions for winter wheat cultivars released in the past 30 years in North China Plain

Abstract To understand the contribution of ear photosynthesis to grain yield and its response to water supply in the improvement of winter wheat, 15 cultivars released from 1980 to 2012 in North China Plain (NCP) were planted under rainfed and irrigated conditions from 2011 to 2013, and the ear photosynthesis was tested by ear shading. During the past 30 years, grain yield significantly increased, the flag leaf area slightly increased under irrigated condition but decreased significantly under rainfed condition, the ratio of grain weight:leaf area significantly increased, and the contribution of ear photosynthesis to grain yield changed from 33.6 to 64.5% and from 32.2 to 57.2% under rainfed and irrigated conditions, respectively. Grain yield, yield components, and ratio of grain weight:leaf area were positively related with contribution of ear photosynthesis. The increase in grain yield in winter wheat was related with improvement in ear photosynthesis contribution in NCP, especially under rainfed condition.

Dynamic Responses of Nitrogen Accumulation and Remobilization in Summer Maize Organs to Nitrogen Fertilizer

A successive two years’ field experiment with five N application rates was conducted using hybrid Zhengdan 958. The results showed that the process of N accumulation in all organs except grain conformed to a unimodal curve in the whole life cycle. The N accumulation in blade, bract, and cob reached the peak at around 12 days after silking, and that in stem and sheath at silking stage and then decreased gradually. The N accumulation in grain and the whole plant continuously increased, and the maximum value appeared at maturity. Compared with other organs, blade was more sensitive to N supply and N deficit stress made the N accumulation peak in advance, accelerated blade N remobilization and promoted senescence of blade. N supply significantly improved N accumulation amount and N accumulation rate in all organs at various stages, but did not change the trend of N accumulation. On the whole, the demands of maize organs for N could be met at the N application rate of 180 kg N ha-1 , and a higher grain yield also achieved. According to the maximum value of accumulated N in organs, the contribution of remobilized N from maize organs to grain showed a trend of blade stem and sheath cob bract, and the mean total contribution rate was 53.3%, of which cob and bract accounted for 12.3%, showing an essential part for grain N, too.

Reduced irrigation increases the water use efficiency and productivity of winter wheat-summer maize rotation on the North China Plain

The groundwater table has fallen sharply over the last 30years on the North China Plain, resulting in a shortage of water for winter wheat irrigation. Reducing irrigation may be an important strategy to maintain agricultural sustainability in the region; however, few studies have evaluated the transition from conventional irrigation management practices to reduced irrigation management practices in the winter wheat-summer maize rotation system. Here, we compare the yield, water consumption, and water use efficiency of winter wheat-summer maize rotation under conventional irrigation and reduced irrigation on the North China Plain from 2012 to 2015. Reducing irrigation decreased the yield but increased the water use efficiency and significantly advanced the harvest date of winter wheat. As a result, the summer maize sowing date advanced significantly, and the flowering date subsequently advanced 2-8days, thus extending the summer maize grain-filling stage. Therefore, the yield and water use efficiency of summer maize were higher under reduced irrigation than conventional irrigation, which compensated for the winter wheat yield loss under reduced irrigation. In addition, under reduced irrigation from 2012 to 2015, the yield and water use efficiency advantage of the winter wheat-summer maize rotation ranged from 0.0 to 9.7% and from 4.1 to 14.7%, respectively, and water consumption and irrigated water decreased by 20-61mm and 150mm, respectively, compared to conventional irrigation. Overall, the reduced irrigation management practice involving no irrigation after sowing winter wheat, and sowing summer maize on June 7 produced the most favorable grain yield with superb water use efficiency in the winter wheat-summer maize rotation. This study indicates that reducing irrigation could be an efficient means to cope with water resource shortages while maintaining crop production sustainability on the North China Plain.

Meta-analysis of no-tillage effect on wheat and maize water use efficiency in China

No-tillage (NT) is a popular agricultural technique worldwide, but it remains unclear how NT affects the yield, evapotranspiration (ET), and water use efficiency (WUE) of maize and wheat. We performed a meta-analysis of the NT effects on the yield, ET and WUE for wheat and maize based on the literatures published during 1950-2018. Yield, ET, and WUE varied by species, region, and agronomic and environmental factors. Averaged across all the geographic locations NT had no effect on the yield, ET, or WUE of wheat in northwestern and northern China, and no effect on the yield or ET of maize, but significantly increased the maize WUE by 5.9%. NT increased the WUE and yield of wheat in regions with ≤400 mm of mean annual precipitation, increased the yield in regions with 400-600 mm of precipitation, and decreased the yield and ET in regions with ≥600 mm, but had no effects on maize. In the first 1-3 years of NT implementation, the wheat ET was reduced. However, a significant decrease in maize yield and ET occurred in 3-6 years of NT implementation. Meanwhile, yield and WUE in both wheat and maize were improved after >6 years. In general, NT effect on yield, ET, or WUE was not related to soil texture. However, NT increased maize WUE in a medium soil texture. Without crop rotation, NT increased wheat yield and ET but decreased maize yield. No NT effects were observed when crop residues retained and under crop rotation. Consequently, optimizing NT effects on yield, ET and WUE for wheat and maize in China was largely dependent on environmental conditions and management practices.

Effect of Source-Sink Manipulation on Photosynthetic Characteristics of Flag Leaf and the Remobilization of Dry Mass and Nitrogen in Vegetative Organs of Wheat

The photosynthetic characteristics of flag leaf and the accumulation and remobilization of pre-anthesis dry mass (DM) and nitrogen (N) in vegetable organs in nine wheat cultivars under different source-sink manipulation treatments including defoliation (DF), spike shading (SS) and half spikelets removal (SR) were investigated. Results showed that the SS treatment increased the photosynthetic rate (Pn) of flag leaf in source limited cultivar, but had no significant effect on sink limited cultivar. The SR treatment decreased the Pn of flag leaf. Grain DM accumulation was limited by source in some cultivars, in other cultivars, it was limited by sink. Grain N accumulation was mainly limited by source supply. The contribution of pre-anthesis dry mass to grain yield from high to low was stem, leaf and chaff, while the contribution of pre-anthesis N to grain N from high to low was leaf, stem and chaff. Cultivars S7221 and TA9818 can increase the contribution of remobilization of DM and N to grain at the maximum ratio under reducing source treatments, which may be the major reason for these cultivars having lower decrease in grain yield and N content under reducing source treatments.

Critical Nitrogen Dilution Curve and Nitrogen Nutrition Index for Summer Maize in North China Plain

In order to verify the applicability of critical nitrogen (N) dilution curve for summer maize in North China Plain, and the feasibility of N nutrition index (NNI) in evaluating N nutrition status of maize plant, a 2-year experiment with five N-fertilizer treatments (0, 60, 120, 180, and 240 kg N ha –1 ) was conducted using the cultivar Zhengdan 958. The results showed that the above ground biomass (W) increased significantly with increasing N-fertilizer application within a certain range. The data of above ground biomass and corresponding N concentration for each sampling stage were divided into N limited group and N non-limited group based on the statistical results, then the critical N concentration (N c ) was calculated and the critical N dilution curve model (N c =34.914W –0.4134 ) for summer maize was established, and the model parameters had a good similarity to these reported. NNI calculated based on the critical N dilution curve model had a significant correlation with relative N uptake amount, or relative above ground biomass or relative yield. Therefore, critical N dilution curve and NNI can be used to predict plant N c and characterize plant N status in summer maize in North China Plain.

Increasing the abscisic acid level in maize grains induces precocious maturation by accelerating grain filling and dehydration

Elevated levels of abscisic acid (ABA) are closely associated with cereal grain filling under water deficit. However, grain dehydration during grain filling has received little attention. In this paper, three experiments with drought stress and exogenous ABA treatments were conducted to investigate the relationship between ABA and grain dehydration in maize (Zea mays L.) during the grain-filling period. The results indicated that exogenous ABA application and drought stress led to the same tendency of the grain ABA concentration, carbohydrate concentration and dehydration rate to increase but the moisture content to decrease. Moreover, the time to reach the maximum grain-filling rate was advanced, and the grain-filling period was shortened. In in vitro culture experiments, the sucrose-to-starch conversion was promoted, mainly influenced by sucrose synthase, ADP-glucose pyrophosphorylase (AGPase), and soluble starch synthase during the middle grain-filling stage, and the improvement in starch synthesis was possibly induced by AGPase. Correlation analysis showed that the ABA level was significantly negatively correlated with the moisture content and positively correlated with the starch level. A close and notably negative correlation was observed between the grain moisture content and starch level. In summary, adequate grain ABA promoted sucrose-to-starch conversion, shortened the duration of grain filling and accelerated grain dehydration, resulting in precocious grain maturation.

Effect of Dry Matter Accumulation Characteristics on Yield of Winter Wheat Analyzed by Dynamic Simulation Model

To disclose the quantitative relationship between yield and dry matter accumulation in winter wheat, we designed three field experiments to obtain wheat populations with varying sowing date, basic seedlings, amounts of basic fertilizers, date and quantity of topdressed nitrogen fertilizer, irrigation amounts before wintering, amounts and date of irrigation after regreening of wheat in 2009–2010 and 2010–2011 growing seasons. Dry matter accumulation before wintering was represented by dry weight per plant and total stem and tiller numbers at prewintering stage, while dry matter after wintering was described by the Logistic curve characteristics based on relative accumulated temperature (R GDDi ). The grain yield and yield components of winter wheat were closely related to characteristic parameters such as maximum rate of dry matter accumulation and two inflection points in the curve for dry matter accumulation rate. Paired-sample t-test was used to validate the models established, and no significant difference was observed between the simulated and observed values. The results indicate that the Logistic model is able to describe the process of dry matter accumulation and the formation of grain yield and its components in winter wheat. The models established can be used in analysis of population regulation in winter wheat.