Effects Of Irrigation At Different Growth Stages On Growth,Yield And Economic Efficiency Of Semi-winter Wheat

Moisture is one of the important factors affecting the wheat yield and quality.Due to the uneven spatial and temporal distribution of precipitation among different climate types and seasons,the amount of precipitation is not synchronized with the water demand at the different growth stages in wheat,which cannot fully meet the needs of wheat growth and development,ultimately affecting the formation of production and economic benefits.The present study was conducted in three locations:The experiment was carried out in the agricultural demonstration zone of Suining County,Xuzhou from November 2016 to June 2018.The semi-winter varieties Xumai 33 was chosen as the research material to study the effects of different periods and different irrigation methods(micro-spray irrigation and irrigation)on wheat yield and its structure,ecological microenvironment,physiological characteristics,and grain quality.From November 2017 to June 2018,an auxiliary test was conducted at the Potting Test Site of Yangzhou University,which was divided into two parts:the seedling stage and late growth stage.Six semi-winter wheat varieties were selected as the research material in the seedling experiment.After the mild drought in the three-leaf stage,the different irrigation rates were applied to investigate the effects of drought stress on the morphological and physiological indexes of different varieties of wheat and the recovery performance after re-irrigation.In the middle and late growth stages,the semi-winter varieties Xumai 33 and Huaimai 33 were chosen to analyze the effects of different irrigation amount on wheat yield,its physiological characteristics and grain quality after moderate drought in the jointing and anthesis stages.The results will provide a basis for rational irrigation in the semi-winter wheat drought conditions in Jiangsu.The main results were as follows:1.Different semi-winter wheat varieties have different drought tolerance.Relative water content(RWC)and chlorophyll content of wheat varieties decreased significantly after drought,and the Malondialdehyde(MDA)content increased significantly.The weight of dry matter per plant,leaf area per plant and seedling height were inhibited.2.Different irrigation rates were applied after mild drought stress in the three-leaf stage.The physiological and morphological indicators of each variety recovered or exceeded the control treatment.Among them,varieties with highly-drought tolerance have a fast recovery rate,but the compensation effect is lower than that of drought-tolerant varieties.3.The irrigation treatment after moderate drought in the jointing and anthesis period reduced spikelet number and the weight of both superior grains and inferior grains.Finally,the yield of Xumai 33 decreased by 9.83%,and Huaimai 33 decreased by 8.85%.After drought stress during the different periods,the yield reduction was the lowest in the jointing stage,and the yield reduction in the re-irrigation treatment was the highest after the two droughts.Among the relative water contents of different soils,the treatment with a relative water content of 60-65%and 70-75%could restore plant growth to varying degrees,and the treatment yield was slightly higher with 70-75%relative water content.4.Under different periods and different irrigation methods(micro-spray irrigation and border irrigation),irrigation significantly increased wheat grain yield,and the final yield increased by an average of 20.64%.Among them,the irrigation yield increased by 15.79%during the jointing stage,and the irrigation yield increased by 27.67%with the jointing and booting irrigation.The increase in the three glasses of water was 32.11%,which was the largest in all treatments.Both watering at the booting stage and anthesis stage can effectively reduce canopy temperature,increase canopy humidity,and improve the field microclimate of wheat growth.Irrigation reduced the soil temperature to a certain extent,which was beneficial to improve the absorption capacity of the root system and the photosynthetic performance of the leaves,and improved the ability of the plants to absorb nutrients in the soil and the photosynthetic capacity of the aboveground.Under different irrigation methods,the effect of micro-spray irrigation is not as good as that of border irrigation,but it saves water consumption significantly.The average irrigation rate is 35.14%,and the irrigation benefit is increased by 34.11%,which effectively improved the growth status and grain quality of wheat plants,and achieves the organic unity of high efficiency and high quality.5.It is preliminarily clarified that the soil moisture of the rice stubble in the southern regions of Yellow and Huai River is better when sowing,and it can be used without irrigation.In the case of the drought season,considering the yield and cost,grain quality,water use efficiency and compensation effect,it is recommended to use micro-spray irrigation.Irrigation in jointing+booting +anthesis stage achieved the supreme yield after drought,and jointing+booting stage micro-spray irrigation obtained the high yield,water saving,efficiency and quality after a drought.