Effects Of Irrigation Once In Spring On Different Dates On Growth And Water Use Efficiency For Winter Wheat

The cultivated area and yield of winter wheat in Hebei Province are at the forefront of the country,and the natural precipitation during wheat growth can not meet the needs of its normal growth.In order to achieve high and stable yield,the spring irrigation of winter wheat are dominated by two to three water in this area,and the demand for irrigation water is large.However,surface water resources of Hebei Province is very lack,agricultural irrigation long-term over-exploitation of groundwater,has caused a large groundwater funnel area,triggered a series of geological disasters such as land subsidence.In this context,Hebei Province has implemented the water-saving pressure mining system,the development of water-saving irrigation technology,reducing irrigation water consumption of winter wheat is one of the main measures.In order to alleviate the pressure of high consumption of agricultural water resources,improve the water use efficiency of agricultural,promote the sustainable development of wheat production,and ensure national food security,it is necessary to reduce spring irrigation frequency of winter wheat to once,and find out the suitable date of irrigation once in spring of winter wheat.This study was carried out at the dryland water-saving agriculture experimental station of Hebei Academy of Agricultural and Forestry Sciences from 2018 to 2020.The single-factor randomized block design was used in the experiment.During the jointing stage of winter wheat,five treatments of spring irrigation with one water at 0 d(AJ0),5 d(AJ5),10 d(AJ10),15 d(AJ15)and 20 d(AJ20)after jointing and two control treatments of no spring irrigation(CK1)and spring irrigation with two water(CK2)were set,to clarify the effects of the treatment with irrigation once in spring on Different Dates on the growth,yield,water consumption law and Water Use Efficiency for Winter Wheat,and determine the appropriate the date of spring irrigation with one water treatment for winter wheat.The main results are as follows:(1)Under the condition of irrigation once in spring,with the delay of irrigation date,the final plant height of winter wheat increased first and then decreased in two experimental years,the highest was AJ5 treatment,followed by AJ0 and AJ10 treatment,and the difference was not significant in this three treaments.With the delay of irrigation date,maximum leaf area index showed a decreasing trend.The final plant height and maximum leaf area index of all treatments with irrigation once in spring were significantly higher than those of CK1,but lower than those of CK2.The length,width and dry weight of flag leaf at anthesis stage of winter wheat under irrigation once in spring treatment decreased with the delay of irrigation date,and the flag leaf traits of all treatments were better than those of CK1.(2)The relative chlorophyll content(the value of SPAD),net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of flag leaves of winter wheat from heading to maturity stage increased first and then decreased under conditions of irrigation once in spring treatment.The the maximum value of SPAD appeared at 7 d after anthesis,and it decreased with the delay of irrigation date.Pn,Tr and Gs reached the maximum values from anthesis to 7 d after anthesis.With the delay of irrigation date,Pn,Tr and Gs in flag leaves of winter wheat at anthesis stage increased first and then decreased.The treatments with the maximum Pn in the two experimental years were AJ15 and AJ5.The value of SPAD at 7 d after anthesis and Pn at anthesis stage of all treatments with irrigation once in spring were higher than those of CK1 and lower than those of CK2.(3)In the two experimental years,under the condition of irrigation once in spring treatment,the treatments with the largest dry matter accumulation on the ground,dry matter translocation befor anthesis and dry matter translocation efficiency befor anthesis of winter wheat were AJ5,the treatments with the largest dry matter accumulation after anthesis were AJ5 and AJ10,respectively,and the treatments with the largest contribution of dry matter accumulation after anthesis to grain yield to grain were AJ20 and AJ15,respectively.With the delay of irrigation date,the average and maximum grain filling rates of winter wheat under Logistic simulation decreased,but the duration of grain filling increased,and the theoretical maximum 1000-grain weight increased.Under the condition of irrigation once in spring,the spike number per area,grain number per spike and grain yield of winter wheat increased first and then decreased with the delay of irrigation date,while the 1000-grain weight increased gradually.The grain yield of AJ5 was the highest,followed by AJ10,there was no significant difference between the two treatments,but they were significantly higher than other treatments with irrigation once in spring.In the two experimental years,the grain yields of all treatments with irrigation once in spring were higher than those of CK1 and lower than those of CK2.Compared with CK1,the yields of AJ5 and AJ10 treatments increased significantly by 52.18%-96.04% and 49.84%-90.15%.Compared with CK2,the grain yields of AJ5 and AJ10 treatments decreased respectively by 0.80%-16.75% and 3.79%-18.03%,and the difference was significant from 2019 to 2020.(4)Under the condition of irrigation once in spring,the soil moisture distribution at maturity stage of winter wheat was similar to that before irrigation at jointing stage,but compared with that before irrigation at jointing stage,the soil moisture content of 0-100 cm soil layer at maturity stage of winter wheat in each treatment decreased,and the soil moisture content of 100-200 cm soil layer in AJ15 and AJ20 treatments decreased significantly.The water consumption(ET)of winter wheat gradually increased with the delay of irrigation date,and the water use efficiency(WUE)first increased and then decreased with the delay of irrigation date.Among them,the WUE of AJ5 was the highest,followed by AJ0 and AJ10,the difference among the three was not significant,but they were significantly greater than that of other one water treatments.Compared with CK1,ET of winter wheat in AJ5 and AJ10 treatments increased respectively by 26.6-158.1 mm and 31.0-176.8 mm,WUE increased significantly by 20.78%-41.07% and 12.34%-37.50%.Compared with CK2,ET in AJ5 and AJ10 treatments decreased significantly by 81.5-99.2 mm and 62.8-94.8 mm,WUE increased respectively by 5.33%-18.4 % and 2.67%-10.19%.Considering the irrigation amount,growth and development characteristics,yield,water consumption and Water Use Efficiency for Winter Wheat,the irrigation once in spring of winter wheat at a suitable date could obtain better water saving effect,higher grain yield and water use efficiency.From the perspective of water saving,stable yield and high efficiency,it is recommended that the date of limited irrigation once in spring of winter wheat is 5-10 d after jointing in groundwater over-exploitation area of Hebei Province.