| Ningxia Yellow River Irrigation District is located in the arid region of northwest China,with rich light and heat resources,fertile soil,and belongs to the dominant wheat production area in China,however,the region has low precipitation and water resources,and most of the crop irrigation relies on the Yellow River water irrigation.With the rapid socio-economic development and ecological construction in the Yellow River basin,the water resources problem in the Yellow River Irrigation Area of Ningxia is becoming more and more prominent.To elucidate the optimum drip irrigation rate of spring wheat under high yield and high efficiency in the Yellow River Diversion Irrigation Area,four drip irrigation treatments with three replications were set up with the new high-yielding wheat Ning3015(W1:4500m3·hm-2),(W2:3600m3·hm-2),(W3:2700m3·hm-2)and(W4:1800 2700m3·hm-2).The effects of different drip irrigation amounts on population growth,post-flowering photosynthetic fluorescence characteristics,physiological and biochemical indexes,starch content and yield of spring wheat were investigated.The results were as follows:1.the number of wheat stem tillers decreased under W3 and W4 treatments compared with W1 and W2 treatments.the W1 treatment caused the number of wheat stem tillers to be more vigorous in the early stage than the other treatments and decayed faster in the later stage,and the ineffective tillers increased.the W2 treatment increased the number of wheat stem tillers by 0.6%,3.5%and 4.6%,leaf area index by 5.11%,21.71%and 25.33%at maturity compared with W1,W3 and W4 treatments The dry matter accumulation was increased by 1.15%-4.73%,and the dry matter accumulation at the spike was significantly increased by 3.10%～18.29%,and the drip irrigation amount of W2 treatment had a promoting effect on the growth of wheat population.2.Spring wheat flag leaf chlorophyll content,SPAD value,photosynthetic characteristics,and fluorescence parameters were affected by the drip irrigation amount.Among the four treatments,W2 treatment increased SPAD values by 3.22%to 16.36%,chlorophyll a content by 1.38%to 16.06%,chlorophyll b content by 5.77%to 25.95%,and actual photochemical efficiency of flag leaf by 9.21%to 25.76%compared with other treatments.Thus,the net photosynthetic rate was affected,and the net photosynthetic rate was significantly increased by 1.31%-4.85%in W2 treatment,and the duration of high photosynthetic rate was significantly increased by 8.88%～22.25%,so W2 treatment could improve the photosynthetic characteristics of wheat flag leaf.3.Wheat flag leaf stress tolerance characteristics were affected by the drip irrigation amount,W2 treatment increased superoxide dismutase activity from 6.36%to 1 8.67%,peroxidase activity from 4.02%to 22.29%,catalase activity from 17.05%to 50.29%,reduced malondialdehyde content from 2.39%to 19.03%compared to other treatments of wheat flag leaf,which reduced membrane permeability and enhanced wheat The strong resistance of flag leaf in wheat can reduce the damage of stress to the plant.4.Starch synthase activity and starch content were higher under W2 treatment,and W2 treatment increased pyrophosphorylase activity by 3.551%～18.84%,starch branching enzyme activity by 6.94%-17.86%,granular starch synthase activity by 6.53%～14.71%,and soluble starch synthase by 0.85%～1.46%compared with other treatments,which increased total starch content by 5.79%～14.06%.The increase in starch content and starch synthase resulted in higher filling rate and longer filling duration,increased thousand grain weight,and yield increase of 2.28%～27.35%compared with other treatments.The drip irrigation rate of 3600 m3·hm-2 is the optimum drip irrigation rate for the new variety of spring wheat Ning "3015" grown in Ningxia Yellow Irrigation Area.This drip irrigation rate can promote wheat population growth rate,enhance photosynthetic rate,improve stress resistance and starch-forming enzyme activity,and increase grain starch content,thousand grain weight and yield. |
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