Effect of Drought Stress before Anthesis on Growth Indexes of Winter Wheat

Due to the global climate change, the intensity, frequency and scope of influence of agricultural drought disasters are increasing. Wheat is an important food and economic crop in China and it occupies an important position in food production. Therefore, to explore how crops respond to the changes of drought environment, and improve the resistance to drought stress and adaptability to drought environment are the key scientific problems to be solved urgently. 【Objective】 To study the effect of drought stress on growth indexes of winter wheat. 【Method】 Select Zhoumai 22 as the test material, set up a full irrigation treatment (namely CK) during the whole growth period, and set mild drought in the jointing and heading stages (soil moisture content is controlled at 60%~70% of field water holding rate, namely T1, T4 treatment), moderate drought (soil moisture content controlled at 50%~60% of field water holding rate, namely T2, T5 treatment) and severe drought (soil moisture content controlled at 40% of field water holding rate %~50%, namely T3 and T6 treatments), and continuous light drought (soil moisture content controlled at 60%~70% of field water holding rate, namely T7 treatment) and continuous moderate drought (soil moisture content) and jointing and heading stage. Controlled at 50%~60% of field water holding rate, namely T8 treatment), continuous heavy drought (soil moisture content controlled at 40%~50% of field water holding rate, namely T9 treatment), comparative analysis of winter wheat root morphology, the change process of root distribution, plant height and leaf area. 【Result】 The root length of the T1—T9 stages of the drought stress treatment were all lower than that of CK, but the total root length of the three treatment stages in the jointing stage increased with the depth of the drought; the root dry quality after continuous treatment was in light drought and medium under drought conditions, it was greater than single-stage treatment. Under severe drought conditions, the root characteristics including root length, root dry mass, and root surface area were significantly reduced; however, the root compensation and restoration ability of jointing treatment after rewatering was higher than that of heading. With the increase of drought stress and time, the root system expands and grows downwards, so that various root system indicators including root length, root dry quality, root surface area, etc. are transferred to the deep layer, but the total absolute amount of root system is significantly reduced. The root dry quality of T9 treatment is compared with CK Reduced by 64.79%, and the inhibition of plant height and leaf area increased. The jointing stage has a greater impact on plant height. Compared with CK, the plant height of T1, T2, and T3 treatments is reduced by 3.78%, 7.59%, and 16.09%; the heading stage has a greater impact on the leaf area, and the leaf area of T4, T5 and T6 treatments is compared CK decreased by 8.11%, 23.45%, and 29.43%; while the plant height and leaf area after continuous drought treatment were significantly lower than each single-stage treatment; the plant height and leaf area after drought stress treatment at heading stage were reduced after one week of drought stress Shows a strong compensation effect, but the jointing stage performance is relatively slow; there is no obvious compensation after continuous drought stress. 【Conclusion】 Continuous drought should be avoided in the actual production of winter wheat. If water control is required before flowering, the water supply at the jointing stage should be satisfied as much as possible, and the water control should be maintained at a light drought level during the heading stage.