关键词: 春小麦, 干旱胁迫, 分蘖和拔节期, 根系生长, 补偿效应

Abstract: 【Objective】The objective of this study is to investigate the differences in morphological and physiological responses of root growth of drip irrigated spring wheat with different drought sensitivity to stage drought stress, to further elaborate the physiological mechanisms of drought resistance and water conservation in drip irrigated spring wheat in Xinjiang, and to provide a theoretical basis for further water-saving and high-yield in Xinjiang wheat region.【Method】From 2021-2022, the strong drought resistance variety Xinchun 6 and the weak drought resistance variety Xinchun 22 were used as the test materials in the soil column cultivation method. Mild (T1 and T3, 60%-65% FC, FC is the field) and moderate (T2 and T4, 45%-50% FC) drought stress treatments were conducted during the tillering and jointing stages, with conventional irrigation as the control (CK, 75%-80% FC), study the effects of pre-reproductive drought stress on root morphological characteristics (root length density (RLD), root volume density (RVD), root surface area density (RSAD) and root mass density (RMD)), antioxidant systems (malondialdehyde (MDA), superoxide anion (O₂^.-), reduced ascorbic acid (AsA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)), proline (Pro), soluble protein (SP), soluble sugars (SS)) and spatial and temporal characteristics of root activity to analyse the compensatory effect of drip irrigated spring wheat root growth on drought-rehydration.【Result】RLD, RVD, RSAD and RMD showed a trend of increasing and then decreasing with increasing drought stress, and under mild drought (T1 and T3) conditions, RLD, RVD, RSAD and RMD in the 20-60 cm soil layer were significantly increased. The MDA content and O₂^.- production rate in the root of each soil layer showed an upward trend with the intensification of stress, while SOD, POD, CAT, AsA, Pro, SP, SS and root activity showed a first increased and then decreased trend with the intensification of drought, and gradually increased with the deepening of the soil layer. After rehydration of T1 treatment, root morphological characteristics, antioxidant enzyme activity, osmotic substances and root activity were maximized, which in turn increased the yield by 2.77% to 19.58% compared to the rest of the treatments. Stepwise regression analysis showed that RVD, RSAD, AsA, SOD, CAT and SS were important determinants of yield, RLD, Pro and SP were the most significant indicators of strong drought resistance in Xinchun 6; RSAD, SP, SS, MDA and POD were the most significant indicators of weak drought resistance in Xinchun 22.【Conclusion】Spring wheat maintains 60%-65% FC during the tillering and jointing stages, after drip irrigation and rehydration, it increases the distribution proportion of the 20-60 cm soil layer root, enhances the root system’s ability to remove reactive oxygen species and osmotic adjustment, delays root senescence and improves root physiological characteristics, thus increasing yield.

Key words: spring wheat, drought stress, tillering and jointing stages, root growth, compensation effect