两个不同耐旱性棉花品种根系生理特性对干旱的响应

为探明不同抗旱性棉花品种的根系生理特性对干旱的响应及其与生物量的关系,以不耐旱性品种‘新陆早17号'(L17)和耐旱性品种‘新陆早22号'(L22)为试材,在土柱栽培条件下设常规灌溉(CK)、轻度干旱(W₁)和中度干旱(W₂)处理,研究干旱胁迫对不同耐旱性棉花品种根系活力、保护酶活性及解剖结构(导管直径、数量)和生物量的影响。结果表明:干旱胁迫下两棉花品种根系可溶性蛋白(SP)含量、根系活力(RV)、木栓层数、根茎导管数量、导管直径显著降低,根系丙二醛(MDA)含量及保护性酶活性显著增加,进而导致地上部干物质量显著降低。与L17相比,L22的SP含量、0～40 cm和80～120 cm土层RV、木栓层数、根茎导管数量、导管直径以及地上部干物质量均显著增加,尤其W₂条件下L22的RV降幅比L17低26.2%,过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性和皮层厚度分别比L17高43.6%、6.9%、25.4%、19.9%,且差异均达到显著水平。干物质量与RV、SOD、POD、木栓层数、导管直径和个数之间均呈显著正相关。因此,耐旱性强的棉花品种在干旱条件下通过保持较高的根系活性、木栓层数、导管直径和数量,进而促进地上部生物量积累,是其具有较高耐旱性的生理机制。

Responses of root physiological characteristics of different drought-tolerant cotton varieties to drought

In order to explore the physiological responses of root system of different drought-resistant cotton varieties to drought and their relationships with biomass, we examined the effects of drought stress on root vigor, antioxidant enzyme activities and anatomic structure (duct diameter, number) and biomass of different drought-tolerant varieties, including the drought-inolerant variety ‘Xinluzao 17' (L17) and the drought-tolerant variety ‘Xinluzao 22' (L22). Both varieties were grown under soil column cultivation conditions, with conventional irrigation (CK), mild drought (W₁) and moderate drought (W₂) treatments. The results showed that drought stress caused significant reductions in soluble protein (SP) content, root vigor (RV), the number of cork layers, the number of rhizome ducts, the diameter of the ducts in both varieties. The higher root MDA content, CAT, POD and SOD activities in response to drought led to reduction of aboveground dry mass. Compared with that of L17, SP content, 0-40 cm and 80-120 cm soil layer RV, the number of cork layers, the number of rhizome ducts, the diameter of ducts, and the aboveground dry mass of L22 all signi-ficantly increased. Under the W₂ treatment, the RV decrease of L22 was 26.2% lower than that of L17, and CAT, POD, SOD activities and the thickness of cortex were 43.6%, 6.9%, 25.4%, 19.9% higher than that of L17. There were positive correlations between dry mass and RV, SOD, POD, the number of cork layers, the diameter and number of rhizome ducts. Therefore, cotton variety with strong drought tolerance could maintain higher root activity, cork layer number, the diameter of rhizome ducts, and number under drought conditions, and thus promote the accumulation of aboveground biomass, which was the physiological mechanism for their stronger drought tolerance.