干旱胁迫下不同抗旱性小麦叶片内源激素含量的变化与抗旱力强弱的关系

以抗旱性强的小麦品种昌乐5号和抗旱性弱的鲁麦5号的幼苗为材料，研究了随着干旱胁迫的加剧，小麦叶片相对含水量、气孔导度和内源激素水平的变化．结果表明，叶片的气孔导度和细胞激动素与脱落酸含量的比值（CTKs/ABA）呈较强的线性正相关关系而与叶片RWC的相关关系较弱，说明气孔导度受CTKs/ABA调控，而不是受叶片RWC的调控．在不同强度的干旱胁迫下我们可以利用CTKs/ABA的变化判断品种抗旱性大小：①抗旱力强的小麦品种叶片的平均CTKs/ABA值较高，而弱者较低，说明强者内源促进型激素含量相对较高，从而在干旱胁迫下保持较高的生活力．②抗旱力强的小麦品种叶片CTKs/ABA与干旱处理天数呈二次负相关关系，而弱者是线性负相关关系，说明强者具有较强的抗逆缓冲能力．③抗旱力强的小麦品种成熟叶（第二叶）CTKs／ABA下降快，新叶（第三叶）下降慢，而弱者反之，说明抗旱性强者可能存在着较强的从成熟叶向新叶的物质运输从而具有自我保护性调节机制．

THE RELATIONSHIP BETWEEN THE CHANGES OF ENDOGENOUS HORMONES CONTEM AND THE DROUGHT RESISTIBILITY IN LEAVES OF WHEAT DURING DROUGHT

Changes of leaf relative water content(RWC), stomatal conductance and levels ofendogenous hormones were investigated in seedling leaves of Wheat cultivars with differentdroughtecsistance under different drought stress conditions. The results showed that therewas a stronger positive linear correlation between the stomatal conductance and the ratioof cytokinins to ABA (CTKs/ABA), while a weaker correlation was observed betweenstomatal conductance and leaf RWC, indicating the stomatal conductance was controlled byCTKs/ABA, not by the leaf RWC. The changes of CTKs/ABA in leaves ndght be used asan indicator to estimate the droughtecsistant ability among wheat cultivars underthe different drought stress conditions. It can be done as follows' the averageCTKs/ABA value in leaves of the more resistant cultivar was higher than the less resistantone or sensitive one, indicating that the former had a higher ratio of promotive hormones,so that it could keep stronger vitality during drought stress, @ the more resistant cultivarshowed a negative quadratic correlation between its leaf CTKs/ABA and drought treatmentdays, while the less resistant one showed a negative linear correlation, indicating the formerhad a higher buffer ability for stress resistance; the decline of CTKs/ABA value inmature leaf (the second leaf) of the more resistant cultivar was faster than that inyoung leaf (the third leaf), while the opposed trend was found in sensitive one, thisimplied that a mechanism of material transport from mature leaves to young leaves ndghtoperate obviously in drought resistant cultivars for self Trotective regulations.