Abstract: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.
