|
In this study, two sugarcane cultivars （ROC22, YUANLIN6） were sprayed with different concentrations of FA and ET. During the course, two experiments were set for different purpose: the spraying concentration of FA was optimized in the first experiment; in the second experiment, there were five treatments, i.e. CK1 （normal water supply） and CK2 （drought stress）, 200mg/L FA （selected from the first experiment）, 200mg/L FA+200mg/L ET, 200mg/L ET were sprayed on the sugarcane leaves at the young shoot stage （four to five leaves）. The purpose of the study was to investigate the effects of FA and ET at initial growth stage in sugarcane under water stress. The main results were as follows:In the first experiment, the six concentrations of FA treatments i.e. CK 1（normal water supply） and CK2 （drought stress）, 200 mg/L, 400 mg/L, 800 mg/L and 1200 mg/L were designed. The 200 mg/L FA treatment conducive to improve the chlorophyll fluorescence, alleviated the chloroplast membrane damage by drought stress, and promoted the tiller under drought stress as comparing with other treatments in ROC22 and YUANLIN6. But there are still some differences between ROC22 and YUANLIN6.For five treatments i.e. CK1（normal water supply）, CK2（drought stress）, 200mg/L FA, 200mg/L FA+200mg/L ET, 200mg/L ET, there are some differences in chlorophyll content, leaf water potential, chlorophyll fluorescence, malondialdehyde（MDA）, peroxidase（POD）, Ca2+-ATP enzyme, Mg2+-ATP enzyme and agronomic characteristics.1. 200mg/L FA, 200mg/L FA+200mg/L ET, 200mg/L ET treatments delayed the decreasing of chlorophyll content and the increasing of MDA obviously in the two cultivars under the arid condition. It had the similar trend for leaf water potential in both, with the optimizing treatment of 200mg/L FA. For chlorophyll content, 200mg/L FA was the optimizing treatment in ROC22, while 200mg/L FA+200mg/L ET was better than other treatments in YUANLIN6. And for the content of MDA, 200mg/L ET treatment had a better effect than 200mg/L FA, 200mg/L FA+200mg/L ET treatments.2. On the aspect of promoting the peroxide enzyme （POD） activity under the arid condition, the 200mg/L ET treatment increased the POD activities in both ROC22 and YUANLIN6 obviously. 200mg/L FA treatment had an obvious effect on increasing the activities of Ca2+ -ATP enzyme and the Mg2+ -ATP enzyme, during the arid stage, but 200mg/L ET treatment had stronger effect after supplying water, treatment 200mg/L FA+200mg/L ET was intermediate between 200mg/L FA treatment and the 200mg/L ET treatment.3. Treated by 200mg/L FA, 200mg/L FA+200mg/L ET and 200mg/L ET respectively, the photochemical efficiency decreasing of PSⅡ（Fv/Fm）, effective quantum yield of PS II （Yield） and photochemical coefficient（qP） in the two sugarcane cultivars were delayed obviously under the arid condition. After supplying water, all that parameters obtained a certain extent enhancement, but there were some differences among the two sugarcane varieties and the treatments.4. For stalk diameter and length of seedling, the 200mg/L FA treatment showed better effect than 200mg/L FA+200mg/L ET, 200mg/L ET treatments, while 200mg/L FA+200mg/L ET, 200mg/L ET treatments showed better effect on plant height and tiller than 200mg/L FA treatment, obviously higher than the control.Based on the analysis of physiological and agronomic characteristics, it is concluded that the applied FA could effectively delay the drop of water potential in sugarcane leaf, maintain the normal physiological function of cells, adjust the MDA content and chlorophyll content on leaves, indicating the remission of photosynthetic organ injury. By comparing the treatment effect of FA and ET, we inferred that, FA could reduce the excessive bleeding of water in leaves and delay the drop of the water potential through adjusting the leaf stomata, so as to maintain the normal physiological function. And for ET treatment, FA could increase the activities of related enzymes, improve the light translation efficiency, and finally provide the material and energy foundation for the growth of stalk and tillers. Either under arid stress or after rehydration, combined applying of FA and ET with certain concentration obtained better treatment effects than the single use of this two chemicals, it could raise the chlorophyll content and light translation efficiency, and promote the growth of stalk and tillers.
|