喷施6-BA对不同种植密度白刺叶衰老的影响

研究了两种种植密度(低密度种植株行距:1.2 m×1.5 m、高密度株行距:0.8 m×1.0 m)下白刺生长期外源喷施不同浓度6-BA(0 mg·L^(-1)、10 mg·L^(-1)、20 mg·L^(-1)、30 mg·L^(-1))后叶光合参数(Pn、Tr、Gs、Ci)、叶绿素(Chl)及叶片渗透调节物质脯氨酸(Pro)、可溶性蛋白(SP)含量、活性氧代谢及抗氧化酶活性的动态变化及其变异规律,探讨6-BA及种植密度对白刺叶衰老的影响及作用机理。结果表明:20 mg·L^(-1)6-BA处理低密度种植下的白刺叶Pn、Tr、Gs较未经6-BA处理显著高出37.72%、117.94%、83.18%,而Ci值较对照显著降低32.29%。相较其他6-BA处理的两种种植密度下白刺叶衰老相关生理指标,20 mg·L^(-1)6-BA处理低密度种植的白刺在叶发育前期(t1至t3时期)可有效促进Chl和SP合成,叶发育后期(t4、t5时期)则可有效缓解Chl、SP、Pro降解和抑制MDA、H2O2含量增加。10 mg·L^(-1)和20mg·L^(-1)6-BA处理可促进白刺叶生长前期抗氧化酶SOD、POD、CAT活性的增加,减缓叶生长后期酶活性的下降。相同浓度6-BA处理的3种酶活性均表现为低密度>高密度。主成分及隶属函数分析综合表明,花芽萌动至果实脱落期间以20 mg·L^(-1)6-BA每隔10 d(共8次)处理低密度种植下的白刺叶片抗衰老能力最强。喷施6-BA和减小种植密度可作为缓解白刺叶衰老、实现白刺高效种植及资源有效开发利用的重要技术措施。

Effects of Water Deficit and Increased Nitrogen Application in the Late Growth Stage on Physiological Characters of Anti-aging of Leaves in Different Hybrid Rice Varieties

[Objective] This study aimed to explore the effects of water and fertilizer regulation on the function of leaves in the filling stage. [Method] Six hybrid rice vari- eties including prematurely aged types and non-prematurely aged ones were selected as experimental materials. Limiting water treatment （with soil water potential of about -25 kpa） and increasing nitrogen treatment （additional 10% of granular nitrogen fertiliz- er in addition to limiting water treatment） were applied after heading to analyse the rates of aging and physiological responses of anti-aging in different hybrid rice vari- eties under water deficit and increased nitrogen conditions taking regular water and fertilizer as control. [Result] The results showed that water deficit accelerated the leaf senescence, and prematurely aged types-＇Zhongyou838＇, ＇Tianyou998＇ and ＇Long- ping601 ＇-were more markedly affected by water deficit, of which the rates of chloro- phyll degradation were 6%-8% higher compared to that in another three hybrids. In- creasing nitrogen treatment raised chlorophyll content and slowed down its degrada- tion. Water deficit caused the increase of abscisic acid （ABA） content to obviously varying degrees in leaves of six hybried rice varieties. Responses of ABA content in six hybried rice varieties to increased nitrogen fertilizer were not consistent. Except in ＇Zhongyou838＇, ABA content in the other five hybrids had varying degrees of in- crease. The responses of the activity of antioxidant enzymes in different hybried rice varieties were inconsistent. In response to increased nitrogen fertilizer in combination with water deficit, the activity of each antioxidant enzyme changed differently. Water deficit enhanced the accumulation of malondialdehyde （MDA） in leaves of each hybrid rice. The correlation analysis showed that chlorophyll content was extremely signifi- cantly positively correlated to the resistance of each antioxidant enzyme; SOD activity in leaves also positively related to ABA content. [Conclusion] The rate of leaf aging, physiological activity of anti-aging, and response to water deficit varied in different hy- bried rice varieties. The activity of antioxidant enzymes were not all induced to improve by ABA. SOD activity can be an indicator of resistance to stress. Increasing nitrogen ap- plication significantly postponed leave senescence in the late growth stage of rice.