Effect Of6Benzyl Adenine (6-BA) On Leaf Senescence In Different Tay Green Maize (Zea Mays L.) Types

A pot experiment was carried out to study the effect of exogenous hormone6benzyladenine （6-BA） in different study green maize Q319and HZ4during leaf senescence processinbred line after anthesis.The aim of this study is to provid theorial and techanical support forhigh and stable yield. The main results were as follows:1. In treatments of nitrogen fertilizer, the grain yield of stay green maize Q319andnon-stay green maize HZ4were increased significantly. In treatments of6-BA, the grain yieldof stay green maize Q319and non-stay green maize HZ4were not increased. Under thenitrogen fertilizer and6-BA interaction conditions, the improvement of ear number,1000-kernel weight and biomass significantly improved the grain yield. Compared with thenon-stay green maize HZ4, the increasing in yield of stay green maize Q319was higher, andthe treatment of6-BA100mg L-1was the best concentration for grain yield.2. Under the nitrogen fertilizer and6-BA interaction conditions, the content ofchlorophyll was increased significantly, the number of grana and grana lamella were increasedsignificantly, the number of osmiophilic granule was decreased significantly, the activity ofRuBPcase and PEPcase and Pnin stay green maize Q319and non-stay green maize HZ4wereincreased significantly, thereby photosynthetic performance significantly improved.Compared with the non-stay green maize HZ4, the increasing in yield of stay green maize Q319was higher.3. In treatments of6-BA without nitrogen fertilizer, the activity of photosystem of staygreen maize Q319and non-stay green maize HZ4were increased significantly. Under thenitrogen fertilizer and6-BA interaction conditions, the activity of photosystem reaction centerof stay green maize Q319were increased significantly, but the co-ordination between the twophotosystem showed no significant enhance. And the activity of PS Ⅱ reaction center ofnon-stay green maize HZ4was increased significantly, the activity of PS Ⅰ reaction center andthe co-ordination between the two photosystem were not increased. Spraying plant with6-BAunder suitable application of nitrogen fertilizer can significantly improve the performance ofelectron transport chain between two phptpsystem, but can not satisfy the requirement tostrengthen the co-ordination between the two photosystem.4. In treatments of6-BA without nitrogen fertilizer, the activity of SOD, POD, CAT,MDA were no significant differences. Under the condition of applying nitrogen fertilizer, thecontent of soluble protein and the activity of SOD, POD, CAT were increased significantly,the content of MDA was decreased significantly, and the rasing effect of stay green maize Q 319was more than non-stay green maize HZ4. Under the condition of applying nitrogenfertilizer, the leaf senscence process was delay.5. The content of IAA, ZR and GS of stay green maize Q319and non-stay green maizeHZ4were increased significantly under spraying plant with6-BA, and the content of ABAwas decreased significantly. Compared to the treatments of6-BA without nitrogen fertilize,the rasing effect of6-BA to endogenous hormones under the nitrogen fertilizer and6-BAinteraction conditions was higher. In treatments of6-BA without nitrogen fertilizer andnitrogen fertilizer without6-BA, the ratio of endogenous hormone IAA/ABA and ZR/ABA ofstay green maize Q319and non-stay green maize HZ4were showed no significant increase,the ratio of endogenous hormone GA₃/ABA was increased significantly. Under the nitrogenfertilizer and6-BA interaction conditions, the ratio of endogenous hormone IAA/ABA andZR/ABA of stay green maize was increased significantly, the ratio of endogenous hormoneGA₃/ABA was showed no significant increased. The correlation coefficients amongphotosynthesis and endogenous hormone contents of leaf in different stay green style maizeindicated that Under the nitrogen fertilizer and6-BA interaction conditions, thephotosynthetic performance had a correlation with the content of IAA and ABA.6. The results showed that spraying6-BA significantly increased uptake rates of N, andkey enzymes （GS, GOGAT and GDH） activities of nitrogen metabolism of maize afteranthesis, that promote the nitrogen accumulation in plants, and it can promote the nutrientsin the organs transport to the grain, the biomass per plant was increased, therefore the grainyield was increased. and the treatment of6-BA100mg L-1was the best concentration forgrain yield and nitrogen use efficeiency.