The Effects Of NAA On Senescence Of Potted Malus Spectabilis

Mains spectabilis is one of the main cultivar of making fruit potted landscape. In this paper, senescence of potted Mains spectabilis fruits and leaves was studied, the content of endogenous hormone, protection enzymes activity, and other index about resistance which impact directly ornamental characteristics in ripening and senescence of fruits and leaves of Mains spectabilis were compared and analyzed.To find out the reason that caused fruits to wrinkle and leaves to turn yellow and drop. Furthermore, the plant growth regulator-NAACnaphthaleneacetic acid)was used to regulate the senescent process, and the relationship between different concentration of NAA and the effect of NAA was releaved. The main results are as follows:1. Ripening and senescence of fruits and leaves of Mains spectabilis had a close relationship with endogenous hormone, The decreasing of IAA (Indole-3-Acetic Acid) content and the increasing of ABA (Abscisic Acid) content engendered some senescence materials.2. After heat stress of some environment factor such as temperature and light etc,the endogenous hormone was changed, metabolism of the active oxygen was increased and the membrane structure was damaged.3 . In ripening and senescence process, membrane permeability increased, Chl (Chlorophyll) content decreased, leading to the organ droped, fruit wrinkled, leaves turned yellow and exterior quality reduced. By testing Chl content and observing of leaf abscission layer microstructure,it was indicated that NAA could retard Chl degradation and inhibit abscission layer forming.The result showed that D treatment (NAA at 140mg/L) had the best effect.4. The treatment at suitable concentration could achieve the peak earlierly in IAA content and inhibit the rising trend of ABA content. The D treatment (NAA at 140mg/L) was the best treatments to delay the ripening and senescence. Otherwise, the treatment at lower concentration have the oppositive effect and accelerated senescence.5. After treatment, the peak of O₂^- and MDA (Malonal dehyde level) content was delayed seven days later than control. The D treatment (NAA at 140mg/L) and the E treatment (NAA at 180mg/L) might improve the protin content and increase the SOD (Superoxide dismutase) activity significantly in fruites. In leaves the peak of MDA content was delay three days later, SOD activity was increased as well, It indicated that the injuryto cell produced by O2" and MDA was weaked.6. Results of the relative membrane permeability of Malus spectabilis leaf as well as leaf stalk, NAA can enhance their frost hardiness, D treatment (NAA at 140mg/L)had the best effect. And the effect to leaves was better in leaves than in leaves stalk.