Study On Physiological Effects Induced By Chemical Substance On Cold Resistance In Banana Seedlings

Banana is one of the most important economic crops in tropical and subtropical area, it is also one of the staple fruit in southern China. Because of the physiological characteristics, banana is apt to suffer low temperature injury, and banana's improvement by traditional breeding procedures has not been very successful because of sterilitas and the lack of genetic variability. Therefore, it is especially urgent to study the cold-resistant mechanism and the infection by exogenous chemical substance to the cold resistance of banana.The study was conducted with Brazil banana (Musa AAA Group Cavendish cv. Brazil) seedlings which is one of varieties grown in China. First, pretreatment on banana leaves, then move into climate-control chest imitating low temperature stess. Physiological effects of several chemicals, Soybean Peptide, Inositol, KH2PO4, Salicylic Acid(SA), vitamin C(Vc), were studied through design of randomized block and subordinate function values. And two chemicals in best or better performance on improving cold resistance were selected: soybean peptide and inositol. Then, the anatomic structures and physiological changes of banana leaves which pretreated by soybean peptide and inositol had been studied. The results were as follows:1. By sprayed on appropriate concentration of soybean peptide, inositol, KH₂PO₄, SA, Vc can distinctly improve cold-resistant physiological effects of banana seedlings under low temperature stress. The relative water content, the content of soluble protein, praline and the protection enzyme activity were obviously enhanced, and the occurs of lipid peroxidation and membrane permeability have been postponed to some extent.2. The effect of cold-resistant in banana seedlings has improved with the accretion of concentration by the five kinds of chemical substance, but the trend ceased as the concentration reached to an optimal value. The optimal values wre: soybean peptide(0.5%), inositol(60 mmol·L^-1), KH₂PO₄(15 mmol·L^-1), SA(0.1 mmol·L^-1), Vc(5 mmol·L^-1).3. Different chemical has different effects on improve cold resistant of banana seedlings, their effects were (under the optimal value): soybean peptide> inositol> KH₂PO₄> SA> Vc.4. Pretreated banana seedlings by soybean peptide(0.5%) and inositol(60 mmol·L^-1), after 12 hour's low temperature stress, palisade tissueis was thicker than CK(low temperature)and close to CK2(normal temperature), spongy tissue was thiner than CK(low temperature), and the CRT is larger than CK(low temperature). After grown 3 days under normal temperature, the R/S ratio is larger than CK(low temperature).5. Pretreated banana seedlings by soybean peptide(0.5%) and inositol(60 mmol·L^-1), in 0～12 hours, the protection enzyme activity and soluble protein content were raising and higher than CK(low temperature), in 12～24 hours, the protection enzyme activity and soluble protein were decrease, but were still higher than CK(low temperature). There were no new enzymatic bands appeared in this process, but brightness were higher than CK(low temperature) and CK2(normal temperature), the most brightness bands belong to the treatment which treated by soybean peptide. All the changes of treatments'bands brightness were alike with POD enzyme activity, increased in 0～12 hours, and decrease in the next 12 hours.