Effects Of5-Aminolevulinic Acid On Physiology Metabolism Of Pepper Under Low Temperature Stress

With the demand of market and consumer, the area of off-season culture pepper is gradually increasing. However, there are many environmental factors severely restricting the normal production of pepper. Among them, chilling is one of the most important influence factors in the off-season cultured pepper. How to improve the cold-stress resistant has. become a top priority issue. In addition to seclect and breed the low-temperature-resistant varieties, using the plant growth regulators of plant to improve the cold tolerance of plant is an alternative important way to improve the cold tolerance of plant. Therefor, our work is to screen a suitable concentration of5-aminolevulinic acid (ALA) to alleviate the chilling stress injuries, and improve their resistance against chilling stress.In this paper, our group offers feasible ways for alleviating chilling injury of pepper in the production, in order to elucidate the influence and mechanisms of ALA on chilling resistance of pepper. Effects of ALA on the plant growth, leaf osmotic adjustment, reactive oxygen metabolism, photosynthesis, fruit quality and yield were conducted with pepper variety’chaoyue No.5’in flowering stage under low temperature stress with the two experiments which are simulation of greenhouses and practice production. The main results are as follows:1. Application of25mg-L"1ALA significantly increased the contents of osmotica, AsA, GSH and the activities of POD, CAT, APX, GR, MDAR and DHAR, and significantly decreased the EL, contents of MDA and the production rate of O2·-under the low temperature stress, thus effectively removing cellular reactive oxygen species.2. Results showed that25mg·L-1ALA significantly raised the height, stem diameter, fresh and dry weight, the chlorophyll content of leaves, the net photosynthetic rate (Pn), intercellular CO2, stomatal conduct (Gs) and transpiration rate (Tr) under low temperature stress.3. Under low temperature stress in the winter and spring, there are different degree of injury with different cover materials. Our results demonstrated that25mg·L-1ALA obviously increased the concentration of prolin, soluble sugar and soluble protein, the activities of SOD, POD and CAT, the chlorophyll contents and the net photosynthetic rate, whereas decreased the EL, MDA content and the production rate of O2·-. It indicates that exogenous ALA treatment could relieve chilling injury of pepper by increasing the content of osmotica and the capacity of antioxidant enzyme, decreasing the production rate of O2·-and improve the photosynthesis and the the plant growth by promoting the synthesis of chlorophyll. But there is indeed significant difference under different cover materials, the degree of mitigation reduce with the temperature going down.4. Under low temperature stress in winter and spring, with different cover materials, using25mg·L-1ALA obviously increased the fruit number, fruit weight, fruit length, the yield, and the content of soluble solids and Vc of pepper fruit, decreased the soluble sugar content and acidity of pepper fruit.