Effect Of Exogenous Substances On Chilling Tolerance Of Pepper Seedlings

Pepper seedlings were chose as experimental material and the low temperature conditions were simulated with artificial room. Impacts of spraying Calcium chloride (CaCl2), Chitosan, Scurose, PEG,5-Aminolevulinic acid (ALA) and Spermidine (Spd) on pepper cold resistance was studied in this article. The optimal concentrations of 6 exogenous substances for enhancing cold resistance of pepper seedling were selected, and the physiological mechanism of cold-enhanced was studied. The results are as follows:Under low temperature, different concentrations of CaCl2, PEG, Spd, Scurose, CS and ALA could significantly reduce seedlings'chilling injury index, mortality and electrolyte leakage rate, and increase Fv/Fm. The most effective concentrations of exogenous ALA, Spd, CaCl2, CS, PEG, Scurose on the 5-6 leaf and one of pepper seedling cold resistance were 0.5 mg·L-1,0.5 mmol·L-1,10mmol·L-1,0.25%,25% and 20% by comprehensive analysis.0.5mg·L-1 ALA,0.5 mmol·L-1Spd,10mmol·L-1 CaCl2,0.25% chitosan,25% PEG, and 20% Scurose could significantly alleviate the accumulation of MDA content, decrease pepper seedlings membrane permeability and induce SOD,POD,CAT activity to increase, and improve the proline and soluble protein content significantly under low temperature stress. It is reasoned that 6 treatments of exogenous substances decreased MDA contents, membrane permeability, higher activities of antioxidant enzymes, osmolyte content and the 6 kinds of exogenous substances increase the cold tolerance of pepper.6 kinds of exogenous compounds improved the antioxidant capacity of pepper leaves to reduce the cold stress-induced lipid peroxidation and improved the pepper seedlings osmoregulation under low temperature stress.Pepper seedlings reduced the chlorophyll fluorescence parameters Fv/Fm,ΦPSⅡ,Fv'/Fm',qP and Ch1(a+b)content.The six exogenous substance treatment increased the pepper leaf chlorophyll fluorescence parameters Fv/Fm,ΦPSⅡ,Fv'/Fm',qP and Ch1(a+b)content under Suboptimal temperature. Showed that the six exogenous substances increased photochemical activity of pepper leaves under Suboptimal temperatures. Pepper seedlings decreased net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (E) in varying degrees, but increased the intercellular carbon dioxide (Ci); the six kinds of exogenous substance treatment increased the pepper leaf Pn, Gs, E, lower Ci under Suboptimal temperature. Showed that the six kinds of exogenous substances improved the pepper cold tolerance related to the improvement of photosynthetic capacity.