| Effect of Carboxymethyl Chitosan on Chilling Tolerance in Cucumber seedlings and growth, physiological characteristics and yield of cucumber cultured in solar greenhouse were studied. The main results were as follows: 1. Effect of Carboxymethyl Chitosan on Chilling Tolerance in Cucumber SeedlingsCarboxymethy chitosan at 0 (CK), 1/1500, 1/1000, 1/500 and 1/100 (w/v) was sprayed with cucumber seedlings with two leaves respectively, and then the cucumber seedlings were stressed under low temperature at 6? 癈 for 5 days, in order to study influence of carboxymethy chitosan on chilling tolerance of the cucumber seedlings. The main results were as follows: 1.1 Under low temperature stress, the cucumber seedlings sprayed with carboxymethy chitosan of favorable concentration obtained lower chilling injury index ,higher root activity and content of chlorophyll compared with control. After low temperature stress, the cucumber seedlings were transferred to greenhouse for 5 days. Increase of dry matter , photosynthetic intensity and carboxlyation efficiency of the cucumber seedlings treated with favorable concentration of carboxymethy chitosan were much higher than these of control. After low temperature stress, the cucumber seedlings treated by carboxymethy chitosan of 1/1000 concentration were the lowest chilling injury index and most quickly renewed. This indicate that the cucumber seedlings'with carboxymethy chitosan physiological function were reinforced conceitedly and the chilling tolerance were enforced markedly.1.2 Compared with other treatment, the leaves of seedlings with sprayed carboxymethy chitosan at 1/1000,1/1500 and 1/500 concentration obtained the higher activities of protein enzyme (SOD,POD and CAT) , content of Vc markedly and lower the MDA content. This indicated the leaves of cucumber seedlings with carboxymethy chitosan of favorable concentration had a stronger capability to offence the oxidation of lipid and also showed that the membranes of cucumber seedlings with carboxymethy chitosan of favorable concentration had a higher stability and maintained longer.1.3 The content of such osmoregulation solutes as soluble sugar and proline decreased but markedly higher than the control with increase in concentration of carboxymethy chitosan under the condition of low temperature stress for 3 days. While the electrolytic leakage of leaves and roots markedly lower than the control besides the 1/100 treatment. This indicate that the electrolytic leakage of cucumber seedlings' cells decreased, the celluar capacity to keep water increased, which maintained the normal level of turgor and insured the physiologic and biochemical cellular process function normally. This fully explained that carboxymethy chitosan in favorable concentration evidently improved chilling tolerance in cucumber seedlings.2.Effect of CMC Irrigating on Yield and Physiological Characteristic of Cucumbers in the GreenhouseCarboxymethy chitosan of four consistencies with 0(ck), 1/1500, 1/1000 and 1/500 (w/v) is used to irrigate to the roots of cucumber in order to research the effect of CMC on the cucumber growth and yield. The main results were as follows: 2.1 Carboxymethy chitosan with proper consistency can markedly improve the rate of photosynthesis, chlorophyll content and root activity. The cucumber of 1/1000 treatment is the best with substrate culture while the 1/500 is the best with the soil culture. This indicate that the correlative physiological function of the cucumber with carboxymethy chitosan were reinforced conceitedly.2.2 Carboxymethy chitosan can markedly increased the growth of cucumber plant. The cucumber plant of 1/500 with soil culture and 1/1000 with substrate culture obtained the higher plant height, leaf area, leaf number and content of dry matter than other treatments markedly.2.2 The yield of cucumber with carboxymethy chitosan was clearly increased and the quality of cucumber fruit was improved. The yield with 1/1000 in substrate culture and 1/500 in soil culture was highest and was in...
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