| In china, cucumber is an important vegetable crop in greenhouse cultivation, and plays an important role both in protected horticulture and in agriculture production. Cultivation area of protected vegetables is at least 1.7×106 hm2 in the year of 2000, and cultivation area of cucumber account for 40% of the total.The formation of soil secondary salted in greenhouse soil is the most technical issue in the greenhouse cropping system. Under the spring and winter greenhouse production in north china, soil salinization caused by continuous cropping for years is the most limiting factor in cucumber production, by which cucumber output and quality was severely influenced.Research on the relationship between greenhouse cucumber and salt injury, the improvement of the ability to against the salt stress, as well as an economic, environmental protection, simple, high efficiency way of reducing salt injury are necessary and pressing. It has great theoretical and practical significance.Chitosan, a kind of natural polymer derived from arthropod shell, belongs to nonpoisonous and pollution-free security animal hormone substance. Chitosan used as plant regulator plays very important roles in many aspects, especially the induction of plant disease resistance, the bioactivity as pesticide and germicide, plant resisting to adverse conditions, seed-coating, fruits and vegetables storage, insecticidal synergism, soil improvement, plastic film degrade, promoting growth, increasing yield and improving quality. Chitosan's extensive applicative prospect in agriculture production was showed.Chitosan was used as a stress-resistant agent in this paper. Under 200 mmol·L-1 NaCl, the effects of different concentrations of chitosan on the stress-resistant capability and growth of cucumber(cv. Jinchun 3) seedling in greenhouse were investigated in order to provide theoretical and practical basis for the application of stress-resistant agent in protected agriculture.The major findings were as follows:Chitosan at appropriate concentration was sprayed on cucumber seedlings under salt stress, salt injury of cucumber seedling was decreased, and the growth and development of cucumber seedling were also improved. Spray of 200 mg·L-1 Chitosan to cucumber seedlings resulted in significant salt-resistant capability, this capability was increased with the delay of time, and 72.9% salt-resistant capability was obtained after 12 d. After spraying the different concentration chitosan, the stem thickness, the plant height, the length of the third main leaf, the fresh weight of stem and leaf, the fresh weight of root, the dry weight of stem and leaf, the dry weight of root, and the healthy seedling index of cucumber seedling were significantly higher than the control. Compared with the control, the treatment 200 mg·L-1 enhanced the healthy seedling index by 24.7%.Under salt stress, spraying appropriate concentration Chitosan significantly inhibited the accumulation of Malondialdehyde (MDA) in cucumber seedling, increased the stability of membrane system, decreased electrolyte leakage, and resulted in the healthy growth of cucumber seedling. MDA content of treatment 200 mg·L-1 was the lowest. Compared with the control, MDA content decreased to 55.6% after 9 d. The lowest electrolyte leakage was obtained by treatment 150 mg·L-1. Compared with the control, electrolyte leakage decreased to 64.6% after 9 d. Results showed that salt injure index of cucumber seedling was significant correlative with MDA content and electrolyte leakage of leaf. Therefore, MDA content and electrolyte leakage may reflect the oxidative damage of the salt stress to cucumber seedlings.Spray of chitosan solution promoted the flower differentiation of cucumber in greenhouse, decreased the first female flower node, increased the number of female flower, advanced the flowering time of female flower, decreased the number of male flower differentiation, increased the ratio of female and male flowers. The female effect of 150 mg·L-1 was the best, the second was 200 mg·L-1. The female flower number of single plant was increased by 55.3%. The first female flower was decreased by 3.2 nodes. The flowing time of first female flower was advanced by 6.8 d. The male flower number of single plant was decreased by 39.6%. The ratio of female and male flowers was increased by 131.3%. The rate of aborted fruit was decreased by 35.0%.Spray of chitosan solution improved the nutrition quality of cucumber in greenhouse. The total content of soluble sugar, the content of soluble protein and the amount of vitamin C in fruit were increased by 61.9%, 44.5%, 112.2% , respectively.Spray of chitosan solution increased the early yield and the total yield of cucumber in greenhouse. The effect of increasing early yield was obvious. Compared with the control, the effect of increasing early yield in treatment 150 mg·L-1 was the best, and the early yield was inceased by 106.5%.Based on the grey relational grade analysis, chitosan has favorable role for improving the salt-resistant capability and growth of cucumber, the effect is obviously different at different concentration, and 150 mg·L-1 treatment was the best.
|
PDF Full Text Request