The Study On Nutrient Requirement And Fertilizer Application Of Cucumber In Protected Cultivation

The objective of this study was to systematically investigate the status of soil nutrient, salinity, pH values, the character of cucumber's growth and development, the behavior in absorption of nitrogen, phosphorus and potassium, the relationship between the growth and development of cucumber and the application of nitrogen, phosphorous and potassium, the relationship between fertilizer and available nutrient and to provide scientific basis for optimal fertilizer of cucumber in protected cultivation. The methods such as laboratory analysis, pot experiment, simulative soil experiment and field experiment were used in my research. The main results obtained from the experiments were summarized as follows:1. The contents of organic matter, alkali-hydrolyzable N, available P and K in the protected-cultivation soils had been markedly increased compared to that in soils of open field. The saline matters in the protected-cultivation soils were 3.78 times as those in the soils of open field, among which the NO₃^- and K⁺ ions were the most ions and the pH value in 0-20 centimeters layer of protected -cultivation soils reduced 0.461 compared to that of open field.2. "S" curves were both described for dry weight of cucumber's shoots and fruits, and accumulation of nitrogen, phosphorous and potassium during the growing process of cucumber. During the same period, N, P and K contents in fruits and shoots of cucumbers increased as fertilizer applications were increased and the increased amplitude in shoots was larger than that in fruits. P and K nutrients were utilized much more during the seedling stage and fruiting period of cucumber while N was absorbed much more from the seedling period to the initial stage of fruit and during the late stage of growth.3. The yield of cucumber increased firstly with the increase of application rates of N and P, then decreased as the yield increased up to some quantitative values, we concluded that the relationship between the cucumber's yield and the application rates of N and P accorded with parabola equation. But the correlation between cucumber's yield and potassium rates was not obvious under the experimental condition and this needed to be further studied.4. The nitrogen rates had no obvious effect on the growth of cucumber seedling because the leaf length, leaf width, shoot height and the shoot diameter of cucumber seedlings didn't show different. The symptom of the N-deficient appeared at the blooming stage. The leaf was small, the main stem was slender and shoot was short. But dried-up on the edge of new leaf and bad stretch were caused by excessive N supply. The cucumber seedlings were sensitive to phosphorus nutrition and the relationships between shoot height, leaf length, leaf width, shoot diameter and phosphorous application all accorded with parabola equation. Under the experimental conditions, the rate of K application hadmore obvious effect on shoot height, shoot diameter and leaf size of cucumber than that of N or P.5. The correlations between the yield of cucumber grown on two different soils and chlorophyll content in cucumber leaf both accorded with the parabola equation under the experimental conditions. One soil was brown earth which was located in Shandong Academy of Agricultural Sciences and the other was fluvo-aquic soil which came from Linyi. The equations were Y=-4676.5x2+16692x-12230 (r =0.9283, n =8) and Y=-2527.8x2+9662.2x-7282.9 (r =0.9820, n =8), separately. So it was shown that theyield of cucumber isn't always high when the chlorophyll content in cucumber leaf is high.6. The straight line correlations were observed between alkali-hydrolyzable N in soil and the amount of N application, available P in the soil and the rate of P application, available K and the application rate of potassium.