Study On Effects Of Fertigation And Distribution Patterns Of Carbon And Nitrogen Nutrition In Sweet Pepper (Capsicum Annul. L)

In order to study the effects of fertigation and distribution patterns of carbon and nitrogen nutrition in sweet pepper grew in the glasshouse, the experiments of soil and nutritional culture were carried by using the fertigation system and ¹⁵N,¹³C-labbeld tracers. The results were summarized as follows: 1.It was proved that the fertigation system is an advanced technology which not only safely but also high yield for the sweet pepper cultured in glasshouse. It was the reason, which maintain higher marketable fruit yield, keeping the stabilization of inorganic nitrogen at the 15cm and 100cm layers of soil. Yield and the percent of marketable fruit would not be reduced even though 1/6 of fertilizer employed by using fertigation system. It was difficult to bring some badness effects for fruit developing and the contents of nitrate and total soluble sugars, using the fertigation system with higher amount of fertilizer compound with N, P and K. The total soluble sugars was as higher as 50%～55% and glucose and fructose in fruit of sweet pepper was the main total soluble sugar. 2. The model of yield or amount of fruit setting can be described as 2(n-1) under moderate nitrogen when it was trained with 2 main branch and one main stem on a single plant. It was difficult to set the first fruit as N excessive. Therefore, fruit harvest delayed for 7 days and this could loss the chance of come into the market. Nitrogen synthesis effect on fruit yield and it's characteristics behaved as follows: the most highest percent of fruit harvested on every fruit set positions of branch was obtained with moderate nitrogen and the higher marketable fruit yield also could be obtained, however both of them induced with lower and excessive nitrogen which is main reasons that decreased the fruit yield of sweet pepper. Compared with the theoretical yield and practical yield of sweet pepper obtained in the experiment, it was found that there was the consistent in fact. 3. The translocation of nitrogen absorbed newly into plant was easier but its translocation percent became lower gradually along with the growth. The ¹⁵N absorbed at flowering period distributed directly in the leaves. After 2 weeks the translocation percent of ¹⁵N into new organs was as higher as 50.6% and 4 weeks it reached upon 57.1% and 6 weeks 58.0%. Amount of ¹⁵N distributed in the fruit followed as position of fruit setting. On the whole plant level, it is affected not only by the intensity and capacity of the nitrogen competition sink–fruit, but also by the factor of the transport time that the labeled nitrogen absorbed at early flowering transported from vegetative organs to the reproductive organs. 4. The nitrogen combined for a time into the leaves and root was easier to export to fruit, which the strong nitrogen sink and the most competitive ability for nitrogen in the plant of sweet pepper. Labeled N absorbed at early fruiting stage remained mainly in the leaves and fruits, which became the most important organs of nitrogen distributed and henceforward the leaves and root became the output organs of nitrogen, and fruit input organs. 5. Moderate nitrogen nutrition is most favorable to the translocation of ¹³C from vegetable organs into fruit. Nitrogen not only controlled the distribution of the ¹⁵N absorbed among different organs, but also affected the translocation during the development stages. Nitrogen affected hardly the distribution of ¹³C assimilated but controlled the translocation and redistribution of ¹³C. The balance of C and N is favorable to the accumulation and translocation to reproductive organ. But unbalance is the main reason decreased yield and quality as excessive N. The action of nitrogen to yield and quality associated to the absorbing time and nutrient status of plant at that time. 6. Maximum efficiency period and critical period of carbon nutrition were changed as the fruit harvest. 25 percent of ¹³C photosynthesized into plant at early harvesting redistributed to fruit at profuse harvesting. About half of the ¹³C retranslocated to newly leaf again.