Effect Of Nitrogen Fertilizer On Yield And Quality Of Tea And Ecoloical Fitness Of Toxoptera Aurantii Boyer

Long-term over-application of nitrogenous fertilizer is a key reason for insect outbreak. The focus point of the research on the interaction between plant nutrition and herbivore is how to control the rates of nitrogen fertilizer application to improve the availability of nitrogen in plants and decrease herbivory. In view of the abuse and wastage of nitrogen fertilizer in tea plantation at present, which leads to numerous negative effects, this thesis discussed the effect of using optimum amount of nitrogenous fertilizer on improving tea productivity, biochemical characters and the impacts of nitrogenous fertilizer application on the ecological fitness of major piercing-sucking pest - Toxoptera aurantii Boyer in Rougui tea plantation. The results were as follows:1 Yield and quality of tea response to different N concerntrationThis research chose the yield and quality of tea as test index, to investigate the optimum rate of nitrogen fertilizers. The result showed that there is a close relationship between tea plant yield and the rate of nitrogen fertilizer application. The tea yield and the concentration of total nitrogen, amino acid, theine and theanine were enhanced by moderate use of nitrogen fertilizer, while C/N and polyphenol concentration were decreased. When the rate of N application exceeded to a certain level, yield, quality and physiological index of tea were decreased. Spring tea, as the most important tea category of the whole year, was greatly affected by N additive application amount. The Wuyi Ruogui tea was higher by fertilized with N 767 kg·ha^-1·y^-1, and the tea quality were higher by fertilized with between 345 kg·ha^-1·y^-1 and two times of 345 kg·ha^-1·y^-1, but Wuyi Ruogui tea is suit to process oolong by fertilized with lower 345 kg·ha^-1·y^-1.2 Ecological fitness of Toxoptera aurantii Boyer response to different N concerntrationInvestigated on a group of Toxoptera aurantii Boyer that fed with tea leaves, which were treated with different N concentrations, concentrated on it's impact on Toxoptera aurantii Boyer population's average lay eggs number, leaf damage rate, relative leaf damage rate, growth rate, relative growth rate, motality, and preference trend. Researcher found that with the growth of tea leave's N concentration, all of the above items shown an increase trend, but when the concentration of N in tea leaves exceeded a certain level (1.5 times of 345 kg·ha^-1·y^-1 ),the concentration of N compounds (eg, amino acid, theine and theanine etc )were improved , while C/N and polyphenol concentration declined ,which create a inhibition on Toxoptera aurantii Boyer individuals ,and lead to an decrease in the average lay eggs number, leaf damage rate, relative leaf damage rate, growth rate, relative growth rate, and worsen the population level conditions. The need of N for Toxoptera aurantii Boyer tends to be increased with the improved N concentration at the first, and then declined, just in the form of parabola.3 The effects of tea leaves' N concentration on stress resistant capability of Toxoptera aurantii BoyerThe Effects of tea leaves' N concentration on stress resistant capability of Toxoptera aurantii Boyer was discussed by the research of Toxoptera aurantii Boyer's resistant capability to high density, high temperature, starvation and pesticide, the Toxoptera aurantii Boyer were fed with tea leaves, which were treated with different N concentrations. The results were as follows: When Toxoptera aurantii Boyer density was high, the proportion of mature nymphae of Toxoptera aurantii Boyer transformed to winged Toxoptera aurantii Boyer enhanced significantly with Toxoptera aurantii Boyer density increase and prolong of time, the phenomenon especially evidence at the low N concentration of tea leaves. At the high temperature and starvation, the hyper-long medianlethal time (LT₅₀) of mature nymphae and aptera adult Toxoptera aurantii Boyer with high N concentration were significantly higher than those with mid N concentration and low N concentration. The antibiotic resistance with pesticide of mature nymphae and aptera adult Toxoptera aurantii Boyer with different N concentration of tea leaves were as follows: high N concentration >mid N contentration >low N contentration, the medianlethal concentration (LC₅₀) of mature nymphae and aptera adult Toxoptera aurantii Boyer were endosulfan≈azadirachtin >imidacoloprid. Those results indicated that the stress resistant capability of Toxoptera aurantii Boyer may be positively by the application of nitrogenous fertilizer in tea plant.