Effect Of Nitrogen Fertilizer On Physiological And Biochemical Parameters Of Tea Plants And Ecological Adaptation Of Tea Aphid (Toxoptera Aurantii Boyer)

Nitrogen (N) is one of the most important nutritional elements for growth and development both of tea plants and arthropods. The excessive application of nitrogen fertilizer is considered as a key factor of rampancy of pest herbivores. But little was known about the effects of nitrogen application on ecological fitness of herbivores. In this thesis, we studied the effects of rate of nitrogen application on physiology of Oolong tea plant (Camellia sinensis) and ecological fitness of tea aphids (Toxoptera aurantii Boyer). The results were as follows:1. Effects of nitrogen application on tea physiologyN application differently affected tea physiology of different year tea plants: with N application increasing, total N and caffeine of annual and biannual tea increased as well as nitrate N, free amino acids and total proteins of annual tea, while C/N and biannual tea nitrate N significantly decreased and a conic regression relationship was found between N application and free amino acids of biannual and 3-year-old tea, 3-year-old tea soluble sugars and tea polyphenols of biannual tea.Nitrate N, free amino acids, soluble proteins and caffeine had a significant positive correlation with total N, but C/N negative, while a conic regression relationship was found between soluble sugars and total N, and tea polyphenols independent. Free amino acids, soluble proteins, soluble sugars and caffeine had a significant negative correlation with C/N, while nitrate N and tea polyphenols independent.2. Effects of nitrogen application on physiology of tea aphidsSoluble proteins of the first generations'aphids(G1) remarkably increased as N application increased, with lower increase rates on later generations, while that of aphids above GN was non-related with N application neither was crude fat.Nitrogen application complicatedly affected aphids'insecticide susceptibility: it had significant effects on carboxlesterase (CarE) activity of the first generations'aphides and acetycholineterase (AChE) activity of G2 aphids, but no effect on CarE or AChE activity of aphids above GN or on glutathione s-transferase (GSHs) activity.3. Physiological relationships between tea plants and tea aphidsProtein content of G3 aphids had a significant correlation with tea free amino acids, while that of aphids above GN had a significant negative correlation with tea soluble proteins, and that of aphids of G1, G2 and above GN was independent of tea free amino acids. No correlation was found between tea soluble proteins and protein contents of the first three generations'aphids. AChE activities of G1, G2, G3 aphids had a significant positive correlation with tea N contents, while CarE activity of aphids above GN negative, and AChE and GSHs activities of aphids not.The study of relationships between aphids'physiological indexes and relevant tea physiological indexes indicated: protein contents of aphids had significant positive correlation with tea total carbon and caffeine; fat had remarkable negative correlation with tea caffeine; AChE activities of aphids had a significant positive correlation with tea soluble sugars; CarE activities of aphids had a significant positive correlation with tea total N and soluble sugars, and a significant negative correlation with tea nitrate N; GSHs activities of aphids was non-related with tea physiological indexes detected.4. Effects of nitrogen application on ecological fitness of tea aphidsInfluences of N application on aphids' hunger tolerance gradually improved on later generations. Aphids'hunger tolerance increased with increasing N application, but decreased at extremely high N application rates.Insecticide susceptibility to imidacloprid of G1, G2, G3 aphides as well as its bottom values lowered as N application increased, but it improved at extremely high N application rates. And susceptibility of aphids above GN improved with N application increasing. With N application increasing, insecticide susceptibility to bifenthrin G1, G2, G3 aphids decreased, but that of GN firstly decreased then improved, with a bottom value at a medium N application rate of 1.5 g/pot.Low temperature tolerance of aphids after G2 improved with N application increasing, but lowered at extremely high N application rates. G1 aphids'40℃tolerance had no significant correlation with N application, while that of G2, G3 aphids improved with N application increasing and that of aphids above GN significantly improved at medium(1.5 g/pot) and high(2.5 g/pot) N application rates. Aphids'45℃tolerance of improved with N application increasing, but lowered at extremely high rates, with peak tolerances at a N application of 1.5 g/pot.