Inorganic nitrogen fertilizers induce changes in ammonium assimilation and gas exchange in Camellia sinensis L.

Authors : Xu Hua DU, Fang Ren PENG, Jiang JIANG, Peng Peng TAN, Zhi Zhuang WU, You Wang LIANG, Zhe Ke ZHONG

Pages : 28-38

Doi:10.3906/tar-1311-82

View : 15 | Download : 8

Publication Date : 2015-02-01

Article Type : Research Paper

Abstract :Camellia sinensis L. is one of the most economically important crops in the world today. The leaves of this plant are harvested for tea production on a massive scale through a process that requires a large amount of inorganic nitrogen insert ignore into journalissuearticles values(N);. However, knowledge of how inorganic nitrogen regulates the growth physiology of C. sinensis L. remains limited. In order to investigate its effects on gas exchange, N assimilation, and the efficiency of N use in C. sinensis L., we carried out experiments with 4 cultivars insert ignore into journalissuearticles values(WNZ, YS, ZN139, and LJ43); under 4 different treatments: 1); a control treatment, 2); a treatment fed only with NO3--N, 3); a treatment fed only with NH4+-N, and 4); a treatment fed with a mixture of NO3--N and NH4+-N in a 1:1 ratio. We found that the application of N, especially in a mixture, encouraged higher foliar N content per unit area insert ignore into journalissuearticles values(Nf);, which in turn promoted glutamine synthetase insert ignore into journalissuearticles values(GS); activity and glutamate synthase insert ignore into journalissuearticles values(GOGAT); activity. Our mixture-fed treatment increased Nf, GS, and GOGAT activity by 26.18%, 110.2%, and 92.21%, respectively, for the WNZ cultivar. The mixed-fed treatment also had the highest net photosynthetic insert ignore into journalissuearticles values(Pn);, stomatal conductance insert ignore into journalissuearticles values(Gs);, and transpiration insert ignore into journalissuearticles values(Tr); rates, while the NH4+-fed treatment had the highest intercellular CO2 content insert ignore into journalissuearticles values(Ci);. The mixture-fed and NO3--fed applications caused significant increases in photosynthetic N-use efficiency insert ignore into journalissuearticles values(PNUE);, but the NH4+-fed application decreased PNUE and water-use efficiency insert ignore into journalissuearticles values(WUE);. Furthermore, we observed that differences among cultivars for some of these parameters were significant due to different N solutions. We found that the YS and LJ43 cultivars showed no significant response to different N applications insert ignore into journalissuearticles values(excluding control); in key enzyme activity and Pn, respectively, but this was not the case for most of the other parameters. Our study indicates that the mixture-fed application promotes increased foliar N content and ammonium assimilation, which in turn increases photosynthesis rates, suggesting that the mixed-feeding of plants provides optimal conditions to promote the growth of C. sinensis L. for tea cultivation.
Keywords : Camellia sinensis L, glutamine synthetase glutamate synthase activity, inorganic nitrogen forms, photosynthesis, photosynthetic N use efficiency, water use efficiency