| Tea industry is traditional in Chinese agricultural economy. The yield and quality of the fresh leaves plays important roles in the commercial yield. Nitrogen is one of the most important elements for the growth of tea plants. The yield and quality of fresh leaves could be improved by fertilizing the soil with nitrogen (N) timely. Therefore, the diagnosis of nitrogen of tea plants, the mechanism of nitrogen metabolism and the high N use efficiency breeding have become the hottest issues recently. The accuracy of predicting the chlorophyll and total nitrogen contents with CCM-200and the nitrogen diagnosis method based on CCI values were tested in field and pot experiments. Effects of nitrogen treatments on sugar, protein, total nitrogen, assimilation enzymes of NH+4and related gene expression in two tea clones, and the differences among these indexes between5tea clones were tested simultaneously. The differences of the N use effiency among the5tea clones were evaluated comprehensively. The following is the summary of the results.1. The measurement method of CCM-200in tea plants. CCI values in the middles of leaves were lest different from the ones in the whole leaves. The difference was not obvious between the mature leaves and the whole ones in the branch. The sample containing20pieces of leaves was accuracy enough. The two sides of the main vein were not different obviously. There was no obvious influence if cleaning the leaves.2. It was feasible to predicate the chlorophyll and total nitrogen contents with CCM-200. Liner correlations between CCI values and chlorophyll a, b, total chlorophyll contents and total nitrogen contents were detected. The determination coefficients (R~2) were0.9728,0.8586,0.9774and0.9828respectively. The chlorophyll contents of different varieties and in different seasons were obviously different. However, the liner correlations appeared all the same. Once the estimate model was founded, the differences of varieties and seasons could be ignored.3. The difference of sensitivities to nitrogen between various positions of tea leaves was obvious. The low positions were more sensitive to nitrogen. The CCI values and total nitrogen contents could reflect the nitrogen status in tea plants. However, CCI values and total nitrogen contents differ obviously between various cultivations and seasons. This resulted in the difference of critical values, causing the limitation of the application of CCM-200. In this study, the relative difference between the6t h and1s t leaves（DSI）could reflect the status of nitrogen in tea plants, and it was not limited by varieties, seasons and soil texture. And it still needs further more tests. 4. The sugar, protein, total nitrogen, assimilation enzymes of NH+4and related gene expression differ significantly among various cultivations. The orders of protein, total nitrogen, assimilation enzymes of NH+4in5varieties were not the same, but the differences were not obvious. These indexes in Shuchazao were the most, in Pingyangtezao and Longjingchangye were the least, and in the Wancha91and Wuniuzao were the medium. The orders of expressions of CsGS and CsGDH2were the same as GS and GDH activities. The orders of sugar were opposite to others, and in Pingyangtezao were the most, while in Shuchazao were the least. Based on membership function, the order of N efficiency was as follows: Camellia sinensis Shuchazao> Camellia sinensis Wancha91> Camellia sinensis Wuniuzao> Camellia sinensis Longjingchangye> Camellia sinensis Pingyangtezao.5. Effects of nitrogen treatments on sugar, protein, total nitrogen, assimilation enzymes of NH+4and related gene expression were obvious. The soluble sugar, sucrose, soluble protein and total nitrogen contents increased. The GS, GOGAT and GDH activities increased, while the CsGS and CsGDH2up-regulated simultaneously. |
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