氮素形态和弱光胁迫对茶树生长代谢的影响

doi:10.13305/j.cnki.jts.2023.03.01

摘要/Abstract

摘要： 为解析氮（N）素形态和弱光胁迫对茶树生长代谢的影响,以2年生龙井43扦插苗为试验材料,通过溶液培养分别供给NH₄⁺-N和NO₃^--N 2种不同形态N源,以及正常光照和弱光2种光照强度。结果表明：（1）茶苗净光合速率主要受N素形态影响,正常光照条件下,NH₄⁺-N处理明显高于NO₃^--N处理;相同氮素条件下,与正常光照相比,弱光胁迫有减弱茶苗净光合速率的趋势。（2）茶苗新梢叶绿素含量主要受氮素形态和光照共同影响,弱光胁迫有助于提高叶绿素含量。正常光照时NH₄⁺-N处理的茶苗新梢叶绿素含量显著高于NO₃^--N处理,但叶绿素a（Chl a）和叶绿素b（Chl b）含量的比值（Chl a/b）基本不变,弱光胁迫后新梢叶绿素含量增加,但NH₄⁺-N处理的新梢Chl a/b值明显提高,而NO₃^--N处理的Chl a/b值略有下降,茶树施用NO₃^--N比施用NH₄⁺-N更具有耐荫性。（3）茶苗N素吸收主要受N素形态和光照共同影响,弱光胁迫有助于提高茶苗新梢N素的累积。正常光照时NH₄⁺-N处理的茶苗新梢N含量要明显高于NO₃^--N处理,弱光胁迫明显增加茶树地上部N含量。（4）新梢品质成分变化主要受到光照影响,但酚氨比的变化受光照和氮源的共同作用影响。正常光照下NH₄⁺-N处理新梢游离氨基酸总量和咖啡碱含量明显高于NO₃^--N处理,而酚氨比则低于NO₃^--N处理。弱光胁迫后新梢中游离氨基酸和咖啡碱含量进一步升高,而茶多酚含量和酚氨比降低,NO₃^--N处理新梢中游离氨基酸总量增加速率和茶多酚含量、酚氨比下降速率更快。研究结果为解析其机制提供理论依据。

关键词: 茶树, 铵态氮, 硝态氮, 光照强度, 光合作用, 品质成分

Abstract: In order to analyze the effects of N form and weak light stress on the tea plant growth and metabolism, the two-year-old cutting seedlings of ‘Longjing 43’ were taken as experimental materials, and two different forms of N sources (NH₄⁺-N and NO₃^--N) and two light intensities (normal light and weak light) were supplied under solution culture. The results show that: (1) the net photosynthetic rate of tea seedlings was mainly affected by the N form under normal light intensity. The net photosynthetic rate of tea seedlings treated with NH₄⁺-N was significantly higher than that treated with NO₃^--N. Under the same nitrogen conditions, compared to normal light, weak light stress had a tendency to reduce the net photosynthetic rate of tea seedlings. (2) Under normal light intensity, the chlorophyll content in young shoots treated with NH₄⁺-N was significantly higher than that treated with NO₃^--N, but the chlorophyll a (Chl a)/chlorophyll b (Chl b) ratio was basically unchanged. The chlorophyll content increased significantly after weak light stress, but Chl a/b ratio under NH₄⁺-N treatment was significantly increased, while Chl a/b ratio under NO₃^--N treatment was slightly decreased. NO₃^--N treated tea plants showed better shade tolerance than that treated with NH₄⁺-N. (3) N uptake by tea seedlings was mainly influenced by both N form and light, and weak light stress helped to improve the accumulation of N in new shoots of tea seedlings. The N content of NH₄⁺-N treated tea seedlings was significantly higher than that treated with NO₃^--N under normal light. Weak light stress significantly increased the above-ground N content in tea plants. (4) Under normal light intensity, the contents of free amino acids and caffeine in young shoots treated with NH₄⁺-N were significantly higher than those treated with NO₃^--N, while the ratio of tea polyphenol to free amino acids was lower. After weak light stress, the contents of free amino acid and caffeine in shoots further increased, while the contents of tea polyphenol and the ratio of tea polyphenol to free amino acids continued to decline. The increase rate of total free amino acid and descent rate of tea polyphenol and tea polyphenol/free amino acids ratio were faster in young shoots treated with NO₃^--N than those treated with NH₄⁺-N. The composition of shoot quality was mainly affected by light intensity, but tea polyphenol-free amino acids ratio was influenced by both light intensity and N form. The research results provide theoretical basis for the analysis of its mechanism.

Key words: tea plant, ammonium nitrogen, nitrate nitrogen, light intensity, photosynthesis, quality component

中图分类号:

S571.1

申瑞寒, 马立锋, 杨向德, 方丽. 氮素形态和弱光胁迫对茶树生长代谢的影响[J]. 茶叶科学, 2023, 43(3): 349-355. doi: 10.13305/j.cnki.jts.2023.03.01.

SHEN Ruihan, MA Lifeng, YANG Xiangde, FANG Li. Effects of Nitrogen Form and Weak Light Stress on Tea Plant Growth and Metabolism[J]. Journal of Tea Science, 2023, 43(3): 349-355. doi: 10.13305/j.cnki.jts.2023.03.01.

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