施肥对短枝木麻黄幼苗总酚和可溶性缩合单宁含量的影响

Effects of fertilization on Casuarina equisetifolia seedlings total phenolics and extractable condensed tannin contents.

研究了施用氮肥和磷肥对短枝木麻黄幼苗总酚(total phenolics,TP)和可溶性缩合单宁(extractable condensed tannin,ECT)含量的影响,探讨短枝木麻黄单宁形成的养分效应.结果表明:施加氮肥使短枝木麻黄幼苗小枝的TP和ECT含量显著降低,支持碳氮平衡假说和生长分化平衡假说,但对氮含量没有显著影响,从而导致TP/N和ECT/N降低;施加磷肥对TP和ECT含量没有显著影响;随着处理时间的延长,短枝木麻黄幼苗小枝TP含量升高了9.91%～14.32%,而ECT含量降低了14.32%～298.88%;TP或ECT与有机物质含量的关系则相反,表明不同类型单宁的合成途径不同,但由于TP和ECT均与氮含量无显著相关性,故不支持蛋白质竞争模型;在贫瘠土壤条件下,TP/N和ECT/N的水平较高,有利于提高短枝木麻黄的防御水平,降低凋落物的分解率,减少养分损失,从而保持较高的生产力.

This paper studied the effects of nitrogen-and phosphorus fertilization on the total phenolics（TP） and extractable condensed tannin（ECT） contents in the branchlets of Casuarina equisetifolia seedlings,aimed to approach the nutrient effect on tannin production.Under nitrogen fertilization,the TP and ECT contents decreased significantly,which supported the hypotheses of carbon-nitrogen balance（CNB） and growth-differentiation balance（GDB）,but the plant nitrogen content had less change,resulting in the decrease of TP/N and ECT/N ratios.Phosphorus fertilization had no significant effects on the TP and ECT production.With prolonged treatment time,the TP content in the branchlets of C.equisetifolia seedlings increased by 9.91%-14.32%,but the ECT content decreased by 14.32%-298.88%.The TP and ECT had opposite relationships with organic matters content,showing that different types of tannin had different biosynthetic pathways.However,both TP and ECT had no significant correlation with nitrogen content,and thus,the protein competition model（PCM） was not supported.Under nutrient-poor condition,the TP/N and ECT/N ratios were relatively high,which would be beneficial for the improvement of defense ability,the decrease of litter decomposition ratio and nutrient loss,and the maintenance of high productivity of C.equisetifolia plantations.