檫木叶片秋季衰老时叶色、色素和营养元素的关系

【目的】从叶片衰老角度研究檫木叶片叶色、色素和营养元素的变化规律,为秋色叶观赏树种檫木的选育以及栽培提供理论依据。【方法】以栽植于同一环境条件下的3年生檫木为试验材料,从檫木叶片停止生长到脱落,分5个时期对叶片的叶色值、色素含量和营养元素含量进行观测和分析。【结果】观测前期与观测后期,檫木叶片叶色值、色素含量和营养元素含量存在极显著差异;叶片进入衰老阶段后,叶绿素含量和类胡萝卜素含量呈下降趋势,而花色素苷含量逐渐上升;N、P、K含量在叶片衰老阶段逐渐下降。由典型相关分析可知,叶色a*值与叶绿素含量具有显著负相关,与花色素苷含量呈显著正相关;花色素苷含量与N含量成反比,类胡萝卜素含量与P含量成正比;N元素再利用效率的载荷值符号与N含量载荷值的符号相反,而P元素再利用效率的载荷值符号与P含量载荷值的符号相同;檫木叶片衰老分为3个阶段,第1阶段从9月中下旬到10月上旬,为叶片衰老准备期;第2阶段从10月中下旬到11月上旬,为叶片缓慢衰老期;第3阶段从11月中下旬到叶片脱落,为叶片衰老末期。【结论】檫木叶色最佳观赏期是从10月中下旬到11月上旬的叶片缓慢衰老期;从叶片衰老准备期到叶片衰老末期,叶绿素和类胡萝卜素被分解,花色素苷合成;N、P、K 3种营养元素逐渐被转移,其中N含量越高,N元素再利用效率就越低;与之相反,P含量越高,P元素再利用效率就越高。

Relationships of Leaf Color and Pigment and Nutrient Elements in Senescing Leaves of Sassafras tsumu

Objective] To study the changes of leaf color, pigment and nutrition concentrations of Sassafras tsumu from the perspective of leaf senescence so as to provide a scientific basis for breeding and cultivation of S. tsumu.Method] Thirty S. tsumu trees planted under the same environment were tested. From leaf stopping growth to falling off, it can be divided into five periods to observe the leaf color, pigment content and nutrient element content.Result] The value of leaf color, pigment and nutrition concentrations in S. tsumu showed highly significant difference from earlier period to late period. They were downtrend when the leaf of S.tsumu in autumn. However, the anthocyanin content increased gradually. The content of N, P, and K decreased gradually in the senescing leaf of S. tsumu. In accordance with the canonical correlation analysis, the leaf color a* value showed a significantly negative correlation with chlorophyll content, but showed a significantly positive correlation with the anthocyanin content. The anthocyanin content was inversely proportional to nitrogen content while the carotenoid content was proportional to the content of phosphorus. The symbol of nitrogen resorption efficiency and nitrogen concentrations were opposite. However, the symbol of proportional resorption efficiency and proportional concentrations were the same. The process of S. tsumu leaf senescence included 3 phases. The first phase was from late September to early November in which the leaf commences growing old.The second phase was from late October to early November in which leaf senescence was in plateau. The third phase, i.e. final phase, was from late November to the defoliation.Conclusion] The best ornamental period of S. tsumu was from late October to early November in which leaf senescence was in plateau. The chlorophyll and carotenoid were decomposed and the anthocyanin was synthesized from the first phase to the third phase. The nitrogen resorption efficiency was lower when the nitrogen concentration was higher. On the contrary, the proportional concentrations had significantly positively correlation with the proportional resorption efficiency.