杉木幼苗非结构性碳水化合物对遮阴及恢复光照的响应

该研究以盆栽杉木(Cunninghamia lanceolata)幼苗为研究对象,采用遮光率为60%的遮光网进行遮阴处理,以正常光照为对照,遮阴处理30 d后部分杉木幼苗进行20 d的光照恢复处理,测定分析遮阴及恢复光照处理后不同组织/器官的非结构性碳水化合物(NSC)浓度及其分配、以及NSC库的变化,以探讨杉木幼苗在遮阴及恢复光照后的NSC调控机制。结果显示:(1)遮阴能够显著降低杉木幼苗各组织/器官可溶性糖浓度,各组织/器官下降幅度依次为细根(71%)>当年生叶(68%)>一年生叶(58%)>树皮(57%)>木质部(55%)>粗根(45%);遮阴使淀粉浓度的下降程度显著高于可溶性糖,在所有组织/器官中粗根的淀粉浓度下降幅度最低(50%),其次是木质部(72%)细根的淀粉浓度下降最大。(2)遮阴处理使杉木幼苗各组织/器官的NSC浓度下降量均超过50%,但杉木幼苗的存活率依然为100%;遮阴后杉木幼苗的生物量变化无明显差异,但NSC库变小,NSC相对分配改变;遮阴后不同组织/器官的NSC下降程度不一,其中粗根的NSC浓度显著高于细根。(3)恢复光照处理后杉木幼苗各组织/器官的NSC浓度均可恢复到对照水平。研究证明,遮阴环境下杉木幼苗能够主动调节其NSC在各组织/器官的分配使其维持在一定范围,从而提高杉木幼苗对遮阴环境的适应性,而不是以牺牲生长为代价。

Responses of Non structural Carbohydrates in Above ground Tissues/organs and Root to Shading and Light Restoration in Cunninghamia lanceolata Saplings

With potted seedlings of Cunninghamia lanceolata as the subject, this research measured and analyzed changes in the concentration and distribution of nonstructural carbohydrates (NSC) and the NSC pool in different tissues/ organs after shading and light restoration. The former treatment being achieved with 60% shade net, normal lighting being the control; after 30 days of shading, some materials were put under light restoration for 20 days. In this way, this paper studied the NSC regulation mechanism of C. lanceolata seedlings after shading and light restoration. The results indicated that: (1) shading could significantly reduce the concentration of soluble sugar in tissues/organs of the seedlings, the amplitude of reduction in turn being: fine roots (71%) > current year needles (68%) > one year old needles (58%) > bark (57%) > xylem (55%) > coarse roots (45%); shading caused decrease of starch concentration was significantly sharper than that of soluble sugar; of all tissues/ organs, the margin of decrease in starch concentration in coarse roots was the smallest (50%), followed by xylem (72%), fine roots being the largest. (2) Under shading, NSC concentration in different tissues/organs of the seedlings all dropped by over 50%, but the survival of the seedlings remained 100%; the change of biomass in the seedlings after shading showed no significant difference, only NSC pool narrowed, and NSC relative distribution modified; after shading, NSC in different tissues/organs declined to varied degrees, NSC concentration of coarse roots being significantly higher than that of fine roots. (3) After light restoration, NSC concentration in the tissues/organs of the seedlings returned to an equivalent level with the control. According to the research, under shading conditions, seedlings of C. lanceolata could actively adjust their NSC distribution in different tissues/organs so that it remained in a certain range, thus enhancing their own adaptability to the shaded environment but not at the expense of growth.