Functional significance of shade-induced leaf senescence in dense canopies: An experimental test using transgenic tobacco
Functional significance of shade-induced leaf senescence in dense canopies: An experimental test using transgenic tobacco
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DOI：
10.1086/508633
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发表时间：
2006-11-01
影响因子：
2.9
通讯作者：
Pons, Thijs L.
中科院分区：
文献类型：
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作者：
Boonman, Alex;Anten, Niels P. R.;Pons, Thijs L.
冠层光合作用模型预测了最佳的叶面积指数（叶面积每单位表面积）和叶氮分布，在整个植物每单位氮碳增益最大化。在这项研究中，我们实验测试这些模型，使用转基因P-SAG 12-IPT烟草（SAG;烟草L.）植物叶片衰老延迟，因此具有比野生型（WT）更大的LAI和更均匀的N分布。在竞争实验中，周围野生型植物的密度增加导致更大的减少，在成熟的SAG目标植物的干重比野生型目标植物，表明在高郁闭度延迟叶片衰老性能的负面影响。营养性SAG植物实现了较低的计算每日碳增益比竞争WT植物，因为前者保留了负碳增益在阴影下，较低的部分冠层的叶子。敏感性分析表明，SAG植物的碳增益将增加，如果这些较低的叶片脱落，从这些叶片重新分配的N被用来形成额外的叶面积在冠层顶部。WT采用的这种策略是最有利的，因为它导致了竞争邻居的阴影。
Canopy photosynthesis models have predicted an optimal leaf area index ( LAI; leaf area per unit surface area) and leaf nitrogen distribution at which whole-plant carbon gain per unit N is maximized. In this study we experimentally tested these models, using transgenic P-SAG12-IPT tobacco ( SAG; Nicotiana tabacum L.) plants with delayed leaf senescence and therefore a greater LAI and more uniform N distribution than the wild type ( WT). In a competition experiment, the increased density of surrounding WT plants caused a greater reduction in dry mass of mature SAG target plants than in that of WT target plants, indicating negative effects of delayed leaf senescence on performance at high canopy density. Vegetative SAG plants achieved a lower calculated daily carbon gain than competing WT plants because the former retained leaves with a negative carbon gain in the shaded, lower part of the canopy. Sensitivity analyses showed that the carbon gain of SAG plants would increase if these lower leaves were shed and the N reallocated from these leaves were used to form additional leaf area at the canopy top. This strategy, which is adopted by the WT, is most advantageous because it results in the shading of competing neighbors.