早竹覆盖栽培的衰老生理机制

Physiological Mechanism of Precocious Senescence of Phyllostachys violascens Stands Promoted by Mulching Cultivation

研究不同覆盖时间不同年龄竹林的内源激素、营养和C/N的变化,揭示早竹覆盖栽培衰老生理机制,丰富植物衰老理论和指导退化竹林更新复壮。结果表明:1)覆盖促进早竹衰老是从竹鞭衰老开始的,与竹叶关系不大。2)根部GA3/ABA、IAA/ABA、(GA3+IAA)/ABA激素比值调控竹子衰老,(GA3+IAA)/ABA降低到一定阈值时触动竹鞭的衰老,反之,比值高抑制衰老;且以GA3/ABA为主,IAA/ABA为辅;而不是一般植物根部CTK合成量减少和向地上部分运输减少所致,CTK不是主要的衰老抑制型激素,没有参与早竹激素衰老调控,显示早竹衰老激素调控机制的特殊性,这是由竹子的生物学特性所决定的。3)早竹衰老不是由于营养亏缺和C/N比值的升高所引发,C/N比值的升高是激素调控的结果,而不是导致竹子衰老的原因,竹子的衰老是由激素调控。

The physiological mechanism of bamboo aging was investigated by measuring endogenious phyto-hormones, nutrients and C/N of the multched Phyllostachys violascens stands with different age. This study intended to develop a bamboo aging theory and find measures for improvment and rejuvinization of degraded bamboo stands. The results showed ： 1 ） Bamboo aging promoted by muhching was initiated in the rhizome, not involved in leaves. 2） Bamboo aging was regulated and controlled by the hormonal ratio of GA3/ABA, IAA/ABA, （GA3 ＋ IAA）/ABA, i.e. bamboo aging was trigged when （GA3 ＋ IAA）/ABA ratio declined below a threshold value, otherwise, the aging was prevented as its ratio was higher than a threshold value. In addition, GA3 / ABA played a more important role than IAA/ABA in promoting senescence. Bamboo aging was involved in neither less synthesis of CTK in root, nor less upward transportation from root. CTK was not the hormone for inhibiting aging, and did not play role in aging inhibition. The results suggested the bamboo had a particular aging mechanism different with general plant, which may be attributed to its biological characteristics. 3） Bamboo aging was not caused by nutrient deficiency or rise of C/N, and rise of C/N was a result of hormonal regulation, but not a reason for the bamboo aging. The bamboo aging was regulated and controlled by hormones.