Abstract:

【Objective】The objectives of this study were to analyze the relationship between the endogeneous hormones of young spike and the senescence of the tillers, and to investigate the regulating effects of planting densities on the endogeneous hormones of young spike in Lankao Aizao 8 with large spike. 【Method】 The experiment was conducted with three density treatments respectively as 150(D1), 262.5(D2) and 375(D3) million basic seeding per hectare in 2007-2008. At the wheat jointing stage, labeled plants were selected to distinguish main stem, tiller Ⅰ and tiller Ⅱ during the young pinicle differentiation process. Young spikes were stored in liquid nitrogen. The contents of indoleacetic acid (IAA), gibberellins (GAs), abscisic acid (ABA), zeatin riboside (ZR) were determined using enzyme-linked immunosorbent assay (ELISA) method. 【Result】The difference of spike differentiation process between main culm and two tillers was small at florets initiation, and increased after then, which indicated that the young pinicle differentiation process in main culm was faster than that of two tillers. The content of GAs, IAA and ZR, the ratio of IAA/ABA and ZR/ABA in young spike appeared as main culm ＞ tillersⅠ＞ tillers Ⅱ during tiller polarizing stage, but the content of ABA was contrary at late jointing stage, higher IAA/ZR had inhibition on tillers growth.【Conclusion】The higher content of GAs, IAA, ZR and ratio of IAA/ABA and ZR/ABA in young spike were beneficial to young spike growth, but higher content of ABA and ratio of IAA/ZR had opposing effect on tillers growth and young pinicle differentiation. The senescence stage of tillers was earilier, the difference of endogeneous hormones content was larger between main culm and tillers, and plant densities had significant regulating effects on endogeneous hormones and tillers decease.

Key words: winter wheat, large spike-type, planting density, spike differentiation, endogenous hormones