芝麻4个播期7个生育时期打顶的研究

The topping effects at seven growing stages under four sowing dates in sesame (S. indicum)

５年１７点次４个播期７个生育时期打顶研究结果表明，各播期接近空梢尖形成始期打顶处理的产量均最高，增产９．８％～１７．６％。归纳了打顶的“三个同步”生育规律，提出了推算最佳打顶期公式。适期打顶优化了冠层结构与生育进程，改善了植株的生育性状及产量要素结构，促使了总生物学产量的增加与经济系数的提高，并使籽实饱满、秕粒减少、色泽纯正、商品品位提高１～２个等级。７２点次示范增产１５．７％。

The topping experiments of 7 growing stages involving 4 sowing dates in sesame had been conducted for 5 years. The result showed that the best topping dates were near the infertile top differentiation stages for all sowing date treatments, which achieved the highest yields by 9.8% 17.6% compared with the control. The growing phenomenon could be characterized as a synchronization in three aspects. The formula K=S-Y-F used to calculate the appropriate topping date was put forward. The topping practice at suitable stage improved the crown structure, growing proceeding and yield-contributors, which resulted in the increases of the total biomass and harvest index, and made the seed fullyfilled. The amount of blighted seed decreased, the seed color more purified and the commercial grade 12 ranks higher than control by topping. The demonstration at 72 locations increased the yield by 15.7% averagely.