土施多效唑对小桐子营养生长与生殖生长的影响

Effects of Soil-applied Paclobutrazol on the Vegetative and Reproductive Growth of Biofuel Plant Jatropha curcas

小桐子(Jatrophacurcas)是一种具有多种用途的植物,其种子含油量高达40%,是一种很有应用前景的能源植物。小桐子在温度、湿度较高的地区,特别是其修剪后新萌发的枝条经常出现营养生长旺盛,成花量较少的现象,导致其种子产量较低。本研究采用多效唑(paclobutrazol,PAC)对小桐子进行土施处理,结果表明:多效唑的使用剂量为0.8g·m-1树冠直径时,可有效抑制小桐子的营养生长,降低株高;同时促进小桐子的生殖生长,增加开花和结果枝条数量,增加花序和果序数量,增加单个花序的总花数和雌花的比例,可将小桐子单株种子产量提高2.4倍。此外,多效唑处理使小桐子的开花期和结果期更加集中,便于田间管理和采收。多效唑作为赤霉素合成的抑制剂,可以有效地促进小桐子由营养生长向生殖生长的转变,对于了解赤霉素在调控小桐子花发育方面的作用具有重要意义;同时也有助于克隆有关功能基因,进一步采用转基因技术对小桐子进行遗传改良。

Multipurpose plant Jatropha curcas seeds contain about 40% oil, which is a promising energy plant for producing biofuels. Jatropha plants, especially those grown in tropical areas, show excessive vegetative growth, and erratic flowering and fruiting, which result in the low seed yield observed. This study was undertaken to determine the effects of plant growth regulator paclobutrazol （PAC）, an inhibitor of phytohormone gibberellin biosynthesis, on the inhibition of vegetative growth, and the promotion of reproductive growth of Jatropha. The results showed that soil application of PAC with an appropriate dose （0.8 g. m-~ canopy diameter） inhibited shoot growth, reduced plant height, and promoted reproductive growth of Jatropha. The number of flowering and fruiting branches and the number of inflorescence and infructescence were significantly increased by PAC treatment. Although PAC treatment significantly increased the total number of flowers and the number of female flowers of each inflorescence, no signifi- cant increase in the number of fruits of each infructescence was found, suggesting that some female flowers from PAC-treated plants failed to mature fruits. PAC treatment at 0.8 g. m-1 canopy diameter did not significantly affect seed size and oil contents, but increased seed yield of Jatropha by 2.4 times. In addition, PAC treatment led to more synchronous flowering and fruiting, which will facilitate harvesting of Jatropha fruits. These results suggest that gibberellin biosynthesis inhibitor PAC can effectively promote reproductive growth of Jatropha, which will help us to understand the physiological role of gibberellin and other plant hormones in regulation of Jatropha flower develop- ment, and are valuable for cloning of functional genes that will be used for the genetic improvement of Jatropha seed yield by transgenic approach.