玉米苗期根系生长与耐低磷的关系

Maize root growth in relation to tolerance to low phosphorus

在田间筛选试验的基础上,利用两个磷高效(181和186)、两个磷低效(153和197)玉米自交系,进一步研究了这些自交系苗期耐低磷能力差异及其与根系生长的关系。结果表明,在低磷胁迫(P 5.78 mg/kg)下,所有自交系玉米地上部重量、初生根重、次生根重及磷累积量降低,但磷高效自交系181和186受影响程度显著小于153和197。在试验所处的玉米生育时期(6叶龄),磷对所用自交系的初生根及次生根数量没有影响。比较181和197的根系形态,在低磷胁迫下,磷低效自交系197的初生根侧根长、轴根长均显著下降,磷高效自交系181则下降幅度很小。而且,低磷使181初生根的侧根/轴根比值、根长度/根重比值较高。说明低磷胁迫下,181自交系可以将根中的有限的养分及干物质作更合理的分配,促进细根的生长,从而获得较长的根系。

The relationship between root growth and tolerance to phosphorus (P) deficiency in maize (Zea mays L.) seedlings was investigated by using two P - efficient (181 and 186) and two P - inefficient (153 and 197) inbred lines which were selected based on the previous field experiment. The shoot biomass, biomass of primary roots and secondary roots, and P content of all the genotypes were reduced at P deficiency (P 5.78 mg/kg soil). However, the P - efficient lines 181 and 186 were less affected. Up to 6 - leaf age of maize, the number of primary and secondary roots of all the genotypes were merely affected. Two lines, 181 and 197, were selected to investigate the root morphology further. It was found that both the lateral and axile roots of 197 decreased drastically with P stress, while those of 181 were not. At P deficiency, the ratio of lateral roots to axile roots, root length to root weight of the primary roots of 181 increased significantly. It was supposed that the allocation of nutrients and dry matter in roots of 181 was more in favor of fine roots so that its total root length was maintained .