野生大豆根系形态对局部磷供应的响应及其对磷吸收的贡献

通过土柱试验模拟局部供磷,定量评价了磷局部供应对野生大豆根系形态参数的影响以及这些根形态参数对植株磷吸收的贡献.磷局部供应明显改变了野生大豆的根形态,使总根长增加了80.5％,比根长增加了32.6％,根表面积扩大了70.7％,根直径减小了27.6％,植株对磷的吸收增加了43.2％,地上干重增加了72.0％；在所有的根形态参数中,总根长、根表面积和比根长对野生大豆植株磷吸收具有较大贡献,其中尤以比根长对植株磷吸收贡献最大,即在根长增加的同时,根直径减小能够明显提高野大豆根系对磷的吸收.结果表明,野生大豆对局部磷供应表现出高度的根系形态可塑性,通过局部养分供应优化根系空间分布和定向调控根系生长能显著提高植物对异质性土壤磷资源的获取能力.

Effect of localized phosphorus supply on root morphological traits and their contribution to phosphorus uptake in wild soybean

 A soil column experiment simulating the localized supplies of phosphorus (P) was conducted to quantitatively evaluate the effect of localized P supply on root morphological parameters and the contribution of root morphological parameters to P uptake in wild soybean (Glycine soja Sieb. et Zucc). The results showed that localized P supply significantly modified the root morphological parameters in wild soybean. Total root length, specific root length and root surface area increased by 80.5%, 32.6% and 70.7%, respectively, while average root diameter decreased by 27.6%. Adjustment of root morphology resulted in the 43.2% increase in shoot P uptake and 72.0% increase in aboveground dry weight, respectively. In all of the root morphological parameters, total root length, root surface and specific root length had significantly greater contribution to shoot P uptake, and specific root length showed the largest contribution to shoot P uptake, indicating that simultaneous increase of total root length and decrease of average root diameter can obviously improve the P uptake of wild soybean. In conclusion, wild soybean exhibited highly plastic responses of root morphology to P localized supply, and enhanced the acquisition of heterogeneous soil P by optimizing root spatial distribution and changing the root morphological traits as an effective strategy of root management.