硅铁施用对水稻生长及磷吸收的影响

为探讨硅铁施用对水稻生长和磷吸收的影响，指导合理施肥、提高磷素利用率，利用水培试验研究了不同浓度铁（0、0.5、1、2 mmol·L^-1）预处理下施加不同浓度硅（0、1、4 mmol·L^-1）对水稻生长及磷吸收的影响。结果表明，低浓度的铁预处理对水稻SPAD、株高、根长和地上部干质量无显著影响，而高浓度的铁预处理下，这些指标则显著降低（P<0.05）。中低浓度铁处理下施硅在一定程度上增加了水稻株高、根长和地上部干质量，但未达到显著水平（P>0.05）。铁预处理显著增加了水稻根表铁膜的厚度及根表铁膜中的磷含量（P<0.05），施硅则显著降低了0.5 mmol·L^-1和1 mmol·L^-1铁预处理的水稻根表铁膜的厚度（P<0.05）。铁预处理对水稻根部的磷含量无显著影响，但显著降低了地上部磷的含量（P<0.05）。施硅对水稻根和地上部的磷含量无显著影响。研究表明，施铁处理显著诱导了根表铁膜的出现，增加了铁膜中的磷含量并且显著降低了地上部的磷含量；施硅在一定程度上缓解了水稻生长中的铁毒害现象，并且能够改变根表铁膜厚度，减少根冠比，从而影响水稻磷的吸收转运。

Effect of silicon and iron on the growth and phosphorus uptake of rice

In order to provide important information for improving the utilization efficiency of phosphorus (P) fertilizer, the effect of silicon (Si) (0, 1, 4 mmol·L^-1) on the growth and P uptake of rice, under iron (Fe) (0, 0.5, 1, 2 mmol·L^-1) pretreatment, was studied using hydroponic experiments. The results showed that pretreatment with low concentration Fe did not significantly affect rice SPAD, plant height, root length and shoot dry weight, but these indexes were significantly decreased under pretreatment with high concentration Fe (P<0.05). Although the application of Si increased plant height, root length, and shoot dry weight of rice to some extent, it was not significant (P>0.05). Fe pretreatment significantly increased the amount of iron plaque on the root surface of the rice and the phosphorus concentration sequestrated on the iron plaque of the root surface (P<0.05). The application of Si significantly reduced the amount of iron plaque on the root surface under pretreatment with 0.5 mmol·L^-1 and 1 mmol·L^-1 Fe (P<0.05). Fe pretreatment did not significantly affect the phosphorus concentration in rice roots, but significantly reduced the phosphorus concentration in the shoots (P<0.05). Silicon application did not significantly affect the phosphorus concentration in rice roots or shoots. Our results indicated that Fe pretreatment induced, significantly, the appearance of iron plaque on the root surface, increased the phosphorus sequestration on iron plaque and significantly reduced the phosphorus concentration in the shoots. Silicon application alleviated Fe toxicity during rice growth to a certain extent, and could affect the uptake and translocation of phosphorus by changing the amount of iron plaque on root surfaces and reducing the root-shoot ratio.