不同pH和氮素形态对作物幼苗生长的影响

Effects of NH_4^+-N and NO_3^--N on crop seedling growth under different pH levels

在pH 4.0和6.0的条件下研究铵态氮(NH4+-N)和硝态氮(NO3--N)对玉米、白羽扇豆、水稻和小麦幼苗生长的影响。结果表明:不同介质pH和氮素形态均能对玉米、白羽扇豆、水稻和小麦幼苗的干物质积累和体内的分布产生影响。就玉米而言,不论供应何种形态的氮素,低pH均明显有利于干物质的积累,但低pH条件下NH4+-N最不利于小麦干物质积累;而对水稻来说,低pH条件下供应NO3--N最不利于干物质积累。pH 6.0条件下玉米、白羽扇豆和小麦3种植物均显示出较大的根冠比,表明较高的pH条件有助于同化产物向根部的运输和在根部的积累。

Solution culture experiments were carried out to study the effects of different pH levels （pH 4.0, 6.0） and N sources （NH4^＋-N, NO3^--N） on crop seedling growth. Maize, white lupin, rice and wheat were used in the experiment. Results showed that different pH and N forms could affect both accumulation of dry matter and its distribution between shoots and roots. In terms of maize, lower pH obviously increased the accumulation of dry matter. However, lower pH made wheat accumulate least dry matter, and coexistance of lower pH and NO3^--N decreased the dry matter accumulation of rice. It was interesting that all of 4 plants used in this experiment showed relatively larger ratios of root to shoot under pH 6.0, namely higher pH was favorable to transfermation of assimilates from aerial parts to roots and to their accumulation in roots.