杂交稻和常规稻生育后期对NO_3^--N和NH_4^+-N的营养效应

COMPARISON OF NH_4^+-N AND NO_3^--N NUTRITION IN HYBRID AND CONVENTIONAL RICE AT THE LATE GROWTH STAGE

利用^(15)N示踪技术研究了杂交稻和常规稻生育后期对不同N源的营养效应。结果表明,杂交稻对抽穗前追施的NO_3^--N的利用率比常规稻高7.8％,回收率高13.2％:追施NH_4^+-N时,杂交稻的N肥利用率比常规稻高6.1％,回收率高14.5％肥源之间比较,收获期NH_4^+-N的利用率和回收率都高于NO_3^--N。肥料N在穗中的分配率,杂交稻比常规稻大15.7—20.2％,但NO_3^--N与NH_4^--N处理间无明显差异。试验结果还表明,抽穗前追施NO_3^--N比追施NH_4^--N能更明显地促进水稻对Ca^(2+),Mg^(2+)的吸收,刺激浮根的生长,增加稻谷产量,而且杂交稻的这些效应大于常规稻。

The difference of NH4+-N/NO3--N nutrition between hybrid and conventional rice varieties at the late growth stage was studied by using 15N-tracer technique. The results showed that the nitrate fertilizer utilization efficiency by the hybrid rice after anthesis was 7.8% higher than that by the ordinary rice variety,and the nitrate fertilizer recovery fraction by the former was 13.2% greater than that by the latter. The varietal difference in NO3--N uptake and utilization was almost twice as that in NH4+ -N.It was also showed that 15N distribution in ear of the hybrid rice was about 20% greater than that of the conventional variety, but there were no obvious differences between NO3--N and NH4+-N. However, 15N distribution in the lower node leaves and root was found to be significant higher with NO3--N than that with NH4+-N in both rice varieties, particularly in the hybrid rice. Compared with NH4+-N, NO3--N top-dressing before anthesis was observed to have much greater positive effects on the uptake of calcium and magnesium and the growth of the superficial root and the grain yield of the tested rice varieties, especially of the hybrid rice.