Abstract:

A field experiment was carried out with Ningjing 28 in direct irrigation zone by Yellow River in Ningxia from 05 to 06, to study the effects of 3 irrigation rate and 4 N rate on the yield, N uptake and water/N use efficiency of rice. The results indicated that both the grain yield and straw yield of two year rice was increased with N rate increasing under the same irrigation rate. N rate significantly influenced on the yield and N uptake of rice, but irrigation rate didn’t yet. Neither N rate or irrigation rate significantly influence on plant height, ear length, ear number per hectare and weight per 1000 seed of rice. Recovery efficiency of applied N of rice in 05 was ranged from 5.1% to 37.6%, that of in 06 was ranged from 14.1% to 25.0%. Under the same N rate, physiological efficiency of applied N of rice in 05 was increased with irrigation rate increasing, that of in 06 had the opposite tendency. Agronomy efficiency of applied N of two year rice was ranged from 8.3 to 19.3 kg/kg. Partial factor productivity from applied N of rice was decreased with N rate increasing under the same irrigation rate, but the difference among of treatments irrigation rate with the same N rate was not significant. Irrigated water use efficiency of rice was declined with irrigation rate increasing under the same N rate. Combination of the yield, N uptake and water/N use efficiency, the rational irrigation rate should be about 1.2×104 m3/hm2 and N rate about 240 kg/hm2 in the experiment.