Effects Of Nitrogen And Potassium Rates And Ratio Of Potassium On Growth And Yield Of Super Rice

Nitrogen (N) and potassium (K) are essential nutrients for rice, and development of proper N and K management strategies are important for achieving high grain yield. The proper management would aim to obtain high and stable yield and minimize environmental pollution from chemical fertilizers. Field experiments with super hybrid rice cultivar Guiliangyou2were conducted to determine the effects of different N and K management strategies on population quality and yield formation of super hybrid rice under different locations. The main results are as follows:1. Rice yield was increased with increase in N rate until the rate reached255kg/ha in Nanning and Guilin and210kg/ha in Hechi. Dry matter accumulation was increased and then decreased with increasing N rate in all three locations.In Nanning and Guilin, leaf area index was increased with increase in N rate, while in Hechi it was increased with increasing N rate until the rate reached255kg/ha. N rate effect on agronomic N efficiency was inconsistent among three locations. With increase in N rate, the agronomic N efficiency was decreased in Hechi, was increased and then decreased in Guilin, and was no significant trends in Nanning.2. With increase in K rate, dry matter accumulation and grain yield were increased in Hechi, while there were no significant trends in Nanning. In Hechi, leaf area index was increased with increasing K rate. However, in Nanning, leaf area index was not increased with increase in K rate. With increasing K rate, partial K efficiency was decreased in both Hechi and Nanning, while agronomic K efficiency was only decreased in Hechi but not in Naning.3. With increase in ratio of splitting K at panicle initiation, rice yield was increased and then decreased and then increased again in Baise and Naning, while it was increased and then decreased in Wuzhou. A similar result was also in dry matter accumulation at maturity. Leaf area index was not significantly influenced by ratio of splitting K at panicle initiation. Nitrogen and potassium accumulation at maturity were slightly increased with increase in ratio of splitting K at panicle initiation, and they were significantly related with the dry matter accumulation at maturity (r=0.933*, r=0.969**).In conclusion, the optimal N rates for Guiliangyou2were165kg/ha,255kg/ha and120kg/ha in Nanning, Guilin and Hechi, respectively. The optimal K rates for Guiliangyou2were144-216kg/ha in Nanning and216kg/ha in Hechi. The best ratios of splitting K (basal fertilizer:tillering:panicle initiation) for Guiliangyou2were4:3:3in Baise and Nanning and5:3:2in Wuzhou. These N and K management strategies could ensure a relatively high dry matter accumulation, N and K use efficiencies and economic benefits.