Effects Of Nitrogen And Potassium Rates On Yield Formation, Physiology Characteristics And Nutrient Uptake Of Super Rice ’Guiliangyou 2’

Field experiments were conducted to study the influence of nitrogen and potassium rates on growth, physiological characteristics and yield of super rice to provide theory basis for super rice nitrogen and potassium comprehensive management. The effects of nitrogen and potassium rates on grain yield, physiology characteristics and nutrient uptake of super hybrid rice were determined. Super hybrid rice cultivated’Guiliangyou 2’was grown under three nitrogen rates (172.5,207,241.5 kg/hm2) and three potassium rates (216,288,360 kg/hm2). A treatment without nitrogen and potassium application (N0K0) was taken as a check. The main results are as follows.1. Effects of nitrogen and potassium rates on yield formation of super riceThe results showed that the basic productivity of the experimental field was high, grain yield under N0K0 was 10.01 and 7.99t/hm2 in early and late season, respectively. Applying nitrogen and potassium fertilizer increased panicle number per unit land area, dry matter accumulation at all growth stages and leaf area index at heading stage and consequently significant increased grain yield (early season increased:11.48-13.62t/hm2; late season increased:9.39-10.63 t/hm2). The positive effect of potassium on grain yield (18.6%-30.3%) was slightly greater than those of nitrogen (18.3%-28.3%). However, no significant differences were found among the three nitrogen rates and among the three potassium rates. These results suggest that, under high foundation soil yield like in the experiment, the nitrogen and potassium rates for super rice Guiliangyou 2 should be not exceeded 172.5kgN/hm2 and 216kgK2O/hm2.2. Effects of nitrogen and potassium rates on physiology characteristics of super riceThe results showed that applying nitrogen and potassium fertilizer increased chlorophyll content (6.44%-37.27%), nitrate reductase activity (19.33%-107.19%), soluble protein content (10.90%-36.43%), glutamine synthetase activity (14.25%-76.99%) and yield (9.39-10.63 t/hm2) of ’Guiliangyou 2’ leaves significantly at all growth stages. However, no significant differences were found among the three nitrogen rates and among the three potassium rates. With high foundation soil yield like in the experiment,. When nitrogen and potassium rates exceed 172.5 kg/hm2 and 216 kg/hm2, increase nitrogen and potassium rates can not significantly improve physiological characteristics of super hybrid rice.3. Effects of nitrogen and potassium rates on nutrient uptake of super riceNitrogen and phosphorus of rice are mainly stored in grain, potassium most residues in straw. Applying nitrogen and potassium fertilizer significantly improved nitrogen(N), phosphorus(P) and potassium(K) uptake in different organs of rice. N, P and K accumulation of rice of all the treatments increased with dry matter accumulation increased. However, no significant differences were found among the three nitrogen rates and among the three potassium rates. Increase nitrogen and potassium rates can not significantly improve nutrient uptake of super rice. With the improvement of production levels, N and P harvest index increased, transport capacity of nutrients to the grain increased. N, P, K requirements above ground plants for production of 1000kg grains of Super rice ’Guiliangyou 2’ were: 16.26-20.31kg,4.67-6.57kg,20.99-20.99kg. The experimental foundation soil yield is high, too much nitrogen and potassium applied even makes fertilizer utilization rate reduced. Therefore, under high foundation soil yield like in the experiment, nitrogen and potassium rates for super rice ’Guiliangyou 2’ should be not exceeded 172.5kgN/hm2 and 216kgK2O/hm, that can conducive to nutrient accumulation and maintaining high fertilizer utilization ratio and improve the yield of rice.