Effects of Interaction between Phosphorus Nutrition and Cultivation Methods on Grain Yield and Phosphorus Utilization of Upland Rice and Paddy Rice

Abstract

The objective of this study was to investigate the grain yield and the phosphorus utilization efficiency in responses to phosphorous (P) fertilizer and the interaction between cultivation methods and P levels in upland rice and paddy rice. One japo- nica upland rice cultivar Zhonghan 3 and one japonica paddy rice cultivar Yangfujing 8 were grown under the moist cultivation (MC, control) or bare dry-cultivation (DC) with low amount of P (LP, 45 kg ha-1), normal amount of P (NP, 90 kg ha-1), and high amount of P (HP, 135 kg ha-1). Under DC, with the increase of P level, both upland rice and paddy rice significantly increased grain yield and P accumulation, and upland rice showed a significant decrease and paddy rice had no difference in P use efficiency of matter production and P use efficiency of grain yield production. Under MC, there was no significant difference in grain yield, P accumulation amount, and P use efficiency of grain yield production.There was a significant decrease in P use efficiency of matter production between HP and NP for the upland rice, but the grain yield and P accumulation at HP were lower than at NP, there was no significant difference in P use efficiency of matter production and P use efficiency of grain yield production between HP and NP for paddy rice. When compared with MC, DC showed less number of adventitious roots, lower P accumulation amount, higher P use efficiency of matter production, lower P use efficiency of grain yield production, and lower grain yield for both upland and paddy rice with more reduction in grain yield for upland rice than for paddy rice. Compared with paddy rice, upland rice showed less number of adventitious roots, lower P accumulation amount, fewer panicles, higher seed setting rate and higher 1000-grain weight, lower grain yield, higher P use efficiency of matter production and higher P use efficiency of grain yield production. Upland rice showed a faster declining in chlorophyll content (SPAD value) of the flag leaf after anthesis. The cultivation methods and phosphorus nutrition had significant or very significant effects on the P accumulation amount after anthesis, P use efficiency of grain yield production, and adventitious roots for both upland rice and paddy rice. The P accumulation amount after anthesis was very significantly and positively correlated with grain yield and adventitious roots, and very significantly and negatively correlated with P use efficiency. Increase in P levels could increase grain yield for both upland and paddy rice under DC, and the response of the two types of rice cultivars to P levels is different under either DC or MC.