Effects of Cultivation Methods on the Absorption and Use Efficiency of Phosphorus in Upland Rice and Paddy Rice

Abstract

Upland rice and dry-cultivated paddy rice have been attracted more and more attention because of limited water re- sources in China, however, there is little information available on effect of cultivation methods on P absorption and use efficiency of upland rice and paddy rice. The objective of this study was to evaluate the difference between upland rice cultivar Zhonghan 3 (japonica) and paddy rice cultivar Wuxiangjing 99-8 (japonica) under three cultivation methods of moist cultivation (MC, con- trol), plastic film mulching cultivation (PFMC), and bare cultivation (BC). Compared with the MC, the grain yield was signifi- cantly lower under PFMC for upland rice, but no significant difference between PFMC and MC for paddy rice, and significantly reduced under BC for both upland rice and paddy rice. P concentration and the amount of P absorption in plants under PFMC and MC were lower, whereas P concentration decreased more slowly from heading to maturity stage under PFMC and BC. The pro- portion of P in leaves was lower, whereas significantly higher in culms and sheaths for upland rice, and was significantly higher under PFMC and significantly lower under BC for paddy rice under dry cultivation than under MC. P use efficiency of matter production (PUEp) was significantly greater under dry cultivation than under MC after heading stage and P use efficiency of grain yield production (PUEg) was lower under PFMC and higher under BC than under MC. Compared with Wuxiangjing 99-8, Zhonghan 3 exhibited lower P concentration and slower decrease in P concentration, smaller P accumulation in plants at later growth stage, higher proportion of P in leaves and grains, greater PUEp, higher PUEg and P harvest index (PHI), no difference at maturity and lower change range of the proportion of P in plants and PUEg production under three cultivations. The amount of P absorption was very significantly positively correlated with adventitious root numbers, root weight, and grain yield (r1 = 0.8227**, r2 = 0.7928**, r3 = 0.7344**). The results suggest that the effect of dry cultivation on the absorption and use efficiency of P varies largely with the cultivation methods and variety types, and dry cultivation could increase PUEp.