Rice bran affects dry-matter production of Chinese and Japanese rice cultivars

The effect of rice bran on dry matter production of different rice cultivars, namely the Chinese panicle weight types and Japanese panicle number types, was evaluated in field conditions, with growth, canopy production structure and the root system determined over a period of 60 days. The treatments consisted of rice cultivars with 1000 kg /ha rice bran without agrochemicals (RB), cultivars with chemical fertilizer and cultivars with herbicide, with the latter serving as a control. The crop growth rate (CGR) and mean leaf area index (mLAI) in RB treatment were lower than that of the control; however, the net assimilation rate (NAR) was higher for all growth stages in this treatment. It was noted that CGR in RB and the control treatment depended greatly on mLAI during the early and middle growth stages, whereas CGR was more dependent on NAR in the late growth stage. Correlation between CGR in middle stage and the extinction coefficient of the canopy (k) at heading was apparent (p < 0.05). NAR in middle stage was positively correlated with mean leaf color and specific leaf weight (SLW). The correlations between NAR in the late stage and bleeding rate per number of primary roots, and per leaf area at maturity was apparent (p < 0.01). Root vitality and NAR were higher in RB treatment. The photosynthesis-related traits after heading in RB treatment were better than the control. Reduction of delta W in RB treatment as well as the spikelets number (SN) was unapparent. The panicle number type cultivars did not inhibit growth during the early and middle growth stages with the presence of rice bran. The difference between growth, panicle number and weight cultivars was insignificant in the late stage.