The Relationship between the Root Growth Analysis and the Growth Analysis in the Paddy Rice at the Vegetative Stage

Abstract

It is important to analyze the plant growth not only from the responses of above ground organs of the plant to various spatial environmental conditions, but also from the processes of mineral uptake by roots at the same time. In the present paper, I discussed the relationships between the derivates which composed the root growth analysis and the growth functions by which the growth analysis was constituted. The cultivar of Oryza sativa L., Koshihikari, was used for the experimental material. As the treatments, five nutrient levels, NO3-N : 5, 10, 25, 50 and 100 ppm, were employed in the experiments. Whole dry weight, top dry weight, root dry weight, plant height, leaf area, number of tillers, number of roots, maximum root length and α-naphtylamine oxidizing activity in the roots were measured. The values of URA (Unit root activity=Ra/Rw : Ra is α-NA oxidizing activity per plant per hour, Rw is root dry weight), RWR (Root weight ratio=Rw/Pw : Pw is plant dry weight), RAR (Root assimilation rate=1/Ra·dPw/dt), were calculated by the procedure proposed by KUJIRA and KANDA which was descrived in the previous paper. The positive correlations were observed between URA and LAR (Fig. 7), and between URA and RGR (Fig. 6). The RWRs indicated the positive correlations to the LARs in the 50 and 100 ppm-N nutrient levels, but this correlations, on the contrary, were negative in the 5, 10 and 25 ppm-N nutrient levels (Fig. 8). It was recognized that the derivatives composed the root growth analysis and the growth analysis were interdependent mutuality in substance.