Root Development of F_1 Rice Hybrid and Parents as Affected by Nitrogen Concentration of Culture Solution

概要

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Nitrogen (N) nutrition is the major factor involved in attaining high yield in rice (Oryza sativa L.). This study was conducted to elucidate the relationship between the ammonium-N concentration of the culture solution and the root system development of F_1 rice hybrid and parents. The rice plants were grown in culture solutions at 0.2, 2, and 20 mg L^<-1> of N for 30 d. Two and 20 mg L^<-1> N of culture solutions suppressed the elongation of both nodal root axes and lateral roots, whereas 20 mg L^<-1> N promoted the proliferation of the lateral roots. As a result, total root length was greatest in the 0.2 mg L^<-1> N^fed plants. On the contrary, the dry matter partitioned to the root systems of the 0.2 mg L^<-1> N-fed plants was the same as or smaller than that of the 2 and 20 mg L^<-1> N-fed plants. The ratio of total length to dry weight of the root system (specific root length) showed a trend similar to the total root length. The trend of root system development was similar in both F_1 hybrid and parents. Moreover, we observed that for the F_1 hybrid, the total root length and the specific root length of the 20 mg L^<-1> N-fed plants were almost the same as those of the 0.2 mg L^<-1> N-fed plants. These results suggest that the root system of the F_1 rice hybrid and parents grown in 0.2 mg L^<-1> N and that of the F_1 rice hybrid grown in 20 mg L^^<-1> N are highly efficient in converting the dry matter into root length increment.