HETEROSIS FOR NUTRIENT-UPTAKE IN F1-RICE HYBRID-SEEDLINGS

Nutrient uptake and morphological features in 12 rice hybrids were compared with the corresponding parental values. The uptakes of ammonium-N, nitrate-N, phosphorus and potassium (in nutrient mg.plant wt g-1*h-1) were determined by using 25-day-old seedlings. The results revealed that: (1) Nutrient uptake showed desirable heterosis, unlike morphological features. (2) Nutrient uptake was larger in the order of potassium, ammonium-N, nitrate-N and phosphorus. Potassium was five times as uptake as phosphorus. These facts also were observed in the F1 hybrids and their parents. (3) The degree of heterosis for nutrient uptake was higher in the order of nitrate-N, phosphorus, ammonium-N and potassium. The degrees for nitrate-N and potassium were 80% and 30%, respectively. (4) Plant weight and its heterosis did not show significant correlations to heterosis for nutrient uptake. (5) Correlations between nitrate-N and potassium uptake, and between the heterosis for their uptakes were highly positive significant. (6) It can be concluded that heterosis for physiological characters such as nutrient uptake appears before that for mophological characters, and that the higher nutrient uptake of the F1 rice hybrid was presumably not dependent on their larger weight, but on the higher rate of physiological ability. © 1990, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.