Nutrient responses of seedlings of wild and cultivated Oryza species

Abstract

Abstract Lines of wild and cultivated species of Oryza from both Asia and Africa were grown in daylight at 27/22°C under a variety of nutritional conditions. The concentration of Fe, N or the complete nutrient solution was varied, as was pH and the aeration of the root medium. The wild species and primitive cultivars were more susceptible to an assumed Fe deficiency than were advanced cultivars of O. sativa . All groups showed a broadly comparable response to increasing concentratoon of nitrogen or of complete nutrient solution. There was no evidence that growth and photosynthesis of either indica or japonica rice were more adversely affected in the advanced than in the primitive cultivars or wild species by the lowest concentrations of nutrients or of nitrogen. In all lines leaf area per plant was strongly reduced at lower nitrogen concentrations, and there was an increase in the proportion of seedling dry weight in the roots, which was highest throughout in advanced cultivars. Photosynthetic rate was closely correlated, across all species and lines, with N content per unit leaf area ( r = 0.85) and also with specific leaf weight ( r = 0.78).