Response of Dry Matter Production and Photosynthesis in Oryza glaberrima Steud. and Oryza sativa L. Introduced from West Africa to the Concentrations of Culture Solution.

Abstract

To elucidate the dry matter productivity of O. glaberrima introduced from West Africa, the responses of several main growth parameters and photosynthetic rate to fertilizing levels were compared with those of O. sativa from West Africa and O. sativa c. v. Nipponbare, one of the leading Japanese cultivars. Seven strains of O. glaberrima, nine strains of O. sativa and c. v. Nipponbare were grown in the rock-wool water culture system with Kimura's B solution. The plants were grown at 75% concentration of the standard solution during the first month after germination. Thereafter the plants were grown in the solutions with three concentration levels (50, 150, and 400% of the standard) for one month, then investigated. The main results were as follows: (1) Both West African species were vigorous in growth. Average values for the two parameters, dry weight and leaf area, were considerably larger in West African species than in c. v. Nipponbare. (2) Dry weight, leaf area and the number of culms were significantly larger in O. glaberrima than in O. sativa at each level of solution concentration. Also a clear interspecific difference was found in the sensitivity of these parameters to solution concentrations. O. glaberrima, a less improved species in productivity, was highly sensitive. (3) Photosynthetic rate in single leaf was lower in O. glaberrima than in O. sativa at all the three levels of solution concentrations, while the range of variation in photosynthetic rate with concentration was larger in O. glaberrima.