Effects of solution pH on the growth and chemical composition of rice plants

Abstract

Rice plants were grown in solution culture for a period of five weeks at pH's ranging from 3.5 to 8.5. Maximum dry matter was obtained at pH 5.5, but substantial reductions in the growth of tops and roots were observed at pH's of 3.5 and 8.5. At pH 3.5, both leaves and roots were short and unhealthy. The roots were thickened with lateral root growth severely inhibited. At pH 8.5, the youngest leaves developed chlorotic symptoms with roots being coarse and discoloured.

Plant concentrations of essential elements were adequate for normal plant growth at pH 5.5. Iron concentration in plant tops substantially decreased with increase in solution pH, but a reverse trend was observed for roots. The concentrations of other elements progressively increased in plant tops and roots with increasing pH.

Key words:

• Hydroponics
• Plant nutrition