Effect of inoculation, pH and lime on nodulation and growth of pinto bean (Phaseolus vulgaris cv. Othello) : a dissertation submitted in partial fulfillment of the requirement for the postgraduate Diploma in Horticultural Science in Lincoln University

Abstract

In a glasshouse experiment, pinto bean (Phaseolus vulgaris cv Othello) was sown in pots on 20 February, 1995. Rhizabium inoculum (CC511) was applied as a solution at sowing. The pH of the potting mixture was manipulated by adding calcium hydroxide [Ca(OH)₂] at the rate of 0, 14 and 35 g per pot to give pHs 5.3, 6.5 and 7.3 respectively. Nodulation and dry matter yield was affected by Rhizobium inoculation during the latter stages of plant growth. The effect of pH on the other hand was significant for most of the parameters measured. The best combination in terms of leaf area, root, stem and leaf dry weights was obtained on inoculated plants at pH 6.5, followed by inoculated plants grown at pH 5.3 and the lowest at at pH 7.3. However, the difference between pod yield at pH 6.5 and 5.3 at final harvest was nil although total dry matter production was higher at pH 6.5. A correlation between shoot growth and nodule growth was also observed. At pH 6.5, higher vegetative growth led to the formation of heavier and bigger nodules compared to pHs 5.3 and 7.5 in the inoculated plants. At pH 7.3 where 35 g/pot Ca(OH)₂ had been applied, plant growth was inhibited and consequent yield markedly was reduced. In addition, yellowing of leaves or chlorosis occurred during the early vegetative growth of the plant.