Soil acidity effects on premature germination in immature maize grain

Abstract

In Southern Africa, premature germination of maize (Zea mays L.) grain in standing crops is a sporadic phenomenon, which may result in serious crop losses. Uncertainty persists regarding the primary causal mechanism. This paper discusses findings obtained over two seasons in soil acidity studies on a Natal Oxisol. Premature germination was related to soil and plant chemical properties. No pre-germination was observed during the 1985/86 season, but a high incidence was recorded in the much wetter 1986/87 season. Soil and leaf chemical properties were similar in both seasons and lime markedly increased Mo uptake and NO₃ reduction. In the second season, strong relationships between pre-germination and plant Mo and NO₃ content were evident, but none of the other plant chemical parameters measured appeared to have played a role. It is concluded that Mo deficiency, correctable by liming, but not by seed treatment, was a primary causal factor, that elevation of pH beyond the point where Al toxicity is eliminated may be required to completely overcome the problem and that the condition is triggered by poorly defined enviromental conditions.