Performance of Maize (Zea mays L.) Genotypes during Post-Germination Drought

摘要

Maize crop establishment is often drought - impaired. A 7 - 10 day dry spell after germination is common. Experiments were designed to mimic this situation to determine if germination ability at low water potential could be used as a criterion to select for ability to sustain post germination growth. The four cultivars used had differences in their germination ability at low water potential. One, the improved variety pool 26, is known to be drought tolerant. Many of the adjustments in plant growth towater stress were typical of those reported for maize; there were no significant differences between indigenous and improved varieties. Decline of seedling height increase begins 2 to 3 days after stress. Leaf area was the most affected parameter; withholding water significantly increased the root: shoot ratio and decreased leaf area: root length ratio. The pool 26 showed a distinct response. Nodal root length significantly differed confirming the fact that many tropical maize cultivars have more nodalroots which absorb moisture from the top soil layer by altering the osmotic adjustment during drought compared to seminals and laterals. The total root length differed significantly between watered and un-watered plants. Results indicate several significant changes between watered and un-watered plants but the differences between cultivars in germination ability at low water potential did not reflect their relative tolerance to the drought situation.