Breeding and selection for drought resistance in Tropical maize
1983
Fischer, K.S. | Johnson, E.C. | Edmeades, G.O.
Throughout the lowland wet tropics, periodic nonprotracted drought caused by irregular rainfall distribution is responsible for sizable reductions in maize yield. This is when reduced water availability coincides with the critical stage of crop development--flowering. Such a drought cannot be escaped by genotype maturity or planting date, nor are other species necessarily better adapted. From a comparison of sorghum and maize under drought, it appears that sorghum maintains photosynthesis and growth at lower water levels and has more developmental plasticity than maize. Increasing the dry matter available for ear development around flowering may help to reduce the detrimental effects of drought occurring at this critical stage in maize. Many morphological and physiological characters have been suggested for modification so as to enhance drougt resistance in maize. At CIMMYT, one lowland tropical maize population is being improved for drought resistance through a recurrent selection program. Progenies are selected using an index based on grain yield under no stress and stress, leaf elongation rate, interval between anthesis and silking, canopy temperature and leaf area loss during grain filling. Evaluation of the progress after three cycles of recurrent selection shows a significant increase in yield under severe drought conditions. Improvement is approximately 9.5 percent per cycle and is mainly associated with a decrease in the number of barren plants. Other morphophysiological traits are being evaluated for their effectiveness in changing plant response to drought.
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