RESPONSES OF POTATO GENOTYPES TO DROUGHT .2. LEAF-AREA INDEX, GROWTH AND YIELD

Canopy expansion, growth and yield were examined in 19 genotypes of potato (Solanum tuberosum L.) grown either with irrigation or droughted from the time of plant emergence. In the irrigated treatment, genotypes differed both in the maximum leaf area index (L(ai)) achieved and in the duration the canopy was maintained. Drought reduced both the rate of canopy expansion and the maximum L(ai) achieved. In the droughted treatment, biomass production was correlated with leaf area duration. The relation between the effect of drought on the growth of individual leaves and biomass or yield is examined. It is concluded that selection for early leaf appearance combined with the ability to sustain leaf growth with increasing soil moisture deficit (SMD) would improve productivity in the presence of drought.