Growth and water use of sorghum (Sorghum bicolor (L.) moench) and pearl millet (Pennisetum americanum (L.) leeke)

Abstract

A field study during the 1981 growing season was conducted at Manhattan, KS, to determine the genotypic differences in grain sorghum and pearl millet performance under favorable soil moisture conditions. Four sorghum hybrids (RS 626, RS 671, G 623-GBR, and A 28+) and four millet genotypes (Senegal bulk, Serere 3A, H 2150 × 1137 and HMP 550) were studied, and soil moisture, leaf and air temperatures, stomatal resistance and xylem water potential were measured. The grain yield of sorghum was about 37% greater than that of millet, whereas the total dry matter yield was similar for both. Among the sorghum hybrids, A 28+ showed the lowest yield while the other three hybrids did not show a definite pattern of superiority. Among the millets, the highest grain yield was found for H 2150 × 1137. The kernel weight and head weight of pearl millet were less than for sorghum, but the number of heads was greater for millet. The average cumulative water use under well-watered conditions was higher for millet (60.4 cm) than for sorghum hybrids (56.2 cm). The water use efficiency (WUE) for total dry matter was about 3.8 times higher for millet, and was 2.4 times higher for sorghum, as compared to grain water use efficiency. The WUE for grain of sorghum was more than twice that of millet. The major quantity of water was extracted from 15 to 120 cm soil depth by the sorghum, whereas millet genotypes extracted water beyond 300 cm soil depth. Xylem water potential and stomatal resistance of sorghum were lower than those of pearl millet, but millet was slightly cooler than sorghum. There was a linear relationship between the vapor pressure deficit (VPD) and canopy minus air temperature ( T c − T a ) for both sorghum and millet.