Genotypic variation for transpiration efficiency in a lowland tropical maize population
1997
Banziger, M. | Edmeades, G.O.
Genotypic variation in transpiration efficiency (TE, biomass production per unit of transpiration) and the relationship between TE and transpiration were examined in 15 S1 lines of a lowland tropical maize population. Six plants per line were grown on stored soil water in 2 m-high, 30 cm diameter pots sealed at the top to prevent evaporation and entry of rain. Transpiration was calculated using time domain reflectometry (TDR) measurements taken from six depths at planting and at final harvest. Final harvest of biomass was made shortly after flowering when plants showed severe symptoms of drought stress. TE averaged 7.6 g kg-1 . Genotypic differences were highly significant. Values ranged from 5.8 to 11.0 g kg-1. TE increased with decreasing transpiration (r = -0.72** ). In some field trials, lines with high TE showed more severe leaf rolling (r = 0.57* ) and less osmotic adjustment (r = 0.46, P 0. 10). They also tended to produce more biomass and grain and have delayed senescence under drought (P 0.15). The results indicate considerable genotypic variation for TE in maize, but confirm as well that the adaptive value of a higher TE under drought may be offset by the negative relationship between TE and transpiration.
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