The effect of pot size on growth and transpiration of maize and soybean during water deficit stress

Abstract

The effects of pot size on transpiration response of maize and soyabean plants undergoing water-deficit stress were examined. Maize and soyabean experiments were conducted similarly, but as separate experiments. Maize plants were grown in 2.3, 4.1, 9.1, and 16.2-litre pots sealed to prevent water loss except by transpiration. For each pot size, plants were divided into two watering regimes, a well-watered control and a water-deficit regime. Water deficits were imposed by not rewatering the pots. Soyabeans were examined in a similar manner, but only the three larger pot sizes were used in the experiment. For both maize and soyabeans, and in both watering regimes, there was a significant reduction of shoot dry weight and total transpiration with decreasing pot size. However, there were no significant differences among pot sizes in the fraction of transpirable soil water (FTSW) point at which transpiration began to decline (FTSW approx equal to 0.31 for maize and approx equal to 0.35 for soyabeans) or in the overall relationship of transpiration rate to soil water content in response to water deficits. It is concluded that, regardless of pot size or plant size, the overriding factor determining transpirational response to drought stress was soil water content.