Temporal water use by two maize lines differing in leaf osmotic potential

Abstract

Two lines of maize which had different levels of expressions of leaf osmotic potential (OP) under water-deficit conditions in the field were previously found to differ in leaf area duration and water extraction at soil depths greater than 0.80 m. In the current study, the hypothesis was explored that the difference in leaf OP between the two lines was associated with differences in transpiration rate which in turn had a major effect on the temporal dynamics of soil water use. The line with the lowest (most negative) OP in the early stages of the soil drying cycle was found to have the greatest transpiration rate and delayed wilting which was consistent with the original field observations. However, with further soil drying, the line with higher OP was able to sustain transpiration over a longer time period and actually reached the end point of transpirable soil water at a later date. The results of these experiments highlighted the necessity of accounting for temporal dynamics when interpreting crop water use in response to soil drying, particularly when comparing genotypes with differing OP.

Abscisic Acid and Sulfate Offer a Possible Explanation for Differences in Physiological Drought Response of Two Maize Near-Isolines

“…It was found that the near-isoline with the lower OP had greater leaf area duration, water extraction at soil depths greater than 0.80 m, and grain yield. In controlled-environment studies, Beseli et al [8] found that the maize near-isoline with the lower (more negative) osmotic potential (LOP) in the early stages of the soil drying cycle had the greatest transpiration rate and delayed wilting, which was consistent with the original field observations. Visual wilting was observed in the LOP plants 4 days after wilting developed in the high osmotic potential (HOP) near-isoline.…”

“…Limiting transpiration by partial stomatal closure, especially early in the crop growing season and high VPD conditions, will allow plants to conserve soil water for use when drought may 2 of 13 develop. This limited-transpiration (TR lim ) trait in response to high VPD has been observed in the genotypes of several crop species [3][4][5][6][7][8].…”

“…Interestingly, the two near-isolines also differed in their expression of the two water-conservation traits [8]. In response to VPD, the LOP near-isoline was found to have a breakpoint in the transpiration response at 2.7 kPa, while the HOP showed no breakpoint.…”

“…Possible differences among genotypes in sensitivity to soil drying can be quantified by the FTSW at which the breakpoint for the decline in NTR is initiated. Genotypes with higher FTSW breakpoints are more conservative in their soil water use, and consequently, these genotypes are likely better suited for arid environments [8,9].…”

Growth and grain yield of eight maize hybrids are aligned with water transport, stomatal conductance, and photosynthesis in a semi‐arid irrigated system

“…The osmotic adjustment in the leaves of the hybrids examined here was closely correlated with end-of-season grain production, predawn water potential, and marginally with water transport and photosynthesis, again suggesting a logical network of traits leading to improved performance (Figures 1 and 3, "wet"). Although osmotic adjustment is a known beneficial drought response in vascular species, including maize (Ashwini et al 2019;Beseli et al 2019), our results suggest that it might serve as a more effective breeding target if other closely aligned traits, namely K leaf and A N can also be targeted.…”