No abstract

No abstract

No abstract

In plants, aquaporins (AQP) occur in multiple isoforms in both plasmalemma and tonoplast membranes resulting in regulation of water flow in and out of cells, and ultimately, water transfer through a series of cells in leaves and roots. Consequently, it is not surprising that physiological and molecular studies have identified AQPs as playing key roles in regulating hydraulic conductance in roots and leaves. As a result, the activity of AQPs influences a range of physiological processes including phloem loading, xylem water exit, stomatal aperture and gas exchange. The influence of AQPs on hydraulic conductance in plants is particularly important in regulating plant transpiration rate, particularly under conditions of developing soil water-deficit stress and elevated atmospheric vapor pressure deficit (VPD). In this review, we examine the impact of AQP activity and hydraulic conductance on crop water use and the identification of genotypes that express soil water conservation as a result of these traits. An important outcome of this research has been the identification and commercialization of cultivars of peanut (Arachis hypogaea L.), maize (Zea mays L.), and soybean (Glycine max (Merr) L.) for dry land production systems.

Temperature and vapor pressure deficit (VPD) are two important environmental factors influencing stomatal conductance and transpiration. A limited transpiration rate (TRlim) trait expressed under high VPD has been shown to offer an approach to increase crop yield in water‐limited areas. The benefit of the TRlim trait is that it lowers the effective VPD under which plants lose water and so conserves soil water to support crop growth for use during drought periods later in the growing season. Previous studies at moderate temperatures (32°C and lower) identified 12 maize (Zea mays L.) hybrids that express the TRlim trait. A critical question is whether the TRlim trait is also expressed by these hybrids under temperatures up to 38°C, which are relevant in environments where maize may be grown. Five hybrids failed to express the TRlim trait at 38°C but seven hybrids had sustained expression of the trait at 38°C. The loss of expression of the TRlim response in the five hybrids was found to occur in the very narrow range of temperature increase from 36 to 38°C. The genetic differences in water use among these maize hybrids could be useful in selecting hybrids that are especially well adapted for temperature conditions in a targeted production area.