Harnessing nighttime transpiration dynamics for drought tolerance in grasses.

Non-negligible nighttime transpiration rates (TR) have been identified in grasses such as wheat and barley. Evidence from the last 30 years indicate that in drought-prone environments with high evaporative demand, TR could amount to 8-55% of daytime TR, leading several investigators to hypothesize that reducing TR might represent a viable water-saving strategy that minimizes seemingly 'wasteful' water loss that is not traded for CO fixation. More recently however, evidence suggests that actual in TR during pre-dawn hours, which are presumably controlled by the circadian clock, mediate drought tolerance - not through water conservation - but by enabling maximized gas exchange early in the morning before midday depression sets in.

Sleep tight and wake-up early: nocturnal transpiration traits to increase wheat drought tolerance in a Mediterranean environment.

In wheat, night-time transpiration rate (TRN) could amount to 14-55% of daytime transpiration rate (TR), depending on the cultivar and environment. Recent evidence suggests that TRN is much less responsive to soil drying than daytime TR, and that such 'wasteful' water losses would increase the impact of drought on yields. In contrast, other evidence indicates that pre-dawn, circadian increases in TRN may enable enhanced radiation use efficiency, resulting in increased productivity under water deficit.

Variability in temperature-independent transpiration responses to evaporative demand correlate with nighttime water use and its circadian control across diverse wheat populations.

Nocturnal transpiration, through its circadian control, plays a role in modulating daytime transpiration response to increasing evaporative demand, to potentially enable drought tolerance in wheat. Limiting plant transpiration rate (TR) in response to increasing vapor pressure deficit (VPD) has been suggested to enable drought tolerance through water conservation. However, there is very little information on the extent of diversity of TR response curves to "true" VPD (i.

Potential involvement of root auxins in drought tolerance by modulating nocturnal and daytime water use in wheat.

Background And Aims: The ability of wheat genotypes to save water by reducing their transpiration rate (TR) at times of the day with high vapour pressure deficit (VPD) has been linked to increasing yields in terminal drought environments. Further, recent evidence shows that reducing nocturnal transpiration (TRN) could amplify water saving. Previous research indicates that such traits involve a root-based hydraulic limitation, but the contribution of hormones, particularly auxin and abscisic acid (ABA), has not been explored to explain the shoot-root link.

Pot binding as a variable confounding plant phenotype: theoretical derivation and experimental observations.

Theoretical derivation predicted growth retardation due to pot water limitations, i.e., pot binding.

Nighttime evaporative demand induces plasticity in leaf and root hydraulic traits.

Increasing evidence suggests that nocturnal transpiration rate (TR ) is a non-negligible contributor to global water cycles. Short-term variation in nocturnal vapor pressure deficit (VPD ) has been suggested to be a key environmental variable influencing TR . However, the long-term effects of VPD on plant growth and development remain unknown, despite recent evidence documenting long-term effects of daytime VPD on plant anatomy, growth and productivity.

High resolution mapping of traits related to whole-plant transpiration under increasing evaporative demand in wheat.

Atmospheric vapor pressure deficit (VPD) is a key component of drought and has a strong influence on yields. Whole-plant transpiration rate (TR) response to increasing VPD has been linked to drought tolerance in wheat, but because of its challenging phenotyping, its genetic basis remains unexplored. Further, the genetic control of other key traits linked to daytime TR such as leaf area, stomata densities and - more recently - nocturnal transpiration remains unknown.

Genotype-dependent influence of night-time vapour pressure deficit on night-time transpiration and daytime gas exchange in wheat.

In crop plants, accumulating evidence indicates non-marginal night-time transpiration (TRNight) that is responsive to environmental conditions, especially in semiarid areas. However, the agronomical advantages resulting from such phenomenon remain obscure. Recently, drought-tolerance strategies directly stemming from daytime TR (TRDay) responses to daytime vapour pressure deficit VPD (VPDDay) were identified in wheat (Triticum spp.

Conservative water use under high evaporative demand associated with smaller root metaxylem and limited trans-membrane water transport in wheat.

Efficient breeding of drought-tolerant wheat (Triticum spp.) genotypes requires identifying mechanisms underlying exceptional performances. Evidence indicates that the drought-tolerant breeding line RAC875 is water-use conservative, limiting its transpiration rate (TR) sensitivity to increasing vapour pressure deficit (VPD), thereby saving soil water moisture for later use.

Transpiration sensitivities to evaporative demand and leaf areas vary with night and day warming regimes among wheat genotypes.

Warmer climates are already contributing to significant decreases in wheat (Triticum spp.) yields worldwide, highlighting the need for more adapted germplasm. Although many studies have addressed the effects of warmer climates on grain physiology and photosynthesis, only a few have considered temperature effects on other key yield-related traits such as the sensitivity of transpiration rate (TR) to vapour pressure deficit (VPD)-a function of air temperature and relative humidity.