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

Abstract

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. In wheat, no reports are available to document such influences. More importantly, the relative contributions of heat-stress night and day conditions on such sensitivity and the plant’s evaporative surface remain to be investigated. The objective of this study was to assess the response of these two physiological processes to long-term (i.e. 3 weeks) exposures to six warming scenarios, consisting of a combination of three target growth-period VPD (2, 2.7 and 4 kPa), and two night temperature (20 and 30°C) regimes among 11 diverse bread and durum wheat lines having different origins. The study revealed (i) a large genetic variability in those responses; (ii) non-linear interactions between the effects of day and night conditions; and (iii) compensation mechanisms between leaf areas and transpiration sensitivities to VPD together with differential acclimation strategies of these sensitivities with respect to increasingly warmer scenarios. These findings open the way to implementing breeding strategies that can improve wheat yields under different warming scenarios.

Component traits of plant water use are modulated by vapour pressure deficit in pearl millet (Pennisetum glaucum (L.) R.Br.)

“…either under the low VPD conditions of the rainy season or the high VPD conditions of the post-rainy and summer season), and no attention was paid to the influence growing conditions could have on the transient response of TR to VPD. Long-term growth conditions, especially with regards to VPD, could indeed influence TR's sensitivity to transient changes in VPD, as recently reported in maize, wheat and turfgrass (Yang et al 2012;Sermons et al 2012;Schoppach and Sadok 2013;Seversike et al 2013;Schoppach et al 2014). The environments where pearl millet is cultivated can experience high VPD conditions (>5 kPa).…”

“…This is important because VPD conditions fluctuate largely in a typical rainy season in the semi-arid tropics (e.g. preceding or following rainfall events) and there could be genetic variation in how growth conditions eventually alters the TR response to transient VPD changes, such as those found in wheat (Schoppach and Sadok 2013).…”

Plant Physiological, Morphological and Yield-Related Responses to Night Temperature Changes across Different Species and Plant Functional Types

“…In fact, the effects of night temperature are different from that of day temperature (Xia et al, 2014) and produced a relatively greater challenge in estimating global change impact on crop yield and ecosystem functions (Jagadish et al, 2015). Previous studies on night temperatures have focused either on the effects of HNT and LNT alone (Friend, 1981; Seddigh and Jolliff, 1984a,b,c; Koscielniak, 1993; Bertamini et al, 2005) or the mixed effects of night temperatures and CO 2 concentration (Mortensen and Moe, 1992; Volder et al, 2004; Cheng et al, 2008, 2009, 2010), light period (Gimenez and Rumi, 1988; Turner and Ewing, 1988; Lee et al, 1991; Verheul et al, 2007), intensity (Bunce, 1985; Mortensen, 1994; Rapacz, 1998; Flexas and Osmond, 1999; Davies et al, 2002) as well as other environmental factors (Schoppach and Sadok, 2013) and growth regulators (Shah et al, 2011; Mohammed et al, 2013; Zhang et al, 2014). These experiments had been conducted on pineapple (Neales et al, 1980), peanut (Bagnall et al, 1988; Wang, 2007; Lin et al, 2011) and shrub-grass ecosystems (Beier et al, 2004).…”

Water: the most important ‘molecular’ component of water stress tolerance research

“…Therefore, even under the short-term time frame of stomatal aperture control, both hydraulic and chemical signalling are likely to be intertwined. Second, the long-term control of leaf water loss via the control of leaf development is under both biochemical and hydraulic control; however, it is becoming increasingly clear that the long-term growth environment eventually conditions a short-term leaf conductance response to VPD (Sermons et al 2012;Schoppach and Sadok 2013).…”