Plant water status and hydraulic conductance during flowering in the southern California coastal sage shrub Salvia mellifera (Lamiaceae)

Abstract

•Premise of the Study: Plant water status during flowering is important for plant reproduction, but the physiology of floral water use is not well understood. We investigated plant water status in relation to leaf and floral physiology in naturally occurring individuals of a semiarid shrub, Salvia mellifera E. Greene.•Methods: We measured stomatal (gs) and corolla (gc) conductance to water vapor, transpiration from leaves (Eleaf) and corollas (Ecorolla), leaf‐specific hydraulic conductance (KH), bulk shoot water potential (Ψshoot), and shoot water content on irrigated and control plants to analyze whether water was limiting to leaf and floral water use.•Key Results: Experimental irrigation caused a 203% increase in soil moisture content, a 20% increase in predawn Ψshoot, a 29% increase in midday Ψshoot, and a 92% increase in KH. Floral and leaf gas exchange did not respond significantly to water addition, indicating that rates were at seasonal maxima and not limited by water availability. Total daily water use by corollas was ∼20% of total shoot water use. There were no significant differences in total daily shoot water use with water addition. Mean shoot water content (5.07 g) was close to mean daily shoot water use (6.71 g), indicating that the equivalent of total shoot water content turned over every 0.76 d.•Conclusions: These results demonstrate that although irrigation improved whole‐plant hydraulic conductance, gas exchange was not limited by water availability. Additionally, the high water use of flowers in this species might limit future flowering and reproductive success during dry years.

Altered water and nitrogen input shifts succession in a southern California coastal sage community

“…(Rundel 2007), which may result in greater water requirements (Lambrecht et al 2011). Decreased water availability likely led to the lower RGR of Malosma laurina and decreased survivorship of Salvia mellifera in water reduction plots.…”

“…CSS shrubs have higher vulnerability to xylem cavitation than chaparral or desert shrubs, possibly making them susceptible to severe drought (Kolb and Davis 1994, Jacobsen et al 2007, Lambrecht et al 2011. Drought has been cited as one of the causes of CSS conversion to nonnative grassland (Heady 1988, Steers 2010.…”

Variation in and adaptive plasticity of flower size and drought-coping traits

“…This floral plasticity may be functional for plants. Given that flowers transpire significant amounts of water (Patiño and Grace 2002;Feild et al 2009;Lambrecht et al 2011;Lambrecht 2013;Teixido and Valladares 2014) and this water loss can affect leaf functioning, particularly under dry conditions (Galen et al 1999;Lambrecht and Dawson 2007;Lambrecht 2013), variation and plasticity in floral size may be an important mechanism to control water loss when plants are faced with drought (Galen et al 1999;Caruso 2006;Lambrecht and Dawson 2007). Investigating the adaptive role of floral size variation and plasticity in conjunction with leaf morphology, physiology, and reproductive traits may provide insight into the evolution of plants in relation to moisture availability (Edwards et al 2012).…”

Floral Mass per Area and Water Maintenance Traits Are Correlated with Floral Longevity in Paphiopedilum (Orchidaceae)

“…Therefore, understanding the physiological mechanisms of floral water transport and water relations may provide new insights into the evolution of flowers (Galen, 2000; Chapotin et al, 2003; Feild et al, 2009a,b; Roddy et al, 2016). Even though water has an essential role throughout the floral lifespan, few studies have focused on water relations in flowers (Feild et al, 2009b; Lambrecht et al, 2011; Roddy et al, 2016). Contrasting results in different species have indicated that some flowers are phloem-hydrated (Trolinder et al, 1993; Chapotin et al, 2003).…”