Phenotypic plasticity in leaf traits in response to experimental precipitation increase: Wettability, foliar water uptake and gas exchange

Abstract

Water availability is one of the factors affecting plant growth and development, especially in arid and semiarid environments. Changes in precipitation due climate change alter water availability to plants impacting on plant physiology. Numerous studies have focused on plant response to reduced precipitation and less on the effects of increased precipitation. The main objective of this study was to evaluate biophysical and physiological leaf traits in response to experimental water addition in four dominant shrubs and one grass species in a Patagonian steppe, during the dry season. The experiment consisted of two treatments: control and water addition, increasing the average annual rainfall by 25% during 6 years. We measured leaf wettability, water status, transpiration, photosynthesis, stomatal conductance, water use efficiency and foliar water uptake (FWU). In addition, we determined the phenotypic plasticity index of these evaluated traits. We expected lower FWU and higher transpiration and photosynthesis rates due changes in leaf surface properties under water addition treatment. All study species responded significantly to treatment with higher loss of water per transpiration and lower FWU. Also, all species increased photosynthesis rate and water use efficiency (WUE). However, water potential and leaf wettability did not change with higher precipitation. Thus, higher phenotypic plasticity was observed in functional than in morphological traits. Since functional traits were more sensitive than leaf surface traits, plants may quickly take advantage when environmental conditions tend to be more favourable to growth. Our findings suggest that plants of Patagonian steppe have adaptive ability to respond to environmental changes through plastic responses.

Nitrogen rather than water availability limits aboveground primary productivity in an arid ecosystem: Substantial differences between grasses and shrubs

“…Our results indicate a low plasticity of Patagonian steppe species to water addition. Although in a recent study in the same area, Cavallaro et al (2023) observed that these species are relatively plastic to water addition, the magnitude of plasticity was higher in functional traits than in morphological traits. Increased leaf carbon assimilation under the +W treatment observed by Cavallaro et al (2023) was not reflected in higher productivity in the present study.…”

“…Although in a recent study in the same area, Cavallaro et al (2023) observed that these species are relatively plastic to water addition, the magnitude of plasticity was higher in functional traits than in morphological traits. Increased leaf carbon assimilation under the +W treatment observed by Cavallaro et al (2023) was not reflected in higher productivity in the present study. Photoassimilates were probably allocated to roots or other functions (e.g., anti-herbivory defences) rather than to increase ANPP.…”

“…The lower intercept value of the function fitted to the +W treatment compared to the control suggests higher nutrient limitation by increasing plant N demand or N losses (Mudge et al, 2017;Ren et al, 2017). However, in previous works in the Patagonian steppe, Carbonell Silletta et al (2022) found no change in soil nutrient availability with water addition and Cavallaro et al (2023) found increased rates of transpiration and photosynthesis in +W plots. This suggests that by increasing water input without nitrogen addition, more photosynthates are allocated to other functions rather than aboveground growth.…”

Factors influencing wettability and surface/interface mechanics of plant surfaces: a review

“…Soil resistance of plant leaves refers to the resistance of plants to adverse factors in the soil, which is a comprehensive ability, including drought resistance, cold resistance, salinity resistance and other abilities. Changes in the wettability of plant leaves affect the exchange of air and water between the plant and the outside world, thereby affecting photosynthesis and respiration (Shi et al, 2011;Holder, 2012;Cavallaro et al, 2023). Wettability of the leaf surface can effectively improve water distribution within the plant (Gotsch et al, 2014;Ali et al, 2022), and also inhibit the exchange of Frontiers in Materials frontiersin.org gases at the interface, which promotes the growth of pathogens (Sase et al, 2008).…”