Leaf mass area determines water use efficiency through its influence on carbon gain in rice mutants

Abstract

Saving water and enhancing rice productivity are consensually the most important research goals globally. While increasing canopy cover would enhance growth rates by higher photosynthetic carbon gain, an accompanied increase in transpiration would have a negative impact on saving water as well as for sustainability under water‐limited conditions. Increased water use efficiency (WUE) by virtue of higher carbon assimilatory capacity can significantly circumvent this trade‐off. Here, we report leaf mass area (LMA) has an important canopy architecture trait which when combined with superior carboxylation efficiency (CE) would achieve higher water productivity in rice. A set of 130 ethyl methanesulfonate induced mutants of an upland cultivar Nagina‐22 (N22), was screened for leaf morphological traits leading to the identification of mutants differing in LMA. The wild‐type, N22, along with a selected low‐LMA (380–4‐3) and two high‐LMA mutants (392–9‐1 and 457–1‐3), all with comparable total leaf area, were raised under well‐watered (100% Field Capacity (FC)) and water‐limited (60% FC) conditions. Low Δ13C and a higher RuBisCO content in high‐LMA mutants indicated higher carboxylation efficiency, leading to increased carbon gain. Single parent backcross populations developed by crossing high and the low‐LMA mutants with N22, separately, were screened for LMA, Δ13C and growth traits. Comparison of dry matter accumulation per unit leaf area among the progenies differing in LMA and Δ13C reiterated the association of LMA with CE. Results illustrated that high‐LMA when combined with higher CE (low Δ13C) lead to increased WUE and growth rates.

Photosynthetic Plasticity and Stomata Adjustment in Chromosome Segment Substitution Lines of Rice Cultivar KDML105 under Drought Stress

“…This result suggests that stomatal conductance had better performance when rice height was short [ 45 , 46 ], whereas net photosynthesis and water-use efficiency were contained together in PC-3 in both drought stress and drought stress plasticity conditions with the same polarity. This suggests that water use efficiency could be increased by improving carbon assimilation [ 47 , 48 ]. Stomatal traits such as upper stomatal density, upper guard cell width, lower guard cell length, and lower maximal pore area were combined in PC-2 under both drought stress and drought stress plasticity.…”

Leaf physiological and morphological constraints of water-use efficiency in C3 plants

“…In the study by Horike et al (2021) , WUE i of five shrub species covaried with LMA under drought stress. LMA differences explained WUE 13C variance across rice mutants through its influence on carbon gain ( Reddy et al 2020 b ). A study by Medrano et al (2009) also reported a positive correlation between WUE i and LMA in Mediterranean herbs and shrubs.…”

Forage crops: a repository of functional trait diversity for current and future climate adaptation

“…Likewise, C 4 forage crops will also have a decisive role in future climatic conditions, having higher carbon-fixation efficiency, water-use efficiency (WUE) and biomass production, and lower photorespiration and N 2 O and methane production, than C 3 plants (Ning et al 2020;Reddy et al 2020;De Haan et al 2021). Therefore, both C 4 and perennial forage crops have great potential to adapt to fluctuating climatic situations.…”