Chickpea (Cicer arietinumL.) root system architecture adaptation to initial soil moisture improves seed development in dry-down conditions

Abstract

Soil water deficit (WD) impacts vascular plant phenology, morpho-physiology, and reproduction. Chickpea, which is mainly grown in semi-arid areas, is a good model plant to dissect mechanisms involved in drought resistance.We used a rhizobox-based phenotyping system to simultaneously and non-destructively characterise root system architecture (RSA) dynamics and water use (WU) patterns. We compared the drought-adaptive strategies of ‘Teketay’ to the drought-sensitive genotype ICC 1882 in high and low initial soil moisture without subsequent irrigation.WD restricted vegetative and reproductive organ biomass for both genotypes. Teketay displayed greater adaptability for RSA dynamics and WU patterns and revealed different drought adaptive strategies depending on initial soil moisture: escape when high, postponement when low. These strategies were manifested in distinct RSA dynamics: in low initial soil moisture, its reduced root growth at the end of the vegetative phase was followed by increased root growth in deeper, wetter soil strata, which facilitated timely WU for seed development and produced better-developed seeds.We demonstrate that RSA adaptation to initial soil moisture is one mechanism by which plants can tolerate WD conditions and ensure reproduction by producing well-developed seeds. Our approach will help in identifying the genetic basis for large plasticity of RSA dynamics which enhances the resilience with which crops can optimally adapt to various drought scenarios.HighlightRoot system architecture and water use patterns change dynamically for distinct drought adaptation strategies in chickpea.

Natural Genotypic Variation Underpins Root System Response to Drought Stress in Bambara Groundnut [Vigna subterranea (L.) Verdc.]

“…However, the various interactions between RSA and different agroecological environments make it difficult to establish a root system ideotype that enhances both the capture of mobile water and nutrients ( Lynch and Wojciechowski, 2015 ). For example, under drying soil conditions, there is generally an increase in root elongation ( Raja and Bishnoi, 1990 ; Schmidhalter et al, 1998 ), but there is also evidence of reduced ( King and Bush, 1985 ; Ogawa et al, 2005 ) and postponed ( Bontpart et al, 2020 ) root length density (RLD). Moreover, when the soil surface slowly dries down, a reduction in RLD in deeper soil depths may aggravate the effects of water stress, triggering the reduction of essential processes such as stomatal conductance.…”

Root-based Responses of Well-watered and Water-stressed Chickpea (Cicer arietinum L.) Genotypes Varying for Drought Tolerance and Biomass

“…However, root system architecture has been largely neglected by researchers, that have primarily focused on above-ground agronomic traits (Canales et al 2019;Fikre et al 2019). The main reasons have been the technical difficulties of simultaneously and accurately measuring whole root system growth in a large set and the requirement of much time and intensive labor, particularly for field and greenhouse-based root phenotyping methods (Akman et al 2012;Bontpart et al 2020).…”