Scope for improvement of yield under drought through the root traits in chickpea (Cicer arietinum L.)

Abstract

a b s t r a c tChickpea (Cicer arietinum L.) is a major grain legume crop in South Asia, and terminal drought severely constrains its productivity. In this review, we describe how root systems can improve the productivity of chickpea under the terminal drought that occurs in a receding stored soil water conditions in central and south India and propose possible breeding and screening methods. In chickpea, total root biomass in early growth stages has been shown to significantly contribute to seed yield under terminal drought in central and south India. Maximising acquisition of water stored in 15-30 cm soil layer by roots had greater implications as the timing of absorption, available soil water and root size matches well for the complete use of water from this zone. However, deeper root systems and a greater exploitation of subsoil water offers potential for further productivity improvements under terminal drought. As proof of this concept, contrasting chickpea accessions for important root traits, such as root biomass and rooting depth, have been screened in a chickpea germplasm collection which comprises rich diversity for root traits. Through analysing mapping populations derived from crosses between these accessions, a 'QTL hotspot' that explained a large part of the phenotypic variation for the major drought tolerance traits including root traits was identified and introgressed into a leading Indian chickpea cultivar. Yield advantages of the introgression lines were demonstrated in multi-location evaluations under terminal drought. As an alternative screening method, that would indirectly asses the root system strength, to identify further promising chickpea genotypes with multiple drought tolerance traits, the leaf canopy temperature and carbon isotope discrimination measurements can be proposed.

Root traits confer grain yield advantages under terminal drought in chickpea ( Cicer arietinum L.)

“…In general, traits responsible for drought tolerance, and particularly drought avoidance, in any genotype are likely to be different from another as plants adapt to DS through different mechanisms and with the help of many different traits (Richards, 2006, Ludlow and Muchow, 1990, Saxena and Johansen, 1990, Johansen et al, 1997, Soltani et al, 2000, Tardieu, 2012). Among these traits, root traits (RDp, RLD, RDW, root surface area, average root diameter, root volume, root hair density) were found to be the major contributors to drought tolerance (avoidance) under rainfed condition (Ludlow and Muchow, 1990, Saxena et al, 1993, Krishnamurthy et al, 2003, Kashiwagi et al, 2006, Kashiwagi et al, 2015, Subbarao et al, 1995, Turner et al, 2001, Passioura, 2006, Zhu et al, 2010, Uga et al, 2013). Also, there were findings that the timings of root growth matters so as to rationalize the available water for a successful completion of the life cycle (Passioura, 1976, Zaman-Allah et al, 2011).…”

Genotypic variation in soil water use and root distribution and their implications for drought tolerance in chickpea

“…Under DS, at any specific growth stage, some specific soil depth(s) facilitated maximum water uptake and this soil zone was found to descend constantly across growing duration (Yu et al 2007;Wang et al 2012;Cutforth et al 2013;Kashiwagi et al 2015). When the integrated water uptake at the last sampling was considered, the maximum soil water uptake under DS was from 45-60 cm soil depth while under OI it was either 0-30 cm as seen in the first year or from 30 to 45 cm as in second year.…”

“…Timely and enhanced soil water uptake by equally large root systems seems to be one of the most promising approaches for enhancing drought tolerance in legumes and this association was documented in many studies (Kamoshita et al 2000;Okada et al 2002;Kashiwagi et al 2006Kashiwagi et al , 2015Bernier et al 2009;Bandyopadhyay 2014). However, there are other studies that contradict this view on the basis of root system sufficiency, soil water environments and on the timings of soil water uptake.…”

“…Plants are forced to mine deeper soil layers only when water is limited (Serraj et al 2004;Pinheiro et al 2005;Yu et al 2007;Manschadi et al 2010;Hammer et al 2009Hammer et al , 2010Wasson et al 2012;Comas et al 2013;Krishnamurthy et al 2013;Lynch 2013;Steele et al 2013). For example, in modelling exercises of soil water utilisation the root system had been considered to extract 40% of the total transpiration from the top quarter of root zone, even if the top layer is desiccated by evapotranspiration (Molz and Remson 1970) that was also confirmed to occur in chickpea (Krishnamurthy et al 1999(Krishnamurthy et al , 2010Serraj et al 2004;Kashiwagi et al 2015). Also the highest quantum of water any single soil depth can offer under DS, had come from 45-60 cm soil depth but from 30-45 cm soil depth or above, when irrigated.…”

“…The surface soil layer 15-30 cm had all the advantages such as early access by roots and better soil aeration but prone to evaporation. Therefore early use of this soil water not only enhanced the total water use but also strengthened the roots for further prolificacy in depth and density (Johansen et al 1997;Kashiwagi et al 2006Kashiwagi et al , 2015; Purushothaman R, Krishnamurthy L, Upadhyaya HD, Vadez V, Varshney RUnpubl. data).…”