Chickpea evolution has selected for contrasting phenological mechanisms among different habitats

Abstract

Arguably the most important adaptive criterion in annual crops is appropriate phenology that minimizes exposure to climatic stresses and maximizes productivity in target environments. To date this has been achieved empirically by selecting among diverse genotypes in target locations. This approach is likely to become inadequate with pending climate change because selection is imposed on the outcome (flowering time) rather than the underlying mechanism (i.e. responses to daylength, ambient or vernalizing temperatures). In contrast to the cereals, in legumes the interaction between phenological mechanisms and environmental selection pressure is largely unknown. This paper addresses this shortcoming through photothermal modelling of chickpea germplasm from the world's key production areas using a meta-analysis of multi-environment trials located from 49°N to 35°S. Germplasm origin had significant effects on temperature and daylength responsiveness, the former strongly correlated to vegetative phase temperatures at the collection or development site (r = 0.8). Accordingly, temperature responses increase from winter-to spring-sown Mediterranean and Australian material, and then to north, central & southern India. Germplasm origin also affects the relationship between photoperiod and temperature response. In Eastern Mediterranean material a strong negative relationship (r = -0.77) enables temperature insensitive genotypes to compensate through a strong photoperiod response. Clearly, chickpea evolution has selected for different phenological mechanisms across the habitat range. Given that under the anticipated global warming temperature sensitive cultivars will flower relatively earlier than those responding largely to photoperiod, it is important to exploit this diversity in developing better-adapted genotypes for future cropping environments.

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

“…The first type of root growth was seen in ICC 4958 that escaped intense drought period (ICRISAT 1992;Saxena et al 1993;Kashiwagi et al 2006), with an enhanced CUSM in all the early growth stages (except at the final stage) that reflected in high levels of partitioning . However, this early growth vigour did not help ICC 8261 as it grew longer and the partitioning into grains had been affected (Berger et al 2011;Purushothaman et al 2014). All the drought tolerant and locally adapted genotypes fell in to the categories that promoted greater root growth at least in one stage for both.…”

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

“…In central-south India where the terminal drought is early and severe, early or extra-early chickpea varieties have been developed for escaping very severe drought intensity at the end of cropping season. This characteristic could be derived from thermo-sensitive chickpea germplasm but not the photoperiodic response (Berger and Turner, 2007;Berger et al, 2011). The photoperiodic sensitivity is clearly a necessity to evade the twin stresses of low winter-spring temperatures and terminal drought in Mediterranean environments where the thermo-sensitivity alone would delay the flowering, and thus would ensure exposure to terminal drought.…”

Nutritionally Enhanced Staple Food Crops

“…Another approach would be to explore the genetic variation of mineral concentration in germplasm from geographic regions deficient in soil micronutrients, given that germplasm from such regions is expected to develop inherent adaptation mechanisms that favor enhanced nutrient uptake, transport, distribution, and relocation in plants/seeds. This approach, which is also known as habitat characterization or focused identification of germplasm selection (FIGS) (Street et al 2008), has been successfully employed to characterize plant habitats and species' adaptive responses to temperature, day length, and stresses (Berger 2007;Kaur et al 2008;Bhullar et al 2009;El Bouhssini et al 2009;Berger et al 2011).…”