Identification of Climate-Smart Bread Wheat Germplasm Lines With Enhanced Adaptation to Global Warming

Abstract

Bread wheat (Triticum aestivum L.) is one of the world's most important staple food crop providing 20% global energy and dietary proteins. It is widely grown in sub-tropical and tropical areas and as such exposed to heat-stress especially at grain filling period (GFP). Global warming has further affected its production and productivity in these heat-stressed environments. We examined the effect of heat-stress on 18 morpho-physiological and yield-related traits in 96 bread wheat accessions. Heat susceptibility index (HSI <0.60) and yield stability (i <0.55) used as criteria for selecting the tolerant accessions. Heat-stress, imposed by delayed sowing, decreased crop growth and GFP, and as a result reduced morphological and yield-related traits, namely days to 50% anthesis, plant height, peduncle length, flag-leaf area, spike length, spikelets per spike, grain length and width, thousand grain weight (TGW), harvest index and yield. The reduction in the trait values was severe in susceptible accessions (48.2% yield reduction in IC277741) than the tolerant. Physiological traits like chlorophyll content, canopy temperature depression (CTD), normalized difference vegetation index (NDVI), plant waxiness and leaf rolling showed higher expression in the tolerant accessions under heat-stress. Scanning electron microscopy of matured wheat grains revealed ultrastructural changes in endosperm and aleurone cells caused due to heat-stress. The reduction of size and density of large starch granules is the major cause of yield and TGW decrease in the heat-stress susceptible lines. The most stable and high-yielding accessions namely IC566223, IC128454, IC335792, EC576707, IC535176, IC529207, IC446713 and IC416019 were identified as the climate-smart germplasm lines. Germplasm lines possessing desirable traits were selected as po-tential parents for the development of bi-parental and multi-parental populations.

Reviewing the essential roles of remote phenotyping, GWAS and explainable AI in practical marker-assisted selection for drought-tolerant winter wheat breeding

“…To expand the germplasm sources of (novel) stress tolerance traits, landraces and crop wild relatives are a valuable resource offering a wealth of diversity (Galluzzi et al, 2020) that could be transferred into breeding programmes, as has been extensively reviewed for wheat (Valkoun, 2001;Reynolds et al, 2006;Trethowan and Mujeeb-Kazi, 2008;Nakhforoosh et al, 2015;Lehnert et al, 2022;Aloisi et al, 2023;Shokat et al, 2023). Specifically, cereal genetic resources could contribute to improved drought tolerance through higher water use efficiency (Konvalina et al, 2010), rapid early development (Mullan and Reynolds, 2010), stem reserve demobilisation, osmotic adjustment (Reynolds et al, 2006), and even plant waxiness (Patidar et al, 2023). Several studies also suggest a contribution of root traits (e.g., Reynolds et al, 2006;Sanguineti et al, 2007;Trethowan and Mujeeb-Kazi, 2008;Lopes and Reynolds, 2010;Nakhforoosh et al, 2014).…”