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

Abstract

Bread wheat (Triticum aestivum L.) is widely grown in sub-tropical and tropical areas and, as such, it is exposed to heatstress especially during the grain filling period (GFP). Global warming has further affected its production and productivity in these heat-stressed environments. We examined the effects of heatstress on 18 morpho-physiological and yield-related traits in 96 bread wheat accessions. Heat stress decreased crop growth and GFP, and consequently reduced morphological and yield-related traits in the delayed sown crop. A low heat susceptibility index and high yield stability were used for selecting tolerant accessions. Under heatstress, the days to 50% anthesis, flag-leaf area, chlorophyll content, normalized difference vegetation index (NDVI), thousand grain weight (TGW), harvest index and grain yield were significantly reduced both in tolerant and susceptible accessions. The reduction was severe in susceptible accessions (48.2% grain yield reduction in IC277741). The plant height, peduncle length and spike length showeda significant reduction in susceptible accessions, but a non-significant reduction in the tolerant accessions under the heatstress. The physiological traits like the canopy temperature depression (CTD), plant waxiness and leaf rolling were increased in tolerant accessions under heatstress. Scanning electron microscopy of matured wheat grains revealed ultrastructural changes in endosperm and aleurone cells due to heat stress. The reduction in size and density of large starch granules is the major cause of the yield and TGW decrease in the heat-stress-susceptible accessions. 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. We selected germplasm lines possessing desirable traits as potential parents for the development of bi-parent and multi-parent mapping 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 ).…”