Heat-resistant germplasm and breeding lines for developing durum wheat under rainfed conditions of Uzbekistan

Durum wheat, a crop of high economic importance, is severely affected by rising temperatures and recurrent heat stress, particularly under rainfed conditions. Heat during flowering and grain filling reduces spike fertility, grain size, and overall yield by 20–30%, threatening food security in regions like Uzbekistan. Since heat resistance is genetically determined, breeding heat-tolerant and early ripening durum wheat varieties with stable yields under drought-prone, rainfed conditions have become an urgent necessity. Based on this, a study was conducted at the Scientific Research Institute of Rainfed Agriculture, Jizzax Region, Uzbekistan to evaluate the heat resistance of 25 nursery collections and 27 competitive variety trial samples of durum wheat under rainfed conditions. Heat tolerance was assessed through seed heating at +54 °C for 20 minutes followed by germination, root and coleoptile growth analysis, and by determining the coagulation temperature of water-soluble proteins in leaves. Over three years of study, the germination percentage of heat-treated seeds varied from –1 to 8% compared with the standard, enabling the identification of promising heat-tolerant lines for breeding. The length of durum wheat coleoptile was from 3.5 cm to 4.7 cm, while that of the norm was 3.8 cm. By results of the research 6 vareity samples (№14 Mrb3*2/Amar, №20 Miki 3, №9 Nemesis 1, №11 Myperno, №11 Pi 277012, №19 MIX 1314), 7 varieties and lines (Marvarid, Kumushdon, RNS-2022 /14, RNS-2022/20, RNS-2022/23, RNS-2022/25, RNS-2022/27), 5 lines (RNS -2022/7, RNS-2022/20, RNS-2022/25, RNS-2022/26, RNS-2022/27) were selected with a high seed germination after heating and based on the coagulation temperature of water-soluble proteins in Durum Wheat leaves. Selecting heat-tolerant, early-maturate, and high-yielding durum wheat varieties is crucial for regions with high temperatures and low rainfall. As a result of the study, promising varieties and lines were identified based on high seed germination after heat treatment and the coagulation temperature of water-soluble proteins in leaves.

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