Excized leaf water status as a measure of drought resistance of Ukrai­nian spring wheat

Drought tolerance of 24 Ukrainian spring wheat (Triticum aestivum L., T. durum Desf., T. turgidum subsp. dicoccum) genotypes was estimated by determining water deficit (WD), relative water content (RWC), excised leaves water loss weight (EL WLW), excised leaves water loss per area (EL WLA) in flag leaves of plants grown in a field conditions during Y2018 vegetative season, that was characterized by low precipitation and high temperatures. Field experimental plots were located near Dmytriv village, Lviv region (50°13´26.6´´N 24°36´50.5´´E) on the Chernozem on eluvium of carbonate rock soil. Wheat was sown in a randomized complete block design in four replications of 30 m2 plot area. The purpose of this study was to verify more reliably a physiological traits used for screening of the performance under the restricted water supply and to correlate the varietal tolerance with the final grain yield. Water status parameters were determined on the Zadoks 4.3 growth stage. Water deficit caused a reduction in the leaf RWC for all studied varieties. Differences in the drought response between T. aestivum and T. durum varieties were confirmed. The WD of flag leaves ranged from 18.0 to 37.8 % for bread and from 19.4 to 33.3 % for durum wheat varieties. The lowest WD (less or equal 20 %) has been recorded for bread varieties Kolektyvna 3, Elehiia myronivs’ka and durum varieties – Diana, Chado. High WD noted for the Simkoda myronivs’ka and MIP Raiduzhna. The low EL WLW and therefore higher drought tolerance was noticed for durum wheat varieties, namely for Spadschyna, Diana. Bread wheat varieties Simkoda myronivs’ka, Panianka, and durum wheat Zhizel’, Tera, MIP Raiduzhna and emmer Holikovs’ka varieties lost less water per leaf area (EL WLA). Past 3 biplot correlation analysis confirmed MIP Raiduzhna drought tolerance, and allowed to choose Zhizel’ (durum), Holikovs’ka (emmer) and Simkoda myronivs’ka (bread) as varieties with a high yield performance and drought tolerance. Bread varieties Bozhena and Dubravka, durum Spadschyna, Diana varieties were susceptible to drought in spite of relatively high leaf RWC. Thus, excised leaves water loss – EL WLW and EL WLA indices characte­rizing water-retaining ability of leaf tissues could be recommended as additional indicators of water stress tolerance. RWC as drought tolerance parameter is more applicable for durum varieties, whereas EL WLA 2–6 h for the bread varieties