Evaluation of Drought Stress Tolerance in Advanced Lines Durum Wheat Using the Selection Index of Ideal Genotype (SIIG)

Drought tolerance of 18 advanced lines durum wheat were evaluated in a randomized complete block design with four replications under dryland and complementary irrigation conditions in GachsaranAgriculturalResearchCenter at 2016-2017. In this study, traits like days to spike formation, days to maturity, plant height, peduncle length, spike length, 1000 seed weight, seed yield, spike number, spike number per m2, canopy temperature reduction of two stages of spike and seed filling, rate of greenness at two stages of spike and grain filling, were measured. Analysis of variance showed that there were significant differences among lines under study for days to spike formation, plant height, peduncle length, spike length, 1000 seed weight, seed yield, crop score, number of seeds per spike, temperature reductions of canopy at two spike stages seed and greenery content in two stages of spike and grain filling were significantly different. Mean comparisons showed that lines 4, 9, 13, 15, 16 and 17 were better than other lines in most traits. Evaluation of sensitive and tolerant lines according to tolerance index (Ti) showed that lines 1, 2, 4, 6, 9, 15 and 17, had high Ti index in most traits, were tolerant. Selection for superior lines, based on SIIG and selection of ideal genotype (SIIG) index, were performed. The results of variance analysis of traits based on Ti index showed that difference among lines in terms of 1000 seed weight, reduction of canopy temperature at grain filling stage, seed yield, grain filling period, chlorophyll content at both clustering and grain filling stage, days to reach and number of days to clustering were significant at 1% probability level. Lines 4, 5, 9 and 15 were the highest values of this index and were suitable for growing under dryland conditions. Lines 7, 8, 10 and 14 having lowest value of the SIIG index were sensitive to rainfed condition. The results of this ranking are similar to the results of cluster decomposition based on Ti index.