Ezatollah Farshadfar, Parvin Elyasi and Shokouh Dabiri
In order to identify drought tolerant genotypes of bread wheat landraces (Triticum aestivum L.) two experiments were carried out in the Agricultural College, Razi university, Kermunshah, Iran, during 2009-2011. Experiment 1 was conducted in the field in a randomized complete block design with three replications under two different rainfed and irrigated conditions. Experiment 2 was carried out in the in vitro conditions using mature embryo cultures in a completely randomized design (CRD) with six replications for callus induction and a 20 × 2 factorial experiment with three replications for response of genotypes to in vitro drought stress. The results of analysis of variance for grain yield under irrigated (Yp) and rainfed (Ys) conditions exhibited the presence of a considerable genotypic variation among the genotypes (P < 0.01) indicating the possibility of discriminating drought tolerant landraces in the field conditions. Based on drought tolerance index (STI) genotypes No. 2, 5, 10, 15 and 18 identified as drought tolerant. Statical analysis also revealed highly significant differences between the genotypes for percentage of callus induction (PCI), callus growth rate (CGR), relative fresh weight growth (RFWG), relative growth rate (RGR), relative water content (RWC), percentage of callus chlorosis (PCC) and proline content (PC) indicating high genotypic variation and possible selection of drought tolerant genotypes at in vitro level. Genotypes were also different for in vitro indicators of drought tolerance such as: in vitro tolerance index (INTOL), callus growth index (CGI), percentage relative tolerance (Rt%) and percentage reduction (R%). To determine the most desirable drought tolerant genotypes according to all indices, mean rank and standard deviation of ranks of all in vitro and in vivo drought tolerance criteria were calculated and based on these two criteria the most desirable drought tolerant genotypes were identified as genotypes no. 2 (WC–4530), 10 (WC – 47399) and 18 (WC – 4931). Correlation analysis between in vivo and in vitro characteristics of drought tolerance also gave the same results.
