Evaluation of Drought Tolerance in Camelina (Camelina Sativa) Doubled Haploid Lines Using Selection Index of Ideal Genotype (SIIG)

Camelina is a crop that has been introduced as a promising alternative to the other oilseeds over the past twenty years. Due to the increasing need of the country to import oil and the introduction of Camelina as a suitable alternative appropriate to the country climate, the present study was aimed to select the best and ideal lines of Camelina oilseeds based on SIIG index and using different drought tolerance indices for using in the future breeding programs.

The present study was conducted to evaluate the superior double haploid lines of Camelina using the selection index of ideal genotype (SIIG) in the research farm of the Faculty of Agriculture, Razi University, Kermanshah during the two cropping years of 2018-2020. The experiment was conducted with 40 lines in randomized complete block designs with three replications under rain-fed and supplementary irrigation conditions. Irrigation under normal conditions was performed based on 80 mm evaporation from class A evaporation pan. Evaluation of drought tolerant and sensitive lines was carried out using Tolerance index (TOL), Mean Productivity (MP), Stress Susceptibility Index (SSI), Geometric Mean Productivity Index (GMP), Drought Resistance Index (DI), Yield Stability Index (YSI), Sensitivity Drought Index(SDI), Relative Drought Index (RDI), Stress Tolerance Index (STI), Harmonic Mean (HAM) and the Selection Index of Ideal Genotype (SIIG) technique was used to select drought tolerant lines using the other stress tolerance indices simultaneously.

Based on the results of this study GMP, MP, HAM and STI indices had positive and significant correlation with grain yield under normal and stress conditions. Based on these indices, line 39 was identified as the most suitable line. Therefore, these indices were identified as appropriate indicators for selecting the top lines. Based on the biplot diagram, lines 39, 120, Soheil, 46, 112 and 49 were selected as the favorable lines. These lines were also identified as tolerant lines based on the SIIG index. On the other hand, line 114 with the highest distance from the ideal genotype (0.56) and the lowest value of SIIG (0.06) was identified as the weakest line in this study.

The overall results of this study showed that the use of selection index of ideal genotype (SIIG) due to the integration of different indices and achieving a single index for the selection of genotypes tolerant to drought stress can provide more reliable results for the researcher. Based on this index, the best genotype will be the genotype for which the value of SIIG index is closer to one and the genotype for which the value of SIIG index is close to zero will be known as weak genotype. Therefore, line 39 with the least distance from the ideal genotype (0.11) and the highest value of SIIG (0.83) was the most tolerant line in terms of drought tolerance, which is in accordance with the results of the biplot diagram.