Evaluation of flood tolerance in some flax genotypes using stress tolerance score index

Flax is a herbaceous plant with the scientific name of Linum usitatissimum L. The origin of this plant is reported to be the western Mediterranean. Flax is one of the most important oily and medicinal plants with wide compatibility and multiple uses. Waterlogging stress is one of the abiotic stresses that has received little attention despite the fact that it causes a lot of damage to the crop.

In this study, 100 flax cultivars were studied. The mentioned cultivars were planted in a greenhouse as a factorial experiment in a randomized complete block design to investigate genetic diversity and select the best cultivars in terms of yield and other morphological traits. First, flax seeds were planted in drainage pots containing field soil and aerated sand in a ratio of 2:1. Soil-related measurements including field capacity (FC) and soil electrical conductivity (EC) were performed. Waterlogging stress was applied in four-leaf stage. For two weeks, the pots that were in normal condition were irrigated according to the field capacity of the soil and the pots that were under stress were irrigated more than the field capacity of the soil. The main purpose of this study was to identify Waterlogging-resistant flax genotypes using all indices simultaneously and also to identify high-yield genotypes under Waterlogging stress and non-stress conditions. MP, STI, GMP, YI, DRI, YSI, SSI, TOL and β indices were calculated and finally tolerant and sensitive genotypes were identified by stress tolerance score (STS) index. STS equation for the raw data is not accurate. All indices in STS equation were standardized according to equation 10. All calculations were performed using SPSS software version 22 and Excel.

There was a significant correlation between Ys and Yp. TOL, STI, MP and GMP indices with positive and significant correlation with performance under normal conditions and STI, MP, GMP, YI and DRI with performance under normal conditions. Dendrogram was drawn based on stress tolerance score. Flax genotypes were divided into 4 groups: resistant, semi-resistant, semi-susceptible and susceptible. Analysis of variance was performed to determine the accuracy of grouping between groups and there was a significant difference between the groups. According to the stress tolerance score index, genotypes 364, 352, 286, 370 and 172 were identified as waterlogging tolerant genotypes in this study and genotypes 263, 269, 295, 325 and 108 were the most sensitive genotypes. According to the stress tolerance score index, genotypes 364, 352, 286, 370 and 172 were submerged as stress tolerant genotypes. These genotypes are predicted to be used as donors of waterlogging tolerance genes. Research findings also indicate that tolerant genotypes ultimately lead to higher production and yields than other genotypes in conditions of heavy rainfall and prolonged waterlogging. These genotypes can also be used in breeding programs based on hybridization and identification of QTLs associated with waterlogging tolerance.

They were overwhelmed by tension. According to the stress tolerance score, genotypes 364, 352, 286, 370 and 172 were identified as flood tolerant genotypes in this study and genotypes 263, 269, 295, 325 and 108 were the most sensitive genotypes.