Genetic resources for enhancing drought tolerance from National Genebank collection of linseed (Linum usitatissimum L.) in India

Drought is one of the leading constraints to linseed production globally. Understanding the genetic diversity and physiological response of linseed to drought stress is essential for developing drought-resilient varieties. Therefore, multi-environment phenotyping of 2,576 linseed accessions from National Genebank of India was undertaken in the present study to identify novel donors imparting drought tolerance.

The germplasm was screened in two water regimes (irrigated and rainfed) in three locations for two consecutive seasons based on 16 morpho-agronomic and 4 physiological traits. To capture the diversity of entire collection, a small subset ‘Reference Set for Drought Tolerance’ (RSD) comprising 200 accessions was constituted based on the Stress Tolerance Indices.

Combined analysis indicated significant reduction in early plant vigour (47.37%), leaf area index (29.95%), plant height (7.70%) and thousand seed weight (24.33%) under the water-stressed environment compared to well-irrigated conditions. Contrarily, mean days to 50% flowering were increased from 24.97 under well-watered conditions to 34.12 under rainfed conditions indicating late onset of flowering. The stress-induced reduction in physiological traits translated into yield losses causing a drastic reduction of 49.01% in mean seed yield/plant under rainfed conditions. The quality evaluation indices based on summary statistics, correlation, and PCA indicated that RSD effectively represented the diversity of entire collection for drought tolerance traits.

The results demonstrated existence of vast natural variations in linseed collection for drought tolerance. The RSD and novel high-yielding drought-tolerant genotypes identified in this study will be a potential resource in linseed improvement for moisture-constrained areas.