Use of genetic variability estimates and interrelationships of agronomic and biochemical characters for selection of Lupin genotypes under different irrigation regimes
Lupin is important grain legume crop and component of the sustainable farming system of the Mediterranean climate region. Low yield and lack of stability of currently registered varieties make white lupin acreage is small.
Therefore, the relationships among grain yield and its components are controversial subjects in agronomic studies, especially under stress conditions. Five genotypes of yellow lupinus were tested in 2-year field trials (2008/2009 and 2009/2010) under two watering regimes: fully irrigated (W0) and water stress (Ws), and two inoculation treatments (commercial inoculation and un-inoculation). The objective was to evaluate the responses of 11 agronomic and biochemical traits to water stress based on estimation of genetic parameters and contribution to seed yield. Results showed that, all traits were significantly affected by irrigation treatments, except number of primary branches and 100 seed weight under W0, and number of primary branches and pods plant-1 under Ws.
According to the analysis of linear regression of the measured traits against seed yield per ha, nodule dry weight, root dry weight, pods plant-1 and 100-seed weights with the greatest genotypic variation, contributed the highest to drought tolerance. However, the contribution of catalase (CAT) was higher under Ws compared to Peroxides POD. The values of phenotypic coefficient of variation in Ws were higher than the corresponding genotypic coefficient of variation values for all characters, but the differences between them were low for all traits. Catalase
and peroxidase activity, seed yield, root and nodule dry weight showed high genetic advance (GA%) and heritability estimates. Drought tolerance index (DTI) and geometric mean (GM) were found to be effective indices for selection of superior drought-tolerant genotype (LR1) with good yield potential under both conditions. Genotypeby-trait biplot analysis showed that, all measured traits had strong positive effects on yield hectare-1 under Ws conditions, except protein percentage and branches plant-1.
Key Words: Biplot, drought stress, Lupinus albus