Genetic Advance Prediction and Multivariate Analysis for Antioxidants and Agronomic Traits in Wheat

Background: The Interrelationship of traits is important for structuring crop populations and modeling selection criteria for increasing grain yield.
Aims: Assessing interrelationship of traits under drought stress and normal irrigation conditions.
Study Design: Landrace varieties from different regions of Iran were selected for evaluating the interrelationship of traits under drought stress.
Place and Duration of Study: The Research Farm of Department of Crop Production and Plant Breeding, College of Agriculture, Shiraz University, Shiraz, Iran, between 2010 and 2012 growing seasons.
Methodology: Thirty five wheat genotypes consisting of 33 landrace varieties and two cultivars were cultivated as a split plot design in three replications in 2010-11 and 2011-12 growing seasons. Drought stress and normal irrigation conditions were considered as main plots and genotypes were cultivated in subplots.
Results: Cryptic relationships among antioxidants and agronomic traits were defined by 7 and 6 factors that explained 80% and 75% of traits variation under fully irrigated and drought stress conditions respectively. Factor 2 was defined as grain yield factor and it was a contrast between antioxidants and morphological traits. In factor 2, grain yield, thousands grain weight, spikelet and grain number had the highest loadings. Stepwise regression for grain yield (Y) and other traits under drought stress indicated that thousand grain weight (X1), biological yield (X2), harvest index (X3) and grain number (X4) entered to grain yield model as Y= 44.4+ 3.03 X1+ 0.389 X2+ 12.635 X3+ 2.639 X4. Except day to heading and canopy temperature, agronomic traits had positive correlations with grain yield. Cluster analysis showed that genotypes assigned to 5 clusters under drought stress and the highest grain yield (5.3 t ha-1) and harvest index (38.1%) belonged to the fifth cluster. The genetic coefficients of variation were from 1.3% (superoxide dismutase) to 19.0% (thousand grain weight) in 2010-11 and 1.52% (superoxide dismutase) to 17.2% (protein) in 2011-12. Canonical analysis showed that canopy temperature and heading were negatively associated with grain yield and with superoxide dismutase (SOD) and catalase (CAT) as antioxidant enzymes under drought stress conditions.
Conclusion: Antioxidants and canopy temperature had lowest genetic advance under drought but thousand grain weight and harvest index had highest genetic advance and can be considered as selection index for drought tolerance improvement.