Heritability of drought resistance traits and correlation of drought resistance and agronomic traits in peanut
Inheritance of traits is important for developing effective breeding schemes for improving desired traits. The aims of this study were to estimate the heritabilities (h2) of drought resistance traits and the genotypic (rG) and phenotypic (rP) correlations between drought resistance traits and agronomic traits, and to examine the relationships between drought resistance traits under stressed and nonstressed conditions. The 140 lines in the F4:7 and F4:8 generations from four peanut (Arachis hypogaea L.) crosses were tested under field capacity (FC) and two-thirds available soil water (2/3 AW) in two field experiments. Data were recorded for specific leaf area (SLA), SPAD chlorophyll meter reading (SCMR), and biomass, pod yield, harvest index, number of mature pods per plant, seed per pod, and seed size. The h2 for biomass, pod yield, DTI (drought tolerance index) (pod yield), DTI (biomass), HI, SLA, and SCMR were high for all tested crosses (0.54–0.98). The rG (–0.61 and –0.66) and rP (–0.61 and –0.66) between SLA and SCMR were strong and negative under 2/3 AW and FC. Under 2/3 AW conditions, SCMR was positively correlated with pod yield and seed size. Compared to SLA, SCMR had higher rG and rP with pod yield, biomass, and other agronomics traits. Significant correlations between FC and 2/3 AW conditions were found for pod yield, biomass, SCMR, and SLA, indicating that these traits could be selected under FC or 2/3 AW conditions. SPAD chlorophyll meter reading, which is easy to measure, is potentially useful as a selection trait for drought resistance because of high h2 and positive correlation with pod yield and agronomic traits.