Heterosis for drought tolerant traits in coconut

Heterosis expressed by four tall (West CoastTall-WCf; Laccadive Ordinary Tall-LCf; Philippines Ordinary Tall-PHOT; andAndaman Ordinary Tall-AOT) and one dwarf coconut cultivar (Chowghat Green Dwarf-CGD) and cross combinations of tall cultivars with CGD (total eight crosses) were examined. Observations on three drought traits viz., leaf water potential, lipid peroxidation and photochemical efficiency were made during non-stress, stress and recovery periods. As the observations made in the three conditions are from the same plant, analysis of repeated measures was employed for testing the effects. Results of the analysis indicate good degree ofheterosis in some ofthe cross combinations for leaf water potential and lipid peroxidation. CGD x WCT recorded significant mid parent heterosis (39 %) for leaf water potential after recovery from stress. Significant heterosis for lipid peroxidation over better parent as well as mid-parent was observed for PHOT x CGD under non-stress (28.9 and 31.3%, respectively). Photochemical efficiency (FvlFm) values did not show significant heterosis «6%) over their parents indicating the trait is likely to be governed by additive genes. To provide an estimate ofheritability ofthe traits, data generated for two consecutive years in the same combinations were pooled and effect due to cultivars/crosses was taken as random. Heritability was also worked out for different conditions separately. Although the study uses an important dwarf cultivar, CGD known for drought and root (wilt) resistance, it needs to be confirmed by experimentation with other dwarf and tall cultivars.