Generative developments and pomological traits of apple (Malus x domestica Borkh.) scion cultivars canopy on dwarf clonal rootstocks in dry temperate ecosystem of north-west Himalayas

Abstract

The investigations were undertaken to study the generative developments of thirteen scion cultivars grafted onto four dwarfing rootstock clones viz., EMLA.111, EMLA.7, MM.111 and BUD.9 for pomological traits in dry temperate ecosystem of north-west Himalaya of India. Comparing scion cultivars after 7 years of planting, the survival was recorded maximum for ‘Gale Gala’ grafted onto EMLA.111 and the poorest for ‘Oregon Spur-II’ grafted onto BUD.9 rootstock clone. EMLA.111 and EMLA.7 performed very well with “Gale Gala” and ‘Golden Spur’ with regard to agro-morphometric traits and elevated yield efficiency. The growth vigor of trees grafted onto EMLA.111 and EMLA.7 was larger than those on BUD.9. After seventh harvest season, the rootstock and scion cultivar significantly affected TCSA, TCV, CA, root suckering, yield efficiency and fruit size. Maximum TCSA, TCA and CA were recorded in scion cultivar grafted onto EMLA.111. The greatest root suckering was developed from EMLA.111 (Gibson Golden) and EMLA.7 (Red Gravenstein, Sparton), and the least in EMLA.111 (Gale Gala). Correlation analysis of different attributes representing the pomological traits also resulted in a significant association at alpha=0.05 attribute pairs. PCA of pomological and fruit quality traits was also worked out to evaluate the differences among scion cultivars tested on different dwarfing rootstock clones. PC4 accounted for 93.9% (pomological traits) and 80.6% (fruit quality) of the cumulative variance of scion cultivars studied. PCA-F1 had the highest positive loadings from plant height, tree girth, TCSA, and TCV followed by PCA-F2 (fruit yield and cumulative fruit yield). Further, no significant differences were obtained when the calculated factor scores of PCA-F1, PCA-F2 and PCA-F3 for fruit quality attributes were analyzed. The study inferred that the ability of the rootstock clones to perform better than current commercial standards, while, promoting orchard health and productivity with enhanced insect-pest and disease resistance.