Horticultural performance of ‘Hass’ avocado grafted onto seedling and clonal rootstocks under tropical wet-dry climate conditions

Abstract

In Brazil, avocado nursery trees are traditionally grafted onto seedling rootstocks obtained from chance seedling trees of unknown origin, which results in great tree variability within the commercial orchards. This study aimed at comparing the horticultural performance of ‘Hass' avocado trees grafted onto seedling rootstocks and onto ‘Dusa’ clonal rootstocks, a well-known root-rot tolerant cultivar. Both rootstocks were studied in an ‘Hass’ avocado orchard between year 4 to 8 after planting, by assessing individual fruit yield (number of fruit and kg plant−1), tree size, yield efficiency, Phytophthora cinnamomi presence in the soil under the canopy and fruit quality variables, such as weight, length (L), diameter (D) and L:D ratio. Postharvest fruit quality was evaluated under cold storage at 5°C and ± 85% relative humidity (RH) during a 28-day period. Along a 5-year period,‘Hass’ avocado trees grafted onto ‘Dusa’ clonal rootstock yielded a larger number of bigger and more elongated fruits per tree, which were classified within the most valued fruit size classes in the market, as compared to ‘Hass’ trees grafted onto seedling rootstocks. No significant differences were found between rootstocks regarding postharvest fruit quality or the abundance of P. cinnamomi in the soil under tree canopy.