Evaluation of aerial and root plant growth behavior, water and nutrient use efficiency and carbohydrate dynamics for Hass avocado grown in a soilless and protected growing system

Abstract

Avocado production is nowadays questioned worldwide and at risk due to climate change and the high water footprint of this crop. Thus, there is need for the development or adoption of new strategies such as alternative production systems. In this study, Hass avocado plants grafted on two rootstocks (Mexicola -seed propagated and Dusa® - vegetative-propagated and referred as clonal) were grown in a greenhouse and substrate (coir growth container, 55 L of volume and 500 × 480 mm, H X W) culture system in Valparaiso Region, Chile. Plant growth and development during the vegetative and reproductive phases until end of flowering (63 weeks) were monitored. Plant aerial and root parameters from these two rootstock types (seed and clonal) were monitored by measuring canopy and trunk area, trunk height, root area, type of roots (rhizotron), non-structural carbohydrates dynamics, further primary metabolites, water use efficiency (WUE) and nitrate and phosphate use efficiency (NUE and PUE). Results of this study corroborated that continuous fertigation with nutrient solution provide better growing conditions resulting in prolonged and more continuous growth and flowering than open field conditions. In addition, differences in aerial and root growth between plants grown on these two different rootstocks under similar fertigation and environmental conditions were found. Plants grown on Mexicola rootstock were more efficient energetically as sustained by higher trunk area, tree height and higher root content of the main non-structural carbohydrates (mannoheptulose and perseitol) than plants grown on the clonal rootstock. Our findings suggest that this alternative growing system for Hass avocado, besides being more intensive could have a positive impact on environmental indicators (WUE, NUE and PUE) related to sustainability.