The growth effect of drench treatments of a seaweed biostimulant made from Ecklonia maxima on transplanted Hass (c.v.) avocado clones within the propagation phase

Abstract

The final stage of the commercial propagation of avocado (Persea americana) plants, requires plants to be replanted in larger bags for a growing out period, prior to being dispatched. The use of drench treatments of Afrikelp™ LG 1, a biostimulant extracted from the South African kelp Ecklonia maxima, on newly replanted clonal avocado (Hass on clonal Dusa rootstocks), was evaluated over a period of 10 weeks, for any growth benefits at this hardening off stage of propagation. Micro-clonal avocado plants were received in 98 plastic inserts and rebagged into 3.3 L Elle growbags containing pine bark augmented with 5g L− 1 Multicote™ 4 and under 40% black/ white shadenet. Three concentrations of Afrikelp™ LG 1 (0.5; 1.0 and 2.0%) together with a control treatment (water), were applied as 500 ml drench applications every two weeks, with a total of five applications. Two weeks after the final drench application, the plants were destructively harvested, and final growth measurements were recorded. Foliar samples from each treatment were sent for nutrient analysis (macro- and micro-nutrients). All Afrikelp™ LG 1 treated plants showed increases in growth, with 0.5% Afrikelp™ LG 1 treatment having significant (p < 0.05) increases in young foliar biomass and increases in percentage height, compared to the control. Even though most growth rate increases were non-significant, it is possible more significant results would be evident after a longer treatment period as most nurseries have a hardening off period of between 6 and 12 months before dispatch.