Doses and application method of seaweed extract to enhance physiological behavior in different ‘Hass’ avocado stages in tropical environments

Abstract Knowledge of Ascophyllum nodosum extracts (ANEs) is still limited to avocado ‘Hass’ in the tropics. The objective of this study was to evaluate the effects of two ANEs application methods (foliar v. drench) at four different doses (0, 2.5, 5 and 7.5 ml/l) on the physiological response of three different avocado stages (seedlings and young and adult trees). Foliar or drench ANEs applications were performed monthly for all plants for 16 weeks. The evaluated variables were recorded at 4 and 20 weeks after the start of treatment (WAT). The results showed that ANEs can be applied to the drench or foliar method at doses ≥5 ml/l in the different growth stages evaluated. In seedlings, foliar or drench ANEs applications increased total dry weight (34.5 and 57.9 g for 0 and ≥5 ml/l, respectively) and stomatal conductance ( g s ) (380 and 205 mmol/m 2 s for 0 and ≥5 ml/l, respectively) at 20 WAT. In young trees, both application methods also improved growing index (88.6 and 102 cm for 0 and ≥5 ml/l, respectively) and g s (516 and 636 mmol/m 2 s for 0 and ≥5 ml/l, respectively) at the last sampling point. Adult trees showed that foliar or drench applications at higher doses also caused an increase in fruit yield (3.4 and 8.7 kg/tree for 0 and ≥5 ml/l, respectively) at 20 WAT. In conclusion, the use of foliar and soil ANEs applications at higher doses (≥5 ml/l) can be considered for integrated crop management of ‘Hass’ avocado.