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Effect of spray and/or soil application of paclobutrazol, and spray application of potassium nitrate during flowering on new shoot growth and cropping of ‘Mendez’ avocado

Oosthuyse, S. A., Berrios, M.
Acta horticulturae 2017 no.1178 pp. 81-84
Persea americana, avocados, cultivars, flowering, fruit yield, fruits, paclobutrazol, potassium nitrate, shoots, soil, soil treatment, spraying, tree trunk, trees, vigor
Bearing 'Mendez' avocado trees were sprayed with paclobutrazol or paclobutrazol (Austar at 1 or 2%) + KNO3 (2%) during inflorescence development and flowering. In addition, soil applications of paclobutrazol were made (3 or 6 mL Austar applied around the trunk). The general effect of paclobutrazol + KNO3 treatment was to reduce the vigour of the new shoots arising after flowering and to increase fruit size. The increase as assessed in terms of individual fruit weight was of the magnitude of 46%. Fruit numbers were not reduced, and hence yield was increased. No cropping benefit or additional reduction in shoot vigour occurred as a result of the added application of paclobutrazol to the soil around the tree trunks. The specific effect of the addition of KNO3 to paclobutrazol was an increase in number of fruits retained until harvest. Retention was increased by an average of 32%. This contributed to an increase in yield. No effect relating specifically to the difference in the rate of paclobutrazol application to the soil around the trunk was observed. Further research to assess the benefit of adding KNO3 to paclobutrazol in spraying other important cultivars of avocado trees during inflorescence development and flowering is justified by the results of the present study.