Evaluation of paclobutrazol on growth, flowering and yield of mango cv. Kensington Pride

Abstract

The growth retardant paclobutrazol was applied after harvest as a foliar spray, a band along the drip line, or a collar drench in trials over 3 years on 3-, 4-, and 5-year-old trees of mango cv. Kensington Pride. The trees were assessed for percentage of branches with vegetative flush, flush length, flowering, and yield. Paclobutrazol reduced length of vegetative growth in all trials. Eight mL a.i. per tree, applied as a single yearly collar drench, significantly (P<0.05) reduced percentage flush. Collar treatments were significantly (P<0.05) more effective than drip line treatment in reducing length of vegetative growth. Two years' collar drench was generally more effective than a band treatment followed by a collar drench. In particular, collar drenches of 4 and 8 mL a.i./tree, applied for 2 consecutive years, reduced summer growth. Flowering and cropping were significantly (P<0.05) increased by paclobutrazol in a year of inadequate winter stress, while a trend towards increased yield was noted under more normal conditions. Yield increases were due to fruit numbers rather than size. Fruit colour was unaffected. Soil-applied treatments were more effective on flowering and cropping than foliar treatment, with collar drenches more effective than drip line treatment. A trend for decreasing yields was found when paclobutrazol was applied as a collar drench for 2 consecutive years at the same rate, compared with an ineffective drip line followed by a single collar treatment. Rates of paclobutrazol >4 mL a.i./tree caused unacceptable compaction of flower panicles. Four mL a.i./tree appeared the best application rate given the prevailing soil type, climatic conditions, and tree size and age.