The Study of Chemical Fertilizer Application Rates in Off-season Longan (Dimocarpus longan Lour.) Production

Abstract

     The study of chemical fertilizer application rates in off-season longan production of “Daw” longan trees was conducted in the longan orchard at Pomology farm, Maejo University, Chiang Mai province, from July 2017 to May 2018. The experimental design was randomized complete block design (RCBD), 7 treatments with 5 replications. The treatments 1 to 4 were the fertilizer formulae recommended by Thai Central Chemical Public Company Limited formulae 1 to 4, respectively. The treatment 5 was the control fertilizer formula. The treatment 6 was the fertilizer formula that longan growers practice, and the treatment 7 was the ‘equal’ fertilizer formula. The results showed that there were no significant differences among all the treatments in terms of flowering, fruit setting, and yield, as well as the longan fruit quality parameters; of which including inflorescence width, inflorescence length, number of inflorescence, fruit panicle width and length, fruit panicle weight, and yield per tree. However, the number of fruits per panicle in the treatment 6 gave the highest number of fruits per panicle (32.20 fruits), with significant differences to the treatment 1, 3 and 7 (22.53, 24.25, and 23.39 fruits, respectively), but showed no significant differences to the treatment 2, 4 and 5 (26.70, 30.57, and 29 fruits, respectively).