Monsuang Ruangkhanab and Mongkol Sae-Lim

pp. 683 - 690

Abstract

The first bearing time of longkong tree is long due to the long juvenile period. A feasibility study on
longkong root and leaf growth acceleration by chemical application to alleviate this problem was conducted
through 2 experiments: 1) Fifteen one-year old of longkong seedlings were used and each seedling was grown
in a 24 litre-pot. All plants were treated with 5 g/plant of 15-30-15 fertilizer, plus 18 ml/plant of humic acid at
3 and 5 week intervals to accelerate root growth and compared with controls (no fertilizer). 2) Four-year old
longkong trees propagated by cuttings (18 plants) were grown in 50 litre-pots and foliar chemical substances
were sprayed for shoot acceleration. There were 6 treatments 3 replications in the experiment: 1 ppm
carboka^®, 400 and 700 ppm thiourea, 400 and 700 ppm BA twice at 3-week intervals and control. The results
indicated that 5-week interval treatment showed highest fresh and dry weight of leaves and roots, and root
length. Furthermore, it also induced high compound leaf number, leaf area and height. The result of foliar
chemical spraying revealed that 1 ppm carboka^®, 400 ppm thiourea and 400 ppm BA treatment induced the
greatest branch number and 1 ppm carboka^® spraying showed a higher number of compound leaves than
the control. The 700 ppm of thiourea application gave the highest longkong leaf area. It is suggested that the
optimum period and quantity of fertilizer and plant growth regulator applications can efficiently manipulate
the growth of longkong plant .