Journal of Applied Horticulture. 2001: 3(2): 88-90

Effect of paclobutrazol on source-sink relationship in mango (Mangifera indica L.)

Kurian, R M; Reddy, Y T N; Sonkar, R K; Reddy, V V P

Division of Fruit Crops, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore - 560 089, India.

The effects of paclobutrazol on the fruit-leaf ratio of twelve-year-old trees of mango cultivars Alphonso and Dashehari were studied in Bangalore, Karnataka, India. The soil was drenched with paclobutrazol at 0.0, 2.5, or 7.5 g a.i. per tree. In each paclobutrazol-treated tree, photosynthate and metabolite translocation to 30 leaves with a single fruit was inhibited by girdling the branch (1 cm wide ring of bark) at a uniform distance from the fruit. Girdling was conducted when Dashehari fruits were 4.9+or-0.7 cm long and weighed 27.9+or-8.5 g, and when Alphonso fruits were 4.0+or-1.0 cm long and weighed 32.9+or-7.5 g. Twenty-eight fruits on ungirdled shoots of trees not treated with paclobutrazol served as the control. In the two cultivars, thirty leaves were not sufficient to promote the growth of a single fruit, especially when the tree was not treated with paclobutrazol. In untreated trees, the weight of fruits from girdled trees of Alphonso and Dashehari was only 60.2 and 64.9%, respectively, of the control. However, the weight of fruits of girdled trees treated with 2.5 and 7.5 g a.i. paclobutrazol was on a par with that of the control. Paclobutrazol appeared to favourably alter the source-sink relationship of mango to support fruit growth with lower leaf number and area.