Keywords: Litchi, ethephon, naphthaleneacetic acid, 2,4-D, growth hormones

To evaluate the effectiveness of plant growth regulators (PGR) such as 2,4-D, ethrel, and planofix (NAA) on reproductive parameters of three cultivars of litchi, these PGR were sprayed on the litchi trees at two stages: one during the second week of January, and the other when the fruit attained pea size, during the first week of April. Water was sprayed in the control treatment. PGR treatments did not show a significant effect on flower number, fruit set number, and fruit set percent although variation existed among the treatments. Varietal differences were also not observed. Maximum fruit drop occurred within 10 days of fruit set; at harvest, the cumulative drop exceeded over 90%. Although NAA sprays retained fruits significantly more in earlier dates the difference among PGR treatments was not significant at harvest. Varieties did not affect fruit drop and fruit retention. NAA treated fruits were the heaviest (16.0 g/fruit) and Calcuttia Late produced the largest fruit weight (17.5 g/fruit). Peel weight was maximum (10.32 g/fruit) with NAA and minimum (9.12 g/fruit) with ethrel sprays. Calcuttia Late showed maximum pulp weight (12.62 g/fruit) and Muzaffarpur showed minimum (7.22 g/fruit). PGR affected fruit length and width significantly. NAA produced the largest fruit size in all dates up to harvest time (3.37 cm × 3.06 cm) and ethrel produced the smallest fruits (3.33 cm × 2.90 cm). Of the 3 cultivars Calcuttia Late produced the biggest fruits (3.39 cm × 3.09 cm). The seed size was the largest in water sprayed control (2.48 cm × 1.44 cm). Treatment with ethrel and 2,4-D decreased seed length to a minimum. Muzaffarpur had maximum seed length in all the dates, including the harvest time (2.78 cm). Calcuttia Late had minimum seed width (1.36 cm). TSS and acidity was not affected by PGR but varieties did affect acidity (0.47% in Calcuttia Late and 0.71% in Rose Scented); however, there was no effect of cultivars on TSS content.