3. EFFECT OF PLANT GROWTH REGULATORS ON INITIAL FRUIT SET, FRUIT SET RETENTION AND FRUIT DROP OF INDIAN BER (Zizyphus mauritiana Lamk.) by SURESH KUMAR1, UPESH KUMAR 2 AND PREM NARESH3
An investigations were undertaken to find out the effect of plant growth regulators (NAA, GA3 and 2,4,5-T ) along with control and water spray replicated thrice in CR D different doses as ( T-0 Control (No spray), T-1(water spray ),T-2(NAA- 10 ppm),T-3(NAA- 20 ppm),T-4(NAA- 30 ppm),T-5(GA3 - 25 ppm),T-6(GA3 - 30 ppm),T-7(GA3 - 35 ppm),T-8(2,4,5-T-15 ppm),T-9(2,4,5-T- 20 ppm),T-10(2,4,5-T- 25 ppm) on initial fruit set ,fuit set retention and fruit drop of Indian ber . fruit set ranged from 157 to 162 during both the years of trial. There were no significant differences in the mean values in this regard, but the highest initial fruit set was recorded under 2,4,5-T 20 ppm (162 in both year) followed by 2,4,5-T 25 ppm (162 and 161) and GA3 25 ppm (162 jn both year ) while the lowest was registered under NAA 10 ppm (159 in both year) being significantly superior over control. The maximum fruit retention was recorded by the application of 2,4,5-T (11.21 and 11.09%) followed by NAA (10.02 and 9.54%) and GA3 (9.24 and 9.13%) over the control (5.16 and 4.74%) but the highest fruit retention was recorded under 2,4,5-T 25 ppm (11.88 and 12.45%) followed by 2,4,5-T 20 ppm (11.24 and 10.85%) and NAA 30 ppm (11.00 and 10.75%) while the lowest was registered under GA3 25 ppm (7.79 and 7.75%) being significantly superior over control. The probable reason for greater fruit retention might be due to the stimulation of natural growth substances on the experimental plant and particularly the limb. The percentage of fruit fall under different treatments (growth regulators and their concentrations) during both the years revealed that all the growth regulators namely, NAA, GA3 and 2,4,5-T reduced the fruit drop irrespective of their concentrations as compared to control. Most effective growth regulator was found to be 2,4,5-T (88.79 and 88.91%) followed by NAA (89.98 and 90.46%) and GA3 (90.76 and 90.87%).
KEY WORDS: Indian Ber (Zizyphus mauritiana Lamk.), Growth regulators, Initial fruit set, Fruit drop, Fruit retention.