Study on changing of gibberellin-like substances and ethylene in shoot apices prior to flowering and use of plant growth regulator to lychee cv. Hong Huay

Gibberellin-like substances in 31 December 1997, 8, 15, 22 and 29 January 1998 were not significantly different and were 0.00155, 0.00110, 0.00108, 0.00263 and 0.00057 micro g GA3 equiv./gram fresh weight, respectively. Ethylene in shoots apices prior to leaf flushing in 31 December 1997 8 January 1998 and 29 January 1998 were 0.1553, 0.1610 and 0.1457 ppm, were not significantly different but were significantly different to the amount in 15 January and 22 January 1998 which were 0.1669 and 0.1890 ppm, respectively. Spraying of paclobutrazol at the rate 1,000 ppm did not increase flowering and giberellin-like substance at the terminal unspray shoo ts after 15 and 30 days were 0.003024 and 0.002845 micro g GA3 equiv/g fr. wt., did not significantly different, but decreased significantly after spraying at 45 days which was 0.001993 micro g GA3 equiv./g ft. wt. Meanwhile, gibberellin-like substance 15 and 30 days after sprayed at terminal shoots which were 0.002587 and 0.002845 micro g GA3 equiv./g fr. wt. did not significantly different to unsprayed at the same period which were 0.003024 and 0.002845 micro g GA3/g fr. wt. and decreased significantly on 1 of February which was 0.001993 micro g GA3/g fr. wt.. Sprayed of ethephon at the rate 200 ppm and unsprayed shoots were found that ethylene at after unsprayed terminal 15, 30 and 45 days which were 0.1186, 0.1214 and 0.1245 ppm, were not significantly different. After sprayed ethephon 15 days ethylene which was 0.1264 ppm, was not significantly different to after 15, 30 and 45 days unsprayed which were 0.1186, 0.1214 and 0.1245 ppm. Ethylene at terminal shoots after sprayed ethephon at 30 and 45 days, were increased with significantly, which were 0.1316 and 0.1341 ppm. Sprayed kinetin 50 ppm and unsprayed shoots, were found that cytokinin-like substance of 15 and 30 days after unsprayed shoots which were 0.1433 and 0.1539 micro g kinetin equiv./g fr. wt., were not significantly different and increased at 45 days with significantly. At 15 days after sprayed terminal shoots which was 0.1856 micro kinetin equiv./g ft. wt, had cytokinin-like substance the same as 15 and 30 days after unsprayed but 30 days and 45 days after sprayed which were 0.2370 and 0.3218 micro g kinetin equiv./g fr. wt had cytokinin-like substance increased with significantly different and was highest at 1 February. There are average flowering at 8.11 and 13.15 percent in first and second year respectively from remain shoots in each tree. Flowering of 3 treatments and control were not significantly different.