Quantitative changes in gibberellin-like substances in stem apex of lychee cv. HongHuay prior to flowering
1996
Suwalee Seangariyanan | Tanart Thunyarpar (Chiang Mai Univ., Chiang Mai (Thailand). Faculty of Agriculture. Dept. of Hortiuclture)
Studies on quantitative changes in gibberellin-like substances in stem apex of lychee cv. Hong Huay prior to flowering were carried out, starting with the study on response of lettuce cultivars to GA3 (Kyowa) by lettuce hypocotyl bioassay (LHB) method. It was found that the length of lettuce hypocotyls increased according to GA3 (Kyowa) concentrations while Dresser was the cultivar which showed the highest response. Interaction was found between cutivars and GA3 (Kyowa) concentrations, since different cultivar respondd to GA3 (Kyowa) concentrations differently. Standard curves of gibberellin-like substance quantification by the method of LHB. It revealed that the minimum detectable of GA3 (Kyowa) was 1*10*[-3) ppm, while linear regression responses of cv. Dresser was found between 1*10*[-3)-1 ppm. The effects of performing date of standard curve (72 days interval) were investigated while no effect was found. An analysis of lychee apex for determination of gibberellin-like substance activities in different Rf zones of the chromatogram showed that the gibberellin activities were Rf 0.2-0.5. Quantitative changes in gibberellin-like substances prior to flowering in stem apex of 4-5 years old lychee tree cv. HongHuay were studied from November 1995 to March 1996. The samples were taken from the orchard of Chiang Mai Land Development Station, Mae Rim district, Chiang Mai, Thailand. It was found that activities of gibberellin-like substances in the 4th week prior to flowering was high while it decrease in the 3rd week and remained constant until the 2nd week, then decreased again to minimum level in the 1st week until flowering.
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