Studies on the effect of certain growth regulators on the extension growth of epicotyl of gram cicer arietinum L

Abstract

The objective of the present investigation was to study the effects of certain growth regulators on the extension growth of excised, etiolated epicotyl sections of gram (Cicer arietinum L.) The effects of IAA and GA3, the two natural growth promoting plant hormones, and the effects of growth inhibitors, both natural and synthetic e.g. ABA, MH, Coumarin, CCC and B-9 were investigated. Further investigations on the responses of the epicotyl sections to chloramphenicol, tetracy-cline, thymine, uracil, adenine, exogenous RNA, sucrose, glucose, KCl, KHCO3 and KNO3 were undertaken. Epicotyls of 5 day old etiolated seedlings of gram grown at room temperature between 180C to 280C were excised and 10 mm, 20 mm and 30 mm long sections were cut starting 2 mm below the apical tip. Samples of 10 sections were floated on 10 ml solu-tions of test meterials taken in petridishes without addition of buffer salts or carbohydrates and were incubated at 280C +- 10C for varying time periods. At the end of each treatment the length of the sections were measured and calculated in terms of percen-tage of growth in control (water) taking corresponding control value as 100. The results were statistically analysed. 10 mm long sections were suitable for analysing growth responses. The growth of 10 mm sections exceeded that of 20 mm or 30 mm long sections. Externally supplied sucrose or glucose enhanced growth increment. Sucrose was superior to glucose in stimulating growth. The epicotyl sections responded to exogenous growth regula-tors. 100 ppm IAA induced maximum of 50 percent of initial length during 36 hour treatment period which recording 24 percent more than the corresponding growth of control samples. 100 ppm GA3 stimulated 45 percent growth over initial length recording 17 percent more than that of control within 36 hours. Concentration as low as 10 ppm of IAA and GA3 enhanced extension of the sections. 1000 ppm of IAA and 2000 ppm of GA3 inhibited growth, this concentrations being supraoptimal inhibiting level. ABA inhibited growth.