I TBS EFFECT OF DEPTH OF SEED BURY ON GERMINATION AND EMERGENCE OF WEED SEEDLINGS.

Abstract

The experiments were conducted at the Sugarcane Research Institute, Udawalawe to study the effect of depth of seed bury on germination and emergence of weed seedlings. Seeds of five selected weed species were allowed to germinate at different depths (from surface to 20 cm) in wooden boxes filed with sterilized soil. The soil boxes were kept in a green house to provide favourable environment for germination and emergence of seedlings. The temperature within the green house was 30 ± 2°c.f in addition, separate seed batches of same weed species were germinated at 30 ± 2°c under spontaneous change of day and night illumination and complete dark to observe their germination characteristics under various light regims. There was no relationship of percentage germination, mean germination time and the rate of germination to the 1000 - seed weight. However, weed seeds showed is continuous germination extending period sometimes more than 40 days for final germination %occur. Also, there was wide difference (0.05 to 0.39 seeds day :) among the species of their rate of germination. The percentage germination, mean germination time and the rate of germination were always high at the spontaneous change of day andnight illumination than that of complete dark. The most of emerged seedlings had come from surface soil. More than 70% 80% oiemerged seedlings of the tested weed species were recorded above 4cm soil depth. Also, seeds at greater soil depth took longer time to emerge their seedlings. In generally, larger seeded weed species could produce seedlings from greater soil depth. I wish to express my appreciation to Dr. S.A. Ranjith, ROJC and Mrs. R.N.T. Kumari Ubayasena, R0 Chemistry division; Lt cdr.S.R. Weerasinghe, ROIC, Biometry & Data Processing Division, SRI,Udawalawa; Mr. H.A. wimalasiri (Library, SRI) , Mr. G. somaweera(Biometry & Data Processing Division, SRI) and Mr. R.P. wijayanunda (Agronomy Division, SRI) for their utmost help.I am grateful to Prof. A. Bamunuarachchi, Former director of Buttala Affiliated University Collage and Consultant of Faculty of Applied Science, Uva campus, Sabaragamuwa University of Sri Lanka,for his kind cooperation.I take this opportunity to express my sincere thanks to Mr.M.A. Jagath Wansapala, Miss. D.M.I.L.K. Bandara, Miss. K.M.Somawathie and Mr. W.M.S.R athnapriya, Lecturers in Faculty of Applied Science, Uva Campus, Sabaragamuwa University of Sri Lanka,for their useful contribution. A special word of thanks to all members of the staff, Faculty Of Applied Science, Uva Campus, for their assistance.I consider it my duty to thankfully mention all members of the staff of the SRI, Udawalawa, who made my i short stay at the Institute a pleasant and useful experience.Finally, my friends who helped me in various ways to make this venture successfully, are gratefully acknowledged.