D. A. Agboola , A. O. Ebofin , A. M. Aduradola , A. A. Ajiboye

Abstract

The effect of some presowing treatments on the germination of seeds of Albizia lebbek (Linn.) Benth. and Cassia siamea Lam., two savannah tree legumes in Nigeria were investigated. Percentage germination in fresh seeds was 15-25%, with 90-100% viability. The percentage germination in pretreated seeds ranged between 60-100%. The seeds of the two species exhibit physical dormancy due to hard seed coat. Dormancy in A. lebbek and C. siamea was terminated by soaking of seeds in concentrated suphuric acid for 10 and 15 minutes; wet heat at 100°C for 30 and 60 seconds; dry heat at 80-100°C for 5 to 10 minutes respectively. The percentage germination of seeds in the two species ranged between 90-100% after presowing treatments. Total carbohydrate and ethanol soluble sugars are well mobilized.

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A. O. Ebofin , D. A. Agboola , A. M. Aduradola , M. S. Ayodele

Abstract

Studies were made on the effect of some growth hormones including Indole Acetic Acid (IAA) , Indole Butyric Acid (lBA) , Kinetin and Gibberellic Acid (GA₃) on seed germination and seedling growth of four savanna tree legumes. The tree species include Prosopis africana (Guil & Perr) Taub (Mimosoidae); Parkia biglobosa (Jacq) R. Br. Ex G. Don (Mimosoidae); Albizia lebbek (Linn.) Benth (Mimosoidae) and Senna siamea (Lam) Irwin Barneby (Caesalpinoidae). 0.01-0.04ppm IAA enhanced germination in A. lebbek , P. biglobosa , P. africana and S. siamea. 0.01-0.05ppm IBA enhanced germination in P. africana and S. siamea. 0.01-0.05ppm kinetin retarded germination in P. biglobosa , P. africana and S. siamea. 0.01-0.05ppm. GA₃ enhanced germination in A. lebbek and P. africana. 0.01-0.05 ppm IAA enhanced plant height and dry weight in the seedlings of the four tree species. 0.01-0.03 ppm IBA enhanced plant height and dry weight in S. siamea and only plant height only in P. biglobosa. IBA (0.03-0.04 ppm) enhanced leaf number in P. biglobosa and A. lebbek. Kinetin (0.01-0.05 ppm) enhanced leaf number in P. biglobosa. GA₃. enhanced leaf number and plant height in P. biglobosa and plant height in A. lebbek.

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D. A. Agboola

Abstract

A study was made of the effect of varying osmotic pressures on the rate and amount of water imbibed by the seeds of three tropical high forest tree species. These are C. pentandra, T. superba and T. ivorensis. Increase in osmotic pressure of the medium where dry seeds are soaked significantly affected the amount of water imbibed. The percentage water imbibed by the seeds of the tree species investigated increased with time until when equilibrium was maintained. The rate of imbibition was faster at 35 °C than at 29 °C or 6-7 °C.

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