Effect of pretreatments on seed viability during fruit development of two varieties of Irvingia gabonensis

Studies to identify the stage at which developing fruits of Irvingia gabonensis (var. excelsa and var. gabonensis), picked from standing trees and/or forest floors, attain maximum viability and germinability were conducted in two harvesting seasons in 2000 and 2001. Some pretreatment methods were used as a means of stimulating expression ofmaximum germinability as source of seeds for seedling production. The moisture contents of whole seeds decreased steadily and significantly (P = 0.05) throughout the developmental stages of both varieties and in both harvests. Seeds harvested from standing trees and forest floors, pretreated by steeping in water for 24 h at 26 oC and sown in sawdustand petri dishes on moist filter paper, gave 80% germination in variety gabonensis, 20 weeks after fruiting. Germination potentials of seeds in both harvests were enhanced significantly (P = 0.05) with seeds pretreated by steeping in water for 24 h at 26 oC, and sown in sawdust and petri dishes on moist filter paper by as much as 60% and 80% for var. excelsa and var. gabonensis, respectively, in the developmental stages, 14–20 weeks after fruiting with significant (P = 0.05) decrease in germination time to 21 and 15 days, respectively. There was also significant (P =0.05) relationship between viability and germination in both harvests and in the two varieties throughout the developmental stages. Potassium nitrate (KNO3) significantly (P = 0.05) enhanced germination potentials of the seeds over the control when soaked in 1.5 g/l concentration in both varieties and in the two harvests (18–20 WAF) by 80%. Mannitol significantly (P = 0.05) reduced germination potential (40%) of the seeds with increased germination time in both harvests and in the two varieties throughout the developmental stages. There was a high significant (P = 0.05) increase in germination potential (60%) of seeds treated with polyethylene glycol (PEG) when soaked in concentration of 10 g/l for 48 and 72 h in both varieties and in the two harvests (18–20 WAF). The study shows that the fruits of I. gabonensis assume ripening characteristics (yellowing) and that the viable seeds can be obtained from standing treesand/or picked from forest floors from the 12th to 20th week after fruiting

Biotechnology, genetic conservation and sustainable use of bioresources

The loss of Africa's forests and bioresources is occurring at an alarming rate, a consequence of increasing population pressure, agricultural land degradation, urbanization and neglect. There is a growing recognition worldwide that conservation and sustainable management of bioresources are pressing priorities in the world today. The choice of conservation methods and techniques depend on the objectives of the particular conservation effort, the breeding system and behaviour of the species in question as well as the available resources including funds, trained personnel, infrastructure and technologies. The use of biotechnological tools and “bioprospecting” will open new vistas in medicine, agriculture, silviculture, horticulture, environment and other important issues. This paper reviews some biotechnological tools that could be harnessed in promoting conservation and sustainable use of bioresources. Key words: Bioresources, genetic conservation, biotechnology. African Journal of Biotechnology Vol. 2 (12), pp. 704-709, December 200

Growth Response of Explants of Irvingia Gabonensis (O'rorke, Baill) to In Vitro Treatment

Growth response of explants of Irvingia gabonensis to in vitro treatment was investigated using full, half and one quarter strength mineral components based on Murashige and Skoog medium. Plant growth regulator (kinetin-Kin) with concentration levels of 0, 1, 2, 3, 4 and 5mg/l were used for shoots initiation, while axillary formed shoots were rooted in various concentration levels of 0, 1, 2, 3, 4 and 5mg/l of indole butyric acid (IBA). One quarter strength growth medium containing 3mg/l kinetin, which supported the highest growth performance was used to study the effect of explant source and number of leaf primordia on shoot initiation of the species. Shoot length of axillary bud explant significantly (P<0.05) increased in one quarter strength medium than those of half and full strength media. Axillary bud explants with 1-2 leaf primordia gave optimum response in terms of regeneration frequency and coefficient of velocity of bud burst. High regeneration frequency and coefficient of velocity of bud burst with low percentage contamination were recorded by seedling and stump sprout explants. This study suggests that axillary bud explants of Irvingia gabonensis can respond to in vitro treatment under optimum culture conditions

Effect of pretreatments on seed viability (tz) during fruit development of Irvingia gabonensis varieties

Studies to identify the stage at which developing fruits of Irvingia gabonensis (Var. excelsa and Var. gabonensis) picked from standing trees and / or forest floors attain maximum viability and germinability were conducted in two harvest seasons in 2000 and 2001. Some pretreatment methods were used as a means of stimulating expression of maximum germinability as source of seeds for seedling production. The moisture contents of whole seeds decreased steadily and significantly (P= 0.05) throughout the developmental stages of both varieties and in both harvests. Seeds harvested from standing trees and forest floors, pretreated by steeping in water for 24 hours at 26°C and sown in sawdust and petri dishes on moist filter paper gave 80% germination in variety gabonensis 20 weeks after fruiting, WAF. Germination potentials of seeds in both harvests were enhanced significantly (P 0.05) with seeds pretreated by steeping in water for 24 hours at 26°C and sown in sawdust and petri dishes on moist filter paper by as much as 60% and 80% for var. excelsa and var. gabonensis respectively in the developmental stages 14 20 weeks after fruiting (WAF) with significant (P = 0.05) decrease in germination time to 21 and 15 days respectively. There was also significant (P = 0.05) relationship between viability and germination in both harvests and in the two varieties throughout the developmental stages. Potassium Nitrate (KNO3) significantly (P = 0.05) enhanced germination potentials of the seeds over the control when soaked in 1.5g/l concentration in both varieties and in the two harvests (18 20 WAF) by 80%. Mannitol significantly (P = 0.05) reduced germination potential (40%) of the seeds with increased germination time in both harvests and in the two varieties throughout the developmental stages. There was a high significant (P = 0.05) increase in germination potential (60%) of seeds treated with Polyethylene glycol (PEG) when soaked in concentration of 10g/l for 48 and 72 hours in both varieties and in the two harvests (18 20 WAF). The study shows that the fruits of Irvingia gabonensis assume ripening characteristics (yellowing) and that the viable seeds can be obtained from standing trees and / or picked from forest floors from the twelveth to twentieth week after fruiting. Keywords: viability, germinability, Irvingia gabonensis, WAF: Week after fruiting, moisture content Global Journal of Pure and Applied Sciences Vol. 12(2) 2006: 141-14