Accelerated Ageing Tests of Nauclea diderrichii Seeds: Evaluating Seed Vigour from Different Forest Provenances to Aid Plus-trees Selection in Ghana

2020

English

Background and Objectives: The selection of plus-trees with high seed vigour is an important step towards efficient ex situ conservation of forest genetic resources and plantation development. The study classified seeds collected from plus-trees of Nauclea diderrichii from 4 different provenances within the high forest zones of Ghana, namely: Abofour (KABO), Amantia (KAMA), Benso (KBEN) and Gambia (KGAM). Materials and Methods: A total of104 individual trees of N. diderrichii were identified across the natural distribution range of the species. These were marked as candidate plus-trees based on a set of standardized phenotypic scores during field surveys. Fruits were collected at maturity from 32 plus-trees and seeds extracted for storage and subsequent accelerated ageing tests. The time and temperature regime for the AA tests were 72 h and 41°C, respectively. Seed samples were placed in hermetically sealed bottles and stored at 4-5°C for 12 months. Germination of seeds before and after AA test was undertaken under ambient temperature by sowing 2.0 g of seeds in 4 replicates. Sterilized river sand was used as germination media for each accession. Results: Significant differences (p<0.05) in germination before and after AA test across all 4 provenances were found. Provenance KAMA produced the highest mean germination of 400 seedlings/2.0 g of seeds compared with KGAM (248), KABO (276) and KBEN (285) during germination after extraction. However, seed lots from provenances KABO and KAMA showed more vigour than the rest after 12 months of storage followed by AA tests. Conclusion: Although provenance KGAM recorded the highest number of plus-trees, seed lots from provenance KABO, KAMA and KBEN will be more suitable for long-term ex situ conservation as they gave higher vigour seeds after 12 months of storage.

Asomaning, J. M.; Amponsah, J. O.; Peprah, T.; Owusu, S.; Opoku-Kwarteng, C.; Ofori, D. A.