EFFECTS OF SEED SOURCE, VARIETY, PACKAGING MATERIALS, STORAGE CONDITIONS AND STORAGE DURATION ON VIABILITY AND PROXIMATE COMPOSITION OF CERTIFIED SOYBEAN SEEDS FROM THREE REGIONS IN NORTHERN GHANA

Abstract

In Ghana, soybean is largely cultivated in the northern sector accounting for about 90% of the soybean produced in the country. Despite the crop's high potential to improve food and economic security, there is very little or insignificant growth in the rate of production of soybean in Ghana. Major factors contributing to the low level of production include poor seed quality and poor storage conditions. To date, there is limited information on the effect of long-term storage of soybean seed on quality, especially regarding seed viability and seedling vigour. This study was conducted to assess the effects of seed source, variety, packaging materials, storage room temperatures and storage durations on three popular certified soybean seed varieties. Three experiments were conducted from April, 2022 to December, 2023. Experiment 1 was a 4 x 3 x 2 factorial arranged in split-split plot design with three replications. The four sources of the seeds were three certified seed companies including Antika (Upper West Region), Heritage (Northern Region), Integrated Water and Agricultural Development (IWAD) (Upper East Region) and the Savana Agricultural Research Institute (Foundation seed) which served as a check. The three varieties evaluated were ‘Afayak’, ‘Favour’, and ‘Jenguma’ and the qualities of these seeds were measured at sampling (zero), and at five (5) and ten (10) months after storage under ambient temperature (zinc roofed room). Experiment 2 was a 5 x 3 factorial arranged in split plot design with three replications. The treatments were five storage conditions (cold room, air-conditioned room, warehouse, thatch house and zinc roofed room) and three storage durations (0, 5 and 10 months) after storage. For experiment 3, the treatments were three varieties (‘Afayak’, ‘Favour’, “Jenguma”), seven packaging materials (Ghana Seed Inspection Division (GSID) branded polypropylene bag, GSID Plastic bag, paper bag, jute bag, jute bags lined with plastic, polypropylene bag and polypropylene bag lined with plastic) and three storage durations (0, 5 and 10 months) arranged in a split split plot design with three replications were used to evaluate treatments. In experiment one, ‘Jenguma’ in the control stored for 10 months maintained the highest number of normal seeds. Similarly, ‘Jenguma’ seed collected from UWR had the highest fat content, while that from UER had the highest ash content at end of the 10 months storage period. ‘Favour’ seeds obtained from UWR and stored for 10 months had the highest germination perectage and protein content. ‘Afayak’ seed sourced from UWR and stored for 10 months exhibited significant increase in the dry matter content, whereas, ‘Jenguma’ seeds from UER showed the highest moisture loss at the end of the 10 month storage period. Principal component analysis shows a strong positive correlation between moisture, protein, normal seeds and germination percent with strong correlation for germination and moisture percentages for seeds obtained from Upper East Region. Although Seed germination deteriorated with storage duration across all sources and varieties, the ‘Favour’ variety exhibited the highest germination percentage irrespective of the sources. Seeds from Upper West Region exhibited best performance in germination for all three varieties after ten months storage. For experiment two, there was a positive correlation between germination and normal seeds (r = 0.669). Cold room, thatch roofed rooms and commercial warehouses significantly preserved seed viability. ‘Favour’ seeds stored in GICS bag for 10 months had the highest normal seeds and germination percent. ‘Jenguma’ seeds stored in (PP) bags for 10 months showed the least decline in fat content. Germination % positively correlated with protein and normal seeds across all soybean varieties. Germination % showed a positive correlation with carbohydrate for the ‘Favour’ variety. For ‘Afayak’ and ‘Jenguma’, germination % was positively correlated with fat and moisture contents. For experiment three, hermetic storage and paper bags proved more effective in maintaining seed viability and vigour compared to other conventional packaging options. The research has therefore demonstrated that, to maintain the viability of certified soybean seeds for longer period, the ‘Favour’ seed variety should be packaged in GICS (hermetic) or paper bags and stored in cold rooms, commercialized seed warehouses or thatch roofed rooms, depending on the availability of these facilities in the soybean growing areas in Ghana. This study suggests that breeders should pay more attention to the fat, carbohydrate and ash traits in breeding for high seed viability and seedling vigour for soybean.