EVALUATION OF SOYBEAN (Glycine max (L.) Merrill) GERMPLASM FOR IMPROVED AGRONOMIC TRAITS FOR POTENTIAL MECHANICAL HARVESTING

Abstract

Soybean (Glycine max (L.) Merrill) is an emerging commercial crop in Ghana with a diversity of uses including being an important oil crop, nutritional security in low-income communities and income generation in Northern Ghana. However, harvesting operations are still done manually which is tedious and time-consuming with high yield losses due to shattering resulting from late harvesting. A two-phase study was conducted in 2022. In phase 1, a survey was conducted in April 2022 using a random sampling method to identify and ascertain the challenges confronting commercial soybean farmers in Northern Ghana. In phase 2, a field experiment was carried out during the cropping season to assess morphological architecture of foreign and local soybean germplasm for possible mechanical harvesting. The field experiment was a single factor experiment using a randomised complete block design with three replications. The treatment consisted of four (4) foreign soybean germplasm (G39, G83, G90, and G119) and three (3) farmers preferred local varieties (Afayak, Favour, and Jenguma). Results from the field survey revealed that difficulty in harvesting (from uprooting to threshing) soybeans was the most prevalent constraint confronting commercial soybean farmers in northern Ghana. It was also revealed that Favour variety was the choice soybean variety used by commercial soybean farmers due to lower shattering ability, while sole cropping was the major cropping system practised by farmers. The field experiment showed that the foreign soybean germplasm significantly (P < 0.05) increased plant height, plant girth, number of pods per plant, first pod height from the ground level by 20% and grain yield compared to the local varieties. The foreign soybean germplasm averagely recorded higher lodged plants and was also more prone to shattering compared to the local varieties. Notably, the local soybean germplasms exceeded the recommended height of 12 cm for mechanical harvesting, whereas one of the foreign germplasms, G119, fell short of the recommended height. The foreign soybean germplasm (G39, G83, and G90), and local soybean germplasm (Afayak Favour and Jenguma) can be harvested mechanically using a combined harvester following the recommendation of 12 cm above ground to the first pod for soybean mechanical harvesting. The results from this study lay the foundation for further studies to commence soybean mechanical harvesting in Ghana