RESPONSE OF MUTANT SOYBEAN (Glycine max L) GENOTYPES TO DROUGHT AND HIGH SOIL TEMPERATURE IN THE GUINEA SAVANNA AGROECOLOGY OF GHANA

Abstract

The Department of Crop Science in the University for Development studies has produced mutant soybean genotypes with improved agronomic traits. A Series of evaluations of these mutant genotypes have been carried out at different agroecological zones in Ghana and high-yielding mutants such as 150 Gy, 200 Gy, 250 Gy, and 300 Gy have been identified. The present study used the above genotypes as planting material for the studies in the dry season and rainy seasons of the year 2020 to evaluate them for tolerance to abiotic stresses such as heat and drought. Two experiments were conducted for this research study. One experiment was conducted in the dry season (pot), and the other was in the rainy season carried out in the field. The design used 5×5×4 and 5×4×2 factorial experiments laid out in Randomized Complete Block Design with three replication in pot and field studies, respectively. The factors involved in the pot experiment were Genotypes (150 Gy, 200 Gy, 250 Gy, 300 Gy, and standard check-Jenguma) and, water application (100 %, 80%, 60%, 40%, and 20 %), where the and Mulching (0 t/ha, 20 t/ha 40 t/ha and 60 t/ha of rice straw). Two seeds per pot were planted and the temperature was recorded at every three-day interval. Two planting dates were used in experiment II which was carried out on the field. The first planting was done on the 17th of June and the second plating was done 17th of July, 2020. For each planting date, the plots were measured 5 m × 4 m. Results from data on water use efficiency, growth, and other agronomic traits were collected and analyzed using the GenStat (12 edition) and means were separated using Least Significance Difference (LSD) at 5% after evaluation both in the pot and in fields studies. The observed variations in the growth, yield, and other traits of these genotypes revealed that mutagenesis had a significant effect on these mutant genotypes. The 200 Gy and 250 Gy as the best performing genotype. The finding of this study observed a significant (P < 0.05) . different in the level of mulch, different applications, and the planting date. The results further revealed a significant (P < 0.05) . different among the interaction of genotypes, heat, and drought stress. Mutants 150 Gy, 200 Gy, and 250 Gy were observed to be tolerant to drought and heat. Early planting of these genotypes mulched with 20-40 t/ha mulch produced outstanding results in term growth and grain yield. I, therefore, recommend that further studies should be carried out in different agroecology to evaluate the mutant soybean genotypes for tolerance to drought and heat stress.