GGE Biplot Analysis for Identification of Ideal Soybean [Glycine max L. Merrill] Test and Production Locations in Zambia

Aim: The aim of the study was to Identify an ideal soybean testing environment in Zambia. The specific objectives were to determine the adaptation of new soybean lines (IITA) in different locations and also identify the existence of soybean mega-environments in Zambia.

Study Design: A Randomised Complete Block Design with four (4) replications at each location was used to carry out the experiment. Each plot had 4 rows of 6 m long each.

Place and Duration of Study: A multi- environment was carried out in the 2013/2014 agricultural season in four locations (Golden Valley Agricultural Research Trust (GART), Kabwe, Msekera and Masumba Research stations) in agro -ecological regions 1 and 2 of Zambia.

Materials and Methods: The experimental material consisted of 15 genotypes of soybeans viz., TGX 1740-2F (G1), TGX 1830-20E (G2), TGX 1835-10E (G3), TGX 1887-65F (G4), TGX 1904-6F (G5), TGX 1987-11F (G6), TGX 1987-23F (G7), TGX 1988-9F (G8), TGX 1988-18F (G9), 1988-22F (G10), TGX 1989-60F (G11), TGX 1990-129F (G12), Magoye (G13), Safari (G14) and Lukanga (G15). Planting was done in the last week of December (2013) to the first week of January (2014) across the locations and weed control was done by hand. Fertilisation with basal dressing at a rate of 200 kg/ha compound D was done with no inoculation for all the genotypes at planting across all locations. Data collection started when the crop had reached 50% flowering and the other parameters were recorded when the crop had reached maturity. Data analysis was done using Genstat version 16 and GGE biplot.

Results: The results showed that the best soybean location for Zambia was Kabwe; which was representative and discriminating. The genotypes yield mean score was 1239 Kg/ha and TGX 1988-22F was the highest yielding genotype with 1517 kg/ha while the lowest was TGX 1835-10E with 418 kg/ha. In terms of variability in accordance to GGE biplot, Safari was the most variable while the most stable was TGX 1988-22F. Therefore, the study concluded that the best genotype for general adaptability was the variety TGX 1988-22F which was ideal across all the locations as it was high yielding and stable. Six genotypes had a yield which was below the mean performance of the genotypes across all the locations; these were Lukanga, TGX 1835-10E, TGX 1830-20E, TGX 1988-18F, TGX 1987-23F and TGX 1987-11F. Also, three mega-environments were identified, Kabwe/Msekera which had TGX 1988-22F as the winning genotype, GART had safari and Masumba had Magoye.

Conclusion: The study was able to establish that Kabwe was the best test and production location for soybean in Zambia.