Abstract:
The study evaluated four soybean genotypes in 2012 and 2013 cropping seasons in the humid
tropics for growth, seed yield and other reproductive characters. A split plot in randomised
complete block design with four replications was used at National Cereals Research Institute,
Amakanma sub-station, Abia State, Nigeria (latitude 05º 28´ N, longitude 07º 29´ E ,154.25 m
asl). Sowing date was the main plot treatment while soybean genotypes were fitted into the subplots. Sowing date significantly affected soybean yield and yield components with the month of
July pointing out as most appropriate sowing time for the crop in the humid tropics of southeast
Nigeria. TGx1485-1D soybean genotype consistently exhibited high performance in seed yield
and in most of the characters studied across both environments while TGx1987-10F had the least,
hence can be tipped as good breeding material for development of high yielding soybean varieties
that would have high adaptation to the agro-ecology. Correlation and path analysis revealed
that number of pods plant-1 among other traits was the most important contributor to seed yield
and demands close attention as selection index for crop improvement. TGx1485-1D though high
yielding exhibited low yield stability across both environments in the GGE bi-plot ranking where
it ranked closest to the ideal genotype, hence, can be recommended as suitable for cultivation in
the humid tropics of southeast Nigeria. Also, the genotype could be exploited for future breeding
programs aimed at boosting research in developing high yielding, adaptable, disease resistance
and stable genotypes for the region.
