Agronomic Response of Soybean Varieties to Plant Population in the Guinea Savannas of Nigeria

Abstract

populations were the main plots, whereas varieties were subplots. The proportion of intercepted photosynthetically active radiation (IPAR) and leaf area index (LAI) increased with increasing plant population at both locations, indicating that high leaf area indices and high degree of canopy closure at higher plant population intercepted more light than the canopy at lower population and subsequently resulted in relatively high grain and fodder yields. At both locations, optimum plant populations ranged from 533,300 to 666,700 plants ha-1 across the years. The northern Guinea savanna location (Samaru Zaria) produced more pods m-2, grain yield, and fodder at higher plant populations than that at the southern Guinea savanna (Samaru-Kataf ). Varieties TGx1448-2E and TGx1904-6F intercepted higher proportion of IPAR had higher LAI and produced a greater number of pods m-2, seeds m-2, grain yield, and fodder than TGx1835-10E at both locations in years of good rainfall. These data suggest that soybean yields in the Guinea savanna of northern Nigeria can be increased using higher plant populations than those currently recommended.