Growth and Productivity of Pigeon Pea Genotypes under Different Plant Geometry and Its Residual Impact on Some Soil Chemical Properties

Abstract

Field experiments were conducted during the 2020 and 2021 cropping seasons at the research fields of CSIR-Savanna Agricultural Research Institute located at Nyankpala in the Guinea savannah agroecology of Ghana. The objective was to test the effect of genotype and plant geometry on the growth and productivity of pigeon pea and its residual effect on some soil chemical properties. The work involved three pigeon pea genotypes (L-2015-2, L-2015-3 and ICP-8863) and four spacing levels; 100 cm x 30 cm, 100 cm x 45 cm, 100 cm x 60 cm and 100 cm x 75 cm. Analysis of variance indicated a significant interaction effect of genotype, year and spacing effect on number of branches per plant, pod length, grain yield, 1000 seed weight and harvest index. Genotype x spacing effect was significant for all traits except the number of seeds per pod. (294.7 cm) whilst genotype L-2015-3 at 100 cm x 60 cm produced the shortest plants (222.9 cm). Genotype L-2015-2 at 100 cm x 60 cm in 2021 had the highest grain yield (2311 kg/ha) whilst genotype ICP8863 at 100 cm x 60 cm in 2020 had the lowest grain yield (391 kg/ha). A post-2020 cropping season soil analysis revealed improvement in key soil chemical properties, explaining the better crop performance in 2021. Genotype L-2015-2 had the highest overall average grain yield (1484 kg/ha) whilst ICP8863 had the lowest overall grain yield. The study indicated that the different genotypes required different spacing for their optimum yield due to differences in plant architecture, growth and branching habit. Spacing had significant influence on plant height, number of leaves at flowering, number of pods per plant and number of seeds per pod which were significantly and positively correlated with grain yield. Therefore, each genotype should be matched with its preferred spacing for optimum growth and maximum grain yield.