Evaluation of the Effects of Nutrient Omissions on the Growth and Seed Yield of Two Castor Plant Varieties in Southwest Nigeria

Purpose: This pot experiment determined the critical nutrient elements for improved performance of two castor varieties in the study area.

Methods: Two castor plant varieties; Indian Brown (IB) and Brazilian White (BW) were raised using ten nutrient types; 120 kg N, 50 kg P, 60 kg K, 10 kg Mo, 5 kg Zn, 2.5 kg Cu, 3 kg Fe and 5 kg Bo all in kg/ha as full nutrient (FN) with omissions of each of the element from FN and the control (no amendment) between August 2021 and January 2022 at Ladoke Akintola University of Technology, Ogbomoso, Nigeria. Data were collected on Plant Height (PH), Stem Girth (SG), Number of Capsules (NC) and Seed Weight (SW).

Results: The IB produced taller (71.0 cm) plants and higher SW (16.9 g/plant) compared to BW with respective values of 57.6 cm and 12.5 g/plant. At 16 weeks after sowing, the full nutrient produced the thickest stem (57.1 mm) while the omission of nitrogen produced the thinnest stem (47.9 mm). The omission of zinc produced the highest NC (30) while the omission of nitrogen (17) and boron (14) produced lowest NC. Omission of potassium produced highest SW (20.3 g/plant), while omission of nitrogen (12.5 g/plant), phosphorus (13.0 g/plant) and boron (11.3 g/plant) produced lowest SW.

Conclusions: IB should be the choice variety over BW while nitrogen, phosphorus and boron are critical nutrient elements for its improved performance in the study area.