Intra-row spacing and nitrogen management in wide-spaced winter castor (Ricinus communis) in heavy rainfall zone of south Gujarat

An experiment was conducted for 3 consecutive winter (rabi) seasons of 2011–12, 2012–13 and 2013–14 on clayey soil of the Soil and Water Management Research Farm, Navsari, Gujarat, to study the response of wide spaced (2.4 m), drip-irrigated winter (rabi) castor (Ricinus communis L.) to intra-row spacing under varying nitrogen (N) levels. In all, 10 treatments comprising 3 intra-row spacings (60, 90 and 120 cm) and 3 N levels (80, 120 and 160 kg N/ha) besides, 1 paired row control [0.6 m × 0.6 m × 1.2 m paired row + recommended dose of fertilizer (RDF)] treatment outside the experimental plot. Intra-row spacing of 120 cm resulted in significantly higher number of branches, leaves, spikes and seed yield/plant. However, intra-row spacing of 60 cm remained superior in respect of plant height, seed, stalk and oil yields and nutrient uptake. Improvement in seed yield under 0.6 m intra-row spacing was 12.68 and 4.18% over 1.2 and 0.9 m respectively. Among the N levels, an application of 160 kg N/ha recorded significantly higher plant height, number of branches, leaves, spikes, seed yield/plant and also resulted in higher seed, stalk and oil yields. On pooled data basis, the magnitude of increase in seed yield under 160 kg N/ha was 5.84 and 2.11% over 80 and 120 kg N/ha respectively.