Foliar fertilization of organic sunflower, enhanced yield components and seed yield in the humid tropics

Abstract In a two year experiment carried out on the organic research plots of the Institute of Food Security, Environmental Resources and Agricultural Research, Nigeria. Two liquid organic fertilizers (ARATI NAWOZ {2.01% N} and ARATI BAJA {1.01% N}) and control were applied to four sunflower varieties (SAMSUN 1, SAMSUN 2, SAMSUN 3 and SAMSUN 4) during the late cropping season (July – Nov.) of 2016 and 2017 to evaluate their agronomic response. The experiment was laid out in a randomized complete block design using a 4 × 3 factorial arrangement in three replicates. Data were collected on plant height at maturity, head diameter and weight, weight and number of seeds per head, 100 seed weight and seed yield. The varietal effect was significant (P < 0.05) on head diameter and weight, and number and weight of seeds per head, and seed yield in 2016. However, during the markedly dry 2017, the varietal effect was not significant for any trait measured. Foliar application of ARATI NAWOZ significantly (P < 0.05) increased height at maturity, the weight of seeds and head per plant and seed yield relative to the control in both years. Significant Variety × Fertilizer interaction effect was also recorded on the height at maturity, head diameter and weight, and seed yield in 2016. SAMSUN 4 (975.6 kg/ha) produced significantly (P < 0.05) higher seed yield than SAMSUN 1 (789.82 kg/ha) and SAMSUN 2 (778.54 kg/ha) in 2016. The efficacy of the application of both fertilizers was on par for most traits in both years. On average, the application of organic fertilizers resulted in a 15.76 and 69.02% increase in seed yield relative to the control in 2016 and 2017, respectively. ARATI NAWOZ and ARATI BAJA appeared promising for sunflower production in the humid tropics.