LAUSR

Abstract The nutrients requirement for Cucurbita pepo L. (summer squash) for optimal yield and quality fruits production can be achieved through adequate nutrient supply. A field experiment was carried out during the cropping season of 2015 and 2016 at Landmark University Teaching and Research Farm, Omu-Aran, Nigeria to investigate the impact of Tithonia diversifolia, poultry manure and NPK fertilizer on the growth, yield, mineral and vitamin C content in the fruit of C. pepo. The experiment consisted of T. diversifolia at 30 tons ha−1, poultry manure at 10 tons ha−1, T. diversifolia at 30 tons ha−1 + Poultry manure 10 tons ha−1, T. diversifolia at 30 tons ha−1 + NPK (20:10:10), NPK (20:10:10) and control (no amendment of any kind) arranged in a randomized complete block design with four replications. The growth and fruit yield of C. pepo using the mean of the two years was increased by 68% and 2% respectively by T. diversifolia + poultry manure as compared to control due to an increase in nutrient availability in the soil with the amendment used. Also, Vitamin C content and Mg value of the fruit was increased by application of T. diversifolia as soil amendments as compared to the control. While the application of NPK fertilizer alone significantly increased the Ca, Mn and Fe contents of fruits. Fruit content of K was increased by 39 % by the application of T. diversifolia + NPK. Therefore, for the purpose of growing squash for the quality of fruits (vitamin C), the use of T. diversifolia at 30 tons ha−1 as organic fertilizer is sufficient for the cultivation, while for growing the crop with interest in quantity, application of T. diversifolia at 30 tons ha−1 + poultry manure at 10 tons ha−1 is recommended.