Assessment of Soil Fertility Improvement Potential of Water and Methanolic Sunflower (Tithonia diversifolia Hemsl.) Leaf Extract on the Growth and Yield of Tomato (Solanum lycopersicon L.)

The field work was carried out at the Screenhouse of Faculty of Agriculture, Obafemi Awolowo University, Ile-Ife, Nigeria to determine the effectiveness of water and methanolic sunflower leaf extract as a fertilizer sources to improve growth and yield of tomato. The experiment consisted of six treatments which are sterilized soil with tomato, unsterilized soil with tomato, water sunflower extract with tomato in sterilized soil, water sunflower extract with tomato in unsterilized soil, methanolic sunflower leaf extract with tomato in sterilized soil and methanolic sunflower leaf extract with tomato in unsterilized soil. Treatments were in triplicate and arranged in randomized complete block design (RCBD). Twelve pots, each containing three kilograms of top soil were used in consideration to the planting duration. One hundred (100) ml of sunflower leaf extracts was added to each of the treatments except the controls.

The growth results at Nine weeks after planting showed that leaf area and vine length was significantly higher in treatment with sunflower methanolic extract in sterilized soil with mean of 78.87 cm2 while girth size and vine length were significantly higher in the control treatment with sterilized soil. The yield results showed that the treatment with methanolic sunflower in sterilized soil had 8 fruits at harvest while the least number of fruit was in treatment of methanolic sunflower in unsterilized soil which had one fruit. The treatment with water extract of sunflower with unsterilized soil had the highest fruit weight of 1.2 gram while the treatment with methanolic sunflower extract with unsterilized soil had the least value of 0.066 gram which was lower than the controls. The diameter of fruit showed that the treatment with methanolic sunflower extract with sterilized soil had the highest value with mean of 25.4 cm while treatment with methanolic sunflower extract in unsterilized had the least with mean of 6.5 cm. Nitrogen and potassium level in the post planting soil were reduced almost all across the treatments. Soil calcium increased in the post planting soil as well as the pH. The experiment concludes that methanolic sunflower extract improves soil fertility.