Proximate qualities and lycopene contents of three watermelon (citrullus lanatus) fruit varieties grown with climate-smart integrated fertilizer management in sandy loam soil

Abstract

The objective of the study was to determine the effect of climate-smart integrated fertilizer management on proximate qualities and lycopene contents of three watermelon (Citrullus lanatus) varieties grown in sandy loam soil. The experiment was conducted at the experimental farm of the Department of Agricultural Education, University of Nigeria, Nsukka between the months of August to October 2017 cropping season. The experiment was laid out in a split-plot design, with three replications, three main plots (Citrullus lanatus varieties (Sugar baby, Koalack and Charleston grey)) and six sub-plots (fertilization treatments). Climate-smart integrated fertilizer considered was combination of Goat manure (GM) and Nitrogen Phosphorus Potassium NPK 15: 15: 15 fertilizer which is regarded as most nutrient-rich fertilizer with climate change mitigation and adaptation potential. The study found that the pH of the watermelon varieties were statistically similar and that Charleston grey treated with 50 kg ha^-1 NPK + 15 t ha^-1 GM had the highest interactive effect on pH value which was statistically similar with 100 kg ha^-1 NPK + 10 t ha^-1 GM treatment. It was discovered that Koalack variety had the highest moisture contents when treated with 100 kg ha^-1 NPK + 10 t ha^-1 GM, crude protein content when treated with 150 kg ha^-1 NPK + 5 t ha^-1 GM, crude fibre content when treated with 20 t ha^-1 GM, ether extract and total soluble solid contents when treated with 50 kg ha^-1 NPK + 15 t ha^-1 GM. For the lycopene content, it was found that Sugar baby variety had the highest mean value (0.61g/100g) when compared with Charleston grey and Koalack varieties. Sugar baby variety treated with 20t/ha^-1 GM had highest (0.89g/100g) interactive effect when compared with other varieties and fertilizer treatments. In conclusion, the proximate qualities and lycopene contents of the three varieties increased with the increase in the amount of GM contents of the fertilizer combinations in sandy loam soil. Climate-smart integrated fertilizer improves the proximate qualities of Koalack variety and the lycopene contents of Sugar baby variety more than in other varieties grown in the same sandy loam soil. Therefore, climate-smart integrated fertilizer is recommended for the production of the identified Citrullus lanatus varieties as a nutrition sensitive production strategy in sandy loam soils by farmers in study area.