Postharvest Quality and Safety of Potted Greenhouse Tomato Grown on Forest Soil-Biosolids substrate,Blended with NPK Fertilizer

摘要

Studies on the effects of biosolids(BS)amended substrate on food quality and safety in tomato production have not been adequately addressed.The objective of this study was to investigate the influence of composted BS and NPK fertilizer on post-harvest quality and safety of potted greenhouse tomato Solanum lycopersicum L.Potted tomatoes"Maxim F1"were grown in a randomized complete block design with four replications.Inorganic fertilizer NPK(17:17:17) fertilizer was applied at 0,100 kg ha^(-1)(5g per pot)and 200 kg ha^(-1);(10g per pot),BS was applied at 0%,10%,20%,30%,and 40%v/v,in all possible combinations.Tomato were harvested and analyzed for ascorbic acid,chlorophylls,carotenoids and total phenolic compounds;weight loss,fruit firmness,titratable acidity and total soluble solids,as well as heavy metals and microbial contaminants.Results revealed that tomato fruit at 10%BS in combination with NPK fertilizer at 100 kg ha^(-1) had the highestβ-carotene(6.1 mg 100 g^(-1)),lycopene(26.1 mg 100 g^(-1)),ascorbic acids(128.0 mg 100 g^(-1)),total phenolic acids(13.2 mg 100 g^(-1)),total soluble solids(17%).However,the same rates produced tomato fruit with lower titratable acidity(2.2%)and had heavy metal residues within the permissible level,according to International EPA standards on biosolids utilization for food crops production.Similarly,no trace of pathogenic bacteria;Salmonella,Escherichia coli,Staphylococcus was observed on the harvested tomato.This study reveals at BS 10% with NPK fertilizer at 100 kg ha^(-1) substrate as a better option of plant nutrient source for quality and safe greenhouse tomato production.