Quality of vegetal products are influenced both by hereditary factors and environmental conditions. Fertilization as an environmental
factor can strongly affect not yield but also quality of produce.
Three kinds of
organic manure, hog manure, poultry and oil cake and Its combination with mineral fertilizer were conducted both in field and pot experiments to study their influence on quality of crop produce. The treatments were designed with and equivalent amount of nitrogen and nitrogen-phosphorous-potassium nutrients to compare manures with chemical fertilisers. As compared to the control(NPK), the organic manure treatments improved the nutritive quality (protein, sugar, vitamin and indesponsible amino acid) outer quality (colour and size homogeneity of fruits) of crop which were
watermelon, tobacco and tomato. The total sugar content and sweet amino acid of watermelon increased by 18.6% and 24. 5mg/ 100gFW respectively. The first class of cured tobacco leaf increased by 8.8% and the lyslne content of tomato Increased by 31.3mg/100gFW. Results also showed that excessive rate of N have a detrimental effect of quality as they reduced the sugar content in watermelon and increased the nicotine and protein content in tobacco leaf. On the other hand, manures result in a slow release of nitrogen from soil due to its specific nutrient-supplying properties.
Reasons for the, superiority of manures is due to: (1)it may ensure a balance plant nutrition to meet the need of crop's good quality; (2) It improved the nitrogen supplying property to avoid a negative effect on the quality from excessive use of N; (3) promoted the content of endohormonces and improved their ratio (ABA/GA, IAA/ABA) in plant tissue.