Abstract:
Organic fertilizers generally comprise a variety of plant-derived materials, animal manures
and agricultural by-products. The use of organic fertilizers has the advantages
of improving soil quality and mitigating problems associated with synthetic fertilizers.
The present study’s objective was to investigate the impact of organic fertilizer on the
nutritional composition of tomato fruits (Solanum lycopersicum L.). Two commonly
cultivated tomato hybrid varieties “Thilina” and “Padma” were grown in poly pots
containing three different substrates; topsoil supplement with recommended levels of
commercial organic fertilizer composed of a mixture of cow manure, plant residues and
biochar (T1), NPK chemical fertilizer (T2) and no added fertilizer (T3). P, K and organic
C content of soil were analyzed by standard methods. Total soluble sugars, lycopene,
carotene, vitamin C and K contents of ripe fruits were analyzed. Analysis of the soil
showed that addition of organic fertilizer significantly improved the P, K and organic C
contents in the soil. However, the P and K contents were relatively lower when compared
to chemical fertilizer-added soil. In contrast, organic C content was significantly higher
in organic fertilizer-added soil. In comparison to plants grown under chemical fertilizer,
lycopene content of tomatoes of both “Thilina” and “Padma” varieties increased by 50%
and 48% respectively, and soluble sugar content was increased by 46.2% in ”Thilina” and
62.0% in “Padma” varieties. carotene was increased under the application of organic
fertilizer but vitamin C contents of fresh tomatoes were lower in “Thilina” and “Padma”
varieties by 8.6% and 7.0%. The K content of tomato was not significantly affected by
organic fertilizer. Taken together, the results suggest that recommended levels of organic
fertilizer can be successfully used to improve the nutritional quality of tomatoes.
