Effect of Variety, Fertilizer Combinations, and Harvest Age on Biochemical Qualities of Carrot (Daucus carota L.) in a Tropical Environment

Abstract

The increasing global concern about ecologically unsafe agricultural practices calls for an investigation of how fertilizer combinations and harvest age interact to influence the biochemical qualities of crops. The study objective was to determine the biochemical responses of three carrot varieties to fertilizer composition, and harvest-age interactions. Three carrot varieties, Graffas, Carrot Touchon, and Nantes; four fertilizer compositions, 10 t/ha of poultry manure + 200 kg of NPK 15:15:15  (PM10 + NPK200), 20 t/ha of pig manure + 200 kg of NPK 15:15:15 (PIG20 + NPK200), 350 kg of NPK 15:15:15 (NPK350), and 0 t/ha (control); and three harvest-age, 10, 12, and 14 weeks after planting (WAP) were evaluated in a 3 x 4 x 3 factorial in randomized complete block design with 3 replications. Variations in biochemical concentrations of carrot roots with variety, fertilizer type, and harvest-age interactions were recorded. Proximate qualities were generally higher in Nantes and Graffas varieties grown with the combined use of organic and inorganic fertilizers harvested at 10 WAP. Phytochemical quality was higher in Graffas and Carrot Touchon grown with PM10 + NPK200 when harvested at 14 WAP. Nantes variety grown with NPK350 and harvested at 12 WAP had higher vitamin contents. Root weight had a positive correlation with saponin (0.22), carbohydrate (0.31), alkaloid (0.33), vitamin E (0.26), and fiber (0.19). Vitamin C displayed positive correlations with vitamin B (0.43), vitamin E (0.56), alkaloid (0.67), tannin (0.31), saponin (0.32), and carbohydrate (0.35), while beta-carotene exhibited positive correlations with vitamin A (0.42) and tannin (0.38).