The development of extractable color of red pepper fruit ('Americano' and 'Fibola' cv.) on sand and perlite substrates, low conditions of fertilization with optimized nutrient solutions for the cultivates control and deficient in potassium from the fruit set to the complete maturation, is studied comparatively. The contents of "a", "b" and "total" chlorophylls decrease quickly with the development of the fruit in all the cases, being high to the 60 and 70 days from of the fruit set, and with most low levels for the deficient sectors. The levels of accumulation of "red", "yellow" and "total" carotenoids grow quickly with the maturation of the fruit in all the cases, where maximum levels of "total" carotenoids reach for both cultivated varieties in perlite substrate. The ratio "red" and "yellow" carotenoids (R/Y) increases with the maturation of the fruit stabilizing in the end step; with inicialy most high levels for the 'Fibola' variety and for 'Americano' variety in perlite substrate to a great extent in the control to the end of the maturation, what evidence a bigger precocity in the maturation for 'Fibola' variety.