Morphological Characteristics of Amaranthus cruentus and Amaranthus tricolor as Influenced by Integration of Organic and Inorganic Fertilizers in Kiambu County, Kenya

A field experiment was conducted to evaluate the effect of organic and inorganic fertilisers application on growth parameters of two amaranth varieties. Fifty-four treatments were evaluated as factorial combinations of organic manure applied at 16.9 t/ha, inorganic NPK fertiliser at 500 kg/ha, zero fertiliser (control treatment) and two amaranth varieties (A. tricolor and A. cruentus varieties). The treatments were fitted into in a randomised complete block design (RCBD) replicated three times. A. cruentus recorded the highest leaf area of 1415 cm2 in the second from 248 cm2 in season one. A. tricolor in the second season recorded 700 cm2 from 387 cm2 at the same treatment of 16.9 t/h+ 500 kg/ha. The number of leaves was highly significant at p≤0.01 in the second season but was significant at p≤0.05 in the first season while sole organic manure was applied at 16.9t/ha, A. tricolor variety had 17.56 number of leaves in season two from 14.56 in season one at 16.9 t/h, in A. tricolor the number of leaves in reduced from 17.06 to 14.06 in season one when 500 kg/ha of NPK 17-17-17- was applied. The longest shoot of 43 cm in the second season from 22 cm in the first season was in A. tricolor at the rate of 16.9 t/ha + 500 kg/ha in season two. In A. cruentus the shoot length increased to 34.7 cm from 31.1 cm in season one when sole organic manure was applied at 16.9 t/ha. The root length was highly significant at p≤0.01 in the first season but was significant at p≤0.05 in the second season A. tricolor had 16.58cm and A. cruentus having 17.39 cm in season one at control, in season two at control, the root length was 18.73 cm in A. cruentus and 18.94 cm in A. tricolor. Root length reduced from 18.23 cm in season one to 12.86 in season two in A. cruentus when 16.9 t/ha of organic quail manure was applied. The root dry weight in A. tricolor recorded 2.392 g from 1.177 g at 8.45 t/h+500 kg/ha, at 16.9 t/h+500 kg/ha in season one, A. cruentus had 0.625 g which increased to 2.468 g but A. tricolor increased to 2.328 g from 0.72 g.