Concentration of macronutrients in potted chrysanthemum, cultivated under different NO3-/NH4+ ratios - DOI: 10.4025/actasciagron.v27i3.1395

Abstract

In order to study the effects of different ratios of NO₃^-/NH⁺⁴ on the development and mineral composition of chrysanthemum plants, an experiment was carried out in a greenhouse. Five plants in each vase containing 0.75 dm³ of substrate (soil: sand: coffee bean skin: manure at volumetric proportion of 2:0.5:1:1) were used. The treatments were arranged in complete randomized blocks in a factorial scheme (5x5) with three replications. There were five varieties (Puritan, Indianápolis, Coral Charm, Festival Time, Fine Time) and five ratios of NO₃^-/NH⁺₄ (100/0, 75/25; 50/50; 25/75, 0/100) totalizing 75 vases. The ratios NO₃^-/NH⁺₄ affected the dry weight accumulation in the aerial portion of the plants. There were differences among the varieties regarding the tolerance to presence of NH₄⁺ in the irrigation solution. The Fine Time was the most sensitive, supporting only 25% of NH₄⁺ in the solution. When 50/50 ratio was used the concentrations of N, P, K, Ca, Mg and S were adequate for the development of the plants.