Cuttings of Euphorbia phosphorea Mart and Euphorbia enterophora Drake at different concentrations of indole-butyric acid and analysis of economic viability

Abstract Defining seedling production protocols for ornamental species through the use of plant regulators requires economic analysis that demonstrates the real financial returns of such activity to horticulturists. The objective was to evaluate the influence of using indole butyric acid regulator (IBA) on rooting of Euphorbia phosphorea (Mart) and Euphorbia enterophora (Drake) cuttings, as well as to analyze the economic viability of seedling production with the use of IBA. The cuttings were 10 cm long, and treated with IBA at concentrations of 0; 1,000; 3,000; and 5,000 mg L-1. The cuttings were place in vermiculite substrate and were irrigated daily inside a greenhouse. The experimental design was completely randomized, with 4 replications, containing 5 cuttings per experimental unit. Evaluations were performed 150 days after establishing the experiments. The Net Present Value (NPV) and the Internal Return Rate (IRR) were analyzed to determine the economic viability analysis of using IBA. For E. phosphorea there was no significant difference between treatments for cuttings survival, number of roots and length of roots. Callus formation was not observed at the base of the cuttings, and the highest survival percentage was observed in T3 (3,000 mg L-1) and T4 (5,000 mg L-1) treatments. Treatment T1 (control) presented a lower number of roots per cutting (12.8) and higher average length of the three largest roots (12.56 cm). The use of the IBA regulator increased the percentage of rooted cuttings and the number of roots per cutting, and the concentration of 3,000 mg L-1 was recommended for E. phosphorea. Regarding aspects of economic viability, using IBA at the commercial nursery level is recommended. For E. enterophora, IBA is not recommended because it is an easily rooted species (95%), therefore, denotes the economic unfeasibility of its use.