Irrigation is a Decisive Factor for Obtaining Higher Economic Viability of Dwarf Castor Hybrids Cultivation in Tropical Fall–Winter Conditions

Castor is recognized as a species adaptable to the different Brazilian edaphoclimatic conditions, being considered tolerant to water deficit. However, when genotypes are subjected to different cultivation systems, the responses can be heterogeneous. The objective was to estimate and evaluate the economic indicators related to the cultivation of three dwarf castor hybrids in two cultivation systems, irrigated and rainfed, and two planting densities in tropical fall–winter conditions. For this purpose, two experiments were conducted, one in an irrigated and another in a rainfed condition. The treatments consisted of three dwarf castor hybrids (HT-5, HT-3, and Ag-IMA) and two planting densities (5.0 and 3.5 plants m−1). All the factors had effects on the productive and economic characteristics evaluated. Irrigation had participation of 27.42% of the total operational cost in irrigated cultivation, which allowed for obtaining positive economic returns. In this condition, the higher planting density provided an average increase of 69.28% in grain yield and 97.97% in operating profit. However, in nonirrigated cultivation conditions, there were no treatments that resulted in a positive return, and the increase in density resulted in greater economic loss due to the cost of seed acquisition. In this condition, the lowest planting density, combined with the Ag-IMA hybrid, resulted in the lowest economic loss. Thus, we conclude that the use of irrigated systems is essential for the cultivation of dwarf castor bean hybrids in regions where there is a heterogenous distribution and low volume of precipitation, and the interaction between genotype and environment must be observed.