Irrigação de palma forrageira cultivada no semiárido mineiro

Abstract

Livestock is a strong activity in the Brazilian semiarid, a region marked by adverse conditions that compromise animal nutrition, hence the need to invest in xerophilous plants, such as the cactus pear. The objective was to present an adequate irrigation management for the cactus pear from the evaluation of the performance, agronomic yield and root distribution of two different cultivars and to define the best genetic material under irrigated conditions. The experiment was conducted in Montalvânia-MG (2017-2018) and involved six water demand treatments (T1, without irrigation; T2, 15% of ETo; T3, 30% of ETo; T4, 45% of ETo; T5, 60 % of ETo and T6, 75% of ETo) and two cactus pear genetic materials (cultivars „Gigante‟ - Opuntia ficus-indica Mill. and „Miúda‟ - Nopalea cochenillifera Salm-Dyck). A split plot was used, with the irrigation treatments in the plots and the genetic materials in the subplots, in a randomized blocks design, with four replicates, to evaluate agronomic performance and three replicates to evaluate root distribution. In the third month after planting and during a growing cycle, growth evaluations were performed and at 390 days after planting, root collection was started. At harvest, the variables of production and water use efficiency (WUE) were evaluated. Water depths interfere in the growth characteristics of the cultivars, however, it is recommended to plant the 'Miúda' under irrigated conditions, as it shows higher dry matter yield and WUE. The root length density (RLD) of very thin roots is concentrated in the proximity of the plant and small, medium and thin roots are concentrated only at the first distances, but all concentrated on the highest irrigation depths. The cultivar Gigante stands out with higher percentage of LDR.