Comportamento de cultivares de mamona nas condições edafoclimáticas do Semiárido

Abstract

Castor beans (Riccinus communis L.) is a widespread species adapted to semi-arid conditions. The crop breeding is one of the advances that can contribute to the sustainability of the production chain in the backcountry, supporting the production of biodiesel. The aim of this study was to prove the hypothesis that there are more viable cultivars in semiarid region for having better interaction with the local climate conditions. The study was conducted in two stages: at first, characterization of two Planosols in the Experimental Farm Vale do Curu (Pentecoste - CE) to evaluate its potential for castor cultivation. At this stage the completely randomized split-plot design was used. In plots were evaluated two profiles of Planosols (P1 and P2), while two horizons (Ap and Btf) were evaluated in the subplots with four replications. In the second stage an experiment was conducted at the same site where the soils were characterized. In this experiment ten treatments consisting of the following castor bean cultivars were evaluated: IAC 20-28; IAC-Guarani; IAC-80; IAC-226; MPA-34; MPB -01; MPA-11; BRS- Energia; Paraguaçu and Nordestina. To evaluate the productivity and oil production from cultivars was used the randomized-block design with four replicates. For assessments on root attributes and soil fertility was used in the randomized-block design with split plots. Ten castor bean cultivars were evaluated in the plots, while the sampling layers were evaluated in the subplots (0-10, 10-20 and 20-30 cm) with four replications. In the characterization step was found that Planosols studied have good yield potential due to its eutrophic character of medium natural fertility. However, the physical attributes checked in P2 showed values close to those considered limiting for plant development. When evaluating the interaction of plants with the soil, it was found that cultivars contributed to the chemical fertility, improving in depth the values of organic carbon (OC), calcium (Ca), phosphorus (P), sum of bases (SB), cation exchange capacity (CEC) and base saturation (V%). The soil cultivated with castor showed low values of total organic carbon (TOC), but most of that TOC was represented by the more stable fraction of soil organic matter. Out of the ten cultivars evaluated in terms of agronomic performance and income, those which responded satisfactorily to semiarid climatic conditions for productivity, oil content, nutritional status and root attributes were: Nordestina, Paraguaçu, BRS- Energia an MPB-01.