Crambe (Crambe abyssinica Hochst. ex R.E. Fries) is an oilseed crop that can be cultivated in tropical conditions and used for the production of industrial oil. While crambe is believed to be a suitable crop for no-tillage systems, identification of appropriate crop species to precede it is necessary to improve its grain yield and oil content. In this study, we aimed to assess the short-term effects of crop rotation on the grain yield and oil content of a crambe crop cultivated after spring-summer cover crops. The experiment was conducted on an Rhodic Hapludox soil in Santa Helena-PR, Brazil. The experimental design consisted of randomized blocks with four replications. The plots consisted of pearl millet (Pennisetum glaucum), grass brachiaria (Brachiaria brizantha), sorghum (Sorghum bicolor), sunn hemp (Crotalaria juncea) and a fallow area (spontaneous vegetation). Grain yield, oil content, and oil yield were measured. Crambe oil content was influenced by the cover crops. The use of crotalaria as predecessor species resulted in higher oil content, but the result did not differ from that observed in the fallow area. However, grain yield and oil content were benefited by the crotalaria cover crop in the short-term. Crambe looks promising as an alternative oilseed crop for South Brazil when seeded in autumn with crotalaria cover crop in Rhodic Hapludox.
The crambe crop is an interesting option for the production of biodiesel, mainly due to the high oil content (35%) and the corn one of the most implanted crops in Brazil. Thus, the objective of this work was to evaluate the allelopathic effect of crambe in the initial development of maize. The experiment was carried out in the laboratory of seed and plant evaluation (LASP) and laboratory of soil physics (LAFIS) of UNIOESTE-Cascavel. The seeds of corn with germination of 93.5% were submitted to four concentrations plus the control in the different parts of the crambe plant, where the growth and mass of corn were valued. The experimental design was completely randomized with 4 replicates per treatment. The statistical analysis consisted of analysis of variance and the means of the treatments were compared by the Tukey test at 5% of significance. The extract of the whole crambe plant stimulated aerial length, root length, fresh and dry mass of corn shoot. Root, stem and leaf extracts inhibited the initial development of maize in relation to growth and fresh and dry shoot mass.
The objective of this work was to evaluate the phytotoxic effect of Brachiaria decumbens Stapf. on the morphometry of Eucalyptus urograndis plants, genetically modified hybrid of Eucalyptus urophylla S. T. Blake × Eucalyptus grandis W. Hill ex Maiden. Pots containing the eucalyptus plants were conditioned in protected environments in a completely randomized experimental design. The treatments were composed of aqueous extract of Brachiaria decumbens grass at different concentrations: 0% (control, distilled water only), 20%, 40%, 60%, 80% and 100% (g/L). On day 30 of the experiment, the following morphological parameters of the plants were evaluated: aerial part height, diameter of stem, aerial dry mass, root dry mass, total dry mass, and robustness index. The data were submitted to analysis of variance at the 5% level of significance, and a regression equation was constructed for the quantitative treatments. The results indicated that the Brachiaria decumbens grass extract did not have an inhibitory effect on aerial part height and robustness index. However, the extract at concentrations higher than 20% had negative effects on root dry mass, aerial dry mass, and total dry mass. For the diameter of the stem, only concentrations above 60% had an inhibitory effect.
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