Castor bean (Ricinus communis L.) is an oilseed found in different regions worldwide, due to its easy propagation and adaptability. Cropping more productive disease-resistant genotypes that enable a mechanized production ensures greater economic returns for farmers. This study aimed to morphologically characterize and select promising castor bean accessions for mechanized cropping, mainly as a source of genetic variability for breeding programs with this purpose. Fifty accessions were assessed. Analysis of variance, dissimilarity clustering via the unweighted pair-group method with arithmetic mean (UPGMA) and principal component analysis were used to analyze the collected data. The dissimilarity analysis based on the Gower distance for qualitative and quantitative variables revealed three groups of accessions and the principal component analysis enabled the selection of those with desirable traits. The accessions BOC1, PRAT1 and SM2 exhibited morpho-agronomic characteristics of interest to the mechanized production, such as ideal plant height, diameter, seed weight and oil content. Such genotypes show a potential for use as genitors in genetic breeding programs of castor bean.

Water and salt stress conditions affect germination and seedling emergence. It is known that physiological priming can not only trigger different mechanisms to increase the speed and uniformity of germination, but also influence the antioxidant defence system of the seeds, especially in adverse conditions. In this context, the objective of this work was to evaluate the physiological seed quality and the activity of antioxidant enzymes in seeds of Petroselinum crispum induced to tolerate saline stress through osmo-priming. Seeds were placed in polyethylene glycol solutions with three osmotic potentials (-0.5, -1.0 or -1.5 MPa) for 2, 4 or 6 days. Subsequently, they were placed on substrates moistened with sodium chloride solution (NaCl), in concentrations that generated osmotic potentials of -0.2, -0.4, -0.6, -0.8 or -1.0 MPa, to germinate. The germination percentage, germination speed index, seedling length, fresh weight, dry weight and activity of the antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were evaluated. Germination and germination speed index decreased linearly with the increase in NaCl concentrations, indicating the species sensitivity. As for length, fresh weight and dry weight of seedlings, this effect was more expressive from the potential of -0.4 MPa. The vigour and activity of SOD, POD, and CAT enzymes were reduced in unprimed seeds, emphasising the effectiveness of the technique. The induction of tolerance to saline stress can be related to the activity of the antioxidant system observed in seeds.

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