Seed Shape of Castor Bean (Ricinus communis L.) Grown in Different Regions of Tunisia

Aims: Seed size, shape and colour intensity were compared in castor bean (Ricinus communis L.) grown in the field in twelve locations corresponding to four climatic regions in Tunisia.

Study Design: Seeds were obtained from plants grown in the field in twelve locations corresponding to four climatic regions in Tunisia.

Place and Duration of Study: Samples were taken in summer 2014 from plants growing spontaneously.

Methodology: Size is estimated as the area of the seed images. Shape is measured by the roundness and J index that gives the percent of similarity of the figure plane of a seed with an ellipse. Colour is measured as gray intensity in seed images.

Results: Among the parameters indicating seed shape, roundness varied more than J index. Values of J index were superior, thus J index describes better than roundness the shape of Ricinus communis seeds. Seed size and colour presented higher variation than magnitudes concerning shape indicating that shape is more conserved in Ricinus communis seeds, than size or colour.

Conclusion: Differences in size and shape were found among the climatic regions. Reduced size and J index values were observed together with increased values of roundness in seeds obtained from the population grown in the dessert.