'Aroeira-branca' [Lithraea molleoides (Vell.) Engl. - Anacardiaceae] seed quality evaluation by the X-ray test

Abstract

'Aroeira-branca', an arboreal species of great ecological and economic importance, is seed propagated and presents limitations with respect to the availability of methods for seed quality evaluation. The X-ray test has been considered of potential value because it is accurate, quick and nondestructive. In this context, the objective of this work was to verify the possibility of this test to detect damage and/or abnormalities in aroeira-branca embryos, in an attempt to correlate these anomalies to germination. Four seed lots were collected in different locations in the southern region of the State of Minas Gerais, Brazil, during 2001. The X-ray test consisted of submitting 100 seeds/lot to radiation (exposure of seeds to radiation of 13 kV/5 minutes) and classifying them according to embryo/embryo cavity proportions of 0, < 50, 50-75 and 100%, with the latter class divided into normal and abnormal according to embryo morphology. The germination test was then carried out to detect possible relationships between seed anatomy and the resulting seedling/seed ratio, as revealed by radiographs. Seeds presenting an embryo/embryo cavity proportion lower than 100%, as determined by the X-ray test, did not germinate, and those presenting abnormal embryos produced abnormal seedlings or did not germinate, providing evidence that the X-ray test is effective to assess seed quality.