Effects of ultraviolet-C radiation on symmetry and morphoanatomy of Rapanea ferruginea

This study analyzed the effects of UV-C radiation on the development of Rapanea ferruginea leaves. Young plants were selected at six months of age, previously identifying the leaves that had already differentiated on the 3rd, 4th, 6th 8th and 9th nodes. After the selection, the plants were divided into three groups and subjected to UV-C radiation for 30, 60 or 120 minutes. The anatomic study was made by using usual techniques of cut and coloration. The morphometric analyses were made by determining three points on the midvein of the leaf, measuring from left (L) and right (R) borders to each of those points. The symmetry deviations, maximum length and width of the limb were measured and the values were submitted to Anova and the Tukey-test (p < 0.05). The responses of R. ferruginea to the UV-C were expressed by variations in the symmetry as well as morphoanatomic injuries, mainly in the palisade parenchyma and mesophyll. The differentiation of leaves did not follow a morphometric pattern, characterizing no directional asymmetry, i.e., fluctuating asymmetry. This study emphasizes the importance of multiscale observations for the determination of plant responses under stress, since several leaves showed anatomic injuries but no morphologic injuries. Key words: stress, ultraviolet radiation, leaves, symmetry deviation, scales of observation. Neste estudo, analisaram-se os efeitos da radiacao UV-C sobre o desenvolvimento de folhas de Rapanea ferruginea. Plantas jovens foram selecionadas com seis meses de idade identificando-se as folhas ja diferenciadas do 3, 4, 6, 8 e 9 no. Posteriormente, as plantas foram divididas em tres grupos e submetidas a radiacao UV-C por 30, 60 ou 120 min. seguidos. Para o estudo anatomico, foram utilizadas tecnicas usuais de corte e coloracao. As analises morfometricas foram realizadas determinando-se tres pontos ao longo da nervura central da folha, medindo-se das bordas esquerda (E) e direita (D) ate cada um desses pontos. Determinaram-se tambem os desvios de simetria, o comprimento e a largura maxima do limbo, submetendo os valores a Anova e ao teste de Tukey (p < 0,05). As respostas de R. ferruginea a UV-C foram expressas por variacoes na simetria, bem como por injurias morfoanatomicas, sobretudo ao parenquima palicadico e mesofilo. A diferenciacao das folhas nao seguiu um padrao morfometrico, caracterizando, assim, uma assimetria nao-direcional, ou seja, flutuante. Este estudo ressalta a importancia de observacoes multiescalare