O aumento em superfície em Adelia membranifolia (Müll. Arg.) Pax & K. Hoffm. e Peltophorum dubium (Spreng.) Taub., em resposta ao estresse por deficiência nutricional e alagamento do substrato
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Data
2003-12-01
Autores
Santiago, Etenaldo F.
Paoli, Adelita Aparecida Sartori [UNESP]
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Editor
Sociedade Botânica de São Paulo
Resumo
Foram estudadas as respostas plásticas em plântulas e plantas jovens de duas espécies arbóreas nativas, Adelia membranifolia (Müll. Arg.) Pax & K. Hoffm. (Euphorbiaceae) e Peltophorum dubium (Spreng.) Taub. (Leguminosae-Caesalpinoidae), submetidas ao alagamento do substrado associado ao déficit nutricional. Avaliou-se o acréscimo em superfície no módulo de expressão, definido como a região do eixo da plântula que, sob condições de estresse, sofre rediferenciação sendo considerada a hipertrofia lenticelar como a expressão morfogenética mais comum. em A. membranifolia a associação do estresse nutricional e alagamento do substrato foi a condição mais restritiva tanto para o crescimento em altura e diâmetro do colo quanto para as expressões morfogenéticas. Já em P. dubium o estado nutricional foi mais restritivo que o alagamento para o crescimento do colo. em geral, para ambas as espécies, plantas nutridas mantidas alagadas restabeleceram seu ritmo de crescimento a partir do terceiro mês de tratamento, além de expressarem respostas plásticas como a hipertrofia lenticelar e a formação de raízes adventícias. Quanto ao aumento em superfície, nos lotes desnutridos, verificou-se que em A. membranifolia de um total de 38% de superfície expressa, 12% corresponderam à hipertrofia lenticelar. em P. dubium verificou-se as maiores variações de aumento em superfície expressa por hipertrofia lenticelar, elevando de 5% para 13%. em geral a superfície modular nos lotes tratados foi o dobro em relação ao controle. É possível que o aumento em superfície, para algumas espécies, seja significativo como tendência ao aumento da estabilidade no desenvolvimento a partir de interações fisiológicas.
Plastic responses in seedlings and young specimens of the native tree species Adelia membranifolia (Müll. Arg.) Paxt. & K. Hoffm. (Euphorbiaceae) and Peltophorum dubium (Spreng.) Taub. (Leguminosae-Caesalpinoidae), submitted to flooding and nutritional deficit, were studied. Surface increase on the expression module, defined as the region on the stem of the seedling which, under stress situations, undertakes re-differentiation, was measured. The lenticels hypertrophy is seen as its most common morphogenetic expression. In A. membranifolia, both for growth in height and stem diameter and for morphogenic expressions, the association of nutritional stress with flooding represented the most restrictive conditions. In P. dubium nutritional state was more restrictive than flooding for stem growth. In general, nourished plants of both species maintained in a flooded condition reestablished their growth rhythms starting from the third month of treatment, besides evidencing plastic responses such as lenticels hypertrophy and the formation of adventitious roots. In regards to surface increase in the undernourished lots, it was verified that in A. membranifolia, from a total of 38% of surface, 12% corresponded to lenticels hypertrophy. In P. dubium the greatest variation of surface increase by lenticels hypertrophy was observed, an increase from 5% to 13%. Generally, the modular surface in the flooded plants was twice as large when compared to the control group. It is possible that the surface increase, for some species, is significant as a trend towards improving growth stability due to physiological interactions.
Plastic responses in seedlings and young specimens of the native tree species Adelia membranifolia (Müll. Arg.) Paxt. & K. Hoffm. (Euphorbiaceae) and Peltophorum dubium (Spreng.) Taub. (Leguminosae-Caesalpinoidae), submitted to flooding and nutritional deficit, were studied. Surface increase on the expression module, defined as the region on the stem of the seedling which, under stress situations, undertakes re-differentiation, was measured. The lenticels hypertrophy is seen as its most common morphogenetic expression. In A. membranifolia, both for growth in height and stem diameter and for morphogenic expressions, the association of nutritional stress with flooding represented the most restrictive conditions. In P. dubium nutritional state was more restrictive than flooding for stem growth. In general, nourished plants of both species maintained in a flooded condition reestablished their growth rhythms starting from the third month of treatment, besides evidencing plastic responses such as lenticels hypertrophy and the formation of adventitious roots. In regards to surface increase in the undernourished lots, it was verified that in A. membranifolia, from a total of 38% of surface, 12% corresponded to lenticels hypertrophy. In P. dubium the greatest variation of surface increase by lenticels hypertrophy was observed, an increase from 5% to 13%. Generally, the modular surface in the flooded plants was twice as large when compared to the control group. It is possible that the surface increase, for some species, is significant as a trend towards improving growth stability due to physiological interactions.
Descrição
Palavras-chave
alagamento, aumento em superfície, lenticelas, módulo de expressão, expression module, flooding, lenticels, surface increase
Como citar
Brazilian Journal of Botany. Sociedade Botânica de São Paulo, v. 26, n. 4, p. 503-513, 2003.