Histology and induction of rooting in rubber tree cuttings (Hevea brasiliensis (Willd. Ex A.Juss.) Müll.Arg.)

Abstract The rubber tree (Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg.), a native Amazonian species, is responsible for more than 50 thousand products and stands out as the world's main source of natural rubber. Commercial production is carried out by grafting, however, the technique has gaps in terms of time and quality for seedling production. Vegetative production via cuttings is an alternative, however, the species is difficult to root. Thus, the study tested the rooting induction, through a chemical method, with the hormonal regulator indolbutyric acid (IBA) of 5000 ppm, and a mechanical method, with the strangulation of stems, and the interaction between the methods, to analyze the survival and sprouting of rubber tree (Hevea brasiliensis) cuttings, as well as verifying the efficiency of breaking the sclerenchyma ring by strangulation. A randomized block design was used, with four treatments (control, with strangulation, with IBA, strangulation x IBA) distributed in six blocks with 36 cuttings. Data were submitted to ANOVA test and Tukey's post-test (p>0.05). The results obtained 12.5% of live cuttings, without rooting, during 68 days, being the combination of strangulation and IBA with greater survival and sprouting. No breakage of the sclerenchyma ring was observed by histological analysis. The data indicate strategic gains in combining chemical and mechanical techniques for species of difficult rooting in vegetative propagation, however, the test was not enough to affirm an answer in relation to each technique, the deepening of the technique on the behavior of the species remains the biggest challenge. Resumo A seringueira (Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg.), espécie nativa da Amazônia, é responsável por mais de 50 mil produtos e se destaca como a principal fonte mundial de borracha natural. A produção comercial é realizada por enxertia, porém, a técnica apresenta lacunas em termos de tempo e qualidade para produção de mudas. A produção vegetativa via estaquia é uma alternativa, porém a espécie é de difícil enraizamento. Assim, o estudo testou a indução do enraizamento, por método químico, com o regulador hormonal ácido indolbutírico (AIB) de 5000 ppm, e método mecânico, com estrangulamento de hastes, e a interação entre os métodos, para analisar a sobrevivência e brotação de estacas de seringueira (Hevea brasiliensis), bem como verificar a eficiência da quebra do anel esclerenquimático por estrangulamento. Utilizou-se o delinea