Sobrevivência e vigor vegetativo de plantas de erva-mate (<i>Ilex paraguariensis</i> A. St.- Hil.) enxertadas diretamente a campo.

Abstract

RESUMOO presente trabalho objetivou avaliar a sobrevivência e o vigor vegetativo de material genético adulto selecionado de erva-mate (Ilex paraguariensis A.St.-Hil.) enxertado diretamente a campo. A enxertia foi realizada em plantas de aproximadamente 3 anos de idade, sendo o material vegetativo enxertado coletado do terço inferior ou próximo da base de duas árvores selecionadas com a idade estimada em torno de 70 anos. O método de enxertia utilizado foi o de garfagem em fenda cheia, onde foram enxertadas 48 plantas com material de cada uma das duas matrizes. Os dados de sobrevivência foram obtidos aos 60 e 90 dias após a enxertia, e de crescimento (quantidade e comprimento total de brotos por enxerto vivo) aos 90 e 120 dias da enxertia. Pôde-se concluir sobre a enxertia da erva-mate realizada diretamente a campo que: é viável tecnicamente, havendo um decréscimo na sobrevivência das plantas enxertadas em função do número de dias após a enxertia; as matrizes utilizadas apresentaram comportamentos distintos na porcentagem de sobrevivência e; os enxertos sobreviventes demonstraram um bom vigor de crescimento.Palavras-chave: propagação vegetativa; enxertia; Ilex paraguariensis. ABSTRACTThe present work aimed to evaluate the survival and the vegetative vigor of adult selected genetic material of Ilex paraguariensis A.St.-Hil. grafted directly in the field. The grafting was accomplished in approximately 3 year-old understocks, and the material collected was close to the base of two selected trees with around 70 years old. The grafting method used was the top cleft, in which 48 plants were grafted with material of each one of the two plus trees. The survival data were obtained at 60 and 90 days after the grafting, and of growth (amount and total length of sprouts) at 90 and 120 days after the grafting. It could be concluded that: there was a decrease in the survival of the grafts in function of the number of days after the grafting; the used plus trees presented different behaviors in the survival percentage; the surviving grafts plants demonstrated a good growth vigor. It is presupposed that the low percentile of success (about of 40%) is linked to the high physiologic age of the plus trees, besides less favorable environmental conditions when compared with the grafting in the nursery.

Nursery and field serial grafting of Ilex paraguariensis

“…The highest graft survival in the field was observed on the 35 th day for clone F1, on the 75 th day for F3, and on the 105 th day for F1, F3, M1, and M3. In a similar way to experiment 1, varying results were found among clones, and that corroborates previous results for yerba mate (Domingos & Wendling, 2006;Brondani et al, 2008;Wendling et al, 2009). In this study, on the 105 th day after grafting, besides clone factor having been observed to influence graft survival, a superiority trend was observed for the field environment for this variable, and that fact runs contrary to the one found by Niklas (1990), whose nursery grafts were observed to be more successful than the field ones.…”

“…Upon comparing the subcultures in each clone at the 105 th day, the survival of grafts from clone 1 was higher in subcultures I and II; for clone 2, however, it was only superior in subculture II. While conducting field grafting with propagules from yerba mate parent trees of approximately 70 years old, Domingos & Wendling (2006) found a survival rate of over 56% (first subculture) at the 90 th day after grafting, which was similar to the result obtained in this study.…”

“…Both rootstocks and scions were fastened together with a plastic ribbon. Afterwards, the grafted region was wrapped with a plastic bag and then a parchment paper bag ( Figure 1C), respectively in order to keep the humidity in the location and to protect grafts from sunrays (Wendling et al, 2004;Domingos & Wendling, 2006). Around 25 days after that, little holes were punched in the paper and plastic bags for acclimatization purposes -bags were taken off after 35 days after grafting, when rootstocks and scions had already inosculated ( Figure 1D).…”

“…In most studies analyzing yerba mate grafting, the aim is to obtain higher percentages of living grafts, which a high number of strong and healthy buds (Niklas, 1990;Wendling et al, 2004Wendling et al, , 2009Domingos & Wendling, 2006). Thus, grafts need to have a high percentage of buds taller than 1 cm in the shortest time following grafting.…”

“…Vegetative propagation is influenced by several factors, among which species, climate, and physiological conditions of parent trees (Eldridge et al, 1994;Xavier et al, 2013). For yerba mate, especially, variation of vegetative propagation ability among different individuals is high (Prat Kricun et al, 1986;Tavares et al, 1992;Domingos & Wendling, 2006). This makes the execution of studies important, to investigate factors related to parent trees, rejuvenation, and grafting environment for this species.…”