ROOTSTOCK AGE AND GROWTH HABIT INFLUENCE TOP GRAFTING IN Araucaria angustifolia

Abstract

ABSTRACT:The objective of this study was to evaluate the technical viability and influence of the rootstock age and grafts growth habit on Araucaria angustifolia top grafting. Two rootstocks (8 and 35-year-old) were grafted with grafts originating from two growth habits (orthotropic and plagiotropic). We used the patch grafting technique in the middle and upper third of the crown of 8-year-old trees, and in the middle and lower third of 35-year-old trees, always near the apex in primary branches. The experiments were performed during the fall and spring/2015. The treatments consisted of: 8-year-old rootstocks and orthotropic grafts; 8-year-old rootstocks and plagiotropic grafts; 35-yearold rootstocks and plagiotropic grafts; 35-year-old rootstocks and orthotropic grafts. We evaluated graft survival throughout the experiment and at 16 months, we evaluated their survival, emission, and number and average length of sprouts. Top grafting is technically feasible for araucaria, with better results using younger rootstocks (8-year-old), especially with plagiotropic propagules and grafting in fall/2015 (71.9%). Growth habits of the grafts are maintained identically as original, independently of rootstock growth habit. IDADE DO PORTA-ENXERTO E HÁBITO DE CRESCIMENTO INFLUENCIAM NA ENXERTIA DE COPA EM Araucaria angustifolia RESUMO:O presente trabalho objetivou avaliar a viabilidade técnica e a influência da idade do porta-enxerto e do hábito de crescimento na enxertia de copa em Araucaria angustifolia. Foram utilizados porta-enxertos de duas idades (8 e 35 anos), com enxertos originários de dois hábitos de crescimento (ortotrópicos e plagiotrópicos). A enxertia foi realizada por borbulhia de placa, no terço médio e superior da copa das árvores de 8 anos e no terço médio e inferior das árvores de 35 anos, sempre próximo ao ápice em ramos primários. Os experimentos foram instalados em duas épocas, no outono e na primavera de 2015. Os tratamentos consistiram de: Porta enxertos com 8 anos de idade e enxertos ortotrópicos; Porta enxertos com 8 anos de idade e enxertos plagiotrópicos; Porta enxertos com 35 anos de idade e enxertos plagiotrópicos; Porta enxertos com 35 anos de idade e enxertos ortotrópicos. Foram avaliadas a sobrevivência dos enxertos ao longo do experimento e aos 16 meses, sua sobrevivência, a emissão, número e comprimento médio de brotações. A enxertia de copa é viável tecnicamente para araucária. O uso de porta-enxertos mais jovens (8 anos) é favorável a sobrevivência dos enxertos, especialmente quando da utilização de propágulos plagiotrópicos e enxertia realizada no outono (71,9%

Some Factors Involved in the Success of Side Veneer Grafting of Pinus engelmannii Carr.

“…Relatively low survival results, after six months of grafting, were obtained for both phenological stages (Table 7). However, some authors have indicated that the season influences the success of grafting [7][8][9]. In a study of grafts of Pinus patula Schiede ex Schltdl.…”

“…For the grafting of Araucaria angustifolia (Bertol.) Kuntze in Parana, Brazil, in April (i.e., autumn, with scions in the dormant stage) with average temperatures that fluctuated between −3 • C and 18 • C and with a high relative humidity, a survival of 60% was reported at 12 months after grafting [7]. In our study, the survival decreased significantly after the second month of evaluation (March) onwards (Figure 4), which is attributed to the continual fluctuations in temperature (up to 42.59 • C) that were detected, and the low relative humidity that was registered within the greenhouse (38% on average).…”

“…Further, for the grafting of woody species, it is advisable to select scions and rootstocks of the highest possible quality [6]. Some authors indicate that the best time to graft woody species is in the winter, i.e., between December and February in the northern hemisphere [7][8][9]. Nonetheless, it has also been noted in the literature that it is possible to graft conifers at any time of the year, if the temperature and humidity of the site where the grafts are maintained are controlled [10].…”

“…Nonetheless, it has also been noted in the literature that it is possible to graft conifers at any time of the year, if the temperature and humidity of the site where the grafts are maintained are controlled [10]. Several studies of conifers have demonstrated that grafting scions obtained from trees that are younger than 50 years of age increases the success of the grafting [1,7,11]. In addition, the geographical provenance of the scions and rootstocks may influence the success rate of the grafting [12].…”

“…The taxonomic affinity, genetic and anatomical compatibility, phenological status of the scion, vigor, health, age of the scion donor tree, and the characteristics of the rootstocks, as well as the temperature and humidity of the environment where the grafts are made and maintained, are reported as the most influential factors for grafting success [19,[33][34][35][36][37]. However, specific information on these factors and their influence on graft survival in conifers is scarce [1,7,19,35,36].…”