Resumo A produção de mudas enxertadas demanda maior período de tempo. A técnica da minigarfagem sobre porta-enxertos obtidos previamente por estaquia herbácea pode garantir a fidelidade genética da copa e do porta-enxerto e possibilitar a enxertia em caules de menor diâmetro, antecipando o período de obtenção dessas mudas. O objetivo deste trabalho foi a antecipação da formação da muda da goiabeira ‘Paluma’ enxertada sobre porta-enxertos clonais com caules de menor diâmetro. Os tratamentos foram constituídos pela enxertia sobre porta-enxertos com cinco classes de diâmetros do caule. O delineamento experimental adotado foi em blocos casualizados, com três repetições e cinco mudas por parcela. Os porta-enxertos foram produzidos por estaquia de ramos herbáceos de matrizes oriundas de cruzamento entre P. guineense x P. cattleianum. Os minigarfos foram obtidos de um minijardim clonal da goiabeira ‘Paluma’. Mudas enxertadas sobre porta-enxertos com diâmetros de caule entre 3,7 e 10,3 mm tiveram a mesma taxa de pegamento de enxertia; entretanto, o maior vigor das mudas foi observado quando estas foram enxertadas sobre porta-enxertos de maior calibre. O pegamento de enxertia e a altura das mudas indicam que a minigarfagem sobre porta-enxertos clonais, com diâmetros entre 3,7 e 5,5 mm, permite a produção de mudas aptas ao transplantio, aos 300 dias após o estaqueamento.

Abstract The production of grafted seedlings requires longer periods of time. The technique of mini-grafting onto rootstocks previously obtained from herbaceous cuttings can guarantee the genetic fidelity of scion and rootstock and allows grafting onto smaller-diameter stems, accelerating the time required to obtain seedlings. The aim of this study was to anticipate the formation of ‘Paluma’ guava seedlings grafted onto clonal rootstocks with smaller-diameter stems. Treatments consisted of grafting onto rootstocks with five stem diameter classes. The experimental design was randomised blocks with three replicates and five seedlings per plot. Rootstocks were produced from cuttings of herbaceous branches of mother plants originating from crossing between P. guineense and P. cattleianum. Mini-grafts were obtained from a clonal ‘Paluma’ guava mini-garden . Seedlings grafted onto rootstocks with stem diameters from 3.7 to 10.3 mm presented the same success rate however the greatest seedling vigour was observed when grafted onto larger-diameter rootstocks. Grafting success and seedling height show that mini-grafting onto clonal rootstocks with diameters from 3.7 to 5.5 mm allows producing seedlings suitable for transplanting 300 days after cutting.

RESUMO Porta-enxertos para goiabeira podem ser multiplicados por miniestaquia em ambiente com alta umidade relativa, sendo necessário um período para aclimatação. Alguns reguladores de crescimento favorecem a aclimatação, sendo os brassinosteroides utilizados com sucesso em outras frutíferas. Objetivou-se reduzir o tempo de multiplicação do híbrido BRS Guaraçá com aplicações de Biobras-16 (BB-16) na fase de aclimatação de mudas obtidas por miniestaquia. Os tratamentos consistiram de cinco concentrações de BB-16 (0; 0,1; 0,3; 0,5; e 1,0 mg L-1), aplicadas em delineamento experimental com blocos casualizados, em esquema de parcelas subdivididas, com quatro repetições e cinco mudas por parcela, repetidos em duas épocas do ano: inverno e primavera/verão. Ao final de sessenta dias de aclimatação, indicadores de crescimento da parte aérea e raízes tiveram incrementos em função da aplicação de BB-16, notadamente nas concentrações entre 0,3 e 0,6 mg L-1. O brassinosteroide pode ser utilizado para estimular o crescimento de mudas de BRS Guaraçá oriundas de miniestaquia, reduzindo o seu tempo de produção e incrementando sua qualidade.

ABSTRACT Guava rootstocks can be multiplied by minicuttings in environment with a high relative humidity, being necessary an acclimatization period. Certain growth regulators favor the acclimatization, with brassinosteroids being successfully used in other fruit plants. This study aimed to shorten the multiplication time of the BRS Guaraçá hybrid by applying Biobras-16 (BB-16) during the acclimatization of seedlings obtained from minicuttings. The treatments consisted of five BB-16 concentrations (0, 0.1, 0.3, 0.5 and 1.0 mg L-1), applied in a randomized block design, in a split-plot arrangement, with four replications and five seedlings per plot, repeated at two seasons: winter and spring/summer. After 60 days of acclimatization, shoot and root growth indicators increased as a function of the BB-16 application, particularly at concentrations between 0.3 and 0.6 mg L-1. The brassinosteroid can be used to stimulate the growth of BRS Guaraçá seedlings obtained from minicuttings, shortening its production time and improving its seedling quality.

ABSTRACT Cattley guava (Psidium catteyanum Sabine) is a widespread native plant species of South America and constitutes important genetic resources for the improvement of guava trees. Fruits of these species are consumed by wild animals and extracted by local human populations. However, the vegetative propagation of adult plants, which is necessary for fixing desired characteristics, has been inefficient. The objective of this work was to evaluate the rescue of adult plants of P. cattleyanum by herbaceous and semi-hardwood cuttings for the establishment of clonal mini-gardens and to evaluate the rooting potential of mini-cuttings of different genotypes. The experimental design was completely randomized in a factorial scheme with the treatments being different propagule or propagation techniques (herbaceous and semi-hardwood cuttings from mother plants cultivated in the field and by mini-cuttings), with five repetitions and six propagules per plot. The potential for multiplication by the mini-cutting technique and plant vigor were evaluated for 20 genotypes of cattley guava during three seasons of the year (autumn, winter and summer). The use of semi-hardwood cuttings is feasible for the rescue of adult plants and the establishment of clonal mini-gardens. The mini-cutting technique provided the highest rooting percentage, and was most efficient in summer. The genotypes evaluated varied in rooting percentage and plant vigor.