Forcing Treatment and Rootstock Affect Budbreak and Growth of Containerized Citrus Nursery Trees

Abstract

<jats:p>Two experiments were conducted to determine the effects of rootstock and bud-forcing treatment on scion budbreak and nursery tree growth of `Hamlin' orange. In Expt. 1, `Carrizo' citrange, `Swingle' citrumelo, and `Cleopatra' mandarin were budded with `Hamlin' orange and forced by one of the following methods: cutting off (purning away the rootstock top about 2 cm above the inserted scion bud); lopping (cutting half to two-thirds of the way through the rootstock stem 2 cm above the bud union, and breaking over the stem but leaving it attached); or bending (bending the rootstock shoot above the inserted scion bud and tying it to the base of the plant). For `Swingle' only, percent budbreak was less for bending or lopping compared to cutting off. For `Carrizo' and `Swingle', scion dry weights were less when plants were forced by cutting off compared to bending or lopping. For all rootstocks, whole-plant dry weights were greater for plants forced by bending and lopping than for plants forced by cutting off. In Expt. 2, scion buds on `Swingle' and `Cleopatra' plants were forced by the three methods in Expt. 1 plus combinations of bending with notching (making an inverted V incision through the bark and into the wood on the rootstock stem directly above the scion bud) and/or topping (removing the teminal 2 cm of rootstock shoot tips of plants forced by bending). Percent scion budbreak was high for `Cleopatra' plants regardless of forcing treatment. For `Swingle', scion budbreak was greater when bending was combined with notching than for bending alone. For `Cleopatra', plant dry weight was greatest for plants forced by lopping. When bending was combined with notching, or notching with topping, `Swingle' scion budbreak was comparable to cutting off, but plant dry weights were greater with these combination treatments than when cutting off was used.</jats:p>

Comparison of Two Citrus Bud-forcing Methods for Rapid Propagation of Scions on New Hybrid Citrumelo Rootstocks

“…Statistical comparisons were conducted only on data for all 19 rootstocks combined. citrumelo, while cutting was much more effective (Williamson and Maust, 1996). This is an economically important issue as nearly 5 million citrus trees are propagated on 'Swingle' citrumelo each year in Florida, and the finished nursery trees have a typical value of $3 to $4 each.…”

“…Previous comparisons of citrus bud forcing have focused on four rootstocks: sour orange (Rouse, 1988), 'Cleopatra' Maust, 1993, 1996), 'Carrizo' citrange (Williamson and Maust, 1996;Williamson et al, 1992), and 'Swingle' citrumelo (Williamson and Maust, 1993;1996). However, Williamson and Maust (1996) found some significant and important differences between rootstocks in forcing behavior. This study expands the number of rootstocks that have been evaluated for forcing behavior from four to 21.…”

“…x Poncirus trifoliata (L.) Raf.] rootstock (Williamson and Maust, 1996). This can present serious problems in producing a specified number of field-ready grafted trees on a predetermined time schedule.…”

“…This can present serious problems in producing a specified number of field-ready grafted trees on a predetermined time schedule. The only previously published study that compared budbreak from bending vs. cutting treatments on 'Swingle' citrumelo rootstock (the most common type of citrus rootstock used in Florida) indicated that the low percentage and slower budbreak obtained following bending made it "unacceptable" for 'Swingle' citrumelo (Williamson and Maust, 1996). Commercial nurseries in Florida often use different methods (bending, lopping, or cutting off) depending on their experience with each particular for each scion by analysis of variance using Statistica ver.…”

Métodos de forçamento de borbulhas e aplicação de cianamida hidrogenada para produção de mudas de laranja 'Valência' sobre citrumelo 'Swingle' em viveiro telado

“…Nos últimos anos, tem ocorrido um grande interesse no citrumelo 'Swingle' (Citrus paradisi Macf x P. trifoliata Raf) para produção de mudas cítricas no Estado de São Paulo, com aumento de 20% no número de mudas produzidas sobre este porta-enxerto no período de 1999 e 2003 (Pompeu Júnior et al, 2004). Comportamento semelhante foi observado no Estado da Flórida-EUA, entre os anos de 1983 e 1993, tendo esta variedade um crescimento de 15% para 51%, considerando todas as outras variedades utilizadas (Williamson & Maust, 1996). Dentre as características vantajosas desse porta-enxerto, destacam-se a excelente qualidade de frutos induzida à copa e, nas condições brasileiras, sua resistência à morte súbita dos citros (MSC), doença de causa ainda não determinada (Barbasso, 2005;Gimenes-Fernandes et al, 2001;Pompeu Júnior, 1999).…”