Development of a Procedure to Maximize Production of Hardy Rootstocks of Citrus Using Stem Cuttings

Abstract

Shoots of Citrus sp. Kuharske were used to develop protocols for rooting reportedly HLB resistance rootstocks under intermittent mist. Investigated were shoot maturity, nodes per cutting, leaves per cutting, effects of buds, auxin concentrations and auxin solvent. Shoot maturity was most influential for success, with cuttings taken below the first 30 cm of active terminal growth producing greater root generation. Use of a thickening agent (Natrosal) to dilute the commercial auxin was second most in importance for rooting success. Root mass increased with increasing number of leaves. Cutting stems between nodes or below the lowest bud were inconsequential. To produce maximum number of viable cuttings, single node-single leaf cuttings were preferred. Single bud cuttings produced one shoot after rooting. This was adventitious since multi-node cuttings usually sprouted new shoots that would need to be removed before budded. Evaluation of the best combination of auxin and cutting-related attributes were evaluated with four additional common rootstocks in June 2016. Rooting was 100% successful. A quick dip (0.5 s) in a 7500 ppm solution of Dip&Gro produced the most root generation in six weeks for all rootstocks. Root quantity varied by rootstock.

Propagation of Citrus Rootstock Cuttings Success Depends on Season

“…On 6 th May 2015, 60 single node/ single leaf and bud cuttings were made from mature stems of the widely used and seed produced Kuharske rootstock [15]. Half of the cuttings were treated with 4000 ppm Dip&Gro (Dip&Gro, Clackamas, OR), the rest treated with 7500 ppm Dip&Gro.…”

“…To evaluate the strength of these chimeras for resistance to HLB and perhaps other diseases, they first have to be propagated, and then propagated in quantities to allow sufficient evaluations. In a previous study in late spring 2005, the effects of stem maturity, diluent and auxin concentrations on rooting success were evaluated [15]. To produce the most rooted cuttings quickly, researchers used single node, single bud cuttings.…”

“…To produce the most rooted cuttings quickly, researchers used single node, single bud cuttings. While small in both shoot and root size, single node cuttings allowed for the greatest number of cuttings to be produced and later reduced the extra labor of removing elongating shoots originated from extra buds of multi-bud cuttings [15]. While some citrus rootstocks have been produced by tissue culture in abundant quantities, it takes time to develop protocols and sufficient size to warrant inclusion in variety trial testing.…”

“…While some citrus rootstocks have been produced by tissue culture in abundant quantities, it takes time to develop protocols and sufficient size to warrant inclusion in variety trial testing. Producing rootstocks by cuttings is much more rapid and can deliver liners ready to bud much sooner, which would accelerate the selection of viable combinations of rootstock and scion [15].…”

Advances in citrus propagation in Brazil

“…derived from juvenile material can be used to obtain rootstocks for the production of grafted trees or be used for inarching in the field (MOURÃO FILHO et al, 2009). Recently, procedures to increase propagation of rootstocks by root cuttings have been evaluated in Florida and found to propagate seedless materials or those with low seed counts, and to accelerate the production of certain rootstocks and budwood for nurseries SILVA, 2017a;.…”