MECHANICAL JOINING OF SCION TO STOCK IN APICAL GRAFTING OF ROSES AND OTHER PLANTS

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1 McFADDEN: APICAL GRAFTING Shear, C. B Responces of tung trees in sand and soil cultures to ratios of ammonium to nitrate nitrogen and levels of potassium and zinc. Amer. Soc. Hort. Sci. 72: Sideris, C. P. and Young, H. Y Effects of nitrogen on growth and ash constituents of Ananas comosus (L.). Plant Phys. 21: Singer, L The physiological response of bahia grass to different forms of nitrogen. M. S. Thesis. U. of Fla. Lib. 13. Tiedjens, V. A Factors affecting assemilation of ammonium and nitrate nitrogen, particularly in tomato and apple. Plant Phys. 9: van der Merwe, A. J Nitrogen nutrition of citrus in the nitrate and ammonium form. Union of S. Afr. Dept. of Ag. Sci. Bull. No MECHANICAL JOINING OF SCION TO STOCK IN APICAL GRAFTING OF ROSES AND OTHER PLANTS S. E. McFadden, Jr. Department of Ornamental Horticulture University of Florida Gainesville Abstract The "Pin-loc" graft joining method, recently submitted by its originator for U. S. Patent, was compared with conventional cleft joining used for cutting grafts of Rosa. The number of suc cessful grafts and later growth of these grafted plants were equal when the two joining methods were compared. Pins made from stainless steel wire and inserted into splice cut stem centers supplied the internal splitting of the pin-loc grafts. These metallic pins, which remained in the grafted plants, caused no apparent injury to growth during the 22 months of this test. Pin-loc grafting is of special interest because the operations involved can be mechanized more easily than formerly used graft fittings. Suit ability of various grafting procedures for mech anization was reviewed with some consideration of designing mechanical grafting tools for gen eral nursery propagation. Introduction Mechanization in large volume production of grafted plants has the potential of making desir able graft combinations less costly and more available from plant propagation centers. In the usual nursery grafting process, a sequence of mechanically different operations can be identified as: (A) cut to form the related graft wound surfaces on both scion (cion) and stock (rootstock), (B) insert and anchor a detached Florida Agricultural Experiment Stations Journal Series No scion on a stock in joining cut surfaces and in matching locations of exposed cambial layers, (C) wrap to stabilize the union and/or to en close graft wound area, (D) shield scion and union area from drying atmospheres and tem perature extremes when total environs are not well regulated. The first operation is the most difficult to perform manually. Operations A and B are assigned to the most skilled grafters and budders available, but a scarcity of these ex perienced workers is often a production limita tion in nurseries that attempt to supply grafted cultivars. Objectives in developing more efficient mechanical grafting tools, at least would be to permit less skilled workers to cut and join scions and stocks, also to speed the training of inex perienced labor for performing grafting opera tions A and B. The general rule that graftage is done en tirely by hand labor already has some exceptions in the production of grafted Vitis, grape vines (1; 5 p. 85). Various mechanized tools have been devised for making uniform graft wound cuts, after which the cut pieces are joined manually. Dormant Vitis stems used for grafting are usually regular, clean, hard, and otherwise un like stems of most plant taxa. The machines devised for making Vitis graft cuts are there fore not likely to be useful in grafting other kinds of plants without changes. For example, stems of Rosa are shredded by the same elec trically driven circular saw blades that cut a neat series of tongues and grooves in Vitis stem ends for a mortice and tenon joining of scion to stock (1). The apical position of scions in production of mechanically grafted grape vines is of interest as a model of procedure. Apical grafting, in which a stem section scion is joined to the term inal cut on a decapitated stock, appears more easily adapted for mechanical handling than

2 408 FLORIDA STATE HORTICULTURAL SOCIETY, 1969 side grafting, in which a single bud or a larger scion is joined to a non-terminal cut on a stock. The current exploration of mechanized grafting possibilities was restricted to procedures using apical scions, but a later exploration may well be directed toward mechanized attachment of scions in non-terminal, intercallary positions on stocks. In addition to use with cutting grafts of Vitis, the apical scion position has proved usable in cutting grafts of Rosa (1) and five other genera of woody plants (16). Side grafting procedures have been preferred in producing cutting grafts of Juniperus (4,9,18), and with certain kinds of rooted-stock graft combinations (12,10,15,2). Certain other guidelines and limitations are foreseen in developing a mechanized grafting technique for general nursery plant production. Using stocks and scions that are nearly equal in shape and size at the point of grafting, may be a requirement if operations B and C are included in the mechanization. Simple, one plane cut surfaces, as in splice grafting or end to end (abut) grafting, appear to be the easiest cuts to form mechanically as well as manually. Current choice of the splice graft cut was based on the number of successful unions formed in preliminary comparisons with end to end and with cone shaped graft fittings, each of which could be made with self-sharpen ing cutters. Stocks used in bench grafting of different plant taxa are supplied to the grafter in various forms or stages of growth. Those that may be suitable for mechanical handling include the following: (a) greenwood or leafy, unrooted stem sections for cutting grafts; (b) hardwood or dormant, unrooted stem sections for cutting grafts; (c) single root sections for piece root grafts, (d) plants growing in easy to move con tainers; (e) whole, bareroot plants. Each of these forms of stock are associated with bench grafting of particular plants: (a) dwarf citrus and other taxa (6,7,16,11); (b) grapes on pest resistant stock (8) ; (c) Double flowered cultivars of Gypsophylla (5 p. 202); (d) florist azaleas (14) ; (e) nut bearing trees in colder regions (13). Forms a and b are especially suit able for mechanical handling, because the stock units can be made more uniform in shape than c, d or e, and are lighter in weight than d or e. Current interest in rooting grafted cuttings as standard nursery procedure, is stimulated by continuing improvements in facilities for con trolling temperature, moisture and light and in techniques of vegetative propagation (17). Cut tings grafts are not new; grafting of Vitis and of Aucuba on unrooted stock cuttings were prac tices of the past century (3). Halma's "twig grafting" of citrus in 1926 (6, 7) supplied a more recent model for apical grafts on leafy, unrooted cuttings. Literature on apical cutting grafts of Citrus, Avocado, Camellia, Hibiscus and Macadamia, , was reviewed by Ryan et al (16), who concluded from tests with these materials that the scion has no influence on the root forming capacity of the stock cut tings. With cutting grafts of Rosa, at least one leaf left intact on the stock cutting is needed for satisfactory rooting of R. fortuniana stock cuttings (11) ; intact leaves are also needed with other rose rootstock when cuttings are taken from actively growing mother plants. The graft joining method suggested by Halma for citrus twig grafts was the whip-and-tongue (7). In California nursery production of dwarf citrus, this method was changed to an elongated splice, with a rubber band wrap stabilizing the union area.* In Florida nursery production of roses the cleft graft joining is used with pres sure sensitive adhesive tape wrap, since the 2- leaf rose scions are heavier and less well bal anced than the short branch tip scions used for citrus cutting grafts.** The "Pin-loc" method of internally splinting graft unions was included in preliminary com parisons of grafting techniques with permission of its originator.*** This method, devised by Robert Hyde in 1966, appeared to resolve prob lems associated with supporting a relatively heavy scion on a stock terminal, when uniting simple cut surfaces as in splice graft joining. In pin-loc joining of grafts, a small coupling pin or bar-pointed at both ends is inserted into the exposed pith center of the scion cut surface for half its length, the remaining length being similarly pressed into the stock. The pin be comes surrounded by the graft union and remains inside the grafted plant. In this experiment, pin-loc cutting grafts of Rosa were assembled by hand labor along with conventional cleft cutting grafts of Rosa, to compare survival and later *Don Dillon; Four Winds Nursery; Fremont, California. **Earl Nelson ; Nelsons Florida Roses ; Apopka, Florida. ***U. S. Patent applied for by Robert Hyde; Hyde Engineering-; Crystal River. Florida.

3 McFADDEN: APICAL GRAFTING 409 growth resulting from these two selected methods. Methods and Materials In the propagation phase of this experiment, cutting grafts joined by the 2 treatment meth ods were prepared December 1, Experi mental units of 6 cutting grafts were assigned to random locations in each of 3 blocks within a greenhouse supplied with intermitent mist dur ing daylight hours. Leafy scions used were taken from greenhouse grown specimens of the florist rose 'Forever Yours.' Leafy Rosa fortuniana stocks were also taken from frost protected mother plants. A 2-leaf stem section from a ma ture flowering stem served as the apical scion. Similar diameter stock cuttings consisted of ca. 4-inch length stem sections with at least one intact leaf, but having leaves and buds removed at the base to reduce later suckering. The 2 treatment differences consisted of the splice pin-loc and the conventional cleft graft methods of joining the basal end of the scion cutting to the distal end of the stock cutting. The splice pin-loc pieces were cut with a 60 slope and joined with a 1-inch length pin cut from a roll of stainless steel wire,.022 inch guage. A pressure sensitive adhesive tape wrapping was placed around the graft union area and in contact with the outer bark cylinder of the joined stems. This wrap consisted of a single layer thickness of the tape, with ends pressed together to form a tab on one side of the union area. Scotch brand polyester film tape No. 850 in 1-inch width was used. The base of each cutting graft was placed in a 2 % -inch plastic pot filled with a 3:3:2 vol./ vol. mix of sphagnum peat moss, horticultural perlite, and calcined (baked) clay. No growth regulators or fungicidal treatments were applied in preparation of graft pieces used in this experiment. The grafted cuttings were kept under mist for 35 days, then removed to shaded benches with twice daily hand watering January 5, At this time, root development and scion condition were rated, each on a graduated scale ranging from 1-dead to 7-superior; a root rating of 4 represented basal wound callus and few root initials present, and a scion rating of 4 repre sented one leaf remained intact and up to 1-inch length new shoot development. On January 25, 1968 those successfully rooted and grafted were placed in their permanent location, at intervals of 2 feet in a single row ground bed planting with a plastic film green house. Survival was recorded February 22, In the later growth phase of this test, the experimental unit consisted of 4 grafted plants per treatment assigned to each of 3 blocks. The hill locations of the 2 treatments were alter nated in the linear row planting. Maintenance of the plants included the type of continual pruning associated with harvesting of cut flowers. Measurements made October 6, 1969 of the top growth development consisted of first: an index derived from measures of the plants maximum height added to it's maximum width and the total divided by 2, and second: a caliper measurement made 1-inch below the graft union, supplying the stock shank diameter. Results A summary of the data obtained is shown in Table 1. An analysis of variance was performed on each of the 4 growth measurements made January 1968 and October These analyses showed no significant differences due to treat ment. A loss of about one third of the cutting grafts occurred during the first 3 months after graft ing, but no further losses occurred after this period. A stem dieback, progressing from one or more of the cutting wound surfaces, was in volved in most of these failures. Progress of this dieback was especially rapid in misting phase. Six samples of necrotic stems were examined in Division of Plant Industry laboratories. Wound infection with spores of the stem canker fungus Leptosphaeria coniothyrium was identified as the main cause of the dieback. Discussion The equal rank of the experimental plants in their propagation phase and in their second year growth, indicates that the two graft joining treatments can safely be interchanged. The cleft' graft joining of cutting grafts on Rosa fortuniana stocks can be replaced by the pin-loc graft joining method. There would be little reason for such a substitution of methods in any plant grafting enterprise, if the pin-loc grafts were to be assembled entirely by hand labor instead of by machines. The pins can be made shorter

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5 MAROUSKY: GLADIOLUS PRE-TREATMENTS Kalma, F. F The propagation on citrus by cuttings. Hilgardia 6 (5) : Jacob, H. E Vineyard planting stock. Cali fornia Agric. Exper. Sta. Circ Keen, R. A Cutting-grafts of juniper. Proc. Amer. Soc. Hort. Soc. 58: McFadden, S. E Production of tree roses on Rosa fortuniana stock. Proc. Fla. St. Hort. Soc. 72: McFadden, S. E Grafting leafy stem cuttings, a technique for propagating roses. Proc. Fla. St. Hort. Soc. 76: Nelson, R., S. Goldweber, and F. J. Fuches Top-working for mangos. Fla. Gr. and Rancher 63 (1) : Pieniazek, S. A Autumn grafting of walnuts. Amer. Nurseryman 128 (1): Potter, C. H Greenhouse propagation. Flor ists' Review 138 (3563) : Potter, C. H Azaleas do grow on trees. Florists' Review 142 (3681) : Ryan, G. F., E. F. Frolich, and T. P. Kinsella Some factors influencing rooting of grafted cuttings. Proc. Amer. Soc. Hort. Sci. 72: Stoutemyer, V. T Propagation by seedage and grafting under fluorescent lamps. Proc. Amer. Soc. Hort. Sci. 62: Westeryelt, D. D. and R. A. Keen Cutting grafts of junipers II. Proc. Amer. Soc. Hort. Sci. 76: CONDITIONING GLADIOLUS SPIKES TO MAINTENANCE OF FRESH WEIGHT WITH PRE-TREATMENTS OF 8-HYDROXYQUINOLINE CITRATE PLUS SUCROSE F. J. MAROUSKY Market Quality Research Division U. S. Department of Agriculture Gulf Coast Experiment Station Bradenton Abstract Attempts were made to condition gladiolus spikes to maintain fresh weight and quality dur ing subsequent vase-life. Spikes were conditioned in water or solutions of 1,000, 5,000 or 10,000 ppm 8-hydroxyquinoline citrate (8-HQC) with or without 4% sucrose for 24 hours. Spikes con ditioned in 1,000 ppm 8-HQC plus 4% for 24 hours weighed more after 4 days of vase life than spikes conditioned in water or 8-HQC alone. Spikes conditioned with 8-HQC plus sucrose were turgid after 4 days of vase life while spikes conditioned with water showed incipient wilting. Spikes conditioned for 24 hours in 8-HQC+ sucrose weighed more after 4 days of vase life than spikes conditioned for 2 or 6 hours. Spikes conditioned in 8-HQC at 110 F weighed more after 4 days of vase life than spikes conditioned at 74op. Spikes conditioned in 1,000 ppm 8-HQC-f sucrose for 24 hours then held for 3 additional days in water did not weigh as much or have as good floret quality as spikes held continuously for 4 days in 600 ppm 8-HQC+4% sucrose. Spikes conditioned in 8-HQC+sucrose had greater fresh weight than spikes conditioned in water but simulated shipping tests negated con ditioning effect from 8-HQC + sucrose. Introduction Most of the work showing that floral pre servatives benefit vase-life and quality of cut flowers has been shown in the retail floral shop or consumers home. Little information is avail able on post-harvest handling of cut-flowers by flower grower and the subsequent influence of handling on vase-life. Waters (12) found that storage temperatures and packaging methods exerted a major effect on gladiolus spike quality. Moisture proof wrappings were superior to paper containers. Spike keeping quality de creased as storage temperature increased from 35 to 80 F. This work agrees with other pub lished information (4). Although little work has been published on handling gladiolus, other cut-flowers have been studied extensively. Parvin and Krone (10) found that hardening immediately after harvest added approximately 1 day to the total life of cut roses, regardless of whether flowers were in water or preservative. They also suggested that growers, wholesalers, and retail florists use preservatives to prolong rose usefulness to the consumer. Mastalerz (9) also stressed that growers and wholesale florists should use pre servatives for maximum flower life. He demon strated that maximum carnation vase-life was attained when flowers were held continuously in floral preservatives (8). Waters (11) held chrysanthemum flowers in commercial preserva tives for 12 and 24 hours, stored the flowers in commercial packages for 3 days at 40 F and replaced flowers in preservative solution or wa-