Grafting in Herbaceous Stems

By B. JOHN SYROCKI Downloaded from http://online.ucpress.edu/abt/article-pdf/33/9/532/28824/4443693.pdf by guest on 24 September 2021

D emonstrate grafting in stems in three weeks? Yes, this can be done, using herbaceous stems. This article tells how biology students can set up successful grafting demonstrations, using cherry tomato plants. Compatible herbaceous plant tissues grow together quickly, whereas grafting in woody stems just takes too long. Grafting as a method of plant propagation is an important commercial practice. Woody plants have been grafted by orchardists for many years. Graft- ing in herbaceous stems can illustrate the fusion of compatible tissues-a concept of great importance to nurserymen, orchardists, and laboratory research- ers. The quest is for increasing the number of plants in a short time by using stem cuttings of grown plants, locating and using vigorous rootstock, yield- ing plants with greater resistance to disease, and stimulating or retarding growth and development in plants by using rootstocks of different plant species. Materials You will need four or more cherry tomato seedlings or a package of seeds; a razor blade; transparent tape; a stick to support the grafted plant; a clay pot about 15 cm in diameter; and plastic pots, if you are growing your own seedlings. Plants can be grown easily from seeds, if they are Fig. 1. Two tomato plants removed from the plastic pots. Note needed during the winter months; or you can pur- that the plants are of equal height and stem diameter. chase seedlings, which in most places become avail- able in May. It will take about eight weeks to grow Be sure that both main stems are of equal diameter your own plants to the size recommended for this to permit alignment of vascular tissues (fig. 1). experiment. Plants should be about 25 cm tall, with a stem diameter of 0.5 cm. Avoid using full-grown Preparing the Stems plants: their stems are knotted and difficult to cut. I tried several accepted wood-grafting techniques

532 THE AMERICANBIOLOGY TEACHER, DECEMBER 1971 Downloaded from http://online.ucpress.edu/abt/article-pdf/33/9/532/28824/4443693.pdf by guest on 24 September 2021

Fig. 3. The scion plant (right) and the incised rootstock plant (left).

Fig. 2. The rootstock plant is incised at a height of 10 cm. in the classroom, but without consistent success. These included the V-graft as well as the tongue grafts. The most successful technique was a modi- fication of the approach-graft technique suggested by J. Weibe, of the Horticultural Experimental Sta- tion, Vineland Station, Ontario, Canada. The rootstock plant is cut about 10 cm above the soil (fig. 2). Note that the rootstock plant is cut only to the degree that will enable the other plant to fit into the stem. Do not cut so far across the stem

B. John Syrocki is professor of biology, State University of New York, College at Brockport 14420, where he has taught for F 7 22 years; presently he is coordinator of general botany and is much interested in individualized instruction. He is an author - of the series "Science for a Changing - World" (1967: Benefic Press, Chicago); of a book, Science Activitiea for Children (1968: Prentice-Hall, Inc., Englewood Cliffs, NJ.); and of numerous articles and documentary science-books. He has been a fellow of the American Association for the Advance- ment of Science, a field reader for the curriculum and research branches of the US. Office of Education, and science consultant to Grade Teacher magazine. His research interests Fig. 4. Diagramshowing method of cutting stems for greatest lie in plant anatomy and plant nutrition (hydroponics). supportof bothwhen they are grafted.

GRAFTINGIN HERBACEOUSSTEMS 533 ow, Downloaded from http://online.ucpress.edu/abt/article-pdf/33/9/532/28824/4443693.pdf by guest on 24 September 2021

Fig. 5. Rootstock plant (below) and scion plant (above) cut Fig. 6. Mature plant resulting from the graft. to make one stem. graft, thereby making the roots of this plant serve as to weaken the entire stem. The scion plant is cut the entire new growth, including the scion. Fig. 5 so that its stem can be fitted to the rootstock plant shows how this is accomplished. The tape may be to make close contact with the vascular tissues. removed from the graft at this time. Notice the cut in the scion plant in fig. 3. This kind Check to see that the stem is held to the stick in of cut in the stems of both plants worked well, but the pot. It may be necessary to rearrange the at- the plants were weakened for further handling. In tachment of the final plant to the stick. subsequent grafting, the stem of the rootstock and of the scion plant was cut as shown in fig. 4. Discussion The explanation of successful fusion of the tissues Operations on the Scion of two plants lies in the compatibility of vascular Insert the scion into the rootstock stem by slant- tissues. Several stem-cuttings of one plant may be ing both stems toward each other. Secure the scion grafted to plant stems that have strong rootstocks with transparent tape; three turns of tape is suffi- but may be inferior in vegetative and reproductive cient. The graft can be seen through the tape as the capacity. experiment continues. The second overlapping cut tends to bring more Put both plants into the large clay pot, fill around vascular tissue into contact to insure stronger fusion. with soil, and pack the soil firmly. Insert the support This growth is effected in the same length of time stick into the soil and secure the stems of both plants as the single-cut type. An additional advantage is to the stick. After two weeks there should be evi- the stronger graft union: the plant is less likely to dence of fusion of the stems. break at the point of junction in further handling. After three weeks, cut off the scion plant from This experimental graft resulted in normal plant its parent stock. This cuts off the scion from its root growth. The plant flowered and produced fruit in system. Now cut off the rootstock plant above the the usual abundance (fig. 6).

534 THE AMERICANBIOLOGY TEACHER, DECEMBER 1971