128 AMERICAN POTATO JOURNAL [Vol. 43

H O W TO O B T A I N T H E M O S T P L A N T S F R O M O N E P O T A T O T U B E R 1

R. W. BUCK, JR. AND R. V. AKELEY 2

It is often advantageous for the potato breeder or pathologist to obtain a large number of plants from a single potato tuber.

A test was run to determine whether a larger number of plants could be obtained from a single potato tuber than by the conventional method of seed cutting. In this test, two groups of four tubers each of Kennebec, Penobscot, Katahdin, and Kasota varieties, weighing ap- proximately 8 ounces each were used. Tubers for the test were harvested in September 1964 at Presque Isle, Maine. They were shipped to Belts- ville, Maryland, and placed in storage at 40 F in October. The tubers were removed from storage on February 6, 1965. In one group the tubers were left whole. In the other group each tuber was cut into four pieces. The whole tubers and the cut pieces were then green-sprouted under day- light conditions in the greenhouse (Fig. 1). The temperature in the greenhouse was maintained at 50 to 55 F at night and at 60 to 65 F during the day. After green-sprouting for 6 weeks, the sprouts were removed from the tubers and seed pieces and cut into sections having either a lateral or terminal bud. These were planted in the greenhouse. Plants were counted approximately 1 month later. Fig. 2 shows the 20 plants from 21 buds from a whole tuber of the variety Kasota.

Table 1 shows the mean number of buds per tuber and the mean number of plants per tuber obtained from the four varieties in the two treatments. The cut-tuber group yielded a mean of 31.2 plants per tuber. This is significantly greater than the 20.2 plants per tuber yielded by the whole-tuber group. Kennebec and Penobscot produced a significantly greater number of plants than Katahdin and Kasota.

TABLE 1.--Buds and plants obtained from green-sprouted whole and cut tubers of potato.

Variety

Kennebec ...... Penobscot ..... Katahdin ....... Kasota ...........

Whole tuber group

Plants whole Buds Plants tuber

pertuber pertuber group Mean M e a n Mean

22.0 18.5 33.8 28.8 26.8 13.8 21.0 19.8

20.2

Cut tuber group

Plants cut Buds Plants tuber

per tuber per tuber group Mean M e a n Mean

42.8 36.2 35.5 34.2 33.5 28.0 27.5 26.2

31.2

Plants per variety

Mean

27.4 31.5 20.9 23.0

XAccepted for publication November 28, 1965. 2Plant Geneticist and Horticulturist, respectively, Crops Research Division, Agri- cultural Research Service, United States Department of Agriculture, Beltsville, Maryland.

1966] BUCK AND AKELEY: PLANTS PER TUBER 129

FIG. 1.--Tuber of potato variety Kennebec after green-sprouting, showing clusters of buds.

130 AMERICAN POTATO JOURNAL [Vol. 43

FIG. 2.--Plants of the potato variety Kasota obtained from the buds of a whole tuber which had been green-sprouted.

The results of this test show that green-sprouting of potato tubers and cutting the sprouts into sections with a lateral or terminal bud yield a large number of plants per tuber. Although varieties differ in the nmnber of green-sprouted buds produced, cutting the tubers, breaking the apical dormancy before green-sprouting, results in the greatest num- ber of plants.