Cucurbit Genetics Cooperative Report 3:35-36 (article 20) 1980

Induction of Perfect Flowers on Gynoecious Muskmelon by Silver Nitrate and Aminoethoxyvinylglycine

K. W. Owens, C. E. Peterson and G. E. Tolla

University of Wisconsin, Madison, WI 53706 (first and second authors); Campbell Institute of Agricultural Research, Napoleon, OH 43545 (third author)

Recently, several hormones have been found to induce staminate flowers on gynoecious cucumber: silver nitrate (AgNO₃) (1, 2, 3, 6), silver thiosulfate (Ag₂S₂O₃) (4), and aminoethoxyvinylglycine (AVG) (5). Silver nitrate and AVG were evaluated along with gibberellic acid₄/gibberellic acid₇ (GA_4/7) for their ability to induce perfect flowers on gynoecious muskmelon.

Gynoecious MSU-1G muskmelon plants grown in the greenhouse in the summer of 1979 were treated with AgNO₃ at 100, 200, and 400 ppm; AVG at 50, 100, and 200 ppm; and GA_4/7 at 100 ppm. All chemical solutions were made up in deionized, distilled H₂O and were applied twice to runoff at either the three-leaf of five-leaf stage with one week between applications.

AgNO₃, the most effective treatment, resulted in approximately 12 out of 20 nodes bearing perfect flowers, often in clusters (Table 1). The AVG treatments were also effective but induced only about half as many perfect flowers as AgNO₃. Plants treated with GA_4/7 at 100 ppm produced an average of only 1.3 nodes in the first 20 bearing perfect flowers while control plants had an average of 0.8.

Some phytotoxicity was observed with AgNO₃ at 200 and 400 ppm and in plants receiving AVG at 100 and 200 ppm, severe stunting and chlorosis persisted for about two weeks. Multiple applications of these chemicals at the lower concentrations may allow good induction without phytotoxicity.

Table 1. Effect of hormone treatment on mean number of nodes bearing a perfect flower on gynoecious muskmelon.^z

Hormones	Concentration (ppm)	Number of perfect-flowered nodes y
GA4/7	100	1.3 c
AgNO3	100	11.9 a
	200	11.4 a
	400	12.0 a
AVG	50	5.5 b
	100	6.9 b
	200	5.9 b
Control	-	0.8 c

^z Based on first 20 nodes of main stem.
^y Mean separation within columns by Duncan's Multiple Range Test, 1% level.

Literature Cited

1. Beyer, E. M., Jr. 1976. Silver ion: A potent antiethylene agent in cucumber and tomato. HortScience 11: 195-196.
2. Franken, K. S. 1978. Chemical induction of staminate flowers on four determinate gynoecious lines of pickling cucumbers. Gartenbauwiessenschaft 43: 280-282.
3. Lower, R. L., D. M. Pharr, and E. K. Horst. 1978. Effects of silver nitrate and gibberellic acid on gynoecious cucumber. Cucurbit Genetics Coop. Rpt. 1:8-9.
4. Nijs, A. P. M. den and D. L. Visser. 1979. Silver compounds inducing male flowers in gynoecious cucumber. Cucurbit Genetics Coop. Rpt. 2: 14-15.
5. Owens, K. E., G. E. Tolla, and C. E. Peterson. 1980. Induction of staminate flowers on gynoecious cucumber by aminoethoxyvinylglycine. HortScience (in review).
6. Tolla, G. E. and C. E. Peterson. 1979. Comparison of gibberellin A₄/A₇ and silver nitrate for induction of staminate flowers in a gynoecious cucumber line. HortScience 14:542-544.