Cucurbit Genetics Cooperative Report 3:25 (article 14) 1980
R.W. Robinson and D.F. Heffernan
New York State Agricultural Experiment Station, Geneva, NY 14456
Pollen was placed with a dissecting needle on different areas of ‘Wisconsin SMR 18’ stigmas to determine the area of greatest receptivity. Five different areas of the stigma were pollinated including (1) the apical tip of each of the three stigmatic lobes, (2) the upper center of the stigma, at the juncture of the three lobes, (3) the upper portion of the outer side of each stigmatic lobe, (4) the lower half of the side of each lobe, and (5) all external areas of a single stigmatic lobe.
Each area of the stigma was receptive to pollination. Each treatment resulted in fruit set and the formation of viable seed (Table 1). However, many of the fruit had poor seed development at the peduncle end of the fruit, probably due to the small amount of pollen applied. Better seed formation occurred when larger amounts of pollen were applied; 106 seeds per fruit resulted when a copious quantity of pollen was applied by hand to all parts of the stigma and open pollination resulted in 177 seeds per fruit, in contrast to 17 to 62 seed per fruit when smaller amounts of pollen were applied for the different treatments.
In-experienced pollinators sometimes apply a small amount of pollen to only the easily accessible apical tips of the stigmatic lobes, but this treatment resulted in the lowest fruit set. To obtain maximum seed production, it is advisable to apply a generous amount of pollen to the entire surface of the stigma.
Pollen tubes may develop laterally as well as basipetally. When pollen was placed on only one of the stigmatic lobes, the preponderance of seeds that developed were in the fruit locule directly below the stigmatic lobe that was pollinated. However, seeds also developed in the other fruit locules, indicating lateral growth of the pollen tubes.
Table 1. Effect of pollen placement on fruit set and seed formation.
Stigmatic area pollinated |
No. of pollinations |
% fruit set |
Seeds per fruit |
Seeds per pollination |
| Tips | 11 | 36 | 62 | 23 |
| Center | 11 | 82 | 17 | 14 |
| Upper half of side | 9 | 56 | 27 | 15 |
| Lower half of side | 11 | 46 | 44 | 18 |
| Single lobe | 11 | 82 | 44 | 36 |