Cucurbit Genetics Cooperative Report 5:24-25 (article 12) 1982
M. B. Magdum1, N. N. Shinde2, and V. S. Seshadri
Division of Vegetable Crops and Floriculture, Indian Agricultural Research Institute, New Delhi 110 012, India
Androecious sex form (bearing only staminate flowers) is a rare phenotype in muskmelon (Cucumis melo L.) Forster and Bond (1) reported an abrachiate, androecious mutant from a cantaloupe field. There is, however, no report of androecious sex form segregating in a normal (branched) plant muskmelon population. Androecious cucumber (Cucumis sativus) was reported by Stembera (4).
In the course of investigations on sex mechanism in muskmelon, two nearly androecious plants were observed, one each in two F2 populations from Hermaphrodite-1 x Monoecious-2, and Monoecious-4 x Hermaphrodite-1 crosses. These two plants which produced only one or two perfect flowers and pistillate flowers, respectively, just before termination of flowering were self-pollinated. In 1980, 3 completely androecious plants out of 46 were recovered in the F³ from the first cross, and 1 out of 39 in the F³ from second cross.
In 1981, 2 androecious segregates out of 58 were picked out in a F² generation of Monoecious-4 x Hermaphrodite-1 cross. These were progeny tested by inducing perfect flowers on rooted cuttings in pots using Ethrel (250 ppm) sprays. Seeds thus obtained were sown for study. The frequency of androecious segregates was low: 8 were androecious and 21 were andromonoecious.
It was also seen that androecious segregates occurred with or without abrachiate condition. In the F² from the first cross combination (androecious x monoecious) 1 abrachiate androecious plant and 2 normal androecious plants occurred among a total of 22 plants. In the F4 from the second cross (androecious x andromonoecious) 1 abrachiate androecious, and 3 normal androecious plants occurred in a population of 16 plants. The small population prevented us from determining the relationship between abrachiate condition and androecious sex form. These observations differ from those of Foster and Bond (1), who regarded the abrachiate condition as a mutant.
It is interesting to note that androecious and gynoecious segregates were obtained in a segregating population from monoecious x hermaphrodite crosses. Gynoecious segregates occurred, however, in higher frequency in these crosses (2, 3).
This is the first report that segregation of androecious sex form (in low frequency) is possible in some specific cross combinations in muskmelon. Observations are inconclusive to say that a stable dioecism is possible in some specific cross combinations in muskmelon. The above results suggest that androecious condition in muskmelon might be genotypicaly similar to andromonoecious sex form, possibly as an aberrant form. Further studies are in progress.
1 Presently at the Department of Horticulture, Konkan Krishi Vidapeeth DAPOLI- 415723 India.
2 Presently at the Department of Horticulture, Marathwada Agricultural University PARBHANI- 431 402, India.
Literature Cited
- Foster, R. E. and W. T. Bond, 1963. Abrachiate- an androecious mutant muskmelon. J. Hered. 58:13-14.
- Kubicki, B. 1966. Genetic basis for obtaining gynoecious muskmelon lines and the possibility of their use for hybrid seed production, Genet. Polon. 7:27-30.
- Stembera, J. 1963. Unisexual plants of greenhouse cucumber varieties and the possibility of using them for breeding. Sborn. Vys. Sk. Zemed. Brne, Rada. A. No. 3, pp 235, 242.