Cucurbit Genetics Cooperative Report 3:63 (article 35) 1980

Taxonomic Position of Dosakaya (Cucumis sp.) - The Acid Melon of India

V. A. Parthasarathy¹ and C. N. Sambandam²

Division of Horticulture, Faculty of Agriculture, Annamalai University, Tamil Nadu - 608 101, India

Dosakaya is a cultivated Cucumis grown in Andhra Pradesh, for its sour fruits which are used in many culinary preparations ranging from curries to pickles. According to Rao (4), Dosakaya types are C. sativus. There are no reports available on the systematic status of Dosakaya, but Kailasam (2) reported that Dosakaya was crossable with both C. melo and C. sativus. However, his studies lacked cytological evidence. With a view to ascertatin the systematic position of Dosakaya, the present studies were undertaken.

Seeds of ten Dosakaya types were used in the study. Counts of somatic chromosomes were made from root tip cells following the procedure of Roy (5) using propiono-orcein stain. To ascertain the compatibility with other Cucuis species, reciprocal crosses were made with Cucumis metuliferus, C. anguria, C. longipes, C. zeyheri, C. myriocarpus, C. dipsaceus, and C. melo. The success of the cross was determined by the per cent of fruit set in crosses, number of developed seeds in crossed fruits, per cent of pollen fertility and viability in F₁. Meiotic studies were carried out in the pollen mother cells of F₁ plants to study the behavior of chromosomes during diakinesis.

Examination of many metaphase plates of root tip cells revealed the chromosome number of 2n=24 in all Dosakaya types studied. The crosses revealed that each Dosakaya type studied was crossable with only C. melo. Fruit set was nil in crosses with other species. However, crosses with C. melo were successful only when C. melo was used as staminate parent. This failure may be due to the fact that the C. melo cultivar (Annamalai) used in the study was an andromonoecious type, and the mutilation due to emasculation might have caused the failure of fruit set (1).

The results clearly show that the fruit set, mean seed number, seed germination, and F₁ pollen fertility and viability of crosses between Dosakaya types and C. melo were well comparable to that of selfing, thus indicating the free crossability of Dosakaya types with C. melo. The presence of 24 somatic chromosomes and free compatability with C. melo as revealed by normal bivalent formation in all the F1s indicate that Dosakaya is C. melo (2n=24) and not C. sativus (2n = 14). Kailasam (2) reported that Dosakaya is crossable with both C. sativus and C. melo, but recently, Parthasarathy and Sampathkumar (3) reported that the material used as C. sativus (cv. Vellari) by Kailasam was actually C. melo. Hence, Kailasam had used Vellari, a cultivar of C. melo, erroneously as C. sativus.

Literature Cited

1. Ganesan, J. 1971. Some studies on six muskmelon varieties with particular reference to plant characters, floral biology, natural crossing and fruit characters. M.Sc. (Ag.) Thesis, Annamalai Univ. 183 pp.
2. Kailasam, M. 1972. Some studies on Dosakaya with particular reference to its relationship with muskmelon (Cucumis melo L.) and cucumber (C. sativus L.). M.Sc. (Ag.) Thesis, Annamalai Univ. 63 pp.
3. Parthasarathy, V. A. and R. Sampathkumar. 1979. Kayo-morphological studies on Cucumis sp. cv. Vellari. Curr. Res. 8: 175-176.
4. Rao, P. V. S. 1932. A note on cucumber cultivation in the Ganjam District. Madras Agric. J. 20:3.

¹ Present address: Scientist S-1 (Horticulture), ICAR Res. Complex for NEH Region, Nongrim Hills, Shillong - 793 003, India. The senior author thanks ICAR for the award of a senior fellowship to him.

² Research Scholar (Horticulture) and Dean, Faculty of Agriculture, respectively.