Euphytica 37(1): 69-75 (1988)
A new interspecific Lathyrus hybrid to introduce the yellow flower character into sweet pea
H. I. T. Khawaja


The morphological description and meiotic behavior is presented for the interspecific hybrid between Lathyrus odoratus and L. chloranthus. This hybrid is compared with another hybrid L. hirsutus x L. odoratus. The two hybrids were intermediate in most of their morphological features. The crossability between the first listed pair of species was perhaps a rare incidence which contrasts with L. hirsutus and odoratus which readily cross. Cytologically both F1 hybrids showed some meiotic irregularities but the majority of cells in both the hybrids showed normal meiosis with 7 bivalents at metaphase I.


Lathyrus odoratus, the sweet pea is the only species in the genus Lathyrus which is widely cultivated as an ornamental. The first interspecific hybrid in the genus was reported in 1916 by Barker between L. hirsutus and L. odoratus. Despite several attempts by a number of sweet pea breeders, no authenticated instance of any other interspecific hybrid involving L. odoratus has been reported (Seen, 1938; Davies, 1997; Brunsberg, 1977).

Sweet pea is currently grown in numerous flower colour forms, except for the yellow corolla, which is as yet not available in this species. There are however, at least five wild species known in the genus Lathyrus which have yellow flowers. These are L. annuus, L. aphaca, L. chloranthus, L. chrysanthus and L. pratensis. One particular objective in the present investigations, therefore, was to explore the possibility of introducing yellow pigment genes for flower colour into L. odoratus via interspecific hybridization. The other objective was to obtain hybrid combinations for a cytological evaluation of species relationships.

Material and methods

Five species namely L. annuus, L., L. odoratus L., L. hirsutus L., L. chloranthus Boiss. and L. pratensis L. (2x and 4x) were used in this study, The first four species were annual diploids with 2n = 14 and the last was a perennial, with diploid and tetraploid cytotypes having 2n = 14 and 2n = 28 respectively. Interspecific crosses were accomplished under greenhouse conditions. Buds were usually pollinated a day after emasculation. For meiotic studies, buds as the appropriate stage were fined in freshly prepared 3 1 absolute ethanol‑acetic acid and stored in a refrigirator. Individual anthers were squas-




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