INDUCTION OF POLYPLOIDY IN LINUM SPECIES

Colchicine was evaluated at 6 concentrations (0.0125, 0.025, 0.05, 0.1, 0.2, and 0.4% in water) for the induction of polyploidy. Three Linum species, L. usitatissimum (cv. "Imperial" and "Abyssinian yellow"), L. angustifolium, and L. narbonense, were treated at different stages of development. The most effective treatment was 0.1% colchicine for 6 hr. on germinating seedlings. Effectiveness of the treatments depended on species, concentration, duration of application, and duration X concentration interaction. Polyploids could be identified 3 weeks after treatment by their increased stomata size and later by their larger flower, seed, and pollen grain size. Meiotic behavior was studied in auto-tetraploids of L. usitatissimum, L. angustifolium, L. africanum, L. altalcum, L. grandiflorum, L. maritimum, L. narbonense, L. rigidum, and L. tenuifolium. A high frequency of quadrivalents was formed by all species at meiosis involving 33 to 71% of the chromosome complement. Chiasmata frequency in tetraploids was lower than in diploids. Pollen viability and number of seeds per capsule were lower in all auto-tetraploids, but seed and capsule size were larger. Oil content and degree of unsaturation were lower in tetraploids, while moisture content of the seed was higher.