Chromosome numbers and ploid levels in 12 species and two hybrids in two orchid genera as Chloraea and Gavilea from Chile were investigated. The chromosome numbers of nine species and one hybrid were commonly 2n=44 or ca.44 (diploid), while those of three species were 2n=88 or ca.88 (tetraploid). One hybrid crossed between plants of diploid and tetraploid was 2n=66 (triploid). Two genera of Chloraea and Gavilea were closely related to each other cytologically with the basic chromosome number of x=22 and the karyomorphology of the simple chromocenter type at resting stage. In addition, the speciation of these members might be occurred and correlated with the diversification of their karyotype and the polyploidization.

View full abstract

Seeds of Brachanthemum krylovii Serg., a member of Chrysanthemum sensu lato collected in 50&drg;23’38”, 26&drg;40’39”on the limestone area near the confluence of the Katun River and Chuya River, Mts. Altai, Altai Republic, Russian Federation, were sown and germinated to perform seedlings of which root tips were used to observe somatic chromosomes. The karyotype was K(2n=18)=14m+2sm+2st. This diploid katyotype was commonly observed in the members of the Anthemideae or Chrysanthemum sensu lato.

View full abstract

　Seeds of Linum usitatissimum L. were treated by gamma rays at different doses such as 100, 200, 300, 400 and 500 Gys from Co-60 source alongwith control and the occurrence of pollen germination and pollen tube growth were reported at various doses of gamma rays along with control. The impact of gamma rays on pollen-fertility, pollen germination and pollen tube growth has also been investigated. The percentage of pollen germination and pollen fertility increases upto 300 Gy and at the treatment dose of 400 Gy and 500 Gy, a reduction in pollen viability and decrease in percentage of pollen germination has been noticed. A decrease in pollen tube length has also been noticed at the dose of 400 and 500 Gys.

View full abstract

The present meiotic study was carried out in 15 species of medicinal importance belonging to 14 genera and nine families. The chromosome numbers n=7 of Aloe vera L., n=10 of Brassica campestris Hook.f. & Thoms, n=12 of Capsicum annuum L., n=12 of Cissampelos pareira L., n=10 of Croton bonplandianum Baill., n=32 of Heliotropium eichwaldi Steud., n=7 of Hordeum vulgare L., n=7 of Lathyrus aphaca L., n=20 of Mazus rugosus Lour., n=7 of Pisum sativum L., n=6 of Sesbania sesban Merrill., n=12 of Solanum verbascifolium L., n=11 of Tephrosia purpurea Pers., n=6 of Vicia faba L. and n=6 of Vicia sativa L. has been observed. The course of meiosis has been found to be normal in all species except in somewhere chromosomal irregularities have also been observed.

View full abstract

Chromosome numbers, ploidy and pollen fertility of the six species of Scrophularia L. were assessed from cold desert regions of Lahaul-Spiti: Scrophularia calycina Benth. (2n=26), S. decomposita Royle ex Benth. (2n=24), S. edgeworthii Benth. (2n=48), S. himalensis Royle ex Benth. (2n=24), S. koelzii Penn. (2n=20), S. polyantha Royle ex Benth (2n=24+2-3B). Meiotic chromosome count in S. decomposita was varied report while in S. koelzii Penn. it was recorded for the first time. Except S. edgeworthii (4x) rest all the species were diploid (2x).

View full abstract