Studies on induced tetraploid in four diverse cultivars of pea (Pisum sativum L.).

Abstract

Tetraploids were induced through colchicine treatment of 1.5-2.0 cm long seedlings in four pea cultivars, namely, T 163 (indigenous), 68 C (W. Germany), 5064-S (Sweden) and P. I. 280064 (Canada). Four hours treatment with 0.025% colchicine produced 10-15% tetraploids. Large seeded cultivars, T 163 and 68 C gave more tetraploids than small seeded ones. Tetraploids showed siginficant varietal differences and were characterised by large stomata, flowers, seeds and pod width and delayed flowering and maturity by 10-15 days while stomata frequency and pod length showed reduction. Both bivalents and quadrivalents were prominent in tetraploid. Chromosome abnormalities were more in T 163 tetraploid (55 per cent cell); laggards were frequent. Pollen and ovule sterility were parallel and ranged from 33 to 85 and 24 to 80 per cent in tetraploid as compared to 0.7 to 5.0 and 0.5 to 3.2 per cent in diploid, respectively. Colchicine treated diploids also showed high pollen and ovule sterility ranging from 16 to 56 and 7 to 56 per cent, respectively but had no chromosome abnormality. The possible role of colchicine and chromosomal abnormalities in reducing fertility were discussed.