Radiation Induced Genetic and Physiological Colour Changes in Jute

X-irradiated and P³² treated populations of five varieties of jute were observed to manifest colour changes which could be classified in two categories, (1) chlorophyll mosaicism and (2) colour (anthocyanin) variants and/or mutations. No such change was observed in the S³⁵ treated populations.

The frequency of plants with chlorophyll mosaic leaves, and the intensity of the colours in them, increased with increase in dosage above 32,000 r X-rays and 5 -0 µc P³² per seed. Evidences have been presented to prove that the colour effects were due to radiation only. Anatomical studies of the chlorophyll mosaic leaves revealed more injury in the palisade and the chloroplasts than the rest of the tissues.

Colour variants often manifested very intense anthocyanin pigmentation, unknown to the species. In extreme cases, the change in pigmentation proved to be lethal. A new scarlet coloured mutation, simulating the variety Tall Mutant, has been isolated in P³² treated material. This has been named Tall Mutant II. Inheritance studies indicated that Tall Mutant II was a dominant, heterozygous mutation, which segregated in the usual monohybrid ratio in appropriate crosses.

From breeding experiments it has been confirmed that the pigmented groups of C. olitorius namely, Chinsura Green (full green), R. 26 (light red), Tall Mutant and Tall Mutant II (scarlet) form a multiple allelomorphic series with scarlet dominant over both light red and full green and light red dominant over full green.

It has been possible to discriminate Tall Mutant II from R. 26 by leaf measurements by suitable discriminant function. Tall Mutant II has, further, been shown to be an early flowering type, compared to Tall Mutant. But both these are late types compared to R. 26.