Abstract
Seeds and seedlings of Cyamopsis psoraloides DC. were treated with different concentrations of colchicine solution for different durations to induce polyploidy. No polyploids could be obtained in seed treatment which can be accounted for the toxic effects of the chemical. Aqueous colchicine solution of two different concentrations viz. 0.25 and 0.5 percent applied on cotton pad around the stem tip at seedling stage responded well. Treatment with 0.25 percent colchicine for 6 hours 2 days treatment gave maximum polyploids.
The induced polyploids were either complete tetraploids, or mixoploids with hypotetraploid chromosome numbers. One plant was hexaploid.
Typical effect of colchicine, like slow growth of plant during early stages of development, thicker, fleshy and deformed leaves, less number and big size of stomata were observed in treated plants in comparison to diploids. Delayed flowering with lesser number of flowers per inflorescence as well as per plant in the tetraploid plants was significant. Pollen size and sterility in the tetraploids increased considerably. Number of fruits and seeds were few in tetraploids in comparison to those in diploids. On the whole C0 and C1 plants were less vigorous in growth.
Detailed cytological studies of the diploid plant have been carried out. Irregularities in chromosome association at metaphase I were prominent in the polyploids. The mean frequency of quadrivalents per cell was 0.89. Unequal separation of chromosomes and laggards were present in the meiosis of the polyploids. The present data have been discussed in relation to the previous reports.
