Decrease in quadrivalent frequency over a 10 year period in autotetraploids in two species of grain Amaranths.

Abstract

C10 autotetraploid lines in 2 grain species of Amaranthus (A. caudatus and A. edulis) were evaluated for their morphology and meiosis. Morphologically the C10 plants in both the species maintained the general gigantism in the determinate parts like leaves, stomata, pollen and seed as observed in C0 and C1. The meiosis was typically autoploid with quadrivalents, trivalents, bivalents and univalents. The mean quadrivalent frequency as observed at metaphase I varied from a minimum of 1.600 to maximum of 3.266 in A. caudatus while the respective figures in A. edulis were 1.400 and 2.33. The mean quadrivalent frequencies for C0 generation in the 2 spp. were 6.800 .+-. 0.29 and 6.00 .+-. 0.27, respectively. These figures represented statistically significant reduction over C0 and C1 data. Results are discussed in relation to similar or contradictory observations of earlier authors on the metaphase I associations in advanced generations of atuotetraploids.