Development of a short duration upland rice mutant line through anther culture of gamma irradiated plants

This experiment was conducted in the field and at the tissue culture laboratory of the Plant Physiology Division, CARI, Yezin from 1994 to 1997. Upland rice, Yar-2 was used as the test variety. Dried seeds (14% moisture content) were treated with gamma rays at doses of 0, 300, 350, 400 and 450 Gy respectively. These seeds were planted separately according to the gamma-ray treatment they received. At booting stage, tillers were cut. Anthers from the top and middle portion of the panicle were taken. The pollen, at developmental stage in each anther, was examined using Acetocarmine dye. Pollens at the uninucleate to early binucleare stage were selected. Tillers having pollens at the above-mentioned stage were placed in a dark room at 25(±) 1 C and 16 hours photoperiod. When plantlets were obtained from these media, well-developed green plantlets were selected and planted in Yoshida solution to attain vigorous root growth. Diploid and haploid plants were formed from the anther culture method. At the heading stage, haploid plants were treated with colchicines to promote development into diploid plants. At maturity, plants produced from materials treated with different gamma doses were harvested separately. These homozygous lines were planted in the field and the characters were compared with their parents grown at the same time. The highest callus induction rate was found in materials treated with 450 Gy of gamma rays, but the lowest green plant regeneration rate was also observed at this dose. Among the forty-five homozygous lines obtained of the above materials, 7 lines, all from the 450 Gy gamma rays treated material, flowered earlier than the parents. One of the 7 early flowering lines, mutant line No 18, matured 19 days earlier but had the same yield as the parent. All other lines had a lower yield than the parent. Comparisons of yield and yield components of mutant line 18 and Yar-2 (parent) and comparison of quality characters are shown in tables.