A Hypodermic Needle Method of Treating Barley and Wheat Florets with Colchicine 1

HE mild winters in the Southwest are conducive to the T g r o w t h of boarley and wheat: Spring types planted in the fall have been superior to winter types for both forage and grain. Plant breeders constantly are searching for new methods to facilitate the development of improved varieties of held crops. The discovery in 1934 that colchicine induced polyploidy in plants and animals opened a new era in plant breeding. Since 1937, the use of colchicine has been successful in certain aspects of plant breeding. For example, tetraploid sugar beets which were larger and had an increased yield have been produced from the use of colchicine. Colchicine also has been used to facilitate crosses between species with different numbers of chromosomes. Colchicine was used successfully in the development of tetraploid rye. A number of different methods of colchicine application in field crops research are described in the literature. Greis2 used the germinating seed method of colchicine application to induce polyploidy in barley. He stated that the best effect of colchicine (14% tetraploid and 18% chimaera) was obtained from germinated seeds placed in a 0.4% colchicine solution for 4 to 8 hours. Luong3 suggested inserting a cotton wad moistened with colchicine into split coleoptiles of rice seedlings for a maximum of 48 hours. However, the foregoing method seldom produced complete tetraploid individuals in rice. Sears4 developed a technique in which the crowns of wheat plants were wrapped with cotton moistened with a 0.5% colchicine solution for 5 days. Approximately 50% of the plants produced tetraploid sections. Sears also applied a colchicine-lanolin mixture to wheat coleoptiles for 24 hours. A 2% colchicine concentration was most effective in producing tetraploid sections. Myers? used a hypodermic needle to inject colchicine solution into perennial ryegrass plant tissue at the base of the tillers. This method produced a 4N sector in 1 of 3 treated plants. All of the foregoing methods of colchicine treatment have b'een used to induce polyploidy in plants. However, no one method was completely successful. The authors found no indication in the literature that any research worker had used a hypodermic needle method of treating barley and wheat flowts with colchicine. The study reported herein is concerned with a hypodermic needle method of treating barley and wheat florets with colchicine in an effort to produce polyploidy and/or variation. In 1956, a hypodermic needle was used to treat spring barley and spring wheat florets with different concentrations