Population Improvement of Baby Corn Composite 1 DMR by S1 and Full-sib Selections

Abstract

A comparison study of the two population improvement methods namely S1 and full-sib selections was conducted to improve yield and quality of young ear corn and downy mildew resistance of Baby Corn Composite 1 DMR in one cycle of selection. The selection intensity was 10 and 20 percent for high quality and high yield. The selection progenies were divided into 4 groups. The first and second groups composed of 20 and 40 S1 progenies having the qualified young ear weight of 200 and 169 kg/ha, respectively. The third and fourth groups composed of 10 and 20 full-sib progenies with their improved young ear weight of 294 and 296 kg/ha respectively. The random mating system was used in these four populations to develop new populations. Newly improved populations were tested in comparison to the 3 recommended varieties ( Suwan 2, Thai Supersweet composite 1 DMR and Rangsit1 ) for yield and downy mildew resistance, in order to evaluate the efficacy of selection methods. The result revealed that all newly improved and original populations were not significantly different in yield. The one cycle improvement of S1 and Full-sib selections showed insignificant difference. However , S1 recurrent selection showed higher potential for young ear weight with husk, unhusk and weight of acceptable young ears than full-sib selections method. At the 10 and 20 percent selection intensities, the yield of hushed young ear in S1 improved population was 9 and 16 percent higher than in the initial population, while the yield was 7 and 10 percent higher in the unhusk and 24 percent higher in the standardized young ear. The full-sib selection intensity at the 10% and 20% gave the yield of husked young ear at 7% higher and 4% lower than the original population. While the yield of the unhusked young ear was 2% and 0% higher , and 10% and 7% higher in the standardized young ear. The average downy mildew infection of newly improved population was a slightly higher than those of the original population. However, the infection of downy mildew to the newly improved populations in the S1 selection at 20 percent selection intensity was decreased by 6%.