An evaluation of a new rhombic grid selection,gridded mass selection and simple mass selection methods for yield improvement in wheat

Summary An experiment was conducted in Winnipeg, Manitoba, Canada to: (1) ascertain the efficiency of gridded mass selection; (2) to determine if additional selection efficiency can be achieved through refinement of the gridded mass selection procedure; and (3) to determine if the degree of homozygosity has an effect on response to single-plant selection. Three selection methods simple mass selection (SMS); gridded mass selection (GMS); and a new rhombic grid selection (RGS)] were applied to four populations a conventional F₂ (CON-F₂); an intermated F₂ (INT-F₂); and 2 partial backcrossed populations] developed from a biparental cross involving the Canadian spring wheat cultivars, Glenlea and Sinton. Averaged over the 4 populations, a single cycle of RGS (10% selection intensity) increased yield by about 9.5%, whereas GMS and SMS increased yield by approximately 4.5% and 3.1%, respectively. The degree of homozygosity of individual plants that make up the population appeared to have an effect on the efficiency of selection. In general, selection was more efficient in the two partial backcrossed populations, and least efficient in the CON-F₂ and INT-F₂ populations. The largest response to selection (15.9%) was attained when RGS was applied in the backcross to Glenlea population, and the lowest response (1.2%) when SMS was enforced in the CON-F₂ population. This paper represents the first report on the efficiency of rhombic grid selection for yield improvement in cereal crops.Contribution No. 550 of Agriculture Canada, Lacombe Research Station, Bag Service 5000, Lacombe, Alberta, Canada TOC ISO