| Bulk and pedigree methods in wheat breeding L. G. L. Copp Crop Research Division, D.S.I.R., Christchurch, New Zealand The author has replied, recently, to a general questionnaire on the comparison of the bulk and pedigree methods of plant breeding sent from the Development Bureau of the Ministry of Agriculture and Forestry, Japan. The information supplied was con cerned mainly with wheat breeding and may be of interest to other wheat breeders. The results of 26 years' work in New Zealand in which the two methods have been carried out simultaneously, have shown that the pedigree method is to be preferred under conditions where diseases are not limiting factors. Using the "pedigree" method, the procedure has been the selection of single plants in F2 and further selection of single plants in F3. In the F4 generation there has been rigid rejection of any of the progenies of the F3 single plants which showed weaknesses in any agronomic character, and in F5 and F6, in small yield trials, lines were rejected for low yield or poor baking quality. Very few crosses have had individual progenies which have survived to F7 or F8 for the first large field trial. By the "bulk" method there has been (a) selection of single plants in F2 followed by eight years without further selection or (b) nine years without selection in F2. In F10 individual grains were sown at wide spacing (10 x 40 cm2) for selection of single plants. The single plant progenies (L1-L4 generations) were grown in the same way as those obtained by the "pedigree "method with the same rejection for defects. Any progenies which survived were sown in their first large field trial in L5 (F15). As the basis for comparison of the two methods the number of crosses is considered from which single plant progenies, selected by either method, were sown in field trials up to 1956. The first hybrid bulk was started in 1930 and all crosses under discussion were made between 1930 and 1941 . Selections were made from some crosses by both methods, in others only the pedigree method was used and some crosses were made specifically for bulks. The numbers of crosses made for each purpose follow :- Single plant progenies selected by pedigree method ..................... 111 Selected by pedigree and bulk methods ...................................... 108 Selected only by bulk method.................................................... 37 F1 generation used for compound crosses, only, and those from which no single plants were selected in F2 .......................... 132 Total number of crosses made (1930-41) .................................... 388 From the 219 crosses used for selection by the pedigree method, 42 crosses (19%) produced 202 progenies which survived for at least one year in large field trials. Of the 145 crosses used for selection by the bulk method, 7 crosses (5%) Produced 34 progenies which were grown in field trials. The average numbers of progenies per cross were 4.8 and 4.9 respectively. Five named varieties were obtained by the pedigree method, Fife Tuscan, Yielder, Hilgendorf, Arawa and Aotea. There were no named varieties produced by the bulk method of breeding. |
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