Clonal Generation Research Articles

Second clonal generation potato seedling selection at two locations

A study has been made to determine the degree of similarity between selections made by two potato breeders working independently with identical, early generation, potato seedling clones in two regions with markedly differing environments; thereby to determine the best clonal generation stage (s) for distribution of the potato seedling material from a central breeding unit to stations in other regions.

Intraplant Morphological Variations in Grasses

Clonal progenies were developed from individual nodal segments of bromegrass, cormlets of timothy, and secondary basal buds of sorghum. The parent plants were morphologically unstable or chimeral and occurred in either hybrid or inbred populations. Intraplant clonal progenies usually continued to be unstable through the second clonal generation. Marked deviating types occurred within clonal rows. Intraplant comparisons were made of inflorescence characters and seed-set following open-pollination of unstable plants from inbred lines of smooth bromegrass. Significant differences occurred between characters in panicles from different parts of the same plant.

INTRAPLANT MORPHOLOGICAL VARIATIONS IN GRASSES

Clonal progenies were developed from individual nodal segments of bromegrass, cormlets of timothy, and secondary basal buds of sorghum. The parent plants were morphologically unstable or chimeral and occurred in either hybrid or inbred populations. Intraplant clonal progenies usually continued to be unstable through the second clonal generation. Marked deviating types occurred within clonal rows. Intraplant comparisons were made of inflorescence characters and seed‐set following open‐pollination of unstable plants from inbred lines of smooth bromegrass. Significant differences occurred between characters in panicles from different parts of the same plant.

Selection of clonal potato seedlings at three widely separated locations

From 210 first clonal generation potato seedlings tested at three widely separated locations 41 different seedlings were selected the first year. Of these only two were selected at more than one location and none at all three. In the second year 19 different selections were retained of which 17 were originally selected by Fredericton. Three were selected at all locations and nine at two locations. There was no evidence to suggest that the different environments at the three locations altered the relative expression of such characters as tuber type, maturity, stolon length, general evaluation, or number of tubers. In general there was no better agreement between seedling ratings at one location than between locations except in the second year at Fredericton. The improved agreement between replicates at Fredericton in 1965 was attributed to the increase from two hills per replicate to 10, and to the greater experience of the evaluators. The present method of selecting initially at Fredericton is supported. It is more economical, does not appear to result in the loss of potentially useful potatoes for the prairies, and enables the potato specialists to be concentrated at one point.

Effect of seed tuber size on first clonal generation yield of potatoes

Regression of yield on seed tuber size in first clonal generation populations was studied in two experiments. Regression coefficients were +0.39 and +0.26 pounds of tubers per quarter inch increment of seed tuber diameter in one experiment and +0.88 in the other experiment. Regression coefficients within and among clones were similar. It is suggested that stratification and/or co-variance analysis might be used to obtain greater precision in evaluation when seed tuber size varies. Improvement in C1 evaluation appears possible by increasing seed tuber size.

First clonal generation potato seedling selection at two locations

First clonal generation potato seedling selection at two locations

First clonal generation potato progeny performance at two Minnesota locations

First clonal generation potato progeny performance at two Minnesota locations