Early generation selection for cold chipping in potato genotypes developed by conventional tetraploid breeding and by interspecific and interploidy hybridizations.

Abstract

A potato cultivar with the cold chipping (CC) trait accumulates less reducing sugars during cold (4C) storage and can therefore produce light colored chips with reduced acrylamide levels directly from storage. Cold chipping cultivars could reduce the losses and costs associated with most potato storage regimes. Development of CC cultivars using sexual polyploidization (SP) coupled with early generation selection (EGS) may accelerate the development of CC cultivars by increasing genetic variation, reducing new parent development time, and reducing population sizes necessary in potato breeding programs. The objectives of this research were to determine the variance and genetic gains that result from EGS for CC on tubers derived from seedling transplants or greenhouse-grown tubers using populations developed from 2x-2x, 2x-4x, 4x-2x, and 4x-4x matings. Agronomic and horticultural traits were also evaluated for selected genotypes. Cold chipping was evaluated after 3 and 6 months cold (4C) storage. Chips were made by frying a 1 mm thick slice from the center of one longitudinally cut tuber per genotype in 185C vegetable oil until bubbling ceased. Chip color scores were visually evaluated using a standard color scale ranging from 1 to 10 with a score of 4 or less considered acceptable. Total and marketable yield, specific gravity, general tuber appearance, eye depth, sprouting, skin and flesh color, tuber shape, and maturity were evaluated for selected genotypes. Large variances, high frequencies of acceptably chipping genotypes, and excellent mean color scores were observed in all 4 mating types. Positive genetic gains resulted from EGS for CC but were reduced by genotype by environment interactions. This illustrates the importance of testing genotypes over multiple locations and storage durations as a part of developing CC varieties. Greater genetic gains from early generation selection may result by using SP with germplasm that has excellent CC coupled with superior agronomic and horticultural trait performance. The excellent performance of the 2x-2x matings in this research suggests that combining EGS with bilateral sexual polyploidization for CC may increase the probability of selecting a tetraploid CC genotype with cultivar potential if accurate and efficient methods of separating the resulting diploid and tetraploid progeny can be utilized.