Average weight of potato tubers from inter-species and inter-variety crossing

Abstract

Purpose and Objectives. To evaluate the average potato tuber weight in the offspring from crosses between interspecies hybrids and breeding intraspecies varieties. Materials and methods. A six-species hybrid (81.459s18), backcrosses of various levels (89.202s79, 08.195/73 and 10.6H38), varieties - interspecies hybrids derived from the same material (Bazis, Podolianka) and intraspecies varieties were used in crossings. We studied the average tuber weight in the parents and offspring obtained from them. Results and discussion. There were differences in the average tuber weight between parents — interspecies hybrids and varieties. The maximum indicator was noted in a five-fold backcross (10.6H38) of the six-species hybrid –65 g. Only variety Tiras was inferior to it by1 g. However, in a one-fold backcross (89.202с79) of the six-species hybrid the average tuber weight was only28 g. The parents’ average depended on the tuber weights of each parent and ranged 31 to57 g. The indicator varied greatly in the offspring. The minimum limit for 2 combinations of 21 was10 g, but for some combinations it reached 43–45 g. The maximum limit varied even in wider margins (86–210 g). The maximum population average was noted in the Verdi x Bazis combination –92 g, which is by 1.4 times higher than that in the best standard variety (Tiras); the minimum population average – in the Bazis x Podolianka population (36 g). Among four combinations in which variety Podoliia was a pollinator, the difference in the average progeny was4 g, which indicates slight effects of the female components on the average tuber weight in the offspring. Similar data were obtained in the populations, for which 10.6H38 served as a female form: the difference between the combinations was17 g. On the contrary, between the three populations with Verdi as a female form the difference in the hybrids’ averages reached40 g. Significant differences in the average tuber weight in the offspring were confirmed by coefficient of variation. The minimum coefficient was found in the 08.195/73 x Melavitsa combination (26%), and the maximum – the offspring from varieties Strumok and Podoliia (86%). A possibility to identify hybrids with a higher indicator than that in the best parent, but with a various frequency, in each combination was valuable for practical breeding. In the Verdi x Bazis population, all the hybrids had such a characteristic. However, in the 10.6H38 x Podoliia combination, only 14.3% of the hybrids had a higher indicator than the best parent, which is attributed to the high value in the female component of the latter combination. There were no hybrids with an average tuber weight of100 gor more in five populations; there was 1 such hybrid in 12 combinations; and there were 2 such hybrids in 4 combinations. There was a medium direct correlation between the indicator in female forms and the parents’ average (r = + 0.65), as well as a portion of the offspring with a higher indicator than that in the best parent (r = + 0.50). Similar result was obtained for the pairs 'the average tuber weights of female forms and pollinators’, ‘the parents’ average and a portion of the offspring with a higher indicator than that in the best parent’ and ‘the population average and hybrids selected as practically valuable’. There was only a reverse moderate correlation between the parents’ indicator and a portion of the offspring with a higher indicator than that in the best parent, as well as between the average tuber weight in the female forms and hybrids with tubers weighing100 gor more. Conclusions. Significant variations in the average tuber weight in the offspring were demonstrated, which were confirmed by margins and coefficient of variation. There were significant differences between the population averages, although in four combinations with variety Podolianka as a pollinator the difference was4 g; in five combinations with backcross 08.195/73 as a female component -17 g; in three populations derived from variety Verdi -40 g. All the combinations were evaluated for possibility of selecting hybrids with a higher average tuber weight than that in the best parent. The majority of populations were evaluated for selection of hybrids with tubers weighing100 gor more.