Estimation of cucumber breeding accession performance created by gametic breeding

Abstract

The estimation data on 7 performance traits of cucumber breeding-valuable accessions created by gametic breeding from parthenocarpic lines.

The aim and tasks of the study. To select high-performance genotypes from the parthenocarpic cucumber gene pool after treatment of gametophyte for heterosis breeding.

Materials and methods. The gametophyte selection of cucumber was conducted by the method that involved pollen collection in parchment bags, heating at +60 ^oC for 2 hours and further use for pollination. The pollen heating experiment was carried out in 2015. In 2016-2017, the test cucumber accessions were reproduced by inbreeding in a glass greenhouse without heating. The gametic breeding of cucumber was carried out using a two-factor design. Starting lines were taken as gradations of factor I (A), factor II (B)gradations were I₁-I₂ gametophyte progeny, which was investigated for performance trait expression, depending on seed layer in fruits (top, middle and bottom of the fruit). Three cucumber lines bred at the IVMG NAAS were taken as study objects: Potomak, [F₈I₆ (N₁₁ / Holubchik)] and [F₆I₅ Kuznechik]. We investigated expression of the following quantitative traits: the number of male flowers per plant; the number of fruits per plant; one plant performance.

Results and discussion. Of the cucumber accessions derived from line Potomak, 2 test accessions were distinguished by expression of the “one plant performance” trait, which was comparable with that of the line - standard: [Potomak, t = 60^oC (top of the fruit)] and [Potomak, 60^oC (middle of the fruit)] – 1,318.89 and 1,663.33 g/plant, respectively. Of the cucumber accessions derived from line [F₈I₆ (N₁₁ / Holubchik)], test accession F₈I₆ (N₁₁ / Holubchik)], t = 23 ^oC (bottom of the fruit), control] (1,259.11 g/plant) proved to be the best. Of the cucumber accessions derived from line [F₆I₅ Kuzhechik], experimental and control accessions were inferior to the standard by this trait, ranging within 781.44 - 941.33 g/plant.

Analysis of variance demonstrated that the null hypothesis for the “one plant performance” trait only deviated in relation to factor A (η = 22.92 %). Interaction between factors A and B (16.35 % <η<24.07 %) had the greatest effect on expression of the two other traits: the number of male flowers per plant and the number of fruits per plant. Thus, expression of these two traits was significantly influenced by dependence of factor B expression (seed layer in the fruit) on factor A (parthenocarpic lines).

Conclusions. Of the obtained gametophyte progeny, two parthenocarpic cucumber accessions derived from line Potomak, which had the plant performance equal to that of the standard, were singled out. It was established that the gametophyte progeny performance significantly depended on the response of a starting line genotype to thermal treatment of pollen.