Influence of high temperature on viability of winter rapeseed polen in vitro conditions

Abstract

Flowering Brassica napus at high temperatures leads to a negative impact on the generative organs of plants, reducing the viability and fertility of pollen, changes in the hormonal background. There is an acceleration of embryo development and, as a result, that significantly increases the level of abortion of embryos, decreases the level of auxin and increases the defects of embryos, worsens the germination of pollen tubes in vitro and in vivo. There is the development of seedless pods, inhibition of seed development and as a consequence, reduced yields. Influencing pollen of different varieties and hybrids by temperature stressors, analyzing its fertility and sterility, the presence of abnormal, defective pollen grains, and their number the length of pollen tubes, the ability of pollen to germinate under both in vivo and in vitro conditions allows to select from the population resistant to this factor genotypes for use in breeding studies The aim of our research was to study the viability of winter rape pollen under the conditions of treatment with high temperature pollen in a nutrient medium. The research was conducted at the Institute of Oilseeds Crops of NAAS. Four varieties and one sample of winter rapeseed of foreign selection were taken for the experiment. Pollen and anthers in the experiment were exposed to the higt temperature of 32 ± 1ºC, in the control variants pollen and anthers not exposed to the stressor. The inhibitory effect of the factor was evaluated by the degree of reduction of pollen viability in experimental variants compared with controls. In the control variants for all tested varieties large differences in the percentage of pollen germination were not observed, the minimum was in the variety Pronto - 41.1%, the maximum in the variety Tenor - 50.5%. Experimental variants for this indicator also differed little from each other. The maximum percentage of pollen germination in the experiment was for the variety Jan - 15.0%, the minimum for the variety K571 - 11.4%. The differences between the control and experimental variants in 4 varieties and the sample were significant. According to the degree of reduction of pollen viability in experimental variants in comparison with control all provided varieties and samples differed, the greatest degree of decrease of 76.3% was noted for Tenor variety, what is the evidence of low resistance of its pollen to high temperature, the smallest degree of reduction of this indicator - 32, 5% was noted for the sample K571, which is an indicator of the highest stability at the pollen level compared to other varieties tested. In the experiment on anther heating, the viability of pollen of all varieties and samples did not differ significantly from similar indicators of the previous experiment. The lowest percentage of pollen germination was observed in the Cornet variety - 0.3, the highest in the Pronto variety - 3.2, respectively. The degree of reduction in the percentage of pollen germination in the experimental variants compared to the control was high in all varieties tested, the differences between this indicator in the control and experimental variants were significan Thus, according to the obtained results germination of pollen in a nutrient medium at high temperatures led to a decrease in its viability. Taking into account the degree of reduction of this indicator in the experimental variants in comparison with the control, all varieties were classified according to resistance to high temperatures. The Tenor variety had the largest and the K571 variety the smallest degree of decline and were characterized by us as correspondingly unstable and resistant to high temperatures at the level of microgametophyte. Heating of anthers led to a significant reduction in pollen viability. All varieties tested had a high degree of reduction of this indicator in the experimental variants in comparison with the control and were characterized by us as unstable to high temperatures at the pollen level. The influence of high temperatures on pollen compared to the germination of pollen in a nutrient medium under the same conditions suppressed the viability of pollen to a much greater extent.