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Background. Learning about morphological and biological features of pollen is very important to make correct estimations of plant productivity and breeding efficiency.Materials and methods. The viability of black currant pollen was analyzed in 2019 at the Laboratory for Long-Term Storage of Plant Genetic Resources, N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). Eleven black currant cultivars of various ecogeographic and genetic origin maintained at Pushkin and Pavlovsk Laboratories of VIR served as the material for the research. Pollen viability was tested on an artificial medium with 10% sucrose and 0.8% agar. Morphological studies were carried out using light and confocal laser scanning microscopy at the Palynology Laboratory and the Core Centrum of Cell and Molecular Technologies in Plant Science housed by the Komarov Botanical Institute (BIN).Results and conclusion. The prevailing adverse weather conditions in 2019 produced a negative impact on the process of male generative structure formation. The level of pollen viability, depending on the cultivar, ranged from 17.98 to 58.60%. After exposure to liquid nitrogen (–196°C) for 6 months, the number of germinated pollen grains increased 1.1 to 3.2 times in all the studied cultivars, except one (‘Pozdnyaya poslevoennaya’, k-7652). A palynomorphological study revealed that reduced pollen viability in some cultivars (‘Krasnoyarskaya 1018’, k-7607; ‘Tsema’, k-25900; ‘Pozdnyaya poslevoennaya’, k-7652) was associated with morphological deviations in the sporoderm structure (small pollen grains, exine thickening and formation of verrucate mesoporium surfaces). A low positive correlation was observed between the level of pollen viability and the diameters of the pore (r = 0.43) and pollen grain (r = 0.27). An insignificant negative correlation was apparent between the level of viability and the exine thickness (r = –0.33).

Background. Sweet cherry is an unconventional fruit crop for the Northwestern region of Russia. Identification of cultivars adapted to the conditions of the northwest requires a comprehensive study of cultivars of different ecogeographic origin and, specifically, morpho-physiological characteristics of pollen, which ensure the productivity of sweet cherries.Materials and methods. The field sweet cherry collection maintained at Pushkin and Pavlovsk Laboratories of VIR served as the material for the study carried out in 2017 at the Plant Diversity Long-Term Storage Laboratory. Twenty-four sweet cherry accessions belonging to five different groups were studied: I – Northwestern (bred at VIR); II – Central; III – Central Black Soil (all three are regions in Russia); IV – Belarus; and V – Estonia. Viability of pollen was assessed by germinating on an artificial medium with 10% sucrose and 0.6% agar. Pollen viability results were statistically processed using StatSoft Statistica 13.0 and Microsoft Excel.Results. The initial viability of pollen for almost all varieties in 2017 was low. High percentage of pollen germination was characteristic of cvs. ‘Krasnaya sladkaya’ (gr. I, 50.0%), ‘Leningradskaya rozovaya’ (gr. I, 61.8%), ‘Adelina’ (gr. III, 53.5%) and ‘Zarya Vostoka’ (gr. III, 60.3%). After storage in liquid nitrogen, the level of pollen germination increased in all cultivars of groups I and V as well as in a number of cultivars from group II (‘Raditza’, ‘Iput’, ‘Rechitsa’ and ‘Fatezh’), group III (‘Zarya Vostoka’, ‘Rondo’ and ‘Orlovskaya rozovaya’) and group IV (‘Severnaya’ and ‘Vityaz’). Pollen viability after cryopreservation significantly decreased by 8.7‑17.3% in cvs. ‘Bryanochka’ (gr. II), ‘Alebastrovaya’ (IV),’ Bryanskaya rozovaya’ (II) and ‘Adelina’ (III). Pollen viability parameters (length of pollen tubes and percentage of germinated pollen grains) positively correlated prior to immersion into liquid nitrogen from r = 0,54 (gr. III) to r = 0,76 (gr. II), while after cryopreservation, they showed weak correlation (r = 0,28) in gr. I, and strong one (r = 0,79) in group IV. In the length of pollen tubes and the level of viability, the parent cv. ‘Leningradskaya chernaya’ had practically no connection with cv. ‘Raditsa’ (r = 0.09), while with cv. ‘Meelika’ the correlation was medium negative (r = –0.49); correlations between the parent cv. ‘Krasnaya plotnaya’ and cvs. ‘Sopernitsa’, ‘Bryanochka’ and ‘Vityaz’ were medium (r = 0.57) and high (r = 0.78 and r = 0.83), respectively.Conclusion. In their level of pollen viability, the introduced sweet cherry cultivars are similar to or even exceed the cultivars native to the northwest (bred at VIR).

The viability of pollen of 5 collectible varieties of Russian plum of the Pushkinskiye and Pavlovskiye VIR Laboratories SPB before and after cryopreservation was studied. It was found that a significant factor for the level of pollen viability is “variety” (p=0.07), the factors “cryopreservation” (p=0.457), “year” (p=0.221), as well as the interaction of the factors “variety× cryopreservation” (p=0.172), were not significant at the p<0.05 level of significance. For long-term storage of Russian plum pollen in liquid nitrogen, the year of pollen collection is not a significant factor. For most genotypes, no negative impact of cryoсonservation on pollen viability was revealed. The varieties ‘Aureus’, 'Podarok Sankt-Peterburgu’ and ‘Exotica’ after cryopreservation for 1 year showed a tendency to increase the pollen viability indicators.

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