Quantitative morphogenetics of the male gametophyte of Juniperus L. species in the Mountainous Crimea

Moscow State University of Civil Engineering (National Research University), 129337, 26, Yaroslavskoe highway, Moscow, Russia

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Abstract

The formation of the male reproductive sphere is one of the most important stages of the reproductive cycle. The quantitative and qualitative characteristics of pollen are integral indicators of seed formation processes and, consequently, the stability of natural stand regeneration. The study of the biometric features of juniper pollen was carried out on 41 sample plots. To determine an integral assessment of pollen quality, our own method was developed, including a comprehensive analysis of its histochemical and morphological features characterizing viability. Juniper pollen grains are unicellular, have a regular spherical shape without air sacs, and are straw-yellow in color. The shrub species J. communis is characterized by the smallest pollen size among all Crimean junipers (25.83±0.63 μm). At the same time, the pollen diameter of the second shrub species growing in Crimea, J. sabina, is similar in size to that of J. deltoides and J. foetidissima, indicating that there is no influence of growth form on pollen grain size. Thus, in the course of the conducted research, it was established that the pollen grain sizes of all juniper species naturally growing on the territory of the Crimean Peninsula have a low and very low level of variability (the coefficient of variation does not exceed 12%), are a genetically fixed trait, and correspond to the values described in literary sources. J. foetidissima is characterized by the highest number of fertile pollen grains (79.51±2.62%), while for J. deltoides and J. excelsa this indicator is 55.19% and 60.38%, respectively.