Introduction Sustainable fructifi cation of walnit varieties depends of different factors. One of the most important problem is effective pollination and fruit set (1, 2, 5). In this paper are presented the results of researches of the morphological and hystochemical peculiarities of pistillate fl ower receptivity to pollination depending on fl owering stage. Studies were done with the scope of determination  of the terms of more effective period of pollination within dichogamous (protandrous, protoginous and homogamous) varieties in the conditions of Republic of Moldova Material and methods 16 moldavian dichogamous varieties and perspective selections were experimented in direct and indirect hybridisations (including hand auto pollination). On the basis of utilisation of cytoembryiological, including hystochemical methodology (3, 4, 5) were tested dynamic of contents and  localisation of enzymes, pollysaccharides, proteins and nucleic acids (ARN and ARN) in the principal parts of pistillate fl owers of protandrous and protoginous genotypes after its hand pollination at different stage of development of stigma and embryo sac. Results and discussions Morphological and histochemical investigations of dichogamous walnut experimentally pollinated fl owers in different phases of stigma opening showed the following results. Chalazogamy solely is peculiar to investigated varieties. Histochemical study of ovule “packing tissue” reveals its high metabolic activity in progamic fertilization phase, that may confi rm expediency of chalazogamy, manifestation. There are concluded that the most favorable morphophysiological state of embryo sac for fertilization coming in 2-3 days after the differentiation of 7-cells stage. This moment coincides approximately with the 4-5 day of total opening of stigma. For the protoginous genotypes with the medium fl owering period the most favorable stage for pollination coming on the third day of fl owering. In this case effi cient receptivity of stigma totally corresponds to morphophysiological preparation of female gametophyt for fertilization. Data of  dynamics of differentiation processes within dichogamy make us to conclude that in the climateric conditions of the Rep. of Moldova the genotypes with simultaneous dates of fl owering of male and female fl owers, as well as the early protoginous genotypes have the most chances for occurrence of double fertilization and for the following normal development of the embryo as a principal and more valuable part of English walnut fruit.  Conclusions 1.Experimental direct and indirect pollination of walnut (Juglans regia L) pistillate fl owers on differ ent phases of stigma opening reveals that it is receptive to pollination during 6 days. 2. The most favorable for fertilization morphophysiological state of embryo sac comes in 2-3 days after it reaches 7-cells state. As a rule this status corresponds to the 4-5 day after the beginning of stigma op ening. 3. In the microclimatic conditions of the republic of Moldova protandrous varieties, as a rule, have a shorter receptivit y period comparatively to protogynous ones.