Evaluation of flowering dates and qualitative characteristics of fruits of promising walnut breeding forms of the gene pool at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine-making

The article presents the results of phenological observation of flowering onset dates for male and female inflorescences. In addition, the study provides the data obtained through assessing a complex of fruit quality characteristics of 26 promising breeding forms. The forms were previously selected for the adaptability and productivity characteristics from the gene pool of hybrid forms at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine-making. Phenological observations showed that the flowering time of female and male inflorescences in 2022-2024 occurred on different dates. Moreover, its duration also varied. The beginning of female inflorescence flowering (the average for a three-year period) was dated April 18; the average flowering duration equaled 11 days. The beginning of male inflorescence flowering (the average for a three-year period) was dated April 11. The average flowering duration was 8 days. When evaluating the flowering type, we found that 12 samples were protandrous, 8 samples were protogynous. 6 samples were characterized as homogamous with protogyny observed in particular years. The identified time and type of flowering enabled us to select the most promising pollenizer samples, as well as to establish forms with a late flowering date in female inflorescences, which is a valuable trait for breeding. The undertaken assessment of the qualitative fruit characteristics showed that forms 17-2-14, 17-2-16, 17-2-20, 17-3-8 had a set of valuable traits such as a high percentage of kernel yield, kernel extraction from the shell whole or in halves, light-colored kernels. Moreover, they have thin/medium-thick shells. Form 17-3-8 has late flowering dates of female inflorescences along with a complex of economically valuable characteristics of fruits, which is of great interest for its further consideration as a cultivar. In addition, the following combinations of parental forms are recommended for use in breeding: samples with homogamous flowering (17-1-14, 17-18, 17-2-25, Vodnik, Timur) and with late flowering of female inflorescences (Novinka, Kazachiy, G-1-37). They produce a low yield or have dark-colored kernels and can be crossed with forms 17-2-16, 17-2-20, 17-3-8 characterized by a large percentage of kernel yield and its extractability, light-colored kernels. This will make it possible to obtain breeding material for selecting forms with the specified characteristics.

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