Application of phenoclimatographic models to establish the period of the greatest need for fruit plants in moisture

DOI: 10.35205/0558-1125-2021-76-223-228

UDC 634.1:631.671



M.F. Sydorenko Melitopol Research Station of Horticulture of the Institute of Horticulture, NAAS of Ukrain, 72311, Melitopol, 99, Vakulenchuk St.,

The author presents results of the original method of calculating the dates of watering, which correspond to the quantitative accumulation of conditional energy by the trees of the cultivars of the apricot 'Melitopolskyi luchistyi' and of the sweet cherry 'Krupnoplidna' respectively at the appropriate stage of their growth and development by means of applying phenoclimatographic models. The above mentioned CU- and ASYMCUR-models are used, first of all, to establish constant limit values for CU (chill unit), which ought to be accumulated by fruit trees to be removed from the period of the biological dormancy and GDH (growing degree hour), that are necessary for the beginning of their flowering. So the sweet cherry trees are to accumulate 1350 °С CU to be removed from the dormancy state, apricot trees – 940 °С CU while for the beginning of blooming – 4839 °С GDH for sweet cherry and 3725 °С GDH – for apricot. The release date from the biological dormancy and flowering period of the sweet cherry and apricot trees was designed on the basis of those limit values. The validation of the models as the comparison of the calculated and actual dates of the beginning of a tree flowering in the orchard has shown that their divergence is in the range from 0 to 3 days. That is indicative of the high prediction accuracy of these dates. According to the calculated CU limit values, we determined the dates of the release from the biological dormancy period and for GDH – those the dates of the beginning of the apricot and sweet cherry trees flowering as well as the dates of the ripening beginning for these crops. The GDH indicators predict the calendar dates of the most critical period of the studies crops trees growth and development, namely: the period of the fruit formation in the phase of the stone hardening. This corresponds to the accumulation of 50 % GDH from the maximum sum required for the beginning of the fruits picking maturity. This term has appeared to be optimal for the timely watering carrying out. The difference between the dates of watering for apricot and sweet cherry varies from 6 to 12 days depending on their biological characteristics, meteorological conditions after the tree flowering, infructescense and development.

Key words: sweet cherry, apricot, phenoclimatographic models, CU, GDH, release from the biological dormancy, beginning of flowering, critical period of growth and development of the fruits, the period of the greatest need for moisture

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