SOWING TIMEFRAMES AND ADAPTABILITY OF ESCAROLE CULTIVARS IN THE SOUTHERN STEPPE OF UKRAINE

Abstract. The article is devoted to topical issues of cultivars' adaptability and improvement of the escarole growing technology in the Southern Steppe of Ukraine. Purpose. To establish the optimal timeframe for escarole sowing, depending on cultivars, and to elucidate the effect of this factor on yield and product quality. Methods. Traditional research methods were used. The greatest attention was paid to biometric indicators of plants' growth and performance. Results. The study showed that escarole cv. 'Vohnyshche' had the fewest leaves (25.6–27.2 leaves/plant). Cvs. 'Red Ball', 'Indigo', 'Palla Rosa', and 'Shcherbet' showed better results when sown within the third ten days of May and had 31.2–31.7 leaves/plant. Cvs. 'Vohnyshche', 'Indigo', and 'Red Ball'  sown within the first ten days of May had the highest plant weights of 242–296 g. Cvs. 'Palla Rosa' and 'Vohnyshche'  had greater weights (258–275 g) when sown within the third ten days of May. High yields were harvested from escarole cvs. 'Vohnyshche', 'Indigo', and 'Red Ball' sown within the first ten days of May and the third ten days of May" 30.3–32.9 t/ha and 28.6–30.5 t/ha, respectively. The best chemical composition of escarole commercial products was recorded for cvs. 'Indigo' and 'Red Ball' sown within the first and third ten days of May. The first and third ten days of May were proven to be the optimal periods for escarole sowing. Discussion. Adherence to the optimal sowing timeframes is quite relevant for escarole dissemination, adaptability evaluation, and improvement of the crop-growing technology in the Southern Steppe of Ukraine. According to Tkach O.V., (2019); De Jaegere I. and al. (2022), and Proskurina K. et al. (2022), even seedlings are an important pre-requisite to harvest a high yield. Other scientists emphasized that delayed sowing led to a decline in the field germination due to a reduction in the moisture content in the soil at the seed embedding depth, resulting in decreased yields (Birsa, M., Sarbu, L., 2023). To make Cichorium endivia production commercially viable, growers should adopt high-performance cultivars. C. endivia cultivars will fruit at different times depending on the latitude where they are grown and day length. Indeed, cultivars that are good for production in Ukraine may not be suitable for production in Italy or China and vice versa. This is important because of the photoperiodism of C. endivia (Moon K. M., Bin Kwon E., Lee B., Kim C. Y., 2020). In addition, as some scientists point out, sowing time affects not only the C. endivia yield but also the quality of products determining their use (Ulianych O.I., Soroka L.V., Voievoda L.I., 2018; Saltveit M., 2018). Therefore, ascertainment of optimal sowing timeframes for escarole to harvest the highest yields of top-quality commercial products is an important and urgent objective, which was pursued and presented in the article. Conclusions. The study demonstrated that the first ten days of May were the optimal timeframe for outdoor sowing escarole cvs. 'Vohhnyshche' and 'Indigo' in the Southern Steppe of Ukraine. It enabled for harvest of 32.9 t/ha and 30.3 t/ha, respectively. The third ten days of May were the optimal timeframe for cvs. 'Palla Rosa' and 'Vohnyshche', which yielded 28.6 t/ha and 30.5 t/ha, respectively, in this variant. The best chemical composition of marketable escarole products was achieved in cvs. 'Indigo' and 'Red Ball' sown within the first and third ten days of May.