N. Valkova, M. Koleva* Agricultural Academy, Field Crops Institute, 6200 Chirpan, Bulgaria (Manuscript received 2 June 2023; accepted for publication 25 March 2024) Abstract. During the period 2016-2019, 21 Bulgarian and 10 foreign cotton varieties were included in a trial set by the

The genotype × environment interaction and stability of five cotton varieties were studied during 2002-2006. The years of the investigation appeared to be as different ecological environments. The stability variances (2i and S2i) of Shukla (1972) and YSi index of Kang (1993) were calc