S. Stamatov*, E. Valchinova, G. Desheva, K. Uzundzhalieva, P. Chavdarov, T. Cholakov, B. Kyosev, R. Ruseva, N. Velcheva
Institute of Plant genetic resources „Konstantin Malkov”, 4122 Sadovo, Bulgaria (Manuscript received 7 June 2017; accepted for publication 1 September 2017)
Abstract. The aim of the current study is to trace the changes in the length of the growing season in accordance with the accumulated effective temperatures, rains and plant nutrition during the vegetation period, as well as the influence of these indices on the grain yield. The study was conducted in the period 2015 – 2016 in the experimental field of Institute of Plant Genetic Resources – Sadovo with the local variety B3E0025 from the National Genebank in Sadovo. The experiment was made in block method in four repetitions. Three sowing times were made – autumn, winter and early spring and two options of N fertilization – without additional N and 3 kg/da input of active N substance in tillеring phase. The beginning of the basic phenophases has been observed. As a result of the study it was established that the vegetation period in T. monococcum L. has 114-238 days’ duration and accumulation of effective temperature of 2266.0- 2714.71°C. The length of the growing season and the necessary accumulated temperature depends on the sowing period, the predecessor, the amount of nutrient substances and soil moisture. The extension of the critical phases of autumn sowing favours the obtaining of higher yield. The significance of the effective temperatures decreases with additional N input.