SummaryThe preservation of plant biodiversity of Bulgarian flora is the main priority in scientific activities of IPGR -Sadovo. It is a part of the National Programme on Plant Genetic resources (PGR). Plant accessions in the base collections are evaluated according to the standards of FAO and European programme for PGR. The scientific programme for conservation of germplasm under controlled conditions in the gene bank is prepared according to the FAO requirements. The national collection of PGR in Sadovo includes crops and crop wild relatives-new varieties, selection lines, old varieties, local populations, mutants and wild species. The collection is divided into 7 main groups: cereals, grain legumes, industrial crops, vegetable crops, forage crops and medical and ornamental plants. The scientific work is carried out in 6 directions: enrichment with new geneplasm; evaluation of PGR; maintenance of PGR; conservation of PGR; documentation of PGR; use of PGR.

The study was conducted during the period 2014 -2016 in the experimental field of Institute of Plant Genetic Resources, Sadovo. The influence of the period of sowing, the predecessor and the fertilization on the elements of productivity and grain yield per hectare in einkorn wheat were studied. It was established that the structural elements of productivity -number of productive tillers, length of the spike, number of spikelets per spike, mass of central spike, number of grains in central spike, weight of the grains from the central spike are with the highest values in plants grown after predecessor peas, sown in autumn and fertilized with extra nitrogen. With least developed productive capabilities are the plant variants sown in spring after sunflower and without additional fertilization with nitrogen. With proved the biggest impact on grain yield per hectare is the date of sowing. The sources of variation: predecessor and combined effect of factors predecessor x fertilization show equal share of influence on the productivity of einkorn. The results from the study give science-based information on the most favorable time of sowing, fertilizing and predecessor in einkorn.

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 fertilizationwithout 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.