Abstract: The aim of this experimental work was to evaluate the productivity and productivity compounds in tomato accessions grown under elevated temperature and reduced irrigation. The experiment was conducted at the Maritsa Vegetable Crops Research Institute with 25 tomato accessions (14 determinate and 11 indeterminate) in the period of 2016 and 2017. Two watering regimes were applied - optimum and 50% reduced. Productivity per plant, number of fruits per plant and average fruit weigh were measured. Environmental descriptors air temperature, air humidity, rainfalls and soil moisture at 15 and 30 cm depth were recorded by weather station Caipos Wave. As a result of reduced irrigation and high temperatures a decrease of the productivity per plant formed on the base of number and average fruit weight was observed. The studied indeterminate tomato accessions showed low heat tolerance compared to the determinate ones. Decrease of the productivity per plant with 25.2% close to the positive control was established in accession BG 985 from the determinate tomato for processing and with 35.5% in accession Spectar belonging to the determinate tomato for fresh consumption. A decrease of the productivity less than 50% was observed only in indeterminate tomato accession BG 21β (47.3%). The reduced irrigation and the high temperatures had a weaker negative effect on the fruit number (13.3-57.1%) and average fruit weight per plant (5.0-57.8%) compared to the productivity. Three-way analysis of variance showed that watering regime influenced mainly the productivity per plant in the three studied tomato groups, fruit number and average fruit weight per plant in determinate tomato for fresh consumption. Differences in number and average fruit weight per plant in determinate tomato for processing and indeterminate ones were determined by genotype. As a result of this study perspective tomato accessions suitable for breeding of drought stress were selected.
Keywords: solanum lycopersicum, high temperature, drought, fruit set