Traditional biochemical methods are resource- and time-consuming; therefore, there is a need for cost-effective alternatives. A spectral analysis is one of the non-destructive techniques that are more widely used for fruit quality determination; however, references are needed for traditional methods. In this study, visible and near-infrared (Vis-NIR) spectroscopy was used to analyze the internal quality attributes of tomatoes. For the first time, 80 varieties with large differences in fruit size, shape, color, and internal structure were used for an analysis. The aim of this study was to develop models suitable to predict a taste index, as well as the content of lycopene, flavonoids, β-carotene, total phenols, and dry matter of intact tomatoes based on Vis-NIR reflectance spectra. The content of phytochemicals was determined in 80 varieties of tomatoes. A total of 140 Vis-NIR reflectance spectra were obtained using the portable spectroradiometer RS-3500 (Spectral Evolution Inc.). Partial least squares regression (PLS) and multiple scatter correction (MSC) were used to develop calibration models. Our results indicated that PLS models with good prediction accuracies were obtained. The present study showed the high capability of Vis-NIR spectroscopy to determine the content of lycopene and dry matter of intact tomatoes with a determination coefficient of 0.90 for both parameters. A regression fit of ${\mathrm{R}}^2$= 0.86, ${\mathrm{R}}^2$= 0.84, ${\mathrm{R}}^2$= 0.82, and ${\mathrm{R}}^2= 0$.73 was also achieved for the taste index, flavonoids, β-carotene, and total phenols, respectively.

Proper selection of rootstock that is adapted to local growing conditions and climate is one of the most important preconditions for obtaining high yield in intensive plum orchards. The aim of the investigation was to evaluate the influence of different rootstocks on the productivity of two plum cultivars: ‘Kubanskaya Kometa’ (Prunus rossica. Erem.) and ‘Victoria’ (P. domestica L.) in different climatic conditions. The following sixteen rootstocks known in Europe were used in the trial: eight vegetatively propagated (‘St. Julien A’, ‘Brompton’, ‘Ackermann’, ‘Pixy’, ‘GF 8/1’, ‘G 5/22’, ‘GF 655/2’, ‘Hamyra’) and eight generatively propagated (‘St. Julien INRA2’, ‘St. Julien d’Orleans’, ‘St. Julien Noir’, ‘Brompton’, ‘Wangenheims Zwetsche’, ‘St. Julien Wädenswil’, ‘Myrobalan’, P. cerasifera var. divaricata). The evaluation was made in experimental orchards in Latvia, Estonia and Belarus. Orchards were established in spring 2001. Trees were planted at spacing 3 × 5 m in four replications, three trees per plot. The data obtained in years 2008-2015 are presented. The yield was influenced by rootstock and differed between years, growing regions and cultivars. The meteorological conditions during wintering period had significant influence on yield for trees on all evaluated rootstocks.

New types of fertilizers based on peat and sapropel were developed and can be used as solid and liquid forms of organic and organicmineral fertilizers and preparations for different crop cultivation. It was shown that use of SAPROAgro and SAPROЕlixir fertilizers increases productivity of agricultural plants by 9-16 %. Use of EleGum liquid humic microelement fertilizers provides an increase of winter wheat grain yield up to 0.88 t ha-1 , maize green mass up to 5.0 t ha-1 and maize grain to 2.06 t ha-1

The aim of the investigation is to evaluate the influence of different rootstocks on the flowering intensity of two plum cultivars: a hybrid `Kubanskaya Kometa` and European plum ‘Victoria’ in diverse locations. Sixteen well known European rootstocks were used, of which eight were clonal (St. Julien A, Brompton, Ackermann, Pixy, GF8/1, G5/22, GF655/2, Hamyra) and eight were seedlings (St. Julien INRA2, St. Julien d Orleans, St. Julien Noir, Brompton, Wangenheims Zwetche, St. Julien Wädenswil, Myrobalan, P. cerasifera var. divaricata). The evaluation was conducted in experimental orchards which were established in spring 2001 in Latvia, Estonia and Belarus. Trees were planted at a spacing of 5 × 3 m in four replications, three trees per plot. The obtained data from the years 2008-2012 are presented. The flowering intensity of plum trees depended on the cultivar rootstock combination. The influence of rootstock on flowering intensity differed between the years and growing region, and was closely correlates with meteorological conditions during the wintering period. Cv. ‘Kometa Kubanskaya’ had the highest blooming intensity in Pûre on rootstocks GF 655/2 and Wangenheims Zwetche; in Brest on Brompton seedlings, Julien d’ Orleans G5/22 and Ackermann; and in Polli on GF 8/1 and Brompton seedlings. ‘Victoria’ plum trees had the highest intensity of flowering on rootstocks Pixy and Wangenheims Zwetche in Pūre; on St. Julien INRA 2 and Ackermann in Brest; and on GF 655/2 and Ackermann in Polli.