Purpose. Jute mallow (Corchorus olitorius L.) is a mucilaginous vegetable and fiber crop cultivated in the tropics, where catnip (Nepeta cataria L.) and Mexican sunflower (Tithonia diversifolia L.) are common weeds. Hence, the study investigated the growth, yield, and nutrient level of jute mallow in weed-free, catnip, and Mexican sunflower environments. Methods. The study involved two screen-house experiments in a Completely Randomized Design (CRD) with six replications. The treatments were 0 (control), 2, 4, 6, 8, and 10 weed plants per pot in both experiments. These are 0, 100, 200, 300, 400, and 500 weed count per square meter equivalent, based on the surface area of the pots used. Mexican sunflower and catnip plants interacted with jute plants in the first and second experiments, respectively. Growth parameters of jute mallow were recorded weekly from 5 to 8 weeks after sowing (WAS), and harvesting was done at 8 WAS. The proximate composition of jute was evaluated using standard procedures outlined by AOAC. The data collected were subjected to analysis of variance (ANOVA), and means were separated using Duncan Multiple Range Test (DMRT) at P < 0.05. Results. Catnip and Mexican sunflower negatively impacted the morphological features of jute mallow from 100 plants per square meter upwards. Catnip and Mexican sunflower, at 300 and 100–500 plants per square meter, respectively, reduced the dry weight of jute mallow. The crude protein content of jute mallow was also lessened by Mexican sunflower at some point. Conclusions. The study recommends that the density of catnip and Mexican sunflower plants interacting with jute mallow should be maintained below 100 plants per square meter to prevent yield loss.

Purpose. To determine the features of the leaf surface area formation and the dynamics of growth of the vege­tative mass of various sainfoin species depending on the influence of mineral fertilizers and inoculation. Methods. Field, laboratory, statistical. Results. In the course of experimental studies, the morphological features of plants in the process of growth and development of various sainfoin species were studied. As our studies showed, all sainfoin species had different plant densities, which accordingly affected the leaf surface area. In the budding phase, the leaf surface area of plants of the first year in continuous cultivation ranged from 17.01 to 24.3 thousand m2/ha on average over three years; in particular, from 18.06 to 24.3 – for common sainfoin; 17.6–20.5 – for transcaucasus sainfoin and 17.1–20.3 thousand m2/ha – for sand sainfoin. The maximum leaf surface area of the plants of the first year of cultivation, regardless of its species, was observed during flowering with the application of complete mineral fertilizer (N45P60K90). In areas without fertilizer this figure was much lower. In the experiments, an increase in the leaf surface on all three studied species and sainfoin varieties from the first to the third year of their cultivation was clearly observed. According to the results of gross productivity for 2 mowings, it was found that common sainfoin forms the maximum increase of top with complete mineral fertilizer and seed inoculation – 43.03 t/ha. Conclusions. The productivity of sainfoin crops depended mostly on the application of complete fertilizer at a dose of N45P60K90 + inoculation of seeds. To a much lesser extent, the species of sainfoin and the cutting height of the first mowing of the grass stand affected its productivity. It was revealed that the greatest dynamics of vegetative mass growth was observed in common sainfoin, and the smallest was recorded in sand sainfoin.

Purpose. To study the influence of fractional composition of seed material on productive properties of spring rape seeds of the ‘Magnat’ variety and ‘MVM’ (‘Gladiator’) variety sample. Methods. Field investigations, laboratory tests, statistical analysis. Results. During 2013–2014, the influence of sown seeds of different size fractions (up to 2,5 g; 2,6–3,5 g; 3,6 g and more) on the indices of productivity of spring rape varie­ties was studied. It was found that over the years of study field germination of sown fractions of seeds in ‘Magnat’ variety averaged 83.5%, in ‘MSM’ variety sample – 86.7%. During the periods of seedling emergence and harvesting, the density of spring rape crops varied depending on relevant fraction of sown seeds. In the ‘Magnat’ variety, photosynthetic potential of crops ranged from 1.1 to 1.3 million m2/ha, in ‘MSM’ variety sample – from 1.2 to 1.6 million m2/ha. Depending on the seed fractions applied, ‘Magnat’ variety crops during the gro­wing season accumulated organic biomass from 2.05 to 2.36 g/m2 per day, ‘MSM’ sample variety – from 1.83 to 2.10 g/m2 per day. Conclusions. It was established that different fractions of spring rape seeds sown in the Northern Forest-Steppe zone of Ukraine affected the indices of germinating energy and laboratory germination, crop density formation, leaf surface area and intensity of photosynthesis process (crop photosynthetic potential, net photosynthesis performance). The highest indices of productivity and yield in the ‘Magnat’ variety was ensured by large-seeded fraction (3,6 g and more), in the ‘MVM’ (‘Gladia­tor’) sample variety – by small-seeded fraction (up to 2,5 g).

Purpose. To establish the optimal seeding time and depth of ‘Dniprovskyi 39’ and ‘Vinets’ sorghum varieties, to prove their effect on the crop photosynthetic capacity in the Right-Bank Forest-Steppe of Ukraine. Methods. Field, laboratory, comparative, analytical, generalizing, mathematical and statistical. Results. It was proved that the best results of crop photosynthetic capacity of sorghum were obtained by sowing in the first decade of May (the second sowing period) at a seeding depth of 4–6 cm. Accordingly, the leaf surface area in these variants reached its maximum during the “panicle-blooming” period and equated 36.13–38.81 thousand m2/ha for the ‘Dniprovskyi 39’ variety and 34.23–36.91 thousand m2/ha for the ‘Vinets’ variety. By sowing seeds in the third decade of April (the first sowing period) at the seedining depth values described above the leaf surface area of the varieties was slightly smaller and amounted to 29.56–31.20 thousand m2/ha for the ‘Dniprovskyi 39’ variety and 27.76–29.40 thousand m2/ha for the ‘Vinets’ variety. By sowing seeds in the second decade of May (the third sowing period), the leaf surface area was 30.68–32.92 thousand m2/ha for the ‘Dniprovskyi 39’ variety and 29.08–31.32 thousand m2/ha for the ‘Vinets’ variety. The highest photosynthetic potential was obtained for sorghum plants in the second sowing period at the seeding depth of 4–6 cm and was 1.27 and 1.34 million m2/ha for the ‘Dniprovskyi 39’ variety and 1.16 and 1.22 million m2/ha for the variety ‘Vinets’. In the first sowing period, this indicator was slightly lower and amounted to 1.18 and 1.23 million m2/ha for the ‘Dniprovskyi 39’ variety and 0.98 and 1.02 million m2/ha for the ‘Vinets’ variety respectively. In the third sowing period, it was the smallest one and equated 1.09 and 1.13 million m2/ha for the ‘Dniprovskyi 39’ variety, and 0.88 and 0.93 million m2/ha for the ‘Vinets’ variety at the optimal seeding depth. The photosynthetic potential was lower at the seeding depth of 2 and 8 cm, which is explained by the different soil and climatic parameters during a certain period of sorghum plant vegetation. The highest value of the photosynthetic capacity net indicator was obtained by sowing seeds at the optimal time and the optimal seeding depth and it equated 3.84–4.02 g/m2 per day for the ‘Dniprovskyi 39’ variety and 3.79 – 3.98 g/m2 per day for the ‘Vinets’ variety. Conclusions. It has been established that the sorghum plants had better vegetation and formed photosynthetic capacity by sowing seeds in the first decade of May at the planting depth of 4–6 cm, which we recommend for growing this crop in the Right-Bank Forest-Steppe of Ukraine.