The yield capacity of cereal-legume grass mixtures with two or three times mowing

the article is devoted to the research of botanical composition, plant density and yield capacity of single-species and mixed grasslands for the 25th year of use. According to the results of experimental data, the two times mowing management is recommended for old-age grasslands.

A Semi-Automated Method to Extract Green and Non-Photosynthetic Vegetation Cover from RGB Images in Mixed Grasslands

Green (GV) and non-photosynthetic vegetation (NPV) cover are both important biophysical parameters for grassland research. The current methodology for cover estimation, including subjective visual estimation and digital image analysis, requires human intervention, lacks automation, batch processing capabilities and extraction accuracy. Therefore, this study proposed to develop a method to quantify both GV and standing dead matter (SDM) fraction cover from field-taken digital RGB images with semi-automated batch processing capabilities (i.e., written as a python script) for mixed grasslands with more complex background information including litter, moss, lichen, rocks and soil. The results show that the GV cover extracted by the method developed in this study is superior to that by subjective visual estimation based on the linear relation with normalized vegetation index (NDVI) calculated from field measured hyper-spectra (R2 = 0.846, p < 0.001 for GV cover estimated from RGB images; R2 = 0.711, p < 0.001 for subjective visual estimated GV cover). The results also show that the developed method has great potential to estimate SDM cover with limited effects of light colored understory components including litter, soil crust and bare soil. In addition, the results of this study indicate that subjective visual estimation tends to estimate higher cover for both GV and SDM compared to that estimated from RGB images.

YIELD AND BOTANICAL COMPOSITION OF BIRD'S-FOOT-TREFOIL CULTIVARS IN TWO-COMPONENT MIXTURE WITH KENTHUCKY BLUEGRASS

PURPOSE of the experiment is to study the influence of bird's-foot-trefoil cultivars of different origins over the productivity and quality of forage when they are grown together with Kenthucky bluegrass. METHODS: In the period of 2013-2015, in the experimental field of RIMSA-Troyan the productivity and botanical composition of bird's-foot-trefoil cultivars were studied, such as 'Targovishte 1', 'Delpon' (France), 'Fabio' (Italy), 'Haki' (Hungary), 'Vega' (USA) in two-component mixtures with Kenthucky bluegrass ('Sobra' cultivar). RESULTS: The share of sown species and cultivars in the mixed grasslands of bird's-foot-trefoil and Kenthucky bluegrass depends on their biological characteristics, combined with the climatic and soil characteristics of the area. 'Fabio' cultivar shows the most pronounced adaptability to the soil climatic conditions of the region compared to all other bird's-foot-trefoil cultivar. CONCLUSIONS: For the conditions of the Central Balkan Mountain, It is recommended to use the two-component mixture: bird's-foot-trefoil ('Delpon') and Kenthucky bluegrass ('Sobra'), which has the best intercompatibility and the most favourable combination of grass and legume component. The latter cultivar in the mixture recorded the highest average yields (650.37 kg/da dry weight) for the three-year study period, compared to other cultivars included in the experiment.

GROWTH AND DEVELOPMENT OF LEGUME AND GRASS COMPONENTS IN MIXED GRASSLANDS GROWN IN THE CENTRAL BALKAN MOUNTAIN

PURPOSE of the present study is to establish the growth, development and competitiveness of grass and legume components in mixed grasslands grown under the conditions of the Central Balkan Mountains. METHODS: In the spring of 2014-2016, the growth and development of typical meadow legumes and grass species for that region were observed in the experimental field of RIMSA - Troyan, in double mixtures: 1. Bird's-foot-trefoil - Red fescue; 2. White clover - Perennial ryegrass; 3. White clover - Kentucky bluegrass; 4. Red clover - Timothy-grass; 5. Blue hybrid alfalfa - Cock's foot; 6. Red clover - Meadow fescue. RESULTS: From all grass crops - Dactylis glomerata L. has the most pronounced competitive ability with respect to the biometric height indicator of plants, while Poa pratensis L. has the slightest one. For the three-year study period, Trifolium repens L. in its mixture with Lolium perenne L. recorded the lowest average growth values compared to the other legumes included in the experiment. CONCLUSIONS: The best intercompatibility and, respectively, the most favorable combination of grass and legume components is found between Trifolium pratense L. and Festuca pratensis L., and the weakest among the components in the blue hybrid alfalfa - cock's foot mixture. The length of the flower-bearing stems and leaf stalks of Trifolium pratense L. in the mixed grassland with meadow fescue have higher values (41.8:89.0 cm) and those with timothy-grass are lower (38.1:52.5 cm).