Nitrogen management strategy in plant growth period based on chlorophyll content evaluation in plant can improve nitrogen usage efficiency and reduce environmental contamination. This study is aimed to determine the impact of different nitrogen and sulphur fertilizers rates on dynamics of chlorophyll content in winter wheat during vegetative growth and to determine the relationship between nitrogen and chlorophyll content and grain yield of winter wheat. Field trial involving a winter wheat (Triticum aestivum L.) variety ‘Kranich’ was conducted at the LUA Research and Study Farm Vecauce during a three-year period (2012-2015). The treatments were 0, 85, 153, 175+S21, 175 (in 2015), 187 N kg haE−1 and different nitrogen norms according to chlorophyll meter Yara N-tester (Konica Minolta Ltd.) data: 180, 150, 205 N kg haE−1 depending on the year. The results of the trial show that the maximum chlorophyll content in different plant parts was observed at the end of flowering stage. The chlorophyll content depended on the level of mineral fertilisation. The highest chlorophyll content in leaves, stems and ears was obtained by using additional sulphur in two trial years. Usage of chlorophyll meter Yara N-tester obtained the highest chlorophyll content in all analysed plant parts in one trial year. Chlorophyll content was significantly dependant on plant growth stage in stems in all trial years, in leaves in two trial years, and in ears in one year. Nitrogen fertilization significantly affected chlorophyll content in leaves and stems in one trial year. Close positive correlation was observed between grain yield and wheat plant chlorophyll content and average nitrogen concentration at the end of flowering stage in all three trial years.

Climatic conditions for soybean cultivation in Latvia are challenging because of their variability. In addition, the sum of sunlight hours and the ratio of temperature and precipitation required to produce a quality crop are unpredictable. There is a risk that even early soybean varieties will not ripen due to weather conditions in a region. Studies show that soybean plants, including the green part of the crop, are well suited for animal nutrition prepared as hay or silage. The aim of this study was to evaluate the chemical composition of different soybean varieties harvested before ripening and assess them as hay or silage raw material. Weight, protein, fat, ash, fibre, acid detergent fibre (ADF) and neutral detergent fibre (NDF) of soybean varieties ‘Erica’, ‘Bolgar’ and ‘Viola’ green mass were determined at different stages of maturity. The results of the study showed a significant increase in protein (from 9.18% to 12.06%) and fat (from 1.18% to 4.40%) content of the dry matter variety ‘Bolgar’ from September to October. The protein content of the dry soya green mass was not affected by variety at the same developing stage but significantly changed among different stages of maturity. As the plant develops, the sucrose content in the green mass increases, the same as the total sugar content.