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.

Legume seed inoculation prior to sowing is a well-known practice in agriculture. Nitrogen fixation, due to the symbiotic relationship between legumes and rhizobia, improves the productivity of legumes. Rhizobia strain specificity can be observed very often, leading to differences in the total protein content. In this study two faba bean cultivars (‘Karmazyn’ and ‘Bartek’) and five pea cultivars (‘Retrija’, ‘Zaiga’, ‘Lāsma’, ‘Vitra’ and ‘Bartek’) were tested using various rhizobia strains. In addition, strain effectivity was observed in four different soil types. Overall, the protein content increase was observed after seed inoculation with Rhizobium sp. Rhizobia strain and plant cultivar interaction specification was observed. Plant cultivar appeared to have a decisive role in the formation of protein content when inoculated with Rhizobium sp. From these pilot experiments, it can be concluded that, when choosing Rhizobium sp. strains for legume inoculation, soil type also should be considered. Rhizobia has the potential to be used as a commercial preparation intended for increasing legume protein content, alongside with increased legume yield; however, different rhizobia strains should be mixed together to achieve the optimal result.