Physiological Aspects of Nitrogen Fertilizer Impact on Latvian Origin Cannabis Sativa L .

The aim of the present study was to evaluate nitrogen fertilizer impact on photosynthesis and yield of hemp, applying modern non-destructive methods. The main object of the investigation – hemp cultivar of Latvian origin ‘Pūriņi’. Laboratory and field experiments showed diverse effects of different nitrogen fertilizer doses on various parameters. Additional nitrogen fertilizer dose of 60 kg ha-1 is most effective as evaluated by chlorophyll content in hemp leaves and changes of chlorophyll a fluorescence parameters. Nitrogen fertilizer negatively affected fiber content in hemp stems, therefore while cultivating hemp only for fiber production use of nitrogen fertilizer should be reduced. According to the seed mass results, additional nitrogen fertilizer doses should be applied following the climatic conditions. In the vegetation period guided with higher rainfall levels, 60 kg of additional nitrogen fertilizer per hectare can be considered as optimal amount. In current investigation hempseed oil composition was not negatively affected by nitrogen fertilizer. Also significant difference between seed yield of N60 and N100 variants has not been observed. To avoid excessive nitrogen fertilizer usage, its negative impact on plant physiology and yield losses, we consider nitrogen fertilizer 60 kg ha-1 as additional fertilizer is optimal for hemp cultivar ‘Pūriņi’. yield