Nitrogen (N) management remains a global challenge for the sustainability of diversified farming systems. Field crops are often over-supplied with nitrogen by farmers aiming to high productivity. Although the increase of nitrogen rates leads in many instances to high yields, degree of effectiveness for nitrogen use remains low. Urease and nitrification inhibitors are technologies which have been present in the fertilizers market at least 50 years. Inhibitors exploitation ensures long-term nitrogen release and improved N-uptake by plants and N-storage in seeds and silage. Avail of inhibitors, such as the decline of nitrogen leaching in form of NO₃⁻, reduction of emissions in NH₃ form, and rise of yield, are some of the desirable attributes that are derived from their integration in fertilization schedules. This review reports the evaluation of applied nitrogen, with inhibitors, and field crops based on nitrogen indices. The examined N-indicators include Nitrogen use efficiency (NUE), Nitrogen Utilization Efficiency (NUtE,) Nitrogen Agronomic Efficiency (NAE), Nitrogen Harvest Index (NHI), and N uptake. This review gathered all, to the best of our knowledge, available data regarding the utilization of nitrification and urease inhibitors under an exclusively agronomic perspective. Either dual or single use of nitrification and urease inhibitors has been reported to significantly increase yield components and promote nitrogen uptake. To conclude, the assessment of N-related indices is vital to promoting sustainability in diversified farming systems, while the integration of inhibitors in national N fertilizations schemes may contribute to system profitability through enhancement of N-supply to crops.

Development of high yielding and stable cultivars of various legume crops across different environments is very important for their adoption by farmers. In addition, climate change sets new challenges to major crop species and especially to grain legumes such as faba bean (Vicia faba L.) for adaptation to stressful environments. The present study focused on evaluating faba bean genotypes developed for yield and stability across different environments. The study was conducted in three areas of Greece (South, Central, and North) for two consecutive growing seasons (2018–2019 and 2019–2020). Biomass yield, seed yield, and yield components were studied together with plant height, earliness, and water use efficiency. Genotype, environment, and their interaction affected most of the studied characteristics. The environment was the major source of variation for most of the characteristics, as it explained 81–93% of total variation, and only in the thousand seed weight the variation was 49% for the environment and 40% for the genotype. Genotype had a much smaller effect on the remaining characteristics (1.2–3.9%), and the interaction between environment x genotype accounted for up to 0.5–17% of the variation. GGE-biplot analysis for high yield and stability across different environments revealed three genotypic types: genotypes well adapted either for biomass or seed yield and genotypes with high adaptation capacity for both traits under typical Mediterranean conditions. These results indicated that screening faba bean genotypes under different environmental field conditions is essential to identify adaptable cultivars to be cultivated for biomass and/or seed yield or to be used in breeding programs.

Trichoderma harzianum, as a natural endophytic biocontrol agent, can ameliorate plant development, nutrient uptake, and resistance to biotic and abiotic stresses. This study aimed to investigate the effect of Trichoderma harzianum inoculation on agronomical and quality characteristics of two monoecious hemp (Cannabis sativa L.) varieties, Fedora 17 and Felina. A greenhouse pot experiment was conducted in a completely randomized design of two treatments of Trichoderma harzianum with a low and high dose of the fungus (T1 and T2). The significance of differences between treatments was estimated by using a Fisher’s test with a significance level p = 0.05. The root density of both varieties was significantly affected by treatments, and higher values were recorded in Fedora 17 (2.32 mm cm⁻³). The Arbuscular Mycorrhizal Fungi (AMF) colonization of the root system and the soil emission of CO₂ were higher after the inoculation of Trichoderma harzianum. The highest values of plant height and dry weight were noticed for T2, especially in variety Felina. Trichoderma harzianum positively influenced characteristics of inflorescences such as their number, fresh weight moisture, and compactness in both varieties, while the dry weight, length, and dry yield of inflorescences were not improved. Finally, the fertigation of Trichoderma harzianum in hemp plants was beneficial by increasing the cannabidiol (CBD) content, especially in T2 treatment (4 × 10¹² CFU kg⁻¹).

Field experiments were conducted during 2019 in two different locations in Greece (Athens and Farsala) to evaluate the effect of urea and urea fertilization with inhibitors on the agronomic yield and quality characteristics of two cannabis varieties (Cannabis sativa L.), “Uso31”and “Fedora 17”. The experimental design was split-plot with four different fertilization treatments—control, Urea (U), urea with Urease Inhibitor (UI), and urea with Nitrification Inhibitor (NI) and urease inhibitor (UI). The significance of differences between treatments was estimated by using Tukey’s test with a significance level of p = 0.05. The plant height was significantly affected by the different fertilizations and different varieties as well as by the two locations. The maximum plant height was 197 cm for “Fedora 17”in Farsala. The seed yield was higher forthe urea with inhibitors treatment in both varieties. The Cannabidiol (CBD) content was significantly affected by the fertilization—it was higher in urea with inhibitors in “Uso31”and “Fedora 17” treatments. The lowest CBD content value was 1.29% (control) and the highest was 1.69% (urea NI + UI). In conclusion, in both varieties, it seems that urea with inhibitors has a positive effect on their growth, as well as on the increase in cannabidiol (CBD) content.

Vicia sativa L. (common vetch) is an annual legume species of high economic and ecological importance which is characterized by high nutritive value for animal feeding and its ability to adapt to various edaphic–climatic conditions. However, limited information is available about genotypic and environmental effects on agronomic, nutritional, and antinutritional traits of common vetch genotypes. Thus, in the present study, four advanced breeding lines and three commercial cultivars were evaluated for yield biomass, color assessment, fiber, crude protein (CP), and polyphenols in three locations (Spata, Larissa, and Thessaloniki) for two consecutive growing seasons (2018–2019 and 2019–2020). The effects of genotype, environment and their interaction (GXE) were significant for all the studied traits. The main source of variation for yield, color, CP, and polyphenols was the environment as it explained 71.5–89.7% of the total variation, whereas for the fibers content it was the GXE interaction. On the other hand, genotype had a much smaller effect on all the traits studied (2.9–16.6%). According to GGE biplot analysis, the ‘Alexandros’ cultivar was the most high-yielding and stable, whereas ‘Leonidas’ was the best performing in terms of nutritional and antinutritional traits. However, one advanced line combined high and stable yield biomass with high nutritive value, indicating the possibility for simultaneous improvement of both features.