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.
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).
D.J. Bilalis, I. Roussis, I. Kakabouki, and A. Folina. 2019. Quinoa (Chenopodium quinoa Willd.) crop under Mediterranean conditions: a review. Cien. Inv. Agr. 46(2): 51-68.Quinoa is a pseudocereal crop that is well adapted to a wide range of climatic conditions and has significant potential for increased production as a new crop in the Mediterranean region and in other parts of the world, including northern Europe, North America, Asia, and Africa. Because of its exceptional nutritional properties, quinoa is highly appreciated among humans as well as in animal nutrition for feeding both ruminants and nonruminating animals. Data obtained from several studies conducted in Greece, Italy, and Turkey demonstrate the high nutritional and functional potential of quinoa. Nitrogen fertilization has a positive effect on the growth and grain yield of quinoa crops. The biomass has high crude protein and low fiber and is competitive with alfalfa. The assessment of quinoa saponin content is of great importance for the industry. The highest saponin content and yield have been found under organic cropping systems. Oat, bean, and duckweed plants have a great phytotoxic response, especially to the inflorescence tissues of quinoa, confirming the potential allelopathic activity of this promising crop. The major part of the root system is concentrated in the upper 0-30 cm of the soil, and the root length density and root mass density increase with increasing applied nitrogen. In conclusion, quinoa may be suggested as a new alternative crop for semiarid and arid Mediterranean conditions affected by multiple abiotic stress factors because of its stresstolerant characteristics, adaptability to several agro-ecological conditions, and nutritional and economic value.
Quinoa is a gluten-free pseudocereal crop recognized for its exceptional nutritional properties. A 3-year field experiment was conducted to evaluate the influence of soil tillage and fertilization on root growth and productivity of quinoa. The experiment was laid out in a split-plot design with two replicates, two main plots [conventional (CT) and minimum tillage (MT)] and four sub-plots [fertilization treatments: untreated, inorganic fertilization with 100 (N1) and 200 kg N ha−1 (N2), and sheep manure]. Mean weight diameter (MWD) of soil aggregates, total porosity, organic matter and soil total nitrogen increased with the long-term fertilization with sheep manure. The major part of the roots (approximately 70%) is concentrated in the 0-30 cm soil layer. Root length density increased with increased rate of applied nitrogen, and a higher value (1.172 cm cm−3) was found in N2 plots. Additionally, higher root mass density (1.114 mg cm−3) was observed under MT. Plant height and dry weight were clearly affected by fertilization, with higher values obtained in N2 plots. Moreover, it was observed that quinoa cultivated under CT and N2 treatment produced a higher seed yield (2595 kg ha−1). As a conclusion, increasing the levels of applied nitrogen up to 200 kg N ha−1 improves root growth and consequently the yields of quinoa.
In order to define the finest cultivation practices for two of the most commercial hemp cultivars (‘Fedora 23’ and ‘Futura 75’) under the Mediterranean climate, the treatment of topping was applied in hemp crop in Central Greece. The object of the study was to assess if topping can increase the cannabidiol (CBD) production. In addition, the growth of the two cultivars was also investigated. Our results showed that the treatment of topping and cultivar affected the CBD content. The inflorescence compactness index and the number of nodes were affected by cultivar and topping. The number of inflorescences on secondary shoots was affected only by topping. The leaf area was affected by the interaction of cultivar and topping. The maximum height was recorded in un-topped Futura 75 plants, while the highest fresh and dry weight were found in topped Futura 75 plants. The total inflorescence dry matter was higher in topped plants.
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