Effect of Nettle (Urtica dioca L.) density on fiber yield and quality in a natural ecosystem under East Mediterranean conditions

Nettle (Urtica dioica L.), a new industrial crop, has been cultivated since the 12th century for its fibers. This study was conducted to specify the optimal density of plants in order to move from wild harvest to nettle cultivation. For the present study, sampling was performed in 21 different fields throughout Greece, during October 2018. The effect of nine different plant densities on several agronomic (plants height, leaf area and dry matter) and fiber quality (straw length, fiber percentage, yield, extension at break, strength, length, diameter) characteristics was determined. The higher fiber yield occurred at the lower density (4 plants m2), while the higher fiber diameter observed at the highest density (12 plants m2). Comparisons were performed at the 5% level of significance (p ≤ 0.05). According to our results, there have been negative correlations between plant density and certain agronomic and quality characteristics such as plant height and fiber length, hence the optimal density is about seven plants per m2

Evaluation of Greenhouse Gas Emissions of Quinoa Seed Production in Greece

Population growth has led to an increase in food production, resulting in an increase in agricultural products in terms of quantity and quality. Quinoa (Chenopodium quinoa Willd.) cultivation is prevalent in most areas of the world due to its high-quality grain and its potential to produce high yields under tough growing conditions. This study aimed to investigate all greenhouse gas (GHG) emissions generated by quinoa seed production in Greece and their relationship with farm-related factors, from fertilizer production to energy consumption for all cultivation techniques. The amount of all GHG emissions was estimated using Cool Farm Tool software. In order to collect data, a questionnaire including questions regarding cultivation details, soil characteristics, inputs, fuel, and water use was distributed and completed by forty quinoa producers from Central Greece. Accordingly, the estimated carbon footprint values per hectare and per kilogram of quinoa seed were 1,159.65 and 0.48 kg CO2-eq, respectively. The present research also found that the highest CO2-eq emissions per kilogram of quinoa seed were found to be associated with the production of fertilizers, with a value of 0.20 kg CO2-eq corresponding to 40.88% of the total emissions per kilogram of produced seed. Consequently, attention must be given for the mitigation of the environmental impact of quinoa seed production. It is particularly important to manage chemical fertilizers and agricultural machinery properly in order to ensure the sustainable cultivation of quinoa

The effect of fertilization and sowing density on the quantitative and qualitative characteristics of black mustard oil (Brassica nigra (L), Koch) for medicinal use

The aim of the present study is the collection and the elaboration of data that are related to the best cultivation practices in terms of the effect of the different fertilizing interventions (Urea, Compost, Urea with inhibitors, Control) but also of the seeding density (46 plants m-2, 76 plants m-2), on the qualitative and quantitative characteristics of black mustard oil (Brassica nigra (L.) Koch) regarding its medicinal use. For this reason, a three-year cultivation was carried out (2019-2020, 2020-2021, 2021-2022), in the experimental field of the Agriculture Laboratory of the Agricultural University of Athens, with an area of 1,000 m2. Where plant agronomic traits (height, fresh and dry weight, leaf area index (LAI), number of inflorescences, number of pods, yield) were measured. In addition, the above-ground biomass of the plant was evaluated for its use as animal feed in addition to the analyzes carried out on the seed oil for its suitability for medicinal use. In addition, crop evaluation indices such as Growing Degree Days (AGDDs), harvest index (HI), nitrogen use efficiency index (NUtE), nitrogen harvest index (NHI), as well as nitrogen agricultural efficiency index (NAE) were calculated. Concluding, that the different fertilization interventions had statistically significant effects on the agronomic traits where the application of urea with inhibitors had the highest values and the low seeding density (46 plants m-2) resulted in the highest seed yields as well as the highest oil yields by 17.7% compared to the high plant density (76 plants m-2). In response to the quality characteristics of the seed oil and specifically to the fatty acid profile, it was recorded that with increasing plant density, a decrease in saturated (SAFA: myristic, palmitic and stearic acid) and polyunsaturated (PUFA) was observed. : linoleic, α-linolenic and eicosadenoic acid) fatty acids, while there was an increase in oleic and neuronic acids and a decrease in the remaining monounsaturated fatty acids (MUFA: vaccenic, cis-11-eicosenoic and erucic acid). In conclusion, plant densities higher than 46 plants m-2 result in lower seed yield, oil content and oil yield, while the effect of inorganic fertilization, especially with urea with dual inhibitors, was equally significant on seed and oil yield. However, when the seed and/or oil are used for their nutritional and medicinal value, composting is recommended, resulting in a significant increase in polyunsaturated fatty acid (PUFA) content. Also, regarding the evaluation of the plant as feedstuff, NDF ( Neutral Detergent Fiber) and ADF (Acid Detergent Fiber) were not affected by plant density. However, there were significant differences between fertilization interventions. The highest ADF and NDF contents in above-ground biomass were found in compost and urea with dual inhibitors. The highest ADF and NDF contents in above-ground biomass were found in compost and urea with dual inhibitors. The high content of ADF, NDF and relatively high content of CP (Crude Protein) characterized in the above-ground biomass of black mustard can meet the requirements of lactating animals and therefore the production of black mustard biomass as a fodder crop could be of great importance. In conclusion, black mustard grown at plant densities higher than 46 plants m−2 and under inorganic fertilization, especially urea with dual inhibitors, could be successfully used as a new forage crop in ruminant nutrition.Σκοπός της παρούσας Διδακτορικής διατριβής είναι η συλλογή και επεξεργασία όλων εκείνων των χαρακτηριστικών που θα οδηγήσουν στις βέλτιστες καλλιεργητικές πρακτικές όσον αφορά την επίδραση των διαφορετικών επεμβάσεων λίπανσης (Ουρία, κομπόστ, ουρία με αναστολείς νιτροποίησης και ουρεάσης, μάρτυρας) αλλά και της πυκνότητας σποράς (46 φυτά m-2, 76 φυτά m-2), στα ποιοτικά και ποσοτικά χαρακτηριστικά του λαδιού του μαύρου σιναπιού (Brassica nigra (L.) Koch) όσον αφορά την φαρμακευτική χρήση αυτού. Για τον λόγο αυτό, πραγματοποιήθηκε τριετής καλλιέργεια (2019-2020, 2020-2021, 2021-2022), στον πειραματικό αγρό του εργαστηρίου Γεωργίας του Γεωπονικού Πανεπιστημίου Αθηνών, έκτασης 1.000 m2. Όπου έλαβαν χώρα μετρήσεις που αφορούσαν τα αγρονομικά χαρακτηριστικά του φυτού (ύψος, νωπό και ξηρό βάρος, δείκτης φυλλικής επιφάνειας (LAI), αριθμός ταξιανθιών, αριθμός λοβών, απόδοση). Επιπλέον, αξιολογήθηκε το υπέργειο μέρος του φυτού για την χρήση του ως κτηνοτροφή πέρα από τις αναλύσεις που πραγματοποιήθηκαν στο έλαιο του σπόρου για την καταλληλότητα του για φαρμακευτική χρήση. Επιπροσθέτως, υπολογίστηκαν δείκτες εκτίμησης της καλλιέργειας όπως είναι οι βαθμοημέρες (AGDDs), ο δείκτης συγκομιδής (HI), ο δείκτης αποτελεσματικότητας χρήσης αζώτου (NUtE), ο δείκτης συγκομιδής αζώτου (NHI), καθώς και ο δείκτης αζωτούχος γεωργικής αποτελεσματικότητας (NAE). Καταλήγοντας, ότι οι διαφορετικές επεμβάσεις λίπανσης είχαν στατιστικά σημαντικές επιπτώσεις στα αγρονομικά χαρακτηριστικά όπου η εφαρμογή της ουρίας με αναστολείς είχε τις υψηλότερες τιμές και η χαμηλή πυκνότητα σποράς (46 φυτά m-2) είχε ως αποτέλεσμα τις μεγαλύτερες αποδόσεις σπόρου καθώς και τις υψηλότερες αποδόσεις λαδιού κατά 17,7% συγκριτικά με την υψηλή πυκνότητα των φυτών (76 φυτά m-2). Ως απάντηση στα ποιοτικά χαρακτηριστικά του ελαίου και συγκεκριμένα με το προφίλ των λιπαρών οξέων, καταγράφηκε ότι με την αύξηση της πυκνότητας των φυτών, παρατηρήθηκε μείωση των κορεσμένων (SAFA: μυριστικό, παλμιτικό και στεατικό οξύ) και των πολυακόρεστων (PUFA). : λινολεϊκό, α-λινολενικό και εικοσαδενοϊκό οξύ) λιπαρά οξέα, ενώ υπήρξε αύξηση στα ελαϊκά και νευρονικά οξέα και μείωση στα υπόλοιπα μονοακόρεστα λιπαρά οξέα (MUFA: vaccenic, cis-11-eicosenoic και erucic acid). Συμπερασματικά, πυκνότητες φυτών υψηλότερες από 46 φυτά m-2 έχουν ως αποτέλεσμα χαμηλότερη απόδοση σπόρων, περιεκτικότητα σε λάδι και απόδοση ελαίου, ενώ το αποτέλεσμα ανόργανης λίπανσης, ειδικά με ουρία με διπλούς αναστολείς, ήταν εξίσου σημαντική στην απόδοση σπόρων και ελαίων. Ωστόσο, όταν ο σπόρος και/ή το λάδι χρησιμοποιούνται για τη θρεπτική και φαρμακευτική τους αξία, συνιστάται η χρήση κομπόστ, με αποτέλεσμα τη σημαντική αύξηση της περιεκτικότητας σε πολυακόρεστα λιπαρά οξέα (PUFA). Επίσης, όσον αφορά την αξιολόγηση του φυτού ως κτηνοτροφή το NDF (Neutral Detergent Fiber) και το ADF (Acid Detergent Fiber) δεν επηρεάστηκαν από την πυκνότητα των φυτών. Ωστόσο, υπήρχαν σημαντικές διαφορές μεταξύ των επεμβάσεων λίπανσης. Οι υψηλότερες περιεκτικότητες ADF και NDF στην υπέργεια βιομάζα βρέθηκαν σε κομπόστ και στην ουρία με διπλούς αναστολείς. Η υψηλή περιεκτικότητα σε ADF, NDF και σχετικά υψηλή περιεκτικότητα σε CP (Crude Protein) που χαρακτηρίζεται στην υπέργεια βιομάζα της μαύρης μουστάρδας μπορεί να καλύψει τις απαιτήσεις των θηλαζόντων ζώων και επομένως η παραγωγή βιομάζας μαύρης μουστάρδας ως κτηνοτροφική καλλιέργεια θα μπορούσε να είναι μεγάλης σημασίας. Συμπερασματικά, η μαύρη μουστάρδα που καλλιεργείται σε πυκνότητες φυτών υψηλότερες από 46 φυτά m−2 και υπό ανόργανη λίπανση, ειδικά με ουρία με διπλούς αναστολείς, θα μπορούσε να χρησιμοποιηθεί με επιτυχία ως νέα κτηνοτροφική καλλιέργεια στη διατροφή των μηρυκαστικών

Effect of organic and inorganic fertilization on weed flora and seed yield in black mustard [Brassica nigra (L.) Koch] crops

Crop production practices affect weed communities in agricultural systems. Field experiments were conducted to determine the effects of organic and inorganic fertilization on weed flora and seed yield in black mustard [Brassica nigra (L.) Koch] crops. The experiments, conducted at two sites (Athens and Agrinio, Greece) during 2019, were laid out in a randomized complete block design with three replicates and three fertilization treatments (untreated, compost fertilizer and inorganic fertilizer). The results of the present study indicated that the total weed density and biomass in the black mustard crops were significantly influenced by fertilization. The highest leaf area index (4.76-4.84 m2 m-2) and canopy interception of incident photosynthetically active radiation (PAR) (93.56-94.98%) were observed under inorganic fertilization at 90 days after sowing. At both experimental sites, the total weed density and biomass were significantly higher under inorganic fertilizer treatment at 45 DAS. The highest densities of the weed species Sinapis arvensis, Chenopodium album and Malva sylvestris were found in the plots treated with inorganic fertilizer. The seed yield was also affected by fertilization, with the highest values (1352-1456 kg ha-1) observed in the plots treated with inorganic fertilizer. In conclusion, the different fertilization practices affected both the weed density and weed biomass; in particular, inorganic fertilization led to the development of he highest weed density. Furthermore, the highest seed yields were recorded under inorganic fertilization in both the experimental areas

Evaluation of yield and nitrogen utilisation with urease and nitrification inhibitors in sweet potato crop (Ipomoea batatas L.)

Sweet potato (Ipomoea batatas L.) is a new tuber crop grown in Greece. It constitutes an innovative dietary component for both humans and animals, due to its nutritional properties. The cultivation of sweet potato focuses on the growth of both tubers and plants. Nitrogen is considered an essential element for almost all crops. This study set out to compare the effect of nitrogen inhibitors on yield components of sweet potato. In the literature, it is stated that in sweet potato cultivation nitrogen mainly affects the plants’ growth such as the tuber's yield and some quality characteristics such as dry matter and protein content. To furthermore explore this particular area, field experiments took place in West Greece, during the years 2018 and 2019. Several urea combination treatments were used in the experimental process. The treatments were urea (46-0-0), urea with urease inhibitor (UI), urea with nitrification inhibitor (NI), urea with double inhibitors (UI + NI) and control (without fertilizer) in a randomised complete block design. Leaf area index (LAI) was significantly affected by the fertilizer marking the highest value of 5.35 under urea + UI + NI treatment. Marketable yield was profoundly affected by the fertilizer in the experimental years and ranged from 18,180 to 23,230 Kg · ha−1 whereas non-marketable yield was not affected by the fertilizer. A considerable impact of fertilizers was noticed on yield where the highest value was 30,923 Kg · ha−1 under urea + NI + UI treatment. The percentage of nitrogen on tubers and upper parts was significantly affected by the fertilizers. Nitrogen markers, such as nitrogen use efficiency (NUE), nitrogen harvest index and nitrogen agronomic efficiency (NAE), were used to evaluate nitrogen release. A significant positive correlation was noticed between marketable yield and NUE (0.774). Also, the significant increase in yield showed a positive correlation with NAE (0.727). For yield components of sweet potato, the highest values were observed in urea with double inhibitors treatment in both experimental years