Organic versus mineral fertilization: Assessing of yield and quality of durum wheat in marginal lands

Durum wheat is often cultivated in marginal areas with great management difficulties. Organic fertilization is a sustainable agricultural practice that allows preserving the environment, but its limit can be the reduction of yield and quality of crops, also in cereals. The aim of research was to evaluate the effects of the organic fertilization on yield and quality of Simeto, a variety of durum wheat, cultivated for two years in three different sites of the internal hill of Campania Region (San Giorgio la Molara, SGM; Ariano Irpino, AI; Sant’Angelo dei Lombardi, SAL). SGM was a sandy-clay-loam soil, with high fertility, while AI and SAL were clay soil. The organic fertilization (ORG), based on roasted leather, was compared to mineral fertilization (MIN) and the not fertilized treatment (N0). In SGM, crop growth rate (CGR) and leaf area index (LAI) were significantly higher than AI and SAL until the flowering (about 2-and 4-fold more, respectively). MIN and ORG significantly boosted CGR compared to N0, while for LAI, ORG was never different from N0. The two-years value of yield was 3.0 t ha–1; in SGM, it reached 4.2 t ha–1, and it was 54.6% more than the mean value of AI and SAL, while N0 was not different from MIN of AI and SAL. ORG yield was lower and not different from NO in AI, where the lowest values of 1000 kernels weight, and hectolitre weight were also recorded. MIN and ORG increased the number of spikes per square meter: 27.0%, and 12.8% over N0, respectively, but ORG showed an 11.2% decrease compared to MIN. The 1000 kernels weight reached the highest values in SAL, without differences between N0, MIN, and ORG. The values of protein and gluten percentage were highest in AI and SGM (about 13.5%, and 11.7%, respectively), but without differences between ORG and MIN in the 3 sites for protein percentage. The worst value of the vitreousness was recorded in SAL (52.3%), six-fold more than that of AI (8.2%), probably due to the high rainfall. NUE reached the highest value in SGM in the first year, when it was significantly different from AI and SAL (0.036 vs 0.030 t kg–1). Overall, the effect of nitrogen fertilization type results site-specific; indeed, organic fertilization had the same performance of mineral in the site with better soil (low clay content, high nitrogen, and organic matter content) and climate conditions

Biodegradable mulching vs traditional polyethylene film for sustainable solarization: Chemical properties and microbial community response to soil management

Abstract Soil solarization is usually performed with polyethylene plastic films, which are often disposed of by taking them to landfills, burying them in soil, burning them or occasionally recycling them, and these approaches have a great impact on the environment. Therefore, the use of biodegradable films seems to be an interesting eco-sustainable alternative to traditional films. The effect of soil solarization carried out by using biodegradable mulch or traditional polyethylene plastic film was determined under greenhouse conditions. The response of the soil was assessed by chemical determinations and microbiological culture-dependent and culture-independent approaches to evaluate the microbial biodiversity, biological status and quality of the soil. The biodegradable film avoided a high ammonia concentration in the soil, thanks to both lower soil water content and slightly lower temperature than polyethylene film, and these conditions probably have been optimal for growth of nitrifying bacteria, which were more efficient in BIO, as highlighted not only by lower ammonia value but also by higher nitrate value. Both films did not affect organic matter and total nitrogen content. Moreover, the modifications of the environmental and ecological conditions associated with the different film covers applied to the soils affected prokaryotic and eukaryotic populations, leading to the establishment of a new dominant microbial community. Interestingly, microbiological analyses highlighted a different behavior modulated with the two films indicating different times of recovery post stress. Overall, the results highlighted the potential of biodegradable film that appears to be a suitable replacement for traditional polyethylene plastic film for soil solarization, with great environmental benefits

Agronomic and environmental benefits of ‘re-using’ a biodegradable mulching film for two consecutive lettuce cycles

Biodegradable films are a valuable and sustainable alternative to plastic films for mulching soils since they avoid the environmental and economic problems related to plastic removal and dis posal. Nevertheless, the fast degradation of such materials could make them unsuitable for mid-to long-term use. In a field experiment, the agronomic performance of a biodegradable mulching film (MB) was compared to that of conventional low-density polyethylene (LDPE) film for two consecutive lettuce cycles (winter and spring). In the conditions of this trial, MB showed good resistance to atmospheric agents, with a reduction of its integrity and mechanical properties only after six months. The effects on soil temperature and lettuce yield did not differ from those obtained with LDPE films. The effect on harvest timing was the same as that with LDPE in the spring cycle, while in the winter cycle, the harvest was delayed by about five days compared to LDPE. Mulching films reduced nitrate accumulation in leaves mainly during the winter cycle. However, the effect needs to be further explored with experiments in different pedoclimatic conditions that consider the effects of mulching on nitrification and nitrate-reductase activity that could be affected by changes in soil temperature and moisture

Phytochemical Responses to Salt Stress in Red and Green Baby Leaf Lettuce (Lactuca sativa L.) Varieties Grown in a Floating Hydroponic Module

Lettuce (Lactuca sativa L.) is one of the most popular leafy vegetables, appreciated globally as a low-calorie food with bioactive compounds. The application of a low dose of abiotic stress is considered a sustainable pre-harvest strategy to modify the nutraceutical value of horticultural products. In this work, we explored the response of two differently colored (red or green) baby leaf lettuce varieties to four NaCl concentrations in the nutrient solution (from 1 to 30 mM), using a full factorial design. We focused on leaf morphological parameters and possible phytochemical enhancement of the main polyphenols and anthocyanins, analyzed by LC-MS. The response to low-to-moderate salt stress exposure was affected mainly by salt concentration for leaf traits or by the cultivar for leaf color, with very limited factors' interactions. Multivariate analysis indicated a predominant role of the genotypic factor in shaping differences in the two weeks growing cycle for baby leaf lettuce. Phytochemically, different dose–response models to sub-optimal saline conditions may be applied to the various compounds. A significant hormetic stimulation was present only for cyanidin-malonyl glucoside, the main anthocyanin present in the red cultivar

Municipal organic waste compost replaces mineral fertilization in the horticultural cropping systems, reducing the pollution risk

Municipal waste compost was evaluated under open field conditions for replacing synthetic fertilizers in a vegetable three-year succession. Three compost rates, 45 t ha–1, 30 t ha–1 and 15 t ha–1 (dry matter), and compost at 15 t ha–1 combined with 25%, and 50% of the full synthetic nitrogen rate, were compared to full and none synthetic nitrogen fertilizations. Crop succession was: tomato followed by endive in the first year; eggplant and, then, broccoli in the second year; tomato and, then, endive/broccoli, in the third year. The application of compost at a dose of at least 30 t ha–1 or at 15 t ha–1 with the addition of 25% of the full synthetic nitrogen rate, in Spring-Summer cycle, sustained growth and yield at levels comparable with those of synthetic nitrogen fertilization. However, only a very poor residual effect of the compost soil treatment on the yield of Autumn-Winter crops, was observed. Monitoring of nitrate content into the soil during cropping seasons, a reduction of the risk of groundwater pollution was displayed due to nitrates released by compost, respect to synthetic nitrogen fertilizer. The cumulative effects of compost application on soil properties were detected at the end of the field trials, registering changes in chemical parameters analysed, except for phosphorus and boron. Highlights - Municipal solid organic waste compost (MSWC) integrated with N fertilizers can sustain vegetable production. - MSWC (at least 30 t ha–1 d.w.) replaced synthetic fertilizers for tomato and eggplant productions. - N fertilizer integration to the compost residual effect is necessary to sustain endive and broccoli productions. - MSWC (at 15 t ha–1 d.w.) needs 25% of N integration to reduce the gap with plant only fertilized with N fertilizer. - MSWC preserved soil quality and avoided accumulation of undesired metals, such as Cu and Zn

Can Seaweed Extract Improve Yield and Quality of Brewing Barley Subjected to Different Levels of Nitrogen Fertilization?

Barley is the primary matrix for malting process of beer production. Farmers count on increasing cultivation inputs, especially nitrogen fertilization, in order to reach a higher yield. Nevertheless, an overuse of nitrogen, besides causing environmental damages, can determine a deterioration of quality traits of malting barley, in particular an increase in grains protein content, which should range between 10 and 11% as required by the mating industry. Over two successive years, barley was grown under 4 different nitrogen (N) doses—0 kg N ha−1—N0; 20 kg N ha−1—N20; 40 kg N ha−1—N40 and 60 kg N ha−1—N60, and subject to a biostimulant treatment (Ecklonia maxima seaweed extract). Barley yield and growth parameters increased with nitrogen and seaweed application. N40 was already sufficient in the second year to reach the plateau of the highest production. Biostimulant application increased 17.9% the nitrogen use efficiency, 15.7% the biomass production, and 17.0% the yield with respect to untreated plants. Our results indicate that a significant reduction in nitrogen is possible and desirable, combined with the application of a plant-based biostimulant like seaweed extract, which determines an improvement in nitrogen use efficiency, assuring a higher production and lower fertilization inputs

Bioactive Compounds and Antioxidant Properties of Wild Rocket (Diplotaxis Tenuifolia L.) Grown under Different Plastic Films and with Different UV-B Radiation Postharvest Treatments

: Rocket species are rich in nutrients with well-known bioactive activity, but their content depends on several factors, such as plant-UV radiation interaction. In this work, we measured the production of nutritional elements in wild rocket (Diplotaxis tenuifolia L.) leaves as a function of exposure to UV-B radiation by adopting a combined approach. The wild rocket plants were grown under three greenhouse cover films (A, B, and C) having different transmittivity to UV-B and the fresh-cut leaves were exposed to UV-B in postharvest for 45, 150, 330, and 660 s. The content of chlorophyll, carotenoids, phenolic compounds, ascorbic acid, and the antioxidant activity were determined. Chlorophyll, carotenoids, and total phenolic content were significantly increased by the combination of Film C and treatment with UV-B for 45 s. The predominant phenolic compounds were kaempferol, isorhamnetin, and quercetin. Film C also elicited an increase in ascorbic acid (the most abundant antioxidant compound in the range 374-1199 per 100 g of dry matter) and antioxidant activity. These findings highlighted an increase in bioactive compound content in the wild rocket when it was cultivated under Film C (diffused light film with a tailored UV-B transmission dose) and treated with UV-B radiation for 45 s postharvest, corresponding to an energy dose of 0.2 KJ m-2

Regulated Salinity Eustress in a Floating Hydroponic Module of Sequentially Harvested Lettuce Modulates Phytochemical Constitution, Plant Resilience, and Post-Harvest Nutraceutical Quality

A mild salinity stress (eustress) may modulate the induction of the plant defense system in horticultural crops and the synthesis of phytochemical components able to enhance plant resilience, post-harvest performance, and the nutraceutical quality of produce. However, the choice of the correct eustress type and dose to induce the synthesis of these protective phytochemicals is pivotal to avoid potential interference with plant growth and productivity. In order to study how green and red lettuce (Lactuca sativa L.) plants equilibrate the nutritional and nutraceutical components of quality with yield components, we applied iso-osmotic concentrations of three different salts (20 mM NaCl, 20 mM KCl, and 13.3 mM CaCl2, with a final total ionic concentration of 40 mM) in combination with two successive harvests in a floating raft system. The biometric parameters, mineral composition, bioactive compounds, and antioxidant activity of both cultivars were analyzed. The green cultivar had a superior response concerning biometric traits and productivity compared to the red one during the first cut but lower phytochemical content (e.g., ascorbic acid). The effect of cut order, independently of cultivar and salinity treatments, demonstrated that at the first harvest plants could redirect metabolism by increasing the lipophilic antioxidant content (LAA) at the expense of plant yield, therefore increasing plant resilience and post-harvest nutraceutical quality; whereas, at the second harvest, plants reverted principally to tissue expansion. The treatments with iso-osmotic salt concentrations did not affect K and Mg ion contents but further increased LAA and resulted only in a moderate decrease of fresh yield. The lettuce nitrate content was reduced during the second cut only when lettuce plants were treated with NaCl and especially CaCl

Morphophysiological Traits and Nitrate Content of Greenhouse Lettuce as Affected by Irrigation with Saline Water

In a 2-year study, the morphophysiological and qualitative changes imposed to greenhouse lettuce (Lactuca sativa L.) by an increasing concentration of NaCl in the irrigation water were determined. Plants were grown under soil conditions and supplied with irrigation water having electrical conductivities (ECs) of 0.7 (control), 0.9, 1.8, 3.6, or 7.2 dS·m−1. Irrigation with saline water resulted in linear decrease in plant growth parameters (i.e., leaf number, total leaf area and head diameter), head fresh weight, and diameter as well as yield, especially at 1.8, 3.6, and 7.2 dS·m−1, confirming that lettuce is a salt-sensitive crop. The percentage of marketable yield reduction in comparison with nonsaline control treatment was 22.7%, 36.4%, 45.4%, and 63.6% at 0.9, 1.8, 3.6, and 7.2 dS·m−1, respectively. The reduction in marketable fresh yield has been partly compensated by a decrease in the nitrate content of salt-treated lettuce. The highest values of hydrophilic antioxidant activity were recorded in the nonsalinized treatment. The lowest values of lipophylic antioxidant activity (LAA) and total ascorbic acid were observed under severe stress conditions (7.2 dS·m−1). Net CO2 assimilation rate and leaf water potential (LWP) declined with increasing NaCl concentration in the irrigation water. Increasing salinity in the irrigation water induced a reduction in stomatal conductance (gs) as LWP dropped below −0.62 MPa

Plant-Derived Biostimulants Differentially Modulate Primary and Secondary Metabolites and Improve the Yield Potential of Red and Green Lettuce Cultivars

The use of biostimulants in modern agriculture has rapidly expanded in recent years, owing to their beneficial effects on crop yield and product quality, which have come under the scope of intensive research. Accordingly, in the present study we appraised the efficacy of two plantderived biostimulants, the legume-derived protein hydrolysates Trainer®® (PH), and the tropical plant extract Auxym®® (TPE) on two lettuce cultivars (green and red salanova®®) in terms of morpho-physiological and biochemical traits (primary and secondary metabolites). The two cultivars differed in their acquisition capacity for nitrate and other beneficial ions, their photosynthetic and transpiration rates, and their ability to synthetize and accumulate organic acids and protective metabolites. The biostimulant effect was significant for almost all the parameters examined but it was subjected to significant cultivar × biostimulant interactions, denoting a cultivardependent response to biostimulant type. Notwithstanding this interaction, biostimulant application could potentially improve the yield and quality of lettuce by stimulating plant physiological processes, as indicated by the SPAD index (leaf chlorophyll index), ACO2 (assimilation rate), E (transpiration), and WUEi (intrinsic water use efficiency), and by increasing concurrently the plant mineral content (total N, K, Ca, Mg) and the biosynthesis of organic acids (malate, citrate), phenols (caffeic acid, coumaroyl quinic acid isomer 1, dicaffeoylquinic acid isomer 1), and flavonoids (quercetin-3-O-glucuronide, quercetin-3-O-glucoside). Biostimulant action may facilitate the bio-enhancement of certain lettuce cultivars that are otherwise limited by their genetic potential, for the accumulation of specific compounds beneficial to human health