Effect of biochar and inorganic or organic fertilizer co-application on soil properties, plant growth and nutrient content in Swiss Chard

From the perspective of sustainable agri-food production, farmers need to make the best use of natural resources. Biochar can be a solution to adopt a more sustainable way of farming. Despite its environmental and agronomic advantages, biochar has a low plant nutrient value. This study evaluated the effect of biochar and the co-application of an inorganic or organic fertilizer on the soil properties, growth and nutrient content of Swiss chard (Beta vulgaris L. var. cycla, Caryophyllales order, Chenopodiaceae family). The experiment consisted of two factors: biochar type (from vineyard prunings and wood chips) and fertilizing source (ammonium nitrate and vermicompost). Biochars were applied at a 2% rate (w/w) and fertilizers at a dose providing 280 kg N ha(-1). The soil properties (pH, EC, extractable anions, cations, total N, Corg and C/N ratio) were measured before the plants were transplanted and at the end of the growing cycle, along with the growth parameters (leaf number, length and fresh weight) of each leaf cut, the productive parameters (total number of leaves and yield per plant) at the end of the growing cycle and the leaf content of anions (NO3-, P2O43-, SO42-), cations (NH4+, Na+, K+, Ca2+, Mg2+) and total N. The co-application of biochar and a fertilizing source had a positive effect on soil properties and leaf nutrient content. Vermicompost increased plant growth by 22% and plant yield by 116%, in contrast to biochar, and increased limited leaf NO3- accumulation by about 81% in comparison to ammonium nitrate. The co-application of biochar and vermicompost is the better option to increase Swiss chard yield while preserving the nutritional and health qualities of the product

Quanti-qualitative response of Swiss Chard (Beta vulgaris L. var. cycla) to soil amendment with biochar-compost mixtures

In recent years, soil addition with organic amendments, such as biochar and compost, has gained attention as an effective agronomic practice to sustain soil fertility, enhance plant growth and crop yield. Well known are the positive effects of compost on yield of a wide crop varieties, while both positive and negative responses are reported for biochar Therefore, the aim of the study was to verify the effect of biochar mixed with three types of compost on quanti-qualitative response of Swiss chard (Beta vulgaris L. cycla), a leafy green vegetable rich in dietary antioxidants, largely consumed worldwide. A factorial experiment in pots with two factors, including biochar (without biochar and with biochar from vine pruning residues) and compost (without compost, with compost from olive pomace, with vermicompost from cattle manure, and with compost from cattle anaerobic digestate), was setup. Two growth cycles were considered, and a set of quantitative (height of plants, number, area and fresh weight of leaves) and qualitative parameters (carotenoids, chlorophyll, total N, and NO3−content of leaves) were analyzed. Biochar decreased plant growth and NO3− leaf content; on the contrary, it increased total N leaf content, while compost improved all the considered parameters. The interactive effect of biochar and compost was evident only on total N and NO3− leaf content. In our experimental conditions, the compost showed to be the best option to improve Swiss chard growth and increase the content of phytopigments, while the biochar-compost mixtures did not produce the expected effect

Evaluation of Vegetative Development of Quinoa under Water Stress by Applying Different Organic Amendments

Prolonged drought periods, increasingly occurring worldwide due to global climate change, could affect the growth and productivity of both traditional and climate-resilient crops, including quinoa. Specifically, the vegetative growing cycle of this species is highly sensitive to drought conditions. In this context, using organic amendments could help plants cope with drought due to their ability to enhance soil water status. So, the current study aimed to investigate the effect of different organic amendments, i.e., two biochars (from woodchips and vineyard prunings) and a vermicompost (from cattle manure), applied to the soil alone and mixed at 2% rate (w/w), on the vegetative development of quinoa (cv. Titicaca), during which a period of water stress was imposed from the twelve-leaf stage to the bud stage. A set of growth-related parameters were measured both during and at the end of the experiment, along with a set of water-related parameters, at the end of the water-stress period and after soil re-watering. The results showed that woodchip biochar, both alone and mixed with vermicompost, significantly affected plant growth during the water-stress period, also allowing a quicker recovery once drought conditions ended. Indeed, the leaf number and area, SPAD index, leaf and stem fresh weight, and dry matter content in plants treated with woodchip biochar, alone and mixed with vermicompost, were higher than vineyard pruning biochar, alone and mixed with vermicompost and similar to the well-watered control plants. Similar results were observed considering the yield contributing traits detected at the end of the experiment, including the main panicle length, number of sub-panicle, as well as fresh weight and dry matter content of both panicle and sub-panicles. Additionally, the water-related parameters, especially the low turgid weight to dry weight ratio of woodchip biochar treated plants, showed evidence of better growth than vineyard pruning biochar. At the end of the experiment, the WUE of plants treated with woodchip biochar and vermicompost, both alone and mixed, was higher than vineyard pruning biochar alone and mixed with vermicompost. Among the tested organic amendments, woodchip biochar alone and mixed with vermicompost positively affected the vegetative growth response of quinoa under water-stress conditions

Cadmium accumulation and physiological response of sunflower plants to Cd during the vegetative growing cycle

The effects of soil Cd contamination on Cd accumulation and distribution, growth and physiological responses of sunflower plants were investigated. Plants were subject to six levels of soil contamination (from 2.5 to 15 mg Cd kg/soil) with an untreated control, from the emergence of the cotyledon leaves until the harvest, when plants were at the flower bud stage. An overall increase of Cd concentration was found in all tissues of the plants (roots, stem, young, mature and old leaves) by increasing the Cd contamination in the soil. Regardless of treatments, Cd concentration in roots always exceeded those in the aboveground dry matter with a low translocation from roots to shoots. At early stage of growth, Cd concentration in plants was higher than at the flower bud stage. Soil Cd contamination did not affect plant growth, relative water content and gas exchange parameters. Negative and significant correlation was only found between Cd concentration in the young leaves and chlorophyll concentration at the end of vegetative growing stage. Roots and old leaves are the main metal sinks suggesting a defense or tolerance mechanism of the plants to avoid toxic levels in physiologically most active apical tissues. These results should be tested in open field to verify the suitability of sunflower in the area of phytotechnologies

Ion distribution and gas exchange of hydroponically grown sunflower plants as affected by salinity

This paper reports the results of a trial carried out on sunflower plants (Helianthus annuus L., Romsun HS90) grown in the greenhouse using inert substrate and two automatic and closed hydroponic systems: one of them hosting the control (C) with plants grown under optimal conditions on Hoagland nutrient solution, the other one, the salt treatment (S), with plants exposed to constant salt stress through adding 150 mM of NaCl to the nutrient solution. Salt supply caused a sharp reduction in leaf area development and dry matter production, especially in the first 4 weeks when leaves showed to be more sensitive than stem and roots. Such a reduction is attributable to the drop in net CO2 assimilation rate, transpiration and stomatal conductance and it was, on average, equal to 30, 26 and 40%, respectively, with respect to the control. The investigated genotype was not able to exclude Cl- and Na+ and considerable amounts accumulated in leaves, stem and roots. Concentration increased in leaves in the basipetal direction. Though sunflower has an efficient endogenous adaptation system by which it redistributes ions in the whole plant, with greater accumulation in older leaves, growth inhibition could be attributed to specific ion toxicity effects, and of chlorine in particular, on metabolic processes and thus on photosynthesis

Enhancement of Yield, Phytochemical Content and Biological Activity of a Leafy Vegetable (Beta vulgaris L. var. cycla) by Using Organic Amendments as an Alternative to Chemical Fertilizer

This study evaluates the effect of a chemical fertilizer (ammonium nitrate), a compost (vermicompost from cattle manure) and two biochars (from vine prunings and wood chips, respectively), applied to the soil alone or in mixture, on the yield, phytochemical content and biological activity of Beta vulgaris L. var. cycla (Swiss chard). The respective treatments, each replicated four times, were arranged according to a completely randomized block design. Results showed that vermicompost, both alone and in mixture with vine pruning biochar, significantly increased yield parameters (plant height and leaf area) and yield over the untreated soil and the biochars alone, similar to ammonium nitrate. Moreover, vermicompost, both alone and in mixture, respectively, with the two biochars, determined lower total N and NO3− contents than ammonium nitrate, both alone and in mixture, respectively, with the two biochars. In particular, NO3− content was within the safe thresholds fixed for leafy vegetables by the European Commission to prevent any adverse implication on human health from dietary NO3− exposure. The biochars alone resulted in very low yield and leaf total N content, likely due to a limited release of N for plant uptake, also evidenced by the undetectable NO3− leaf content, similarly shown by plants grown in untreated soil. Vermicompost, alone or in mixture, respectively, with the two biochars, increased the content of specialized metabolites, with a positive effect on antioxidant activity. The organic amendments, particularly compost, could be an alternative to chemical fertilizers to reach a trade-off between yield, nutritional and health qualities in Swiss chard, meeting the needs of farmers and consumers as well as the targets for sustainable food production

Glucosinolates determination in tissues of horseradish plant

Glucosinolates (GLS) are secondary metabolites mainly found in plants belonging to the Brassicaceae family, including also horseradish (Armoracia rusticana P. Gaertner, B. Meyer & Scherbius), a popular spice with a characteristic pungent flavor due to the abundance of GLS. Such compounds exhibit antibacterial, antifungal, and insecticidal activities, as well as human health properties. Therefore, it is very important to have a full understanding of their levels and profiles in plants. However, the characterization of GLS from horseradish crude extracts is a tough task, due to the complexity of the vegetal matrix and the occurrence of many GLS in trace amounts. Here we describe two alternative effective and rapid methods for GLS characterization in horseradish plants: liquid chromatography coupled to high resolution mass spectrometry (LC-MS) for determination of intact GLS and HPLC-UV for determination of desulfo-GLS

Effects of Zeolite and Deficit Irrigation on Sweet Pepper Growth

The use of zeolites in agriculture as a soil conditioner is becoming an important field of research in crop growth. To study the effect of synthetic zeolites and deficit irrigation on sweet pepper (Capsicum annuum L.) cultivation, an experiment was conducted in a controlled environment. In particular, sweet peppers were cultivated in a glasshouse using polypropylene pots filled with sandy loam soil, to which 2% zeolite was added. The zeolite employed in the experiments was obtained using coal fly ash as a raw material. The experiment consisted of two main treatments: (a) soil with a zeolite at 2% (Z) and (b) soil without a zeolite as a control (C). Three subplot treatments consisted of (1) full irrigation at 100% of the available water content (AWC) (100); (2) deficit irrigation at 70% of the AWC (70); and (3) deficit irrigation at 50% of the AWC (50). Sweet pepper cultivation started on 24 April 2023 and lasted until 23 June 2023; during the trial, the environmental data, such as the soil humidity, air temperature, and relative humidity, and some crop parameters, such as the plant height, leaf number, and the SPAD index, were monitored. At the end of the trial, the fresh and dry plant weights, the dry matter content, and the leaf water potential were measured. The results showed that, for the plant fresh weight and dry matter content, no significant differences were observed in the treatments and their interactions, whereas, for the other parameters, the statistical analysis showed significant differences. The study suggests that the soil’s structural benefits, resulting from zeolite application, are not followed by an equal positive effect in terms of sweet pepper growth under deficit irrigation conditions