Francesco Di Gioia

A decision support system (GesCoN) for managing fertigation in vegetable crops. Part II—model calibration and validation under different environmental growing conditions on field grown tomato

The GesCoN model was evaluated for its capability to simulate growth, nitrogen uptake, and productivity of open field tomato grown under different environmental and cultural conditions. Five datasets collected from experimental trials carried out in Foggia (IT) were used for calibration and 13 datasets collected from trials conducted in Foggia, Perugia (IT), and Florida (USA) were used for validation. The goodness of fitting was performed by comparing the observed and simulated shoot dry weight (SDW) and N crop uptake during crop seasons, total dry weight (TDW), N uptake and fresh yield (TFY). In SDW model calibration, the relative RMSE values fell within the good 10–15% range, percent BIAS (PBIAS) ranged between −11.5 and 7.4%. The Nash-Sutcliffe efficiency (NSE) was very close to the optimal value 1. In the N uptake calibration RRMSE and PBIAS were very low (7%, and −1.78, respectively) and NSE close to 1. The validation of SDW (RRMSE = 16.7%; NSE = 0.96) and N uptake (RRMSE = 16.8%; NSE = 0.96) showed the good accuracy of GesCoN. A model under- or overestimation of the SDW and N uptake occurred when higher or a lower N rates and/or a more or less efficient system were used compared to the calibration trial. The in-season adjustment, using the “SDWcheck” procedure, greatly improved model simulations both in the calibration and in the validation phases. The TFY prediction was quite good except in Florida, where a large overestimation (+16%) was linked to a different harvest index (0.53) compared to the cultivars used for model calibration and validation in Italian areas. The soil water content at the 10–30 cm depth appears to be well-simulated by the software, and the GesCoN proved to be able to adaptively control potential yield and DW accumulation under limited N soil availability scenarios and consequently to modify fertilizer application. The DSSwell simulate SDW accumulation and N uptake of different tomato genotypes grown under Mediterranean and subtropical conditions.

Assessment of ionic interferences to nitrate and potassium analyses with ion-selective electrodes.

Ion-selective electrodes (ISEs) are simple tools used for rapid measurement of nitrate nitrogen (NO3-N) and potassium (K) concentrations in plant sap. With the development of best management practices (BMPs), interest exists in using ISEs for soil leachate and soil and fertilizer solutions. Nitrate N and K concentrations in the 0 to 10,000 mg L–1 ISE working range were measured in diluted solutions of common salts to assess ionic interference of calcium (Ca2+), ammonium (NH4 +), chloride (Cl–), and sulfate (SO4 2–). The effects of meter (replication) were unexpectedly significant in one out of three ranges for NO3-N and K (P values of 0.50, 0.72, and 0.01 for NO3-N and 0.99, 0.01, and 0.74 for K, for the 0–100, 100–1,000 and 1,000–10,000 mg L–1 ranges, respectively). The responses of calculated NO3-N and K concentrations to measured NO3-N and K concentrations were linear, but slopes ranged from 0.85 to 1.54, from 0.24 to 2.72, and from 0.93 to 5.48 for NO3-N and from 0.80 to 1.01, from 0.71 to 1.39, and from 0.93 to 2.21 for K for the 0–100, 100–1,000, and 1,000–10,000 mg L–1 measuring ranges, respectively. All slopes were significantly different from zero, and several were significantly different from each other and the 1:1 line. Pairwise slope comparisons conducted with covariance analysis showed that SO4 2– alone interfered with NO3-N measurements at concentrations ranging from 34 to 171 mg L–1, which was less than the manufacturers information, and by its presence in combination with K+, NH4 +, Ca2+, and Cl– within the medium and high concentration ranges. Potassium measurements were not subject to interference from the ions tested for all three concentration ranges. These results highlight the importance of using quality assurance / quality control (QA/QC) samples in the set of unknown samples to detect inacceptable departure from linearity in routine analysis. The increase in measurement variability from one range to the next showed the importance of keeping measurements within a single concentration range by using dilutions. Hence, ISEs may be used for field measurements of NO3-N and K concentrations in soil leachate as well as soil and nutrient solutions and are therefore a practical BMP tool. However, ISEs should not be used as substitutes for the laboratory methods when official measurements are needed.

Physicochemical, agronomical and microbiological evaluation of alternative growing media for the production of rapini (Brassica rapa L.) microgreens

BACKGROUND Peat-based mixes and synthetic mats are the main substrates used for microgreens production. However, both are expensive and non-renewable. Recycled fibrous materials may represent low-cost and renewable alternative substrates. Recycled textile-fiber (TF; polyester, cotton and polyurethane traces) and jute-kenaf-fiber (JKF; 85% jute, 15% kenaf-fibers) mats were characterized and compared with peat and Sure to Grow® (Sure to Grow, Beachwood, OH, USA; http://suretogrow.com) (STG; 100% polyethylene-terephthalate) for the production of rapini (Brassica rapa L.; Broccoletto group) microgreens. RESULTS All substrates had suitable physicochemical properties for the production of microgreens. On average, microgreens fresh yield was 1502 g m-2 in peat, TF and JKF, and was 13.1% lower with STG. Peat-grown microgreen shoots had a higher concentration of K+ and SO42- and a two-fold higher NO3- concentration [1959 versus 940 mg kg-1 fresh weight (FW)] than those grown on STG, TF and JKF. At harvest, substrates did not influence microgreens aerobic bacterial populations (log 6.48 CFU g-1 FW). Peat- and JKF-grown microgreens had higher yeast-mould counts than TF- and STG microgreens (log 2.64 versus 1.80 CFU g-1 FW). Peat-grown microgreens had the highest population of Enterobacteriaceae (log 5.46 ± 0.82 CFU g-1 ) and Escherichia coli (log 1.46 ± 0.15 CFU g-1 ). Escherichia coli was not detected in microgreens grown on other media. CONCLUSION TF and JKF may be valid alternatives to peat and STG because both ensured a competitive yield, low nitrate content and a similar or higher microbiological quality.

Culinary Assessment of Self-Produced Microgreens as Basic Ingredients in Sweet and Savory Dishes

ABSTRACT “Microgreens” is a marketing term used to describe young and tender edible seedlings. In this work, a new culinary concept was developed to stimulate the culinary use of self-produced microgreens as basic ingredients of sweet and savory dishes. The production of microgreens in a soilless growing system was considered as a preliminary part of the culinary process for the dishes’ preparation. In order to obtain customized microgreens for the culinary assessment, three different species were self-produced. As a result of the pilot consumer test, all species of microgreens resulted acceptable. A gastronomic session was also applied to develop some dishes using microgreens in the recipe. The culinary promotion of self-produced microgreens not only as garnishing greens may offer to the international gastronomy new ingredients and support the exploitation of local varieties and wild edible plants.

Sprouts, Microgreens and “Baby Leaf” Vegetables

After a brief introduction regarding the definitions of sprouts, microgreens and “baby leaf” vegetables, this chapter provides an overview of this growing market segment within the sector of vegetable products. Given their short growth cycle (4–10 days), sprouts are usually grown in the dark, without a growing medium and without fertilizers and agrochemicals. Their edible portion is constituted by the entire sprout, including the rootlets. From a biological point of view, the sprout represents the first stage of growth of a plant that starts from seed germination. “Microgreens” is instead a marketing term used to describe a category of products that has no legal definition. They differ from sprouts because they require light and a growing medium and have a longer growth cycle (7–28 days); the edible portion is constituted by stem and cotyledons and often by the emerging first true leaves. By contrast, “baby leaf” vegetables are grown in the presence of light, either in soil or soilless systems, have a longer growth cycle (20–40), usually require the use of fertilizers and agrochemicals and are harvested after the development of the true leaves.