Sensor-based irrigation reduces water consumption without compromising yield and postharvest quality of soilless green bean

Real-time monitoring of substrate parameters in the root-zone through dielectric sensors is considered a promising and feasible approach for precision irrigation and fertilization management of greenhouse soilless vegetable crops. This research investigates the effects of timer-based (TIMER) compared with dielectric sensor-based irrigation management with different irrigation set-points [SENSOR_0.35, SENSOR_0.30 and SENSOR_0.25, corresponding to substrate volumetric water contents (VWC) of 0.35, 0.30 and 0.25 m3 m−3, respectively] on water use, crop performance, plant growth and physiology, product quality and post-harvest parameters of soilless green bean (Phaseolus vulgaris L., cv Maestrale). In SENSOR treatments, an automatic system managed irrigation in order to maintain substrate moisture constantly close to the specific irrigation set-point. The highest water amount was used in TIMER treatment, with a water saving of roughly 36%, 41% and 47% in SENSOR_0.35, SENSOR_0.30 and SENSOR_0.25, respectively. In TIMER, the leaching rate was ≈31% of the total water consumption, while little leaching (<10%) was observed in SENSOR treatments. TIMER and SENSOR_0.35 resulted in similar plant growth and yield, while irrigation set-points corresponding to lower VWC values (SENSOR_0.30 and SENSOR_0.25) resulted in inad-equate water availability conditions and impaired the crop performance. The study confirms that rational sensor-based irrigation allows to save water without compromising anyhow the product quality. In SENSOR irrigation management, in fact, especially in the case of optimal water availability conditions, it was possible to obtain high quality pods, with fully satisfactory characteristics during storage at 7◦ C for 15 days

Atmospheric Density Uncertainty Quantification for Satellite Conjunction Assessment

Conjunction assessment requires knowledge of the uncertainty in the predicted orbit. Errors in the atmospheric density are a major source of error in the prediction of low Earth orbits. Therefore, accurate estimation of the density and quantification of the uncertainty in the density is required. Most atmospheric density models, however, do not provide an estimate of the uncertainty in the density. In this work, we present a new approach to quantify uncertainties in the density and to include these for calculating the probability of collision Pc. For this, we employ a recently developed dynamic reduced-order density model that enables efficient prediction of the thermospheric density. First, the model is used to obtain accurate estimates of the density and of the uncertainty in the estimates. Second, the density uncertainties are propagated forward simultaneously with orbit propagation to include the density uncertainties for Pc calculation. For this, we account for the effect of cross-correlation in position uncertainties due to density errors on the Pc. Finally, the effect of density uncertainties and cross-correlation on the Pc is assessed. The presented approach provides the distinctive capability to quantify the uncertainty in atmospheric density and to include this uncertainty for conjunction assessment while taking into account the dependence of the density errors on location and time. In addition, the results show that it is important to consider the effect of cross-correlation on the Pc, because ignoring this effect can result in severe underestimation of the collision probability.Comment: 15 pages, 6 figures, 5 table

Extending postharvest life of ready-to-use zucchini flowers: Effects of the atmosphere composition

Male zucchini flowers (Cucurbita pepo L.) are greatly appreciated by consumers although, because of their high perishability, they are destined only for local markets. The effects of four different atmosphere compositions (air, 3% O2 in nitrogen, 3% O2 + 10% CO2 in air, and 10% CO2 in air) on quality attributes of fresh zucchini flowers (color, weight loss, respiration, fermentative volatiles, and vitamin C) were studied. Storage in a controlled atmosphere significantly affected postharvest quality and marketability. At 5°C, an atmosphere containing 3% O2 in nitrogen resulted in a reduction in respiration rate and weight loss, preserved visual appearance, sensorial and nutritional quality, and maintained the vitamin C content during the entire storage period. Under these conditions, fresh zucchini flowers were scored marketable and with a good appearance after 9 days of storage. On the other hand, flowers stored in air deteriorated rapidly, resulting in a score just above the limit of marketability (score 3) after 5 days of storage, whereas adding CO2 to air slightly increased flower shelf-life. Flowers stored in air (with or without CO2) showed the same spoilage symptoms, defined by water soaking, wilting and brightness loss, all symptoms that were reduced in a low-oxygen atmosphere. Based on these results, the correct atmosphere conditions for male zucchini flowers should attain low oxygen levels (3%) and avoid excessive accumulation of CO2. Further studies will be needed to investigate the possibility of introducing washing in the processing, due to the high sensitivity of this product to manipulation

Compositional and Marketable Quality of Fresh-Cut Florets of Four Specialty Brassicas in Relation to Controlled Atmosphere Storage

Brassica vegetables are consumed year-round as raw salad or cooked ingredients. Four Brassica species were selected for this study, broccoli (Brassica oleracea var. italica), broccoli raab (Brassica rapa L.), choisum (Brassica rapa var. parachinensis), and gailan (Brassica oleracea var. alboglabra). While there is abundant information about broccoli, research on gailan, choisum and broccoli raab is very limited. The effect of CA (3% O-2 alone or in combination with 7 or 15% CO2, 1% O-2 alone or combined with 15% CO2) and air on marketable quality (overall visual, yellowing, discoloration, decay) and chemical parameters (antioxidant activity, chlorophyll, sugar, fermentative volatiles, and ammonia content) during storage at 5 degrees C was evaluated. Products were obtained from a wholesaler, washed in chlorinated water, trimmed into florets and placed in unsealed polyethylene bags that were held in polycarbonate chambers through which humidified air or the controlled atmospheres flowed. Visual quality was evaluated after 0, 8, 12, 16 and 20 days, while chemical parameters were measured after 0, 8, 16 days. Generally, CA treatments did not affect the antioxidant activity, chlorophyll or sugar concentrations in any of the specialty brassicas studied. On the other hand, both ammonia content and visual quality evaluations were affected by atmosphere composition. Florets stored in low oxygen (3% O-2) often had the best visual quality but generally all atmospheres maintained better marketable quality than air storage. The 3% oxygen CA improved marketability to about 16 days. Low oxygen delayed postharvest and post-cutting deterioration of florets from all Brassica species, and based on changes in ammonia concentrations, was considered beneficial to maintain quality of fresh-cut brassicas stored at 5 degrees C

Changes in Bacterial Composition of Zucchini Flowers Exposed to Refrigeration Temperatures

Microbial spoilage is one of the main factors affecting the quality of fresh fruits and vegetables, leading to off-flavor, fermented aroma, and tissue decay. The knowledge of microbial growth kinetics is essential for estimating a correct risk assessment associated with consuming raw vegetables and better managing the development of spoilage microorganisms. This study shows, for the first time, that only a part of total microbial community, originally present on fresh harvested female zucchini flowers, was able to adapt itself to refrigerated conditions. Through the study of microbial growth kinetics it was possible to isolate forty-four strains belonging to twenty-two species of the genera Acinetobacter, Arthrobacter, Bacillus, Enterobacter, Erwinia, Klebsiella, Pantoea, Pseudoclavibacter, Pseudomonas, Serratia, Staphylococcus, and Weissella, suggesting Enterobacteriaceae as potentially responsible for pistil spoilage

Computer vision system based on conventional imaging for non-destructively evaluating quality attributes in fresh and packaged fruit and vegetables

Quality assessment of fresh fruit and vegetables is an arduous and complex process which needs very intensive labour of correlation among sensory and subjective determinations and conventional destructive methods. Consumers' requests for fruit and vegetables with high quality in terms of appearance, nutritional value and safety have prompted industries and researchers to develop rapid, precise and low-cost techniques for food analysis. Among innovative techniques, image analysis by computer vision systems based on conventional imaging (CVS-CI) have proved to be effective and suitable for application at industrial level. This review summarizes developments on CVS-CI technology for the evaluation, along the entire distribution chain, of external defects, colour changes and internal chemical-physical attributes of fresh fruit and vegetables, with or without the presence of plastic packaging. The most interesting researches carried out during the last ten years on CVS-CI employments are reported and discussed. The description of each application points out the performances obtained, the hardware components, the image processing techniques used to extract information from the images acquired, the classification/regression models used to grade products and to estimate their quality traits. Finally, future perspectives and possible new applications of CVS-CI in postharvest field are proposed