Nitrogen uptake and N-use efficiency of Mediterranean cotton under varied deficit irrigation and N fertilization

Efficient N management is essential to optimize yields and reduce degradation of the environment, but requires knowledge of deficit irrigation effects on crop yields and crop N outputs. This study assessed the N content and N-use efficiency of cotton over the 2008 and 2009 growing seasons in a single field site of the Thessaly Plain (central Greece). The experiment consisted of nine treatments with three fertilizer rates (60, 110 and 160 kg N ha⁻¹) split into three irrigation levels (approx. 1.0, 0.7 and 0.4 of the amount applied by the producer). Reduced water supply induced a shift in the distribution of N within the plant with seeds becoming an N sink under conditions of water stress. Total crop N increased linearly with irrigation level and reached a maximum average of 261 and 192 kg N ha⁻¹ in 2008 and 2009, respectively. Fertilizer application did not trigger a crop N or yield response and indicated that N inputs were in excess of crop needs. Variation in weather patterns appeared to explain annual differences of nitrate-N in the top soil and N uptake by the crop.The index of lint production efficiency (iNUE) detected crop responses caused by irrigation and annual effects, but failed to account for excessive N inputs due to mineral fertilizer applications. A maximum average iNUE of 9.6 was obtained under deficit irrigation, whereas an iNUE of 8.1 was obtained under 40 cm irrigation when crop N uptake was not excessive (192 kg ha⁻¹ in 2009). In contrast, NUE, as an estimator of N recovery efficiency, identified excessive fertilizer inputs as N losses to the environment and indicated that 60 kg N ha⁻¹ was a rate of high N removal efficiency and long-term N balance. However, NUE failed to account for crop N responses to irrigation and weather/management patterns. In this case study, neither index was able to detect all the factors influencing the N mass balance and both were required in order to provide a comprehensive evaluation of the environmental performance of our cropping system.     

Yield,water use and radiation use efficiencies of kenaf (Hibiscus cannabinus L.) under reduced water and nitrogen soil availability in a semi-arid Mediterranean area

Kenaf is a warm-season species that recently has been proved to be a good source of biomass for cellulose pulp for the paper industry in Mediterranean countries, where the use of hemp is problematic for legal reasons. A two-year research program aiming at studying the effects of different water regimes and nitrogen fertilization levels, upon plant growth, leaf area index, biomass accumulation, water and radiation use efficiency, was carried out on kenaf under a typically semi-arid Mediterranean climate of South Italy. In cv. Tainung 2, four different water regimes (I₀ = no irrigation, I₂₅, I₅₀ and I₁₀₀ = 25, 50 and 100% ETc restoration, respectively) and three nitrogen levels (N₀ = no nitrogen, N₇₅ and N₁₅₀ = 75 and 150 kg ha⁻¹ of N, respectively) were studied. The amount of water applied strongly affected plant growth (in terms of LAI, plant height and biomass) and final total and stem dry yield, which significantly increased from I₀ to I₁₀₀. Nitrogen did not exert any beneficial effect upon dry yield. Radiation Use Efficiency (RUE), calculated in the second year only, was the highest (1.95 g DM MJ⁻¹) in fully irrigated treatment (I₁₀₀) and the lowest (0.86 g DM MJ⁻¹) in the dry control.Water use efficiency (WUE) was rather similar among water regimes, whilst irrigation water use efficiency (IWUE) progressively increased with the decrease of total volume of water distributed to the crop by irrigation, from 3.47 to 12.45 kg m⁻³ in 2004 and from 4.27 to 7.72 kg m⁻³ in 2005. The results obtained from this research demonstrate that in semi-arid areas of South Italy, irrigation at a reduced rate (50% ETc restoration) may be advantageous, since it allowed a 42–45% irrigation water saving, when compared to the fully irrigation treatment, against a 23% (in 2004) and 36% (in 2005) yield reduction, and a still good efficiency (near that potential) in transforming the solar radiation in dry biomass was maintained (RUE = 1.76 g DM MJ⁻¹, against 1.95 g DM MJ⁻¹ in fully irrigated treatment).     

Optimized single irrigation can achieve high corn yield and water use efficiency in the Corn Belt of Northeast China

Decreasing the corn (Zea mays L.) gap between the potential yield and farm yield and reducing the risk of grain yield of drought are very important for corn production in the Corn Belt of Northeast China (CBNC). To achieve a high and stable corn yield, the effects of supplementary irrigation on yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) were studied using a modelling approach. The Root Zone Water Quality Model 2 was parameterized and evaluated using two years of experimental data in aeolian sandy soil and black soil. The evaluated model was then used to investigate responses to various irrigation strategies (rainfed, full irrigation and 12 single irrigation scenarios) using long-term weather data from 1980 to 2012. Full irrigation guarantees a high and stable corn grain yield (12.92 Mg ha⁻¹ and has a coefficient of variation (CV) of 14.8% in aeolian sandy soil; 12.30 kg Ma⁻¹ and CV of 11.1% in black soil), but has a low water use efficiency (19.92 and 21.81 kg ha⁻¹ mm⁻¹) and a low irrigation water use efficiency (10.01 and 11.03 kg ha⁻¹ mm⁻¹). A single irrigation can increase corn yields by 3–35% for aeolian sandy soil and 5–35% for black soil over different irrigation dates compared with no irrigation. The most suitable single irrigation date was during late June to early July for aeolian sandy soil (yield = 10.73 Mg ha⁻¹ and WUE = 27.94 kg ha⁻¹ mm⁻¹) and early to mid-July for black soil (yield = 11.20 Mg ha⁻¹ and WUE = 27.70 kg ha⁻¹ mm⁻¹). The lowest yield risk of falling short of the yield goal of 8, 9, and 10 Mg ha⁻¹ were 9.1%, 18.2%, and 33.33% in aeolian sandy soil and 3.0%, 15.25, and 21.2% in black soil when an optimized single irrigation was applied in late June or early July, respectively. Therefore, an optimized single irrigation should be applied in late June to early July with the irrigation amount to refill soil water storage of root zone to field capacity in CBNC.     

Effect of irrigation and nitrogen fertilization on the production of biogas from maize and sorghum in a water limited environment

The expansion of biogas production from anaerobic digestion in the Po Valley (Northern Italy) has stimulated the cultivation of dedicated biomass crops, and maize in particular. A mid-term experiment was carried out from 2006 to 2010 on a silt loamy soil in Northern Italy to compare water use and energy efficiency of maize and sorghum cultivation under rain fed and well-watered treatments and at two rates of nitrogen fertilization. The present work hypothesis were: (i) biomass sorghum, for its efficient use of water and nitrogen, could be a valuable alternative to maize for biogas production; (ii) reduction of irrigation level and (iii) application of low nitrogen fertilizer rate increase the efficiency of bioenergy production. Water treatments, a rain fed control (I0) and two irrigation levels (I1 and I2; only one in 2006 and 2009), were compared in a split–split plot design with four replicates. Two fertilizer rates were also tested: low (N1, 60 kg ha⁻¹ of nitrogen; 0 kg ha⁻¹ of nitrogen in 2010) and high (N2, 120 kg ha⁻¹ of nitrogen; 100 kg ha⁻¹ of nitrogen in 2010). Across treatments, sorghum produced more aboveground biomass than maize, respectively 21.6 Mg ha⁻¹ and 16.8 Mg ha⁻¹ (p < 0.01). In both species, biomass yield was lower in I0 than in I1 and I2 (p < 0.01), while I1 and I2 did differ significantly. Nitrogen level never affected biomass yield. Water use efficiency was generally higher in sorghum (52 kg ha⁻¹ mm⁻¹) than in maize (38 kg ha⁻¹ mm⁻¹); the significant interaction between crop and irrigation revealed that water use efficiency did not differ across water levels in sorghum, whereas it significantly increased from I0 and I1 to I2 in maize (p < 0.01). The potential methane production was similar in maize and sorghum, while it was significantly lower in I0 (16505 MJ ha⁻¹) than in I1 and I2 (21700 MJ ha⁻¹). The only significant effect of nitrogen fertilization was found in the calculation of energy efficiency (ratio of energy output and input) that was higher in N1 than in N2 (p < 0.01). These results support the hypothesis that (i) sorghum should be cultivated rather than maize to increase energy efficiency, (ii) irrigation level should replace up to 36% of ETr and (iii) nitrogen fertilizer rate should be minimized to maximize the efficiency in biomass production for anaerobic digestion in the Po Valley.     

Spatial distribution of soil water,soil temperature,and plant roots in a drip-irrigated intercropping field with plastic mulch

Intercropping and drip irrigation with plastic mulch are two agricultural practices used worldwide. Coupling of these two practices may further increase crop yields and land and water use efficiencies when an optimal spatial distribution of soil water contents (SWC), soil temperatures, and plant roots is achieved. However, this coupling causes the distribution of SWCs, soil temperatures, and plant roots to be more complex than when only one of these agricultural practices are used. The objective of this study thus was to investigate the effects of different irrigation treatments on spatial distributions of SWCs, soil temperatures, and root growth in a drip-irrigated intercropping field with plastic mulch. Three field experiments with different irrigation treatments (high T1, moderate T2, and low T3) were conducted to evaluate the spatial distribution of SWCs, soil temperatures, and plant roots with respect to dripper lines and plant locations. There were significant differences (p < 0.05) in SWCs in the 0–40 cm soil layer for different irrigation treatments and between different locations. The maximum SWC was measured under the plant/mulch for the T1 treatment, while the minimum SWC was measured under the bare soil surface for the T3 treatment. This was mainly due to the location of drippers and mulch. However, no differences in SWCs were measured in the 60 100 cm soil layer. Significant differences in soil temperatures were measured in the 0 5 cm soil layer between different irrigation treatments and different locations. The soil temperature in the subsoil (15 25 cm) under mulch was higher than under the bare surface. The overlaps of two plant root systems in an intercropping field gradually increased and then decreased during the growing season. The roots in the 0 30 cm soil layer accounted for about 60% 70% of all roots. Higher irrigation rates produced higher root length and weight densities in the 0 30 cm soil layer and lower densities in the 30 100 cm soil layers. Spatial distributions of SWCs, soil temperatures, and plant roots in the intercropping field under drip irrigation were significantly influenced by irrigation treatments and plastic mulch. Collected experimental data may contribute to designing an optimal irrigation program for a drip-irrigated intercropping field with plastic mulch.     

Response of giant reed (Arundo donax L.) to nitrogen fertilization and soil water availability in semi-arid Mediterranean environment

The aim of the present work was to evaluate the effect of soil water availability and nitrogen fertilization on yield, water use efficiency and agronomic nitrogen use efficiency of giant reed (Arundo donax L.) over four-year field experiment.After the year of establishment, three levels for each factor were studied in the following three years: I₀ (irrigation only during the year of establishment), I₁ (50% ETm restitution) and I₂ (100% ETm restitution); N₀ (0 kg N ha⁻¹), N₁ (60 kg N ha⁻¹) and N₂ (120 kg N ha⁻¹).Irrigation and nitrogen effects resulted significant for stem height and leaf area index (LAI) before senescence, while no differences were observed for stem density and LAI at harvest.Aboveground biomass dry matter (DM) yield increased following the year of establishment in all irrigation and N fertilization treatments. It was always the highest in I₂N₂ (18.3, 28.8 and 28.9 t DM ha⁻¹ at second, third and fourth year growing season, respectively). The lowest values were observed in I₀N₀ (11.0, 13.4 and 12.9 t DM ha⁻¹, respectively).Water use efficiency (WUE) was significantly higher in the most stressed irrigation treatment (I₀), decreasing in the intermediate (I₁) and further in the highest irrigation treatment (I₂). N fertilization lead to greater values of WUE in all irrigation treatment.The effect of N fertilization on agronomic nitrogen use efficiency (NUE) was significant only at the first and second growing season.Giant reed was able to uptake water at 160–180 cm soil depth when irrigation was applied, while up to 140–160 cm under water stress condition.Giant reed appeared to be particularly suited to semi-arid Mediterranean environments, showing high yields even in absence of agro-input supply.     

Energy of biomass sorghum irrigated with reclaimed wastewaters

The sustainability of biomass sorghum (Sorghum bicolor L. Moench) in the Mediterranean environments is linked to the potential to increasing the crop productivity using irrigation water of different qualities: fresh and wastewater. An experiment was conducted in Southern Italy during 2012 and 2013 growing seasons to determine the biomass production and to estimate the yielded energy from sorghum irrigated with fresh water and municipal wastewaters. Two stages of wastewater reclamation process were compared: tertiary and secondary treatments.During the growing seasons, the crop growth (biomass and LAI) was surveyed on sorghum crops irrigated with three water qualities. In order to determine the effects of the irrigation water qualities on the final energy yielded, on the harvested biomass, structural components (cellulose, hemicellulose and lignin contents for deriving the ethanol production) and high heating value were analyzed. The data obtained during two crop seasons showed that, sorghum irrigated with municipal wastewater plant produced more dry biomass (23.3 vs 20.3 t ha⁻¹), energy yield (383 vs 335 GJ ha⁻¹), and ethanol (6824 vs 6092 L ha⁻¹) than sorghum biomass with fresh water. As a consequence, the water efficiency for producing bioenergy increased when the waste waters were supplied in substitution of fresh waters. Different indices were calculated for comparing the effect of the water quality on the water use efficiency (WUE) of biomass sorghum crops.     

Short and long-term effects of different irrigation and tillage systems on soil properties and rice productivity under Mediterranean conditions

In Mediterranean environments, flood irrigation of rice (Oryza sativa L.) crops is in danger of disappearance due to its unsustainable nature. The aim of the present study was to determine the short- and long-term effects of aerobic rice production, combined with conventional and no-tillage practices, on soils' physical, physicochemical, and biological properties, as well as on the rice yield components and productivity in the semi-arid Mediterranean conditions of SW Spain. A field experiment was conducted for three consecutive years (2011, 2012, and 2013), with four treatments: anaerobic with conventional tillage and flooding (CTF), aerobic with conventional tillage and sprinkler irrigation (CTS), aerobic with no-tillage and sprinkler irrigation (NTS), and long-term aerobic with no-tillage and sprinkler irrigation (NTS7). Significant soil properties improvements were achieved after the long-term implementation of no-tillage and sprinkler irrigation (NTS7). The short-term no-tillage and sprinkler irrigated treatment (NTS) gave lower yields than CTF in 2011 and 2012, but reached similar yields in the third year (NTS 8229 kg ha⁻¹; CTF 8926 kg ha⁻¹), with average savings of 75% of the total amount of water applied in CTF. The NTS7 data showed that high yields (reaching 9805 kg ha⁻¹ in 2012) and water savings are sustainable in the long term. The highest water productivity was with NTS7 in 2011 (0.66 g L⁻¹) and 2012 (1.46 g L⁻¹), and with NTS in 2013 (1.05 g L⁻¹). Thus, mid- and long-term implementation of sprinkler irrigation combined with no-tillage may be considered as a potentially productive and sustainable rice cropping system under Mediterranean conditions.     

Aloe vera gel coating maintains quality and safety of ready-to-eat pomegranate arils

Several postharvest treatments were performed on pomegranate arils prior to storage in rigid polypropylene boxes for 12 days at 3 °C: water (control), ascorbic + citric acids (at 0.5 or 1%), Aloe vera gel (at 50 or 100%), 50% A. vera gel + 0.5% ascorbic and 0.5% citric acid, and 100% A. vera gel + 1% ascorbic and 1% citric acid. A. vera (alone or in combination with acids) led to lower CO₂ and higher O₂ concentrations inside the packages compared with arils treated with water (control). With respect to quality attributes, A. vera coatings led to firmness retention and increased levels of total anthocyanins and total phenolics. In addition, A. vera treatments led to significantly lower counts for both mesophilic aerobics and yeast and moulds. Sensory analysis scores for flavour, texture, aroma, colour and purchase decision were higher in arils treated with A. vera, especially in those arils treated with 100% A. vera + 1% ascorbic and citric acids. Finally, no off-flavours in pomegranate arils were perceived by judges as a consequence of A. vera gel treatment.     

Effect of sustained deficit irrigation on physicochemical properties,bioactive compounds and postharvest life of pomegranate fruit (cv. ‘Mollar de Elche’)

In this study, the influence of sustained deficit irrigation (SDI; 32% of reference evapotranspiration (ET₀)) on physicochemical and sensory quality and bioactive compounds of pomegranates stored for 30, 60 and 90 days in air at 5 °C + 4 days at 15 °C, at each storage period, was studied and compared to a control (100% ET₀). Fruit from SDI had higher peel redness and greater firmness, soluble solids contents, vitamin C (27%), phloretin (98%) and protocatechuic acid (10%) levels, and total antioxidant capacity (TAC) (46%) than the control. Cold storage and shelf-life did not induce significant changes in soluble solids, pH, titratable acidity, and chroma and Hue. SDI fruit had retarded development of chilling injury (CI) symptoms, which appeared after 60 days of storage in comparison to 30 days in the controls. Anthocyanins, catechin, phloretin and protocatechuic, caffeic, p-coumaric and caffeic acids contents had greater increases in SDI fruit than in controls throughout the postharvest life. TAC was significantly (P < 0.05) correlated to anthocyanins, gallic acid and total vitamin C contents. Generally, after long term storage, the fruit grown under SDI showed higher sensory and nutritional quality, more health attributes and a longer shelf-life (up to 90 days at 5 °C + 4 at 15 °C) than fruit irrigated at 100% ET₀.     

The role of soil characteristics,soil tillage and drip irrigation in the timber production of a wild cherry orchard under Mediterranean conditions

Over the last decade high-quality timber plantations have increased in Europe because of the constant high market price of timber and economical incentives from the EU. These latter are mainly due to timber plantations’ role in CO₂ capture. Noble wood plantations have also been established in Mediterranean areas, but many of them suffer from low growth rates due to deficient plantation management and/or non-optimal environmental conditions. Furthermore, little information exists about soil and water management in these plantations and how different soil characteristics may affect management results. In this study, a trial was established in a pure wild cherry plantation under Mediterranean conditions. The trial evaluated the effects that soil type (low soil quality versus good performance for woody crops), soil management (soil tillage versus no tillage), irrigation regime (drip irrigation versus no irrigation) and their interactions may have on wood production. Soil water content and the spontaneous vegetation that appeared in the alleys of the no-tillage treatments were also measured.The results showed that sandy-clay-loam soil with a water-holding capacity of 101.5 ± 5.2 mm had 65% more wood volume increase during the study period than sandy-loam soil with a water-holding capacity of 37.9 ± 8.0 mm. Conventional tillage or zero tillage with the presence of spontaneous vegetation did not differ significantly in wood volume increment, regardless of the type of soil. Although soil water content was significantly increased by tillage in sandy-loam soil, this effect was not enough to increase tree wood volume. On the other hand, the application of drip irrigation did increase wood production by up to 50%. Therefore, 10 years less on the plantation's rotation length can be anticipated when applying irrigation: from 40 to 30 years (sandy–clay–loam soil) and from 56 to 46 years (sandy-loam soil).In conclusion, deep soil characterization of the site is essential before deciding whether to develop a plantation of this type in areas under soil water content limitations caused by deficient soil structure and texture. In addition, our results show important savings can be made by reducing soil tillage, as less tillage leads to greater ground cover and biodiversity. Further investigations are required to examine how long-lasting the effects are and what other benefits can be expected when this type of plantation is managed in a more sustainable way.     

Hot water and ethanol treatments can effectively inhibit the discoloration of fresh-cut sunchoke (Helianthus tuberosus L.) tubers

The main problem affecting the quality of fresh-cut sunchoke tubers is cut surface discoloration. Pre- and post-cutting hot water and ethanol treatments were evaluated for their potential to inhibit discoloration, color changes, and associated phenolic metabolism in tuber slices stored in air at 5 °C. Some of the treatments tested inhibited discoloration and changes in a* and hue color values. Slices that were post-cut treated with hot water at 50 °C for 6–8 min or 55 °C for 3–4 min and pre-cut treated with water at 50 °C for 20–25 min maintained good color for 8–12 days at 5 °C. Post-cut ethanol fumigation (150–750 μL/L for 5 h at 5 °C) can prevent discoloration for 30 d at 5 °C. Post-cut dips with ethanol solutions (3, 5, 8 or 10% for 5 min) increased shelf-life twofold or longer compared to untreated slices. Ethanol fumigation retarded the onset of wound-induced respiration rates as well as reducing maximum rates. A post-cut 10% ethanol dip also reduced respiration rates and reduced PAL activity and total phenolics. Ethanol dips had no effect and hot water treatments had no persistent effect on microbial loads over 12 d.     

Hot water dipping treatments on Tarocco orange fruit and their effects on peel essential oil

The most common and serious diseases which affect citrus fruit after harvest in Italy are induced by Penicillium digitatum Sacc. and Penicillium italicum Weh., responsible respectively for green and blue mold rots. This paper deals with the effectiveness of hot water dipping (HWD) treatments as alternative means to control postharvest decay on Tarocco orange fruit [Citrus sinensis (L.) Osbeck], and their effect on fruit quality with special regard to peel essential oils. Selected treatments were HWD at 52 °C for 180 s and at 56 °C for 20 s. These treatments were compared with an effective fungicide standard treatment (Imazalil) and an untreated control. The results showed that HWD at 56 °C for 20 s was more effective in inhibiting P. digitatum spore germination than HWD at 52 °C for longer exposure time. In addition, HWD treatment at 56 °C significantly increased the level of alcohols, esters and aliphatic (fatty) aldehydes. Therefore, the lowest values of decay incidence recorded in HWD fruit treated at 56 °C may be due to the increase in oxygenated monoterpenes, esters and aldehydes. Finally, HWD treatments did not cause surface damage or color change and did not influence internal quality parameters.     

Respiration rate response of four baby leaf Brassica species to cutting at harvest and fresh-cut washing

The influence of the first and second cutting at harvest on the physiological response of four baby leaf Brassica species was studied. The species were salad rocket (Eruca vesicaria), wild rocket (Diplotaxis tenuifolia), mizuna (Brassica rapa L. ssp. nipposinica) and watercress (Nasturtium officinale) stored at 1, 4, 8 and 12 °C. In addition, the microbial and metabolic behaviours of baby leaves were evaluated after different washing treatments including water, ozonated water (10 mg L⁻¹ total dose), ozonated water activated with ultraviolet C light (UV-C) and heat shock wash (50 °C, 1 min). Temperature had a significant effect on both respiration rate and post-cutting life. The production of CO₂ increased between 2- and 4-fold when temperature increased from 1 to 12 °C. Minor differences in leaf respiration rate between the first and second leaf cutting were observed for salad rocket and wild rocket, while leaves from the second cutting of mizuna and watercress leaves had a higher respiration rate than from the first cutting. Ozone, and ozone combined with UV-C, were the most efficient washing treatments in reducing total mesophilic counts, while heat shock treatment did not affect them. Additionally, naturally occurring Listeria spp. were controlled well in wild rocket and mizuna (<1 log cfu g⁻¹) when the ozone treatments were applied. On the other hand, respiration rates of the Brassica species were not substantially affected by the washing treatments when stored at 4 °C. Maximum CO₂ production was observed immediately after washing but decreased during the first 24 h of storage. Baby leaves washed with cold water consistently showed a lower respiration rate than the other washing treatments. Heat shock was the washing treatment that most influenced the increase in the respiration rate of baby leaves during storage at 8 °C.     

Radiation interception and radiation use efficiency of potato affected by different N fertigation and irrigation regimes

Three years of field experiments were carried out to explore the response of potato dry matter production, accumulated intercepted photosynthetic active radiation (Aipar) and radiation use efficiency (RUE) to five N levels providing 0, 60, 100, 140 and 180 kg N ha⁻¹ and three drip irrigation strategies, which were full, deficit and none irrigation. Results showed that, irrespective of years, dry matter production and Aipar were increased by prolonged N fertigation, even though N fertigation was carried out from middle to late growing season. The highest total and tuber dry matter and accumulated radiation interception in all three years were obtained when potatoes were provided with 180 kg N ha⁻¹. RUE on the other hand was not affected by N regime. Thus, increases in total dry matter production with increasing N levels were essentially caused by higher Aipar. The strongest response to N fertilization occurred when most N was applied early in the growing season and the latest N fertilization should be applied no later than 41–50 days after emergence. Deficit irrigation, which received ca.70% of irrigation applied to full irrigation, did not reduce radiation interception and radiation use efficiency.     

Use of soil and vegetation spectroradiometry to investigate crop water use efficiency of a drip irrigated tomato

An agronomic research was conducted in Tuscany (Central Italy) to evaluate the effects of an advanced irrigation system on the water use efficiency (WUE) of a tomato crop and to investigate the ability of soil and vegetation spectroradiometry to detect and map WUE. Irrigation was applied following an innovative approach based on CropSense system. Soil water content was monitored at four soil depths (10, 20, 30 and 50 cm) by a probe. Rainfall during the crop cycle reached 162 mm and irrigation water applied with a drip system amounted to 207 mm, distributed with 16 irrigation events. Tomato yield varied from 7.10 to 14.4 kg m⁻², with a WUE ranging from 19.1 to 38.9 kg m⁻³. The irrigation system allowed a high yield levels and a low depth of water applied, as compared to seasonal ET crop estimated with Hargraves’ formula and with the literature data on irrigated tomato. Measurements were carried out on geo-referenced points to gather information on crop (crop yield, eighteen Vegetation indices, leaf area index) and on soil (spectroradiometric and traditional analysis). Eight VIs, out of nineteen ones analyzed, showed a significant relationship with georeferenced yield data; PVI maps seemed able to return the best response, before harvesting, to improve the knowledge of the area of cultivation and irrigation system. CropSense irrigation system reduced seasonal irrigation volumes. Some vegetation indexes were significantly correlated to tomato yield and well identify, a posteriori, crop area with low WUE; spectroradiometry can be a valuable tool to improve irrigated tomato field management.     

Combination of electrolysed water,UV-C and superatmospheric O2 packaging for improving fresh-cut broccoli quality

The effects of neutral electrolysed water (NEW), ultraviolet light C (UV-C) and superatmospheric O₂ packaging (HO), single or combined, on the quality of fresh-cut kailan-hybrid broccoli for 19 days at 5 °C were studied. As controls, washing with water and sanitation with NaClO were both used. Electrolyte leakage, sensory, microbial and nutritional quality changes throughout shelf-life were studied. At day 15, the combined treatments achieved lower mesophilic and psychrophilic growth compared to the single ones. Single treatments produced higher ascorbate peroxidase (APX) reductions just after its application, while superoxide dismutase (SOD) showed the opposite behaviour. After 5 days at 5 °C, a great increase of APX and guaiacol peroxidase (GPX) activity was observed, NEW + UV-C + HO and HO-including treatments achieving the highest and the lowest APX increases, respectively. UV-C-including treatments produced the highest α-linolenic acid (ALA) decreases ranging 35–38% over control contents on the processing day. NEW-including treatments greatly reduced, throughout shelf-life, ALA and stearic acid (SA) content by 27–44% and 31–61%, respectively. Total phenolic content and antioxidant capacity (1415 mg ChAE kg⁻¹ fw and 287 mg AAE kg⁻¹ fw, respectively) remained quite constant during shelf-life. In general, the treatments and their possible combinations seem to be promising techniques to preserve, or even enhance, the quality of fresh-cut kailan-hybrid broccoli and, probably, other vegetables.     

Effects of composite chemical pretreatment on maintaining quality in button mushrooms (Agaricus bisporus) during postharvest storage

This study evaluated the effects of composite chemical pretreatment on the quality of postharvest button mushrooms. Three different treatments, including (T1) control (water), (T2) 1 mmol L⁻¹ Na₂EDTA + 10 mmol L⁻¹ CaCl₂ and (T3) 1 mmol L⁻¹ Na₂EDTA + 2.5% CaCl₂ + 0.5% citric acid + 2.5% sorbitol were used for pretreatments. The results showed that T3-treated samples maintained good firmness and color and had less weight loss during the postharvest storage. Lower levels of H₂O₂, ⁻OH and low malondialdehyde content (MDA) were observed in T3 compared with T1 and T2 samples. Significantly higher soluble protein contents and higher activities in the antioxidant enzymes, i.e., superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) were observed in T3 compared with T1 and T2 at the end of the storage period (P < 0.05). These results suggest that the T3 treatment could be useful in preserving button mushrooms.     

Cold quarantine responses of ‘Tarocco’ oranges to short hot water and thiabendazole postharvest dip treatments

This study investigated the effects of brief hot water and thiabendazole (TBZ) postharvest dip treatments on ultrastructural changes of fruit epicuticular wax (ECW), TBZ residues, decay development and quality traits of ‘Tarocco’ oranges [Citrus sinensis (L.) Osbek] subjected to cold quarantine, subsequent simulated transport and shelf-life. Commercially mature fruit were submerged in water at 20 °C (control fruit) or TBZ at 1000 mg/L and 20 °C for 60 s, or in hot water without or with TBZ at 300 mg/L and 53, 56, or 59 °C for 60, 30, and 15 s respectively. Following treatments, fruit were stored for 3 weeks at 1 °C (simulated quarantine conditions for fruit disinfestations against Mediterranean fruit fly, Medfly), followed by 4 days at 3 °C (simulated long distance transport), and finally kept at 20 °C for 3 days (shelf-life, SL). Scanning electron microscopy (SEM) analysis of ‘Tarocco’ orange surface showed that the typical wax platelets, lifting around edges of wax plates and areas free of epicuticular wax (ECW), that disappeared after hot water dips at 53–59 °C for 60–15 s, become visible again after storage for 21 days at 1 °C (quarantine conditions), and changes involving the appearance of rough ultrastructure, presence large curled plates, fissured wax crusts, and areas with ECW deficiencies, became much more pronounced after shelf-life. These occurrences were related to the transient effect of hot water treatment in decay control. Conversely, treatments with 300 mg/L TBZ 53 °C for 60 s or 56 °C for 30 s effectively reduced decay after quarantine. These treatments were as effective as standard treatment with 1000 mg/L TBZ at 20 °C and produced similar TBZ residue levels in fruit, without impairing fruit quality traits such as visual appearance, weight loss, compression test, sensory attributes, juice color parameters (a*, b*, h, L*, and Chroma), and juice chemical characteristics (soluble solids content, titratable acidity, ascorbic acid, glucose, sucrose, citric acid, total phenols, total anthocyanins, and total antioxidant activity).     

Blueberry leaf extracts incorporated chitosan coatings for preserving postharvest quality of fresh blueberries

The phenolic compounds in blueberry (Vaccinium spp.) fruit and leaf extracts (BLE) were determined based on HPLC analysis. Antimicrobial assays against Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli, as well as fungi isolated from the rotting blueberry fruit were conducted. The effects of chitosan coating incorporating different concentrations of BLE on the quality of fresh fruit during postharvest storage at 2 ± 1 °C and 95 ± 2% relative humidity (RH) for 35 d and then at room conditions for 3 d were also investigated. Five different coating treatments were applied including 2% (w/v) chitosan coating (T1), 2% (w/v) chitosan coating containing 4% (w/v, T2), 8% (w/v, T3), or 12% (w/v, T4) BLE, and 2% (w/v) chitosan coating containing 12% BLE plus modified atmosphere packaging (MAP at 3 kPa O₂ + 12 kPa CO₂) (T5). A sample of blueberries dipped into distilled water was used as control (T0). BLE had a greater variety of phenolic compounds than fruit extracts with syringic acid the highest concentration (0.259 ± 0.003 g kg⁻¹), but the total phenolic content in BLE was lower (P < 0.05) than in fruit extracts. BLE showed good antimicrobial activity against all tested microorganisms, with a minimum inhibition concentration from 25 to 50 g L⁻¹. The 2% chitosan coating that incorporated 8% or 12% BLE showed some degree of decreasing decay rate of fruit compared with the control, and the coating with BLE plus MAP had more effective control of fruit decay. All treated samples maintained higher total phenolic content and radical scavenging activity than the control. This study suggested that chitosan coating incorporating BLE can be employed to extend shelf-life and maintain high nutritional value of fresh blueberries during postharvest storage.