Enhancing Lettuce Yield through Innovative Foliar Spray of Biopolymers Derived from Municipal Biowastes.

Municipal waste biomass could be valorized as an alternative feedstock to produce compounds beneficial for agricultural applications. The foliar spray application of biostimulants emerges as a promising and innovative technique due to its environmental safety and ability to enhance crop yields. In recent years, the exploitation of biopolymers obtained through alkaline hydrolysis of the solid anaerobic digestate from municipal biowastes has attracted researchers' interest. The aim of this study is to investigate the effects on lettuce growth of a product obtained through alkaline hydrolysis from municipal biowaste, Biopolymers (BPs), and of a derivate subjected to a further oxidation process, Biopolymers Oxidate (BPs OX). The effects of the treatments at various concentrations were evaluated by monitoring plant growth and observing the trends in the activities of the main enzymes involved in the nitrogen metabolic pathway of lettuce. Results suggest that the best treatments in terms of fresh weight were achieved by using BPs at 10 mg/L and BPs OX at 100 mg/L, increasing yield by around 28% and 34%, respectively. The innovative aspect of this work was to make easier for farmers the biopolymers application by testing a foliar spray methodology for BPs and BPs OX, which has never been tested before in any crop.

A Low-Cost Ecofriendly Oxidation Process to Manufacture High-Performance Polymeric Biosurfactants Derived from Municipal Biowaste.

Biosurfactants account for about 12% of the global value of the surfactant market, which is currently dominated by synthetic surfactants obtained from fossil sources. Yet, the production of biosurfactants from renewable feedstock is bound to increase, driven by the increasing pressure from both society and governments for chemistry-based industries to become more ecofriendly and economically sustainable. A photo-chemical oxidation process is reported here, yielding new biosurfactants from urban biowaste in water that perform as a solvent and terminal oxidant reagent at room temperature without the addition of conventional oxidants and catalysts. Products with 200-500 kDa molecular weight are obtained. They lower the surface tension of water down to 34 mN/m at 0.5-2 g/L concentration. The estimated cost is rather low (0.1-1.5 EUR/kg), which is competitive with the cost of synthetic surfactants but much lower than the cost of the best-performing bacterial surfactants. For the implementation of the photo-chemical oxidation process at the industrial level, the results suggest that the new biosurfactants obtained in the present work may not reach the performance level of the best-performing bacterial surfactants capable of lowering the surface tension of water down to 28 mN/m. Yet, the biosurfactants produced by the photo-chemical process have a greater chance of being marketed on large scales.

Salicylic acid foliar application meliorates Portulaca oleraceae L. growth responses under Pb and Ni over-availability while keeping reliable phytoremediation potential.

The efficacy of SA foliar use on Pb and Ni-induced stress tolerance and phytoremediation potential by Portulaca oleraceae L. were assayed as a factorial trial based on a completely randomized design with four repetitions. The factors included; SA foliar application (0 and 100 µM) and HMs application of Pb [0, 150, and 225 mg kg-1 soil Lead (II) nitrate] and Ni [0, 220, and 330 mg kg-1 soil Nickel (II) nitrate]. Plant height, stem diameter, shoot and root fresh and dry weight, photosynthetic pigments, total soluble proteins, palmitic acid, stearic acid, arachidic acid, and some macro- and micro-elements contents were reduced facing the HMs stress, but SA foliar application ameliorated these traits. HMs stress increased malondialdehyde content, total antioxidant activity, total flavonoids, phenolics, and linolenic acid content, while SA foliar application declined the mentioned parameters. Moreover, shoot and root Pb and Ni content enhanced in the purslane plants supplemented by SA under the HMs stress. The results propose SA foliar application as a reliable methodology to recover purslane growth characters and fatty acid profiles in the soil contaminated with the HMs. The idea is that SA would be potentially effective in alleviating HMs contamination while keeping reasonable phytoremediation potential.

There is no information available in previous literature about the impact of Pb and Ni on the phytochemical profile of oil in purslane. Therefore, in this report, we evaluated the purslane plant's growth and physiological responses and its seed oil's components in response to SA foliar application under conditions of Pb and Ni over-availability. Additionally, we examined the role of SA treatment in improving phytoremediation of Pb and Ni.

The Autocatalytic Chemical Reaction of a Soluble Biopolymer Derived from Municipal Biowaste.

The paper discusses the perspectives of further implementation of the autocatalytic properties of a soluble biopolymer (SBP) derived from municipal biowastes for the realisation of a biorefinery producing value-added bio-products for consumer use. The reaction of an SBP and water is reported to cause the depolymerisation and oxidation of the pristine SBP organic matter with the formation of carboxyl-functionalised polymers having lower molecular weight and CO2. These findings demonstrate the oxidation of the SBP via water, which could only occur through the production of O and OH radicals catalysed by the SBP. According to the adopted experimental plan, the anaerobic digestate supplied by an Italian municipal biowaste treatment plant was hydrolysed in pH 13 water at 60 °C. The dry product was re-dissolved in plain water at pH 10 and used as a control against the same solution with hydrogen peroxide at 0.1-3 H2O2 moles per SBP carbon mole added. The control and test solutions were kept at room temperature, in the dark or in a climatic chamber under irradiation with simulated solar light, until the pH of the solutions remained constant. Afterwards, the solutions were processed to recover and analyse the crude soluble products. The present work reports the results obtained for the control solution and for the test solutions treated in the presence and absence of H2O2, with and without pH control, in the dark and under irradiation with simulated solar light.

Mild Chemical Treatment of Unsorted Urban Food Wastes.

Municipal biowastes are conventionally treated by assessed anaerobic and aerobic fermentation to produce biogas, anaerobic digestate, and compost. Low-temperature hydrolysis and the oxidation of the digestate and compost, which are still at the experimental stage, are known to yield water-soluble value-added chemical specialities for use in different sectors of the chemical industry and in agriculture. The present paper reports the application of the two chemical reactions to the biowastes before fermentation. The products obtained in this manner are compared with those obtained from the chemical reactions applied to the fermented biowastes. Based on the experimental results, the paper discusses the expected environmental and economic benefits of the above chemical processes and products in comparison with the products obtained by other known biotechnologies for the valorisation of biomass as a feedstock for the biobased chemical industry. The results point out that a sustainable biowaste-based refinery that produces biofuel and biobased chemicals may be developed by integrating chemical and fermentation technologies.

Transcriptomic and physiological approaches to decipher cold stress mitigation exerted by brown-seaweed extract application in tomato.

Chilling temperatures represent a challenge for crop species originating from warm geographical areas. In this situation, biostimulants serve as an eco-friendly resource to mitigate cold stress in crops. Tomato (Solanum lycopersicum L.) is an economically important vegetable crop, but quite sensitive to cold stress, which it encounters in both open field and greenhouse settings. In this study, the biostimulant effect of a brown-seaweed extract (BSE) has been evaluated in tomato exposed to low temperature. To assess the product effects, physiological and molecular characterizations were conducted. Under cold stress conditions, stomatal conductance, net photosynthesis, and yield were significantly (p ≤ 0.05) higher in BSE-treated plants compared to the untreated ones. A global transcriptomic survey after BSE application revealed the impact of the BSE treatment on genes leading to key responses to cold stress. This was highlighted by the significantly enriched GO categories relative to proline (GO:0006560), flavonoids (GO:0009812, GO:0009813), and chlorophyll (GO:0015994). Molecular data were integrated by biochemical analysis showing that the BSE treatment causes greater proline, polyphenols, flavonoids, tannins, and carotenoids contents.The study highlighted the role of antioxidant molecules to enhance tomato tolerance to low temperature mediated by BSE-based biostimulant.

Transcriptomic profile of lettuce seedlings (Lactuca sativa) response to microalgae extracts used as biostimulant agents.

To reduce the use of chemical fertilizers and maximize agricultural yields, the use of microalgae extracts as biostimulants has recently attracted significant attention due to their favourable impact on both plant growth and their ability to induce tolerance towards environmental stressors. Lettuce (Lactuca sativa) is one of the most important fresh vegetables that often requires applications of chemical fertilizers to increase quality and productivity. Accordingly, the purpose of this study was to analyse the transcriptome reprogramming of lettuce (L. sativa) seedlings in response to either Chlorella vulgaris or Scenedesmus quadricauda extracts by applying an RNAseq approach. Differential gene expression analysis revealed that the core gene set that responded to microalgal treatments in a species-independent manner includes 1330 clusters, 1184 of which were down-regulated and 146 up-regulated, clearly suggesting that the repression of gene expression is the main effect of algal treatments. The deregulation of 7197 transcripts in the C. vulgaris treated seedlings compared to control samples (LsCv vs. LsCK) and 7118 transcripts in the S. quadricauda treated seedlings compared to control samples (LsSq vs. LsCK) were counted. Although the number of deregulated genes turned out to be similar between the algal treatments, the level of deregulation was higher in LsCv versus LsCK than in LsSq versus LsCK. In addition, 2439 deregulated transcripts were observed in the C. vulgaris treated seedlings compared to S. quadricauda treated samples (LsCv vs. LsSq comparison) suggesting that a specific transcriptomic profile was induced by the single algal extracts. 'Plant hormone signal transduction' category includes a very elevated number of DEGs, many of them specifically indicating that C. vulgaris actives both genes involved in the auxin biosynthesis and transduction pathways, whereas S. quadricauda up-regulates genes implicated in the cytokinin biosynthesis pathway. Finally, algal treatments induced the deregulation of genes encoding small hormone-like molecules that are known to act alone or by interacting with major plant hormones. In conclusion, this study offers the groundwork to draw up a list of putative gene targets with the aim of lettuce genetic improvement that will allow a limited or even null use of synthetic fertilizers and pesticides in the management of this crop.

Improvements in the biochemical responses and Pb and Ni phytoremediation of lavender (Lavandula angustifolia L.) plants through Funneliformis mosseae inoculation.

BACKGROUND: Heavy metals (HMs) phytoremediation is a well-recognized protocol to remove toxic elements from the soil. As known, arbuscular mycorrhizal fungi (AMF) enhance the plants' growth responses. The idea of the present study was to assay the response of lavender plants to HMs stress under AMF inoculation. We hypothesized that mycorrhiza will enhance the phytoremediation and simultaneously reduce the harmful effects of heavy HMs. So, lavender (Lavandula angustifolia L.) plants were inoculated with AMF (0 and 5 g Kg-1 soil) under Pb [150 and 225 mg kg-1 soil from Pb (NO3)2] and Ni [220 and 330 mg kg-1 soil from Ni (NO3)2] pollution, in the greenhouse conditions. The control treatment was plants not treated with AMF and HMs. Doing this, the root colonization, HMs uptake, enzymatic and non-enzymatic antioxidants pool, MDA, proline, total phenolics (TPC), flavonoids (TFC), anthocyanins, and essential oil (EO) components were evaluated. RESULTS: According to the findings, the AMF inoculation enhanced shoot and root Pb and Ni content, antioxidant enzymes activity, the total antioxidant activity by DPPH and FRAP methods, TPC, TFC, anthocyanins, and H2O2 content in the lavender plants subjected to Pb and Ni stress. Moreover, the highest (28.91%) and the least (15.81%) percentages of borneol were identified in the lavender plants subjected to AMF under 150 mg kg-1 of Pb and the control plants without AMF application, respectively. Furthermore, the top 1,8-cineole (12.75%) content was recorded in AMF-inoculated plants. CONCLUSIONS: The overall results verify that AMF inoculation can be a reliable methodology to enhance the phytoremediation of Pb and Ni by lavender plants while maintaining reliable growth potential. The treatments improved the main EO constituents content, especially under moderate HMs stress conditions. With more detailed studies, the results will be advisable for the extension section for the phytoremediation of polluted soils.

Effect of municipal biowaste derived biostimulant on nitrogen fate in the plant-soil system during lettuce cultivation.

A main concern of agriculture is to improve plant nutrient efficiency to enhance crop yield and quality, and at the same time to decrease the environmental impact caused by the lixiviation of excess N fertilizer application. The aim of this study was to evaluate the potential use of biopolymers (BPs), obtained by alkaline hydrolysis of the solid anaerobic digestate of municipal biowastes, in order to face up these main concerns of agriculture. The experimental trials involved the application of BPs (at 50 and 150 kg/ha) alone or mixed with different amounts (100%, 60% and 0%) of mineral fertilizer (MF). Three different controls were routinely included in the experimental trials (MF 100%, 60% and 0%). The effect of BPs on lettuce was evaluated by monitoring growth parameters (fresh and dry weights of shoot and root, nitrogen use efficiency), and the N-flux in plant-soil system, taking into account the nitrate leached due to over irrigation events. The activities of enzymes involved in the nitrogen uptake (nitrate reductase, glutamate synthase and glutamine synthase), and the nitrogen form accumulated in the plant tissues (total N, protein and NO3-) were evaluated. The results show that the application to the soil of 150 kg/ha BPs allows to increase lettuce growth and nitrogen use efficiency, trough stimulation of N-metabolism and accumulation of proteins, and hence to reduce the use of MF by 40%, thus decreasing the nitrate leaching. These findings suggest that the use of BPs as biostimulant greatly contributes to reduce the consumption of mineral fertilizers, and to mitigate the environmental impact caused by nutrients leaching, according to European common agricultural policy, that encourages R&D of new bioproducts for sustainable eco-friendly agriculture.

Sequential extraction of labile and recalcitrant fractions of soil organic matter: A case study focusing on antimony (Sb) in humic acids, fulvic acids and humin fractions of long-term aged contaminated soils.

Soil organic matter (SOM) plays a key role in environmental chemistry of macro and micro nutrients as well as heavy metal (loids). In this research, a modified sequential extraction scheme was used to isolate labile and recalcitrant SOM from organic rich soils after 18 months of ageing with antimony. Humic substances were extracted with a mixture of 0.5 M sodium hydroxide +0.1 M sodium pyrophosphate solution from soils. Then soils deprived of humic substances were sequentially subjected to extraction with glycerol, citric acid, pre-treated with acid and extracted with boiling alkali mixture. The humic acids (HA) and fulvic acids (FA) of isolated SOM fractions were separated and HAs been characterized using FTIR, 1H NMR, and UV-VIS. Acid-alkali treatment of the most recalcitrant SOM fraction (A1-ROM) led to the extraction of sparingly soluble, highly aromatic compound with considerable amounts of N (44% of the extractable N), possibly due to the breakdown of bounds between aromatic rings and amine functional groups. Nevertheless, the highest content of C and TOC was associated with the glycerol extractable SOM. Substantial amounts of Fe and Al were extracted with glycerol, resulting in a dramatic rise of Sb in SOM extracts. The largest increase (60%) in Sb concentrations was observed after the removal of Fe with citric acid. The humic substances (HS) were responsible for 63% of extractable Sb, whereas even after exhaustive alkali extractions 22% of the total Sb remained in the residual humin fraction. Within the HS fraction, 95% of antimony was associated with the low molecular weight FAs. Antimony concentrations in organic fractions correlated significantly with TOC and N contents, possibly due to the role of amine functional groups in Sb complexation. The results of this research highlight the importance of Fe-Al-SOM bridging and humin fraction in sequestration of Sb in recalcitrant SOM pools.

Brown Seaweed Extract (BSE) Application Influences Auxin- and ABA-Related Gene Expression, Root Development, and Sugar Yield in Beta vulgaris L.

The molecular and phenotypic effects of a brown seaweed extract (BSE) were assessed in sugar beet (Beta vulgaris L.). Transcript levels of BSE-treated and untreated plants were studied by RNA-seq and validated by quantitative real-time PCR analysis (RT-qPCR). Root morphology, sugar yield, and processing quality traits were also analyzed to better elucidate the treatment effects. RNA-seq revealed 1019 differentially expressed genes (DEGs) between the BSE-treated and untreated plants. An adjusted p-value < 0.1 and an absolute value of log2 (fold change) greater than one was used as criteria to select the DEGs. Gene ontology (GO) identified hormone pathways as an enriched biological process. Six DEGs involved in auxin and ABA pathways were validated using RT-qPCR. The phenotypic characterization indicated that BSE treatment led to a significant increase (p < 0.05) in total root length and the length of fine roots of plants grown under hydroponics conditions. The sugar yield of plants grown under field conditions was higher (p < 0.05) in the treated field plots compared with the control treatment, without impacting the processing quality. Our study unveiled the relevant effects of BSE application in regulating auxin- and ABA-related gene expression and critical traits related to sugar beet development and yield.

An Easy and Cheap Kiwi-Based Preparation as Vegetable Milk Coagulant: Preliminary Study at the Laboratory Scale.

In the present study, a kiwifruit aqueous extract was developed and used as a coagulant enzyme in cheesemaking. In detail, polyacrylamide gel electrophoresis (SDS-PAGE) was used to investigate the presence of actinidin, the kiwifruit enzyme involved in κ-casein hydrolysis, in different tissues (pulp, peel, and whole fruit) of ripe and unripe kiwifruits. Data revealed the presence of the enzyme both in the peel and in the pulp of the fruit. Although the aqueous extract obtained from the kiwifruit peel was able to hydrolyze semi-skimmed milk, it did not break down κ-casein. The aqueous extract obtained from the pulp showed a hydrolytic activity toward both κ-casein and semi-skimmed milk. The values for milk-clotting and proteolytic activity of the kiwifruit pulp extract were evaluated at different temperatures and pH parameters in order to obtain a high value of the MCA/PA ratio; we found that a temperature of 40 °C in combination with a pH value of 5.5 allowed us to obtain the best performance. In addition, the data revealed a higher hydrolytic activity of the enzymatic preparation from ripe kiwifruits than that from unripe ones, suggesting the use of the extract from pulp of ripe kiwifruits in the laboratory-scale cheesemaking. The data showed that 3% (v/v) of the ripe kiwifruit pulp extract determined a curd yield of 20.27%, comparable to chymosin yield. In conclusion, the extraction procedure for kiwifruit aqueous extract proposed in the present study was shown to be a fast, cheap, chemical-free, and ecofriendly technology as a plant coagulant for cheese manufacturing.

Endophytic Microbiome Responses to Sulfur Availability in Beta vulgaris (L.).

Sulfur is an essential plant macronutrient, and its adequate supply allows an efficient root storage and sugar extractability in sugar beets (Beta vulgaris L.). In this study, we investigated the effect of changes in sulfur availability on the endophytic community structure of sugar beets. Plants were hydroponically grown in a complete nutrient solution (S-supplied), a nutrient solution without MgSO4 (S-deprived), and a nutrient solution without MgSO4 for six days and resupplied with 100 µM MgSO4 for 48 h (S-resupplied). The sulfur status was monitored by inductively coupled plasma ICP-OES, and combustion analysis together with the evaluation of microRNA395 as a biomarker for sulfate status. Metabarcoding of the bacterial 16S rRNA gene was carried out in order to determine leaf endophytic community structure. The Shannon diversity index significantly differed (p < 0.05) between sulfate-supplied and sulfate-deprived seedlings. Validation by Real-Time PCR showed a significant increase (p < 0.05) of Burkholderia spp. in sulfate-deprived plants as compared to sulfate-supplied ones. The study sheds new light on the effects of nutrient deficiency on the microbiome of sugar beet plants.

Novel Effects of Leonardite-Based Applications on Sugar Beet.

The present study aimed to explore the effects of foliar application of a leonardite-based product on sugar beet (Beta vulgaris L.) plants grown in the field. The approach concerned the evaluation of the community compositional structure of plant endophytic bacteria through a metabarcoding approach, the expression level of a gene panel related to hormonal metabolism and signaling, and the main sugar beet productivity traits. Results indicated that plants treated with leonardite (dosage of 2,000 ml ha-1, dilution 1:125, 4 mg C l-1) compared with untreated ones had a significant increase (p < 0.05) in (i) the abundance of Oxalicibacterium spp., recognized to be an endophyte bacterial genus with plant growth-promoting activity; (ii) the expression level of LAX2 gene, coding for auxin transport proteins; and (iii) sugar yield. This study represents a step forward to advance our understanding of the changes induced by leonardite-based biostimulant in sugar beet.

[The management of nephropathic patients during the Covid-19 pandemic: the experience of Ragusa].

The public emergency caused by Covid-19 has forced health services to reorganize in order to separate positive patients from negative ones. In nephrology, this reorganization involves several levels of assistance concerning hospitalizations, ambulatory care and haemodialysis. Within the Complex Unit of Nephrology in Ragusa, the distribution of nephro-dialytic resources has involved four different hospitals, hence ensuring haemodialysis services for asymptomatic and pauci-symptomatic Covid-19 patients as well as for patients in Covid-Unit, Sub-Intensive Therapy and Intensive Care Unit. In this complex context, we had to create a common protocol involving all the professionals who provide assistance in our Unit, across the different structures. We also report some encouraging data that seem to indicate the effectiveness of the protocols put in place.

Side effects of two citrus essential oil formulations on a generalist insect predator, plant and soil enzymatic activities.

The widespread use of chemical pesticides for crop protection, despite having contributed to ensure food security, have shown to exert negative impacts on the environment and on human health. In addition, the frequent emergence of resistance to pesticides and their adverse effects toward non-target organisms have generated the need to develop novel ecofriendly tools for pest control. Among these, plant essential oils (EOs) may play a central role in arthropod pest control. Recently, two formulations (Emulsion and PEG-nanoparticles) of three citrus EOs (lemon, mandarin and sweet orange) showed a promising potential against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a key tomato pest. Here, we evaluated the side effects of these experimental insecticides active substances toward (i) the generalist predator of several tomato pests, Nesidiocoris tenuis Reuter (Hemiptera: Miridae); (ii) the soil enzymatic activities (dehydrogenase activity, alkaline phosphomonoesterase, acid phosphomonoesterase and urease) and (iii) the tomato plant antioxidant enzymes (ascorbate peroxidase, catalase, superoxide dismutase and polyphenol oxidase). Among the tested formulations, mandarin EO-based insecticide presented a significant impact on the predator survival and reproduction. Conversely, all the tested compounds proved to be harmless for the soil enzymatic and the plant antioxidant activities. Overall, these results provide solid bases for the development of novel biopesticides for sustainable tomato crop protection.

Effect of Microalgal Extracts from Chlorella vulgaris and Scenedesmus quadricauda on Germination of Beta vulgaris Seeds.

Sugar beet (Beta vulgaris subsp. vulgaris) is a commercially important biennial root crop, providing about 20% of the world's annual sugar production. Seed quality is crucial for adequate plant growth and production. The productivity of sugar beet is often limited by heterogeneous germination in the field. In order to improve the sugar beet germination process, the effect of different concentrations of microalgal extracts from Chlorella vulgaris or Scenedesmus quadricauda was investigated by calculating several indices useful to evaluate the germination performance. Moreover, root morphological analysis was performed by using WinRHIZO software. B. vulgaris seeds were soaked with five different concentrations (from 0.1 to 10 mg Corg/L) of the microalgal extracts, considering the amount of organic carbon (Corg) in each extract. Our results show that these microalgal extracts exert a positive effect on sugar beet germination, by increasing efficiency and regularity of this critical process for B. vulgaris seeds. The best results, in terms of germination indices as well as root morphological traits, were reached by using C. vulgaris extract at the concentrations C2 (1 mg Corg/L) and C3 (2 mg Corg/L).

Biostimulant Effect and Biochemical Response in Lettuce Seedlings Treated with A Scenedesmus quadricauda Extract.

The use of natural biostimulants is becoming an attractive option in order to reduce the use of fertilizer and increase the yield of crops. In particular, algal extracts are suitable candidates as they positively affect plant physiology. Among crops, lettuce often requires the use of biostimulants to improve both the quality and quantity of production. The aim of this work is to investigate the potential use of a Scenedesmus quadricauda extract as a biostimulant in order to obtain sustainable cultivation and a reduction in the cost of chemical fertilizers in lettuce cultivation. Therefore, the effect of S. quadricauda extract on lettuce seedlings was explored by evaluating the physiological parameters, chlorophyll, carotenoid, and total protein contents as well as several plant enzymatic activities involved in primary and secondary metabolisms. The experiment was performed by growing plants on inert substrate (pumice) with a 16-h photoperiod, by carrying out two consecutive radical treatments, one week apart, using a concentration of the extract corresponding to 1 mg Corg L-1. Lettuce plants were sampled at 1, 4, and 7 days from the first treatment and 7 days from the second treatment. The results showed that the S. quadricauda extract positively affected the growth of lettuce seedlings, mainly acting at the shoot level, determining an increase in dry matter, chlorophylls, carotenoids, proteins, and influencing the activities of several enzymes involved in the primary metabolism.

Physiological and Biochemical Responses of Orange Trees to Different Deficit Irrigation Regimes.

The article presents the results of research consisting of the application of deficit irrigation (DI) criteria, combined with the adoption of micro-irrigation methods, on orange orchards (Citrus sinensis (L.) Osbeck) in Sicily (Italy) during the irrigation season of 2015. Regulated deficit irrigation (RDI, T3) and partial root-zone drying (PRD, T4) strategies were compared with full irrigation (T1) and sustained deficit irrigation (SDI, T2) treatments in terms of physiological, biochemical, and productive crop response. A geophysical survey (electrical resistivity tomography, ERT) was carried out to identify a link between the percentages of drying soil volume in T4 with leaves abscisic acid (ABA) signal. Results highlight that the orange trees physiological response to water stress conditions did not show particular differences among the different irrigation treatments, not inducing detrimental effects on crop production features. ABA levels in leaves were rather constant in all the treatments, except in T4 during late irrigation season. ERT technique identified that prolonged drying cycles during alternate PRD exposed more roots to severe soil drying, thus increasing leaf ABA accumulation.

Expression Profiling of Candidate Genes in Sugar Beet Leaves Treated with Leonardite-Based Biostimulant.

Leonardite-based biostimulants are a large class of compounds, including humic acid substances. Foliar application of biostimulants at field level improves plant growth, yield and quality through metabolic changes and stimulation of plant proton pumps. The present study aimed at identifying optimum dosage of BLACKJAK, a humic acid-based substance, which is able to modify genes involved in sugar beet growth. Thirty-three genes belonging to various biochemical pathway categories were tested in leaves of treated sugar beet (Beta vulgaris L.) samples to assess gene expression profiling in response to BLACKJAK. Seedlings of a diploid and multigerm variety were grown in plastic pots and sprayed with two dilutions of BLACKJAK (dilution 1:500-1.0 mg C L-1 and dilution 1:1000-0.5 mg C L-1). Leaf samples were collected after 24, 48, and 72 h treatment with BLACKJAK for each dilution. RNA was extracted and the quantification of gene expression was performed while using an OpenArray platform. Results of analysis of variance demonstrated that, 15 genes out of a total of 33 genes tested with OpenArray qPCR were significantly affected by treatment and exposure time. Analysis for annotation of gene products and pathways revealed that genes belonging to the mitochondrial respiratory pathways, nitrogen and hormone metabolisms, and nutrient uptake were up-regulated in the BLACKJAK treated samples. Among the up-regulated genes, Bv_PHT2;1 and Bv_GLN1 expression exerted a 2-fold change in 1:1000 and 1:500 BLACKJAK concentrations. Overall, the gene expression data in the BLACKJAK treated leaves demonstrated the induction of plant growth-related genes that were contributed almost to amino acid and nitrogen metabolism, plant defense system, and plant growth.