Application Of Oxalic Acid Research Articles

Optimizing Oxalic Acid Application Regime to Maximize Sunflower Remediation Efficacy in Cd-Contaminated Soils

The exogenous application of oxalic acid is a potential approach to amplifying phytoremediation performance on Cd-contaminated soils. However, few studies explore the optimal oxalic acid application regime from a perspective of coupling different concentrations and timings to maximize Cd removal rate. Given this, a pot experiment was conducted using oil sunflower (Helianthus annuus L.) as the test plant. Oxalic acid was added to the pots at concentrations of 1, 2, 3, 4, 5, and 6 mmol/kg at 20, 30, 40, and 50 days after emergence. A control (CK) without exogenous oxalic acid was also included. We examined the discrepancies in various soil Cd forms, sunflower height, plant non-protein thiol (NPT) levels, and soil Cd remediation efficiency under different oxalic acid application regimes. The results showed that applying oxalic acid at a concentration of 4 mmol/kg reduced the proportion of Fe-Mn oxide Cd and organic Cd compared to the control (CK), while increased the proportion of available Cd. The optimal application time is 30 or 40 days after emergence. The addition of exogenous oxalic acid promoted the growth of sunflowers, with the greatest increase in plant height observed when 4 mmol/kg oxalic acid was applied at 30 days after emergence. Exogenous oxalic acid enhanced the absorption of Cd by sunflower roots, with the total Cd accumulation in roots, stems, and leaves being higher than in the control (CK). When 4 mmol/kg oxalic acid was applied at 30 days after emergence, the total Cd accumulation in roots, stems, and leaves was highest. Under different application times and concentration levels of oxalic acid, Cd accumulation was highest in roots, followed by leaves, with stems showing the lowest accumulation. The NPT content in each part is as follows: root > stem > leaf. Applying 5 mmol/kg oxalic acid after 30 days of sunflower emergence resulted in relatively higher total NPT content in roots, stems, and leaves compared to the control (CK). The TOPSIS model was used for comprehensive evaluation, which showed that 4 mmol/kg oxalic acid application at 30 days after emergence could be used as the optimal oxalic acid application regime for phytoremediation. These findings indicate that the addition of oxalic acid effectively promoted the absorption of Cd by sunflower and increased the efficiency of Cd removal from the rhizosphere soil, with the optimal removal of soil Cd achieved by applying oxalic acid at a concentration of 4 mmol/kg 30 days after the emergence of oilseed sunflower seedlings.

Colonies under dysbiosis benefit from oxalic acid application: the role of landscape and beekeeping practices in microbiota response to treatment

AbstractThe Varroa destructor mite causes severe losses of Apis mellifera colonies, requiring recurring treatments. One such treatment is oxalic acid (OA), considered ecological. However, it is unclear whether OA affects the honey bee gut microbiota or other hive-associated microbiotas. Herein, we studied the effect of three OA treatments (trickling at 2.1% or 4.2%, and sublimation through Varrox®) upon microbial communities associated with workers’ gut, hive bee bread and pupae, sampled from conventionally or ecologically managed colonies under different anthropization levels (located in urban, rural or mountainous landscapes). We hypothesized that treatment with OA would impact the diversity and composition of bacteria and/or eukaryotic communities, and that the effect would be dose-dependent and specific to the beehive niche. Results showed that the microbiomes of apiaries under different anthropization levels and management strategies differed prior to OA application. Neither the bacterial nor the fungal communities of bee bread and pupae shifted due to OA treatment. Independent of the dosage and the application method (trickling or sublimation), OA induced slight compositional changes in the bacterial profiles of honeybee guts. Those changes were stronger the higher the anthropization (in colonies from urban areas under conventional management). OA treatment reduced the relative abundance of several pathogens, such as Nosema ceranae, and decreased the overall bacterial diversity down to values found in less anthropized colonies. Thus, our results suggest that, aside from managing Varroa infestations, OA could have beneficial effects for stressed colonies while not impairing honey bee resilience from a microbial point of view.

Effect of Three Bleaching Protocols on Tooth Discoloration Caused by Hemoglobin.

Objectives: This study assessed the efficacy of different combinations of oxalic acid, 35% hydrogen peroxide, and 5.25% sodium hypochlorite (NaOCl) for bleaching of tooth discolorations caused by hemoglobin. Materials and Methods: In this in vitro study, 40 sound extracted human premolars were disinfected and decoronated. Their primary color parameters were measured (T1). The teeth were then centrifuged with human blood for 3 days, rinsed, polished, and their color parameters were measured again (T2). They were randomly divided into 4 groups (N=10) and treated as follows: Group A: in-office bleaching with Pola-Office Plus followed by 30 seconds of light-curing, group B: 0.24 M oxalic acid for 5 minutes followed by in-office bleaching, group C: 5.25% NaOCl for 5 minutes followed by in-office bleaching, and group D: 0.24 M oxalic acid (5 minutes) followed by 5.25% NaOCl (5 minutes) and subsequent application of in-office bleaching gel. The color parameters of the teeth were measured again (T3). Data were analyzed by one-way ANOVA and paired sample t-test (alpha=0.05). Results: T2-T3 ∆E in groups B and D was significantly higher than that in group A (P<0.05); the difference between groups B and D was not significant. The mean ∆E and ∆L in group C were not significantly different from those in group A (P>0.05). ∆L significantly and equally increased in groups B and D after bleaching. Conclusion: Application of oxalic acid followed by in-office bleaching gel is more effective than the bleaching gel alone for correction of tooth discolorations caused by hemoglobin.

Nitrogen migration and transformation characteristics of the soil in karst areas under the combined application of oxalic acid and urea inhibitors.

We investigated the horizontal migration and transformation of nitrogen in soil with oxalic acid and inhibitors (e.g., nitrification inhibitors, DMPP, urease inhibitors, and NBPT) under different soil water contents to provide a basis for the efficient utilization of nitrogen fertilizer in agricultural production in karst areas. Four nitrogen fertilizers (e.g., ammonium bicarbonate, ammonium sulfate, ammonium chloride, and urea) were applied separately and combined with oxalic acid, DMPP, and NBPT. The ammonium and nitrate nitrogen contents in the different soil layers were measured. The soil columns were cultured through an indoor soil column simulation at water content levels of 30%, 40%, and flooded (50%) for 30 days. Ammonium bicarbonate with inhibitors increased soil NH4 +-N content by 15.42-21.12%. Ammonium sulfate with oxalic acid or NBPT increased soil NH4 +-N content by 27.56-52.25% at 30% and 40% moisture content treatments, compared to ammonium sulfate alone. Urea with DMPP application significantly increased soil NH4 +-N content by 11.93-14.87% at 40% water content and flooded conditions. In all treatments, the NH4 +-N content in the soil treated with 30% water content of ammonium chloride with oxalic acid was the highest. The NH4 +-N content showed a decreasing trend with an increase in the water content. The NO3 --N content in soil treated with ammonium bicarbonate and DMPP was higher than that treated with other nitrogen fertilizers at 30% moisture. The NO3 --N content decreased with increased water content. Under all treatments, ammonium chloride with oxalic acid had the highest percentage of soil NH4 +-N and soil soluble inorganic nitrogen at 30% water content, with 55.29% and 55.97%, respectively. Among the nitrogen fertilizer treatments, the soil NH4 +-N content increased in ammonium bicarbonate with DMPP or NBPT, ammonium sulfate with oxalic acid or NBPT, and urea with DMPP. The four nitrogen fertilizers with DMPP increased the soil NO3 --N content. Nitrogen fertilizer combined with oxalic acid and inhibitors could effectively improve the effective use of nitrogen fertilizer.

Effect of oxalic acid on postharvest life of tomato modified with the TomLoxB gene in anti-sense

Oxalic acid is an organic compound found in green leafy vegetables, which has proven to be effective in delaying ripening by inhibiting ethylene synthesis in fruits such as banana, mango, peach, tomato, plum, and others. In this study, the response of oxalic acid application on postharvest physiology was evaluated in transgenic tomatoes (Solanum lycopersicum) variety TA234 with the TomLoxB gene insertion in antisense, at two concentrations of oxalic acid: 3 and 10 mM, during 30 d of storage at 25 ± 1 ºC and a relative humidity of 65 - 70 %. The fruits were harvested at break stage and immersed for 10 minutes in the oxalic acid solution, which was maintained at 25 ºC. Upon treatment, less weight loss, better retention of lightness, delay in the decrease of firmness and hue angle, decrease in lipoxygenase activity, low electrolyte leakage and increase in total phenolics content were observed. The most effective oxalic acid concentration was 3 mM, that extended postharvest life by up to 30 d and reduced deterioration of the genetically modified (GM) tomatoes. In turn, the untreated GM tomatoes showed an acceptable appearance up to day 24 of storage, while the wild type fruits were kept satisfactorily for 15 d.

Exogenous application of oxalic acid improves the storage quality of Asian pears (Patharnakh) by regulating physiological and biochemical changes

Exogenous application of oxalic acid improves the storage quality of Asian pears (Patharnakh) by regulating physiological and biochemical changes

Physiological mechanisms of exogenous organic acids to alleviate aluminum toxicity in seedlings of mungbean, buckwheat, and rice

One of the major constraints for crop yield in acidic soils is the phytotoxicity of aluminum ions (Al3+), which primarily affects the roots. To mitigate the harmful effects of Al toxicity, plants use organic acids to chelate Al internally and externally. In this study, the effects of exogenous organic acids on Al toxicity in rice, mung bean, and buckwheat were investigated. Specifically, the study examined the ameliorative effect of three organic acids (oxalic acid, malic acid, and citric acid, each at a concentration of (100 μmol/L) on root elongation, fresh weight, Al content, organic acid key enzymes, and rhizosphere pH in hydroponic media containing (100 μmol/L) Al. The experimental results revealed species-specific responses to aluminum tolerance and the alleviating effects of different organic acids. Buckwheat was found to be the most aluminum-tolerant, followed by mung bean, while rice was the least tolerant. Exogenous application of oxalic acid promoted root elongation, increased root fresh weight, and enhanced the activity of the PEPC enzyme in mung bean. Malic acid, on the other hand, alleviated Al toxicity in rice by promoting root elongation, increasing root fresh weight, enhancing the activity of the PEPC enzyme, and decreasing the activity of the MDH enzyme. In buckwheat, citric acid application reduced Al toxicity by promoting root elongation, increasing root weight, and decreasing the activities of CS and GO enzymes. These findings indicate that different organic acids can reduce Al toxicity in different plant species by employing different physiological mechanisms.

Oxalic acid: an important organic acid to increase yield and quality in lettuce

In the present study, the effects of different doses of oxalic acid applications on yield and quality in lettuce cultivation were evaluated. Yedikule 5107 variety was used as plant material and four different doses of oxalic acid (0-2-4-6 mM) were applied to lettuce plants from leaves. Plant weight varied between 343.02-432.57 g/plant, plant height 28.0-30.35 cm, plant diameter 26.67-28.72 cm, leaf length 21.23-22.44 cm, root collar diameter 19.11-21.49 mm and number of leaves 47.57-55.63 per plant depending on oxalic acid doses, and the highest yield was obtained from 2 mM oxalic acid application. Total chlorophyll and total phenolic contents varied between 37.47-39.31 and 67.35-103.98 mg/100g, respectively. While the highest chlorophyll value was obtained from 2 mM oxalic acid; the highest phenolic substance value was obtained from 4 mM oxalic acid application. It was determined that L*, a*, b*, and C* values varied from 47.43 to 48.76, -17.55 to -18.26, 27.89 to 28.68, and 32.95 to 34.00 depending on applications, and the highest L* value was obtained from 2 mM oxalic acid application and the highest a*, b* and C* values were observed in 2 mM and 4 mM oxalic acid applications. The antiradical values in lettuce varied between 42.36-82.64%. At the end of the study, when all these parameters were considered, it was determined that oxalic acid applications significantly and positively affect the yield and quality of lettuce.

Exogenous application of low and high molecular weight organic acids differentially affected the uptake of cadmium in wheat-rice cropping system in alkaline calcareous soil

Anthropogenic cadmium (Cd) in arable soils is becoming a global concern due to its harmful effects on crop yield and quality. The current study examined the role of exogenously applied low molecular weight organic acids (LMWOAs) including oxalic acid (OxA), tartaric acid (TA) and high molecular weight organic acids (HMWOAs) like citric acid (CA) and humic acid (HA) for the bioavailability of Cd in wheat-rice cropping system. Maximum increase in root dry-weight, shoot dry-weight, and grain/paddy yields was recorded with HA for both crops. The HA significantly decreased AB-DTPA Cd in contaminated soils which remained 41% for wheat and 48% for rice compared with their respective controls. The minimum concentration of Cd in roots, shoots and grain/paddy was observed in HA treatment in both crops. The organic acids significantly increased the growth parameters, photosynthetic activity, and relative leaf moisture contents for both wheat and rice crops compared to that with the contaminated control. Application of OxA and TA increased the bioavailability of Cd in soils and plant tissues while CA and HA decreased the bioavailability of Cd in soils and plants. The highest decrease in Cd uptake, bioaccumulation, translocation factor, immobilization, translocation, harvest, and health risk indices were observed with HA while maximum increase was recorded with OxA for both wheat and rice. The results concluded that use of HMWOAs is effective in soil Cd immobilization being maximum with HA. While LMWOAs can be used for the phytoextraction of Cd in contaminated soils having maximum potential with OxA.

Simultaneous Application of Oxalic Acid and Sodium Dithionite for Synchronous Removal of Iron and Silica from Low-Grade Bauxite: Kinetics and Mechanism

Simultaneous Application of Oxalic Acid and Sodium Dithionite for Synchronous Removal of Iron and Silica from Low-Grade Bauxite: Kinetics and Mechanism

Oxalic acid treated low grade rock phosphate can be a potent supplemental P source to grow wheat in inceptisol

High grade rock phosphates (HGRP) are only used to prepare phosphorus (P) fertilizers. But the finite reserve of HGRP is pushing the agricultural sectors to use low grade rock phosphates (LGRP) for growing crops. In this study an attempt was made to treat LGRP with oxalic acid and use it as a supplement to P fertilizer for growing wheat in Inceptisol. Incubation study revealed that oxalic acid treated rock phosphate (RP) can significantly increase soil available P status as compared to inert untreated RP treatment. Pot study established that oxalic acid treated RP (@60 mg P2O5 kg−1) under DAP30+ RP60(OA) treatment has supplemented 50% P fertilizer without affecting wheat yields and P uptake. DAP30+ RP60(OA) treatment also had maintained significantly higher Saloid-P, organic-P and statistically at par available P, dehydrogenase, acid phosphatase and alkaline phosphatase activities as compared to chemical fertilizer treatment (DAP60). Thus it can be inferred that, application of oxalic acid treated LGRP (@ 60 mg P2O5 kg−1) can supplement 50% of the P fertilizer demand to grow wheat in Inceptisol.

Polystyrene stabilized Pd-Au nanoalloy for efficient synthesis of bis(indolyl)methanes from aryl iodides using oxalic acid as CO and H2 source

Herein, first example of heterogeneously catalyzed carbonylative synthesis of bis(indolyl)methanes from aryl iodides in one-pot and single-step manner has been reported. The reaction was best catalyzed by polystyrene supported bimetallic Pd-Au (Pd-Au@PS) nanoparticles (NPs) in comparison to various supported monometallic Pd-catalysts. The key feature of this protocol involves the application of oxalic acid as economic, solid, and safe multi-functional reagent which acts as a CO, H2 source as well as acid co-catalyst with PEG-200 as green solvent reaction medium for delivering moderate to excellent yields of the desired products, bis(indolyl)methanes (BIMs). The developed protocol is additive, phosphine ligand-free under air/moisture stable recyclable catalyst bearing easy accessibility/affordability to starting materials.

Impact of low molecular weight organic acids on soil phosphorus fractions and its content in wheat (Triticum aestivum) and soybean (Glycine max)

A greenhouse experiment was conducted at ICAR-IARI, New Delhi during 2017-18 to study the effect of low molecular weight organic acids on phosphorus fractions and its content in wheat and soybean. The results revealed that the applied LMWOAs showed significant increase in the plant available P fraction over control and oxalic acid application out rated the citric acid. The applied citric acid was found to be significantly superior in decreasing the Al and Fe bound P, whereas, oxalic acid was superior to citric acid in reducing the Ca bound P. Application of 20 mg LMWOAs kg-1 was found to be better dose in enhancing the available P and reducing the Al, Fe and Ca bound P. The applied 100% recommended dose of phosphorus showed significant increase in available, calcium, aluminium and reductant P fractions over other levels of applied P. The application of LMWOAs significantly enhanced the P content in both wheat and soybean crops. However, both oxalic and citric acid were found at par with each other in enhancing the P content in the crops. Overall, 15 mg LMWOAs kg-1 was found to be economic level in enhancing the P content in the crops and 100% RDP application showed significant enhancement in grain, straw and root P content over other levels of applied P. The LMWOAs are actually the organic compounds, so there will be no adverse effect of these products application to the soil compared to the inorganic chemicals and fertilizers

Impact of low molecular weight organic acids on soil phosphorus fractions and its content in wheat (Triticum aestivum) and soybean (Glycine max)

A greenhouse experiment was conducted at ICAR-IARI, New Delhi during 2017-18 to study the effect of low molecular weight organic acids on phosphorus fractions and its content in wheat and soybean. The results revealed that the applied LMWOAs showed significant increase in the plant available P fraction over control and oxalic acid application out rated the citric acid. The applied citric acid was found to be significantly superior in decreasing the Al and Fe bound P, whereas, oxalic acid was superior to citric acid in reducing the Ca bound P. Application of 20 mg LMWOAs kg-1 was found to be better dose in enhancing the available P and reducing the Al, Fe and Ca bound P. The applied 100% recommended dose of phosphorus showed significant increase in available, calcium, aluminium and reductant P fractions over other levels of applied P. The application of LMWOAs significantly enhanced the P content in both wheat and soybean crops. However, both oxalic and citric acid were found at par with each other in enhancing the P content in the crops. Overall, 15 mg LMWOAs kg-1 was found to be economic level in enhancing the P content in the crops and 100% RDP application showed significant enhancement in grain, straw and root P content over other levels of applied P. The LMWOAs are actually the organic compounds, so there will be no adverse effect of these products application to the soil compared to the inorganic chemicals and fertilizers.

Effects of lime and oxalic acid on antioxidant enzymes and active components of Panax notoginseng under cadmium stress

Cadmium (Cd) pollution poses potential safety risks for Panax notoginseng cultivation, a medicinal plant in Yunnan. Under exogenous Cd stress, field experiments were conducted to understand the effects of lime (0, 750, 2250 and 3750 kg hm−2) applied and oxalic acid (0, 0.1 and 0.2 mol L−1) leaves sprayed on Cd accumulation, antioxidant system and medicinal components of P. notoginseng. The results showed that Lime and foliar spray of oxalic acid were able to elevate Ca2+ and alleviate Cd2+ toxicity in P. notoginseng under Cd stress. The addition of lime and oxalic acid increased the activities of antioxidant enzymes and alters osmoregulator metabolism. The most significant increase in CAT activities increased by 2.77 folds. And the highest increase of SOD activities was 1.78 folds under the application of oxalic acid. While MDA content decreased by 58.38%. There were very significant correlation with soluble sugar, free amino acid, proline and soluble protein. Lime and oxalic acid were able to increase calcium ions (Ca2+), decrease Cd content and improve the stress resistance of P. notoginseng, while increasing the production of total saponins and flavonoids. Cd content were the lowest, 68.57% lower than controls, and met the standard value (Cd ≤ 0.5 mg kg−1, GB/T 19086-2008). The proportion of SPN was 7.73%, which reached the highest level of all treatments, the flavonoids content increased significantly by 21.74%, which reached the medicinal standard value and optimal yield.

Spatial clusters of Varroa destructor control strategies in Europe

Beekeepers have various options to control the parasitic mite Varroa destructor in honey bee colonies, but no empirical data are available on the methods they apply in practice. We surveyed 28,409 beekeepers maintaining 507,641 colonies in 30 European countries concerning Varroa control methods. The set of 19 different Varroa diagnosis and control measures was taken from the annual COLOSS questionnaire on honey bee colony losses. The most frequent activities were monitoring of Varroa infestations, drone brood removal, various oxalic acid applications and formic acid applications. Correspondence analysis and hierarchical clustering on principal components showed that six Varroa control options (not necessarily the most used ones) significantly contribute to defining three distinctive clusters of countries in terms of Varroa control in Europe. Cluster I (eight Western European countries) is characterized by use of amitraz strips. Cluster II comprises 15 countries from Scandinavia, the Baltics, and Central-Southern Europe. This cluster is characterized by long-term formic acid treatments. Cluster III is characterized by dominant usage of amitraz fumigation and formed by seven Eastern European countries. The median number of different treatments applied per beekeeper was lowest in cluster III. Based on estimation of colony numbers in included countries, we extrapolated the proportions of colonies treated with different methods in Europe. This suggests that circa 62% of colonies in Europe are treated with amitraz, followed by oxalic acid for the next largest percentage of colonies. We discuss possible factors determining the choice of Varroa control measures in the different clusters.

Towards Understanding the Involvement of H+-ATPase in Programmed Cell Death of Psammosilene tunicoides after Oxalic Acid Application.

Psammosilene tunicoides is a unique perennial medicinal plant species native to the Southwestern regions of China. Its wild population is rare and endangered due to over-excessive collection and extended growth (4–5 years). This research shows that H+-ATPase activity was a key factor for oxalate-inducing programmed cell death (PCD) of P. tunicoides suspension cells. Oxalic acid (OA) is an effective abiotic elicitor that enhances a plant cell’s resistance to environmental stress. However, the role of OA in this process remains to be mechanistically unveiled. The present study evaluated the role of OA-induced cell death using an inverted fluorescence microscope after staining with Evans blue, FDA, PI, and Rd123. OA-stimulated changes in K+ and Ca2+ trans-membrane flows using a patch-clamp method, together with OA modulation of H+-ATPase activity, were further examined. OA treatment increased cell death rate in a dosage-and duration-dependent manner. OA significantly decreased the mitochondria activity and damaged its electron transport chain. The OA treatment also decreased intracellular pH, while the FC increased the pH value. Simultaneously, NH4Cl caused intracellular acidification. The OA treatment independently resulted in 90% and the FC led to 25% cell death rates. Consistently, the combined treatments caused a 31% cell death rate. Furthermore, treatment with EGTA caused a similar change in intracellular pH value to the La3+ and OA application. Combined results suggest that OA-caused cell death could be attributed to intracellular acidification and the involvement of OA in the influx of extracellular Ca2+, thereby leading to membrane depolarization. Here we explore the resistance mechanism of P. tunicoides cells against various stresses endowed by OA treatment.

Pre-Harvest Oxalic Acid Application Improves Fruit Size at Harvest, Physico-Chemical and Sensory Attributes of ‘Red Flesh’ Apricot During Fruit Ripening

Apricot is a highly nutritive stone fruit which ripens quickly after harvest and exhibits rapid fruit quality deterioration at ambient conditions. The current research work was executed to evaluate the effect of pre-harvest application of oxalic acid (OA); (0, 0.5, 1, and 2mM) on fruit quality of ‘Red Flesh’ apricot during fruit ripening at shelf under ambient conditions (25±1 °C; 60-65% RH). Fruit size, average fruit weight, fruit juice percentage was determined at harvest. While, fruit weight loss, fruit colour, fruit firmness, titratable acidity (TA), soluble solid contents (SSC), ratio of SSC to TA, ascorbic acid, total phenolics content (TPC), anti-oxidative scavenging activity (ASA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) enzymes activity were determined during fruit ripening. Fruit sensory attributes (fruit pulp colour, fruit taste, fruit flavour and overall acceptability were determined at fruit ripening. Pre-harvest application of 2mM-OA was found the most effective in improving fruit size, average fruit weight, juice percentage at harvest, about 5%, 6% and 15% higher than control, respectively. Additionally, pre-harvest application of 2mM-OA retained higher fruit firmness, ascorbic acid, TPC, ASA and activities of POD, CAT enzymes in apricot fruit during fruit ripening at ambient conditions. On day-5 of fruit ripening 2mM-OA-treated apricot fruit exhibited about 28%, 20%, 17%, 7%, 9% and 23% higher fruit firmness, ascorbic acid, TPC, ASA and activities of POD, CAT enzymes, respectively as compared to control. Moreover, significant lower fruit weight loss (35%), SSC (20%) and SSC:TA ratio (30%) were exhibited by the apricot fruit treated with 2mM-OA than unsprayed apricot fruit. However, fruit treated with 1 mM-OA exhibited better fruit sensory attributes compared to other treatments at fruit ripening. Conclusively, pre-harvest application of 2 mM-OA improved the fruit size, delayed fruit ripening, and retained higher fruit antioxidants of apricot at ambient conditions.

Salicylic acid and oxalic acid in enhancing the quality and extending the shelf life of grape cv. Thompson seedless.

Postharvest life of table grapes is usually shortened by berry softening, berry drop, stem browning, fungal decay. Salicylic acid reduces fruit respiration and ethylene biosynthesis, during storage of fruits. Similarly, application of oxalic acid is a secure and hopeful postharvest handling technology for keeping quality and prolonging storage life of fruit. To study the effect of Salicylic acid and oxalic acid in enhancing the quality and extending the shelf life of grape, the present investigation was conducted. The grape berries were treated with Oxalic acid (OA) (1, 2, 3, 4, and 5 mM) and Salicylic acid (SA) (0.5, 1, 1.5 and 2 mM). The treatments were compared within 16th days at an interval of 4 days. Among the treatments, SA (2 mM) showed superiority in different quality attributing characters like physiological loss in weight (PLW), berry firmness, rachis browning, berry appearance, fungal decay, berry shattering, TSS, ascorbic acid, titratable acidity, total sugars, reducing sugars, TSS: acid ratio, taste, overall acceptability and shelf life. Hence, SA (2 mM) can be used as an effective strategy for maintaining quality of table grapes.

Application of Oxalic Acid and 1-Methylcyclopropane (1-Mcp) with Low and High-Density Polyethylene on Post-Harvest Storage of Litchi Fruit

The present study investigates the effects of oxalic acid and 1-methylcyclopropane (1-MCP) treatments in combination with low-density polyethylene (LDPE) and high-density polyethylene (HDPE) on the post-harvest storage of litchi fruits. The physicochemical properties, bioactive compounds, antioxidant activities, and dismutase enzyme activity (SOD) of treated and untreated litchi fruits were examined during 30 days of storage at 4 ℃. The most effective combination was 1-MCP and HDPE packaging, which lowered the weight loss and preserved the red pericarp. Fruits treated with 1-MCP and HDPE also exhibited higher content of ascorbic acid (74.73–34.95 mg/100 g), total phenol (55.70–28.83 mg/100 g), and total flavonoid content (82.46–48.54 mg/100 g), whereas anthocyanin content (0.24–0.39 mg/100 g) was lowered during the entire storage period. In addition, higher levels of DPPH activity, reducing power, and SOD activity were observed in 1-MCP and HDPE-treated fruits. While antioxidants, SOD activities, and acidity were positively associated with total phenol and flavonoid content, these were negatively associated with anthocyanin content. Thus, the combined treatment of 1-MCP and HDPE are proposed as a sustainable strategy to preserve red pericarp, improve quality, and increase fruit shelf life of litchi.