Evaluation of phytoremediation potential and resistance of Gladiolus grandiflora L. against cadmium stress.

Although irrigation water is a fundamental need for plant growth, it is also a source of pollutants if contaminated with harmful materials like cadmium (Cd). Irrigation water possessing abundant Cd causes damage to soil, plants, animals and ultimately human beings through the food chain. A pot experiment was conducted to evaluate the gladiolus (Gladiolus grandiflora L.) potential of Cd accumulation and the capability of the plant to be an economically beneficial choice in presence of high Cd irrigation water supply. Artificially prepared four levels of Cd irrigation water were applied to the plants viz., 30, 60, 90 and 120 mg L-1. The results revealed that 30 mg L-1 Cd had no difference in all growth-related parameters when compared to the control. Photosynthesis rate, stomatal conductance and transpiration rate along with plant height and spike length were reduced with high accumulation levels of Cd in plants. The main plant portion for Cd storage found in Gladiolus grandiflora L was corm where the amount of Cd was 10-12 times higher than the amount found in leaves, and 2-4 times more than the stem. This deportment was further established by the translocation factor (TF). In corm to shoot TF and corm to stem TF, the factor reduced with increasing Cd levels, while, in corm to leaves TF, Cd levels were statistically non-significant. From corm to shoot TF value of 0.68 and 0.43 in case of 30 and 60 mg L-1, Cd treatments indicates good phytoremediation potential of Gladiolus in low and moderate Cd-polluted environments. Conclusively, the study reveals the good capability of Gladiolus grandiflora L. to harvest Cd from the soil and water in reasonably good amount with sufficient potential to grow under irrigation-based Cd stress. Under revelations of the study, Gladiolus grandiflora L appeared as a Cd accumulator which could potentially be used as a sustainable approach for phytoremediation of Cd.

Aloe vera gel coating delays softening and maintains quality of stored persimmon (Diospyros kaki Thunb.) Fruits.

The effect of Aloe vera (AV) gel coating was studied on antioxidant enzymes activities, oxidative stress, softening and associated quality attributes of persimmon fruits. The fruits were coated with 0 and 50% AV-gel coating and stored for 20 days at 20 ± 1 ºC. AV-gel coated fruits exhibited considerably less weight loss, hydrogen peroxide level, electrolyte leakage and malondialdehyde content. AV-gel coated fruits had significantly higher ascorbate peroxidase, peroxidase, superoxide dismutase and catalase activities. In addition, AV-gel coating suppressed pectin methylesterase, polygalacturonase and cellulase activities and showed higher ascorbic acid, DPPH scavenging antioxidants and phenolics, and lower sugars and carotenoids. To the best of our knowledge, these results are the first evidence that AV-gel coating modulates the activities of cell wall degrading enzymes to delay ripening in climacteric fruits. So, AV-gel coating prohibited the onset of senescence by activating enzymatic antioxidant system, accumulating bioactive compounds and suppressing cell wall degradation. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05412-5.

Physiological and iTRAQ-Based Quantitative Proteomics Analysis of Methyl Jasmonate-Induced Tolerance in Brassica napus Under Arsenic Stress.

Brassica napus plants exposed to 200 µM arsenic (As) exhibited high-level of stress condition, which led to inhibited growth, enhanced lipid peroxidation, and disrupted cellular ultrastructures. Exogenous application of methyl jasmonate (MeJA) alleviated the As-induced oxidative stress and improved the plant growth and photosynthesis. In this study, changes in the B. napus leaf proteome are investigated in order to identify molecular mechanisms involved in MeJA-induced As tolerance. The study identifies 177 proteins that are differentially expressed in cultivar ZS 758; while 200 differentially expressed proteins are accumulated in Zheda 622, when exposed to As alone and MeJA+As treatments, respectively. The main objective was to identify the MeJA-regulated protein under As stress. Consistent with this, iTRAQ detected 61 proteins which are significantly accumulated in ZS 758 leaves treated with MeJA under As stress. While in Zheda 622, iTRAQ detected 49 MeJA-induced proteins under As stress. These significantly expressed proteins are further divided into five groups on the base of their function, that is, stress and defense, photosynthesis, carbohydrates and energy production, protein metabolism, and secondary metabolites. Taken together, this study sheds light on the molecular mechanisms involved in MeJA-induced As tolerance in B. napus leaves and suggests a more active involvement of MeJA in plant physiological processes.

Physiological changes and sHSPs genes relative transcription in relation to the acquisition of seed germination during maturation of hybrid rice seed.

BACKGROUND: During the production of early hybrid rice seed, the seeds dehydrated slowly and retained high moisture levels when rainy weather lasted for a couple of days, and the rice seeds easily occurred pre-harvest sprouting (PHS) along with high temperature. Therefore it is necessary to harvest the seeds before the PHS occurred. RESULTS: The seeds of hybrid rice (Oryza sativa L. subsp. indica) cv. Qianyou No1 that harvests from 19 to 28 days after pollination (DAP) all had high seed vigour. The seed moisture content at 10 DAP was 36.1%, and declined to 28.6% at 19 DAP; the contents of soluble sugar and total starch increased significantly with the development of seeds. The soluble protein content, the level of abscisic acid (ABA) and gibberellin (GA3 ), and ascorbate peroxidase (APX) activity continued to decrease from 10 DAP to 19 DAP. The seeds at 19 DAP had the highest peroxidase (POD) activity and lowest catalase (CAT) activity while the superoxide dismutase (SOD) activity had no significant difference among the different developing periods. The relative expressions of genes 64S Hsp18.0 and Os03g0267200 transcripts increased significantly from 10 to 19 DAP, and then decreased. However, no significant change was recorded in soluble protein, sugar and GA3 after 16 DAP, and they all significantly correlated with seed viability and vigour during the process of seed maturity. CONCLUSION: The seeds of hybrid rice Qianyou No1 had a higher viability and vigour when harvested from 19 DAP to 28 DAP, the transcription levels of 64S Hsp18.0 and Os03g0267200 increased significantly from 10 DAP to 19 DAP and the highest value was recorded at 19 DAP. The seeds could be harvested as early as 19 DAP without negative influence on seed vigour and viability.

Layer by layer application of chitosan and carboxymethyl cellulose coatings delays ripening of mango fruit by suppressing cell wall polysaccharides disassembly.

Mango is a climacteric fruit that ripens quickly after harvest due to its climacteric nature. Edible coatings have been reported to delay the ripening of various harvested fruit. The efficacy of the applied edible coatings could be improved by using in combination as a layer-by-layer (LBL) approach. So, the influence of LBL application of chitosan (CH) and carboxymethyl cellulose (CMC) was studied on mangoes during postharvest storage at 15 °C for 20 days. Mangoes were coated with monolayers of CH (1 % w/v) and CMC (1 % w/v) as well as LBL application of CH and CMC and were compared with control. The treatment of mangoes with CH and CMC-based LBL treatment resulted in lower decay percentage and weight loss along with higher total chlorophyll pigments and suppressed total carotenoid accumulation. The LBL application of CH and CMC showed lower activity of chlorophyll degrading such as chlorophyllase (CPS), pheophytinase (Phe), Mg-dechalatase (MGD) and chlorophyll degrading peroxidase (Chl-POD) enzymes as well as reduced changes in b*, a* and L* along with a suppressed increase in ethylene (EP) and CO2 production (CPR) rates having higher antioxidant such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD) enzymes activity. In addition, mangoes coated with LBL treatment of CH and CMC exhibited lower water-soluble pectin (WSP) and higher protopectin (PP) having higher concentrations of chelate soluble (CSP) and sodium carbonate-soluble pectin (SCP). Similarly, LBL-coated mangoes showed significantly higher hemicellulose (HCLS) and cellulose (CLS) contents in contrast with control. It was observed that mangoes coated with CH and CMC-based LBL coating exhibited higher flesh firmness and showed suppressed cellulase (CS), pectin methylesterase (PME), polygalacturonase (PG) and ß-galactosidase (ß-Gal) enzymes activity. The concentrations of total soluble solids and ripening index were markedly lower and titratable acidity was higher in the LBL-based coating treatment in comparison with control. In conclusion, LBL treatment based on CH and CMC coatings could be used for the delay of ripening and softening of harvested mangoes.

A novel edible coating based on Albizia [Albizia lebbeck (L.) Benth.] gum delays softening and maintains quality of harvested guava fruits during storage.

Guava, a commercially important fruit crop, is being grown in tropical and subtropical regions around the world. Due to the perishable nature of guava fruits, there are great losses during marketing, transport and storage. The application of edible coating is emerging as a low-cost, simple to implement and efficient method for extending the postharvest life of fresh horticultural produces, such as fruits and vegetables. This study aimed to assess the potential of Albizia gum (AZG) to improve storability and maintain the overall fruit quality of stored guava fruits. Freshly harvested guava fruits were coated with 0 % (control), 1.5 %, 3 % or 4.5 % AZG. After coating treatment, the fruits were stored at 20 ± 1 °C and 85-90 % relative humidity for 15 days. The results revealed that 4.5% AZG coating suppressed the weight loss and decay incidence up to 27 % and 36 %, respectively, as compared with control. The fruits coated with 4.5 % AZG had the maximum titratable acidity (0.40 %), ascorbic acid (104.47 mg·100 g-1), total antioxidants (118.84 mmol Trolox·100 g-1), total phenolics (285.57 mg·kg-1) and flavonoids (60.12 g·kg-1) on 15th day of storage. However, the minimum total soluble solids (11.97 %), sugar-acid ratio (29.31), relative ion leakage (68.40 %), malondialdehyde (0.11 nmol·kg-1 FW) and hydrogen peroxide (16.05 µmol·kg-1 FW) were recorded in the fruits of same treatment on 15th day of storage. Furthermore, the activities of antioxidant enzymes "i.e., superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)" were increased under the influence of AZG coating. Consequently, as compared to uncoated fruits, AZG-coated fruits exhibited reduced activities of fruit softening enzymes "i.e., cellulase, pectin methylesterase (PME), and polygalacturonase (PG)". To sum up, the application of AZG-based edible coating could markedly improve the storage life of guavas and maintain overall fruit quality.

Zeolite amendment reduces lead accumulation and improves growth and yield in tomato plants irrigated with sewage water.

Although sewage water (SW) is a source of nutrients, it also causes heavy metal accumulation in soil; especially, lead (Pb+) contamination of soil is a serious concern in agriculture. Soil contaminants limit the bioavailability of nutrients to plants. So, they affect plant growth and produce quality. Therefore, a pot experiment was conducted to investigate the effect of zeolite soil amendment on the accumulation of Pb+ in tomato crop grown with SW irrigation. The pot media of SW-irrigated plants was amended with different concentrations of zeolite, viz., 0.75%, 1.50%, and 2.25%. The results showed that the application of 0.75% zeolite increased leaf area, plant height, fruit number, and plant fresh and dry biomasses by 37%, 17%, 14%, 24%, and 7% compared to freshwater irrigation. Moreover, the lowest zeolite dose also led to higher chlorophyll content (68.02 SPAD) compared to SW-irrigated plants (55.13 SPAD). Similarly physiological traits, such as A, gs, and E, were higher (17.68 µmol m-2 s-1, gs 0.28 mmol m-2 s-1, and 7.88 mmol m-2 s-1, respectively) in 0.75% zeolite-treated plants than in SW-irrigated plants (12.99 µmol m-2 s -1, 0.19 mmol m-2 s-1, and 7.00 mmol m-2 s -1, respectively). On the contrary, a reduced level of hydrogen peroxide and malondialdehyde and decreased activity of antioxidant enzymes were observed in low-dose zeolite applied plants. Zeolite reduced Pb+ accumulation in tomato plants as compared to SW-irrigated plants, whereby Pb accumulation in the fruits of SW-irrigated plants was 80% more than those of zeolite + SW-treated plants. Conclusively, this study has revealed the improvement in morphological and physiological growth attributes of the SW-irrigated tomato plant in response to zeolite application.

The combined application of Arabic gum coating and γ-aminobutyric acid mitigates chilling injury and maintains eating quality of 'Kinnow' mandarin fruits.

Low temperature storage of citrus generally extends the storage potential but leads to chilling injury appearance on the rind of fruits. The said physiological disorder has been found associated with changes in the metabolism of cell walls and other attributes. In this work, the influence of Arabic gum [AG (10 %)] and γ-amminobutyric acid [GABA (10 mmol L-1)] either alone or in combined form was studied on fruits of 'Kinnow' mandarin during storage at 5 ± 1 °C for 60 days. The results exhibited that the combined AG + GABA treatment significantly suppressed weight loss (5.13 %), chilling injury (CI) symptoms (2.41 score), incidence of disease (13.33 %), respiration rate [(4.81 µmol kg-1 h-1) RPR] and ethylene production [(0.86 nmol kg-1 h-1) EPR]. In addition, AG + GABA application reduced relative electrolyte (37.89 %) leakage (REL), malondialdehyde [(25.99 nmol kg-1) MDA], superoxide anion [(15.23 nmol min-1 kg-1) O2•-] and hydrogen peroxide [(27.08 nmol kg-1) H2O2] along with lower lipoxygenase [(23.81 U mg-1 protein) LOX] and phospholipase D [(14.07 U mg-1 protein) PLD] enzyme activities compared with control. The AG + GABA treated 'Kinnow' group showed higher glutamate decarboxylase [(43.18 U mg-1 protein) GAD] and lower GABA transaminase [(15.93 U mg-1 protein) GABA-T] activity having higher endogenous GABA (42.02 mg kg-1) content. The fruits treated with AG + GABA exhibited higher cell walls (CW) components such as Na2CO3-soluble pectin [(6.55 g kg-1) NCSP], chelate-soluble pectin [(7.13 g kg-1) CSP] and protopectin [(11.03 g kg-1) PRP] concentrations along with lower water-soluble pectin [(10.64 g kg-1) WSP] compared to control. In addition, 'Kinnow' fruits treated with AG + GABA showed higher firmness (8.63 N) and lower activities of CW degrading such as cellulase [(11.23 U mg-1 protein) CX], polygalacturonase [(22.59 U mg-1 protein) PG], pectin methylesterase [(15.61 U mg-1 protein) PME] and ß-galactosidase [(20.64 U mg-1 protein) ß-Gal] enzymes. The activity of catalase [(41.56 U mg-1 protein) CAT], ascorbate peroxidase [(55.57 U mg-1 protein) APX], superoxide dismutase [(52.93 U mg-1 protein) SOD] and peroxidase [(31.02 U mg-1 protein) POD] was also higher in combined treatment. In addition, AG + GABA treated fruits showed better biochemical and sensory attributes than the control. So, combined AG + GABA could be used for CI mitigation and storage life prolongation of 'Kinnow' fruits.

Enhancement of Salinity Stress Tolerance in Lettuce (Lactuca sativa L.) via Foliar Application of Nitric Oxide.

Salt stress negatively affects the growth, development, and yield of horticultural crops. Nitric oxide (NO) is considered a signaling molecule that plays a key role in the plant defense system under salt stress. This study investigated the impact of exogenous application of 0.2 mM of sodium nitroprusside (SNP, an NO donor) on the salt tolerance and physiological and morphological characteristics of lettuce (Lactuca sativa L.) under salt stress (25, 50, 75, and 100 mM). Salt stress caused a marked decrease in growth, yield, carotenoids and photosynthetic pigments in stressed plants as compared to control ones. Results showed that salt stress significantly affected the oxidative compounds (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX)) and non-oxidative compounds (ascorbic acid, total phenols, malondialdehyde (MDA), proline, and H2O2) in lettuce. Moreover, salt stress decreased nitrogen (N), phosphorous (P), and potassium ions (K+) while increasing Na ions (Na+) in the leaves of lettuce under salt stress. The exogenous application of NO increased ascorbic acid, total phenols, antioxidant enzymes (SOD, POD, CAT, and APX) and MDA content in the leaves of lettuce under salt stress. In addition, the exogenous application of NO decreased H2O2 content in plants under salt stress. Moreover, the exogenous application of NO increased leaf N in control, and leaf P and leaf and root K+ content in all treatments while decreasing leaf Na+ in salt-stressed lettuce plants. These results provide evidence that the exogenous application of NO on lettuce helps mitigate salt stress effects.

Tragacanth gum coating suppresses the disassembly of cell wall polysaccharides and delays softening of harvested mango (Mangifera indica L.) fruit.

Mango is a climacteric fruit and is prone to high perishability. The rapid softening and ripening (due to degradation and disassembly of cell wall polysaccharides) are the major limitations in extending the storability of the harvested mango fruits. Various types of gum-based edible coatings have been reported for the shelf life extension of mango fruits. Tragacanth gum (TCG) also has appropriate coating properties. Its use as an edible coating has been reported on certain fruits. However, the effect of TCG coating in the regulation of harvested mango fruits ripening and softening has not been reported yet. So, the objective of this work was to investigate the effect of TCG (control, 0.5 %, 1 % and 1.5 %) coating on postharvest softening and ripening of harvested mango fruits. TCG coating affected the ripening and softening of mango in a dose-dependent manner. Results exhibited that mango fruits coated with 1.5 % TCG showed substantially lower disease incidence and weight loss. The 1.5 % TCG-coated mangoes showed substantially lower ethylene biosynthesis and respiration rate peaks as well as superoxide anion and hydrogen peroxide contents compared with the control. In the same way, 1.5 % TCG-coated mango fruits had markedly higher total chlorophyll content and lower L*, b* and a* along with substantially lower total carotenoids in peel tissues. Mango fruits coated with 1.5 % TCG exhibited markedly lower water-soluble pectin and higher chelate-soluble pectin, Na2CO3-soluble pectin, protopectin, cellulose and hemicellulose in flesh tissues compared with control. The activity of polygalacturonase (PG), cellulase (CX), pectin methylesterase (PME), ß-galactosidase (ß-Gal) and ß-glucosidase (ß-Glu) were significantly lower in flesh of 1.5 % TCG treated fruits along with substantially higher firmness in contrast with control. In addition, 1.5 % TCG coating treatment showed significantly higher activity of antioxidative enzymes and delayed the increase in soluble solids content (SSC) and ripening index (RI) along with considerably higher titratable acidity (TA) compared with the untreated control. So, pre-storage TCG based edible coating (1.5 %) could be applied to delay ripening and softening in mango fruit industry under postharvest ambient conditions.

Hydrogen Sulfide Mitigates Chilling Injury of Postharvest Banana Fruits by Regulating γ-Aminobutyric Acid Shunt Pathway and Ascorbate-Glutathione Cycle.

This study aimed to determine the effect of hydrogen sulfide on chilling injury (CI) of banana (Musa spp.) during cold storage (7°C). It was observed that hydrogen sulfide application (2 mmol L-1) markedly reduced the CI index and showed significantly higher chlorophyll contents, along with suppressed chlorophyll peroxidase and chlorophyllase enzyme activity. The treated banana fruits exhibited substantially higher peel lightness (L*), along with significantly a lower browning degree and soluble quinone content. The treated bananas had substantially a higher endogenous hydrogen sulfide content and higher activity of its biosynthesis-associated enzymes such as D-cysteine desulfhydrase (DCD) and L-cysteine desulfhydrase (LCD), along with significantly lower ion leakage, lipid peroxidation, hydrogen peroxide, and superoxide anion concentrations. Hydrogen sulfide-treated banana fruits showed an increased proline content and proline metabolism-associated enzymes including ornithine aminotransferase (OAT), Δ1-pyrroline-5-carboxylate synthetase (P5CS), and proline dehydrogenase (PDH). In the same way, hydrogen sulfide-fumigated banana fruits accumulated higher endogenous γ-aminobutyric acid (GABA) due to enhanced activity of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) enzymes. The hydrogen sulfide-treated fruits exhibited higher total phenolics owing to lower polyphenol oxidase (PPO) and peroxidase (POD) activity and stimulated phenylalanine ammonia lyase (PAL). The treated banana exhibited higher ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and superoxide dismutase (SOD) activity, along with higher glutathione (GSH) and ascorbic acid (AsA) concentrations and a significantly lower dehydroascorbic acid (DHA) content. In conclusion, hydrogen sulfide treatment could be utilized for CI alleviation of banana fruits during cold storage.

Synergistic effect of gum Arabic and carboxymethyl cellulose as biocomposite coating delays senescence in stored tomatoes by regulating antioxidants and cell wall degradation.

This study tested a novel combination of hydrocolloid gum arabic (GA) and carboxymethyl cellulose (CMC) to extend postharvest life of tomatoes. For this purpose, tomato fruits were coated with GA 10%, CMC 0.5% and GA 10% + CMC 0.5%, and stored for 20 days at 20 °C and 90 ± 2% RH. Application of biocomposite hydrocolloid coating reduced physiological weight loss, respiration rate, ethylene production, decay percentage and stress markers viz. malondialdehyde and hydrogen peroxide. Biocomposite hydrocolloid coating inhibited change in bioactive compounds (phenolics, ascorbic acid, and lycopene), color, organic acids, soluble sugars and up-regulated enzymatic ROS scavenging mechanism in tomato fruit more than GA or CMC coating. Moreover, biocomposite coatings delayed senescence by reducing activity of cell wall degrading enzymes and maintaining cell wall fractions. Conclusively, the biocomposite coating based on GA and CMC was superior to their individual coating in prolonging ripening phase, delaying senescence and increasing the acceptability of tomato fruits for longer duration.

Carboxymethyl cellulose coating delays ripening of harvested mango fruits by regulating softening enzymes activities.

The effect of carboxymethyl cellulose [(1%) CMC] was evaluated on mango fruits under storage at 20 ± 1 °C for 20 days. The CMC coating noticeably reduced weight loss and disease incidence. Application of CMC delayed climacteric peak of ethylene and respiration rate with significantly reduced relative ion leakage, malondialdehyde, superoxide anion and hydrogen peroxide content. The treated mangoes showed significantly lower L*, a*, b* and total carotenoids. The CMC treatment reduced the increase in cellulase, pectin methylesterase and polygalacturonase activity that delayed softening of mango fruits. In addition, activities of peroxidase, catalase, ascorbate peroxidase and superoxide dismutase were substantially higher in CMC-treated mango fruits. The treated fruits showed significantly lower soluble solids and higher titratable acidity which thereby reduced the ripening index of mangoes. In conclusion, CMC treatment could be considered a potential pre-storage treatment to delay postharvest ripening and to conserve the eating quality of ambient stored mango fruits.

Effect of gum arabic coating on antioxidative enzyme activities and quality of apricot (Prunus armeniaca L.) fruit during ambient storage.

The effect of gum arabic (GA) coating was studied on apricot fruit at 20 ± 1°C for 8 days. GA coating substantially reduced weight loss, disease incidence, malondialdehyde concentration, and hydrogen peroxide compared to the control. GA coating resulted in significantly higher total phenols, ascorbic acid, and antioxidant activity in contrast to the control. GA coating also suppressed cellulase, pectin methylesterase, and polygalacturonase activity in contrast to the non-coated fruit. In addition, GA-coated apricot fruit had substantially higher catalase, peroxidase, ascorbate peroxidase, and superoxide dismutase enzymes activities in contrast with the control. Similarly, GA coating inhibited soluble solids content increase and inhibited the reduction in titratable acidity in coated fruit. The fruit coated with GA coating also had significantly better sensory and overall eating quality compared to the control apricots. In conclusion, GA could be considered an appropriate edible coating for quality conservation of apricots. PRACTICAL APPLICATIONS: Apricot is a well renowned and nutrients rich fruit. However, apricot has comparatively short shelf life potential due to its susceptibility to rapid senescence and deterioration under ambient conditions. GA is an eco-friendly and biodegradable coating which is considered relatively cheap as compared with other coating types. In our present work, application of gum arabic [GA (10%)] edible coating maintained significantly higher quality of harvested apricot fruit as compared with the control. The outcomes of the present work are of global significance with respect to apricot industry. So, GA coating could be considered an appropriate edible coating for quality conservation of the harvested apricot fruit.

Combined application of ascorbic and oxalic acids delays postharvest browning of litchi fruits under controlled atmosphere conditions.

The effect of ascorbic acid [AA (40 mmol L-1)] and oxalic acid [OA (2 mmol L-1)] on browning of litchi fruit was investigated under 5% CO2 + 1% O2 controlled atmosphere (CA) and compared with air at 5 ± 1 °C for 28 days. The combined application of AA and OA suppressed browning index, soluble quinones, and activities of polyphenol oxidase and peroxidase under CA compared with control. The combination of CA along with AA + OA reduced weight loss and maintained higher anthocyanins, total phenolics, membrane integrity, ascorbate peroxidase, catalase, glutathione reductase and superoxide dismutase activities compared with control. In addition, AA + OA + CA combination showed markedly lower malondialdehyde, superoxide anion and hydrogen peroxide with substantially higher soluble solids content, ascorbic acid, titratable acidity and sensory quality compared with control. In conclusion, AA + OA combination could be considered appropriate to delay browning and to conserve litchi fruit visual appearance under CA storage conditions.

Effect of pre-storage ascorbic acid and Aloe vera gel coating application on enzymatic browning and quality of lotus root slices.

The effect of ascorbic acid [AA (1%)] and Aloe vera gel [AVG (50%)] coating alone and in combination was investigated on enzymatic browning and quality of lotus root slices during storage at 20 ± 1°C. The combined application of AA and AVG coating delayed surface browning, reduced increase in relative electrolyte leakage (REL) and showed higher overall visual quality (OVQ). Similarly, AA and AVG combined treatment reduced superoxide anion ( O2-· ) and hydrogen peroxide (H2 O2 ) production and malondialdehyde (MDA) content, and suppressed peroxidase (POD) and polyphenol oxidase (PPO) activities. In addition, AA and AVG treatment conserved higher AA content, ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT) enzymes activities along with higher total phenolics and radical scavenging activity. In conclusion, the combined application of AA and AVG coating could be an appropriate treatment to delay surface browning and quality loss of lotus root slices. PRACTICAL APPLICATIONS: Lotus root is an aquatic rhizome vegetable. The fresh-cut slices of lotus roots are prone to post-cut enzymatic browning and quality deterioration during postharvest storage. Browning induced loss of visual quality and microbial infestations are the leading constraints in extending storage and/or shelf life of lotus root slices. Surface browning results in loss of characteristic color eventually leading to significant reduction in market potential and visual quality. However, quality deterioration and development of browning could be delayed with some suitable postharvest treatments. So, the effect of AA and Aloe vera gel based coating was investigated for quality conservation of lotus root slices. The findings of the current work are of global importance in reducing browning and conserving visual quality of lotus root slices in particular and fresh-cut produce in general.

Effect of postharvest oxalic acid application on enzymatic browning and quality of lotus (Nelumbo nuciferaGaertn.) root slices.

Post-cut surface browning is one of the major constraints for shelf-life extension of lotus root slices. In the present study, lotus roots slices were treated with 0, 5 and 10 mmol L-1 oxalic acid and stored at 20 ± 1 °C for 5 days. Results showed that 10 mmol L-1 oxalic acid treated lotus slices exhibited reduced browning, superoxide anion, hydrogen peroxide, electrolyte leakage and malondialdehyde content than control. The 10 mmol L-1 treated slices had better visual quality and higher ascorbic acid and total phenolic contents. In addition, 10 mmol L-1 treated slices showed reduced total bacterial count along with lower soluble quinones, peroxidase and polyphenol oxidase activities in contrast to control. Similarly, 10 mmol L-1 treatment showed higher superoxide dismutase, catalase and ascorbate peroxidase activities as compared to control. In conclusion, 10 mmol L-1 oxalic acid application could be considered suitable to delay post-cut browning of lotus root slices.

Tragacanth gum coating modulates oxidative stress and maintains quality of harvested apricot fruits.

Tragacanth gum is a polysaccharide-based complex with a good coating property. However, its use in postharvest storage of fresh fruits and vegetables is very limited. In the current work, the effect of tragacanth gum (1%) was investigated on postharvest quality of apricot fruits during storage at 20 ± 1 °C for 8 days. Apricot fruits coated with tragacanth gum coating showed significantly reduced weight loss, decay and electrolyte leakage, hydrogen peroxide and malondialdehyde production. Tragacanth gum coating suppressed increase in total soluble solids and showed higher titratable acidity compared with control. The coated fruits had higher total phenolics and ascorbic acid along with greater 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in contrast with control. Postharvest application of tragacanth gum coating maintained markedly higher activities of ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) enzymes activities as compared with control. In addition, tragacanth gum application suppressed polygalacturonase (PG), pectin methylesterase (PME), and cellulase (CX) enzymes activities, thereby suppressed softening of apricot fruits. Sensory quality attributes such as taste, juiciness, aroma, appearance, and overall acceptability were also significantly higher in tragacanth gum coated fruits compared with control. In conclusion, tragacanth gum coating could be considered suitable for postharvest quality conservation of apricot fruits.