Ethylene Evolution Rate Research Articles

Evaluation and characterization of TILLING-based putative mutant populations of papaya cv. Arka Prabhath

Manifestation of virus resistance, shelf-life with dwarf stature are important pre-requisites for successful cultivation of papaya in India as it facilitates improved production, productivity and reduced post-harvest loss. One of the methods to create variability is to use mutagens in selected cultivar of papaya. Accordingly, the TILLING-based mutant populations of papaya cv. Arka Prabhath were generated through irradiation of gamma rays ranging from 50 to 500 Gy dosage. In this experiment, the putative mutant populations were evaluated and characterized based on morphological, fruit quality and physiological parameters. Desirable traits such as early flowering, reduced plant height and bearing height, papaya ring spot virus tolerant plants and fruits with extended shelf life were observed in the mutant population. Early flowering and reduced plant height with wide variation was found at 50 Gy wherein the first flowering was on 57 days with 43 cm of plant height in contrast to 80 days in control plants with 79 cm of plant height. Reduced bearing height (40 cm) was observed in 100 Gy with a mean bearing height of 70.65 cm in comparison to control plants (72.97 cm), range being 55 to 115 cm. Further, based on morphological traits twenty-one lines were selected for physiological and fruit quality trait evaluation. Reduction in physiological loss in weight, ethylene evolution rate and respiration rate were observed in the mutant lines treated with 150 Gy dosage. The results advocate the efficacy of gamma induced mutation for developing dwarf cultivar with improved quality and shelf-life of fruits.

Treatment of 'cripps pink' apples with nitric oxide in a controlled atmosphere ultra-low oxygen: Impacts on overall fruit quality and anaerobic compounds

The objective of this work was to evaluate the impact of nitric oxide application (in different doses 0, 1, 2, 5 e 10 μL L−1 of NO) on fruit quality and formation of anaerobic metabolism products of 'Cripps Pink' apples stored in a controlled atmosphere ultra-low oxygen (CA - ULO). Fruit were harvested at two maturity stages (less and more mature) and stored in CA - ULO (0.8 kPa of O2, <0.5 kPa of CO2, at temperature of 1.5 ± 0.2 °C, and 94 ± 2% RH) for four and eight months, followed by seven days of shelf life. Fruit in CA - ULO were treated weekly with 0, 1, 2, 5, or 10 μL L−1 of NO. In general, linear and quadratic models adjusted to quantitative levels of NO showed reduced respiration and ethylene evolution rates with the increase of NO concentrations. Also, the increase of NO concentration consistently reduced the activities of β-GAL and PG, preserved flesh firmness, and reduced the production of anaerobic metabolites (acetaldehyde and ethanol) and the incidence of decay in the fruit. These effects of NO concentrations on each quality attribute were dependent on maturity stage and storage duration (period in CA - ULO and/or subsequent shelf life). However, the results show that weekly application of 5–7 μL L−1 of NO during storage in CA - ULO maintained the quality of 'Cripps Pink' apples.

Extending shelf life of Ney Poovan banana through active packaging for export market

The present study focuses on the impact of active packaging technology on the Ney Poovan banana variety, aiming to extend its shelf life for export purpose. The experiment comprised four treatments: an ethylene absorber, a moisture absorber, a control group, and packaging in vacuum-sealed polythene bags. These banana samples were subsequently stored at two different temperatures, namely room temperature (RT) and 13.5°C. The results obtained from the experiment indicated that the fruits packed with an ethylene absorber exhibited an extended shelf life of 72 days when stored at 13.5°C. The fruits remained fresh for 20 days when stored at RT. These ethylene-treated fruits also displayed the highest pulp-to-peel ratio (PPR) of 7.34 when held at 13.5°C, while the highest acid content (0.673%) was registered at RT. On the other hand, the control group fruits stored at RT tended to show the highest TSS content (29oBrix). The fruits stored at RT, irrespective of the treatments exhibited the highest content of TSS (21.11oBrix). The physiological loss in weight increased gradually during storage in both temperatures but was low in fruits packed with moisture absorbers. Though the ethylene evolution rate increased towards extended storage in both temperatures, the concentration was less in fruits packed with ethylene absorber.

Attenuating sugar spot and retaining quality of banana fruits by combined use of hot water and calcium lactate during storage.

Combined use of hot water (HW) treatment and calcium lactate (CL) is a promising postharvest approach to preserve the food value and prolong the shelf life of fruits. The present experiment aims to determine the physiological loss in weight, firmness, respiration rate, ethylene and biochemical attributes of banana fruits treated with hot water (50 °C for 7 min) and aqueous CL dipping (1, 2, and 3% for 2 min). Treated fruits were stored under ambient conditions (22-25°C temperature and 60-65% of relative humidity) for up to 9 days. The study showed that combined use of HW and CL (3%) maintained higher hue angle, peel firmness (4.4 N), reduced decay loss (10.63%), respiration and ethylene evolution rate of stored fruits. Also, CL treatments (3%) with HW proved the best which reduced 6-fold sugar spot and 1.5-fold decay loss over untreated fruits. At the end of storage sensory parameters such as mouthfeel, peel colour and overall acceptability (score 6.9) were recorded higher in HW and CL 3% treated fruits. The findings indicated that pre-storage combined use of HW and CL has a great potential to preserve quality, delay ripening, and reduce sugar spots, and postharvest decay loss in banana fruit without any adverse effect on consumer appeal.

Maturity indices of specific mango varieties produced at medium altitude agro-ecological zone in Kenya

The high postharvest losses (40 – 50%) reported in the mango value chain are partly attributed to lack of reliable maturity indices. Harvest maturity is dictated by the intended use and the target market for the fruits. The aim of this study was to establish maturity indices of three commercial mango varieties namely ‘Van dyke,’ ‘Kent’ and ‘Tommy Atkins’ in Embu County of Kenya. At least eighteen mango trees (six per variety) were randomly tagged at 50% flowering in each of the three selected small-scale farms in Embu County. Number of days from flowering to different maturity stages were recorded (computational method). For each variety and maturity stage, five fruits were randomly sampled from the pool and analysed for physical (size, density, firmness, colour), physiological (ethylene evolution and respiration rate) and biochemical (obrix/Total Soluble Solids (TSS), total titratable acidity (TTA) and their ratio) indices of maturity. The results showed that although size increased as the fruits developed, it was not a reliable index of maturity since some small-sized fruits attained advanced maturity earlier than others that were large-sized. The weight of the fruits fluctuated as the fruits developed and similar trend was observed on the specific gravity. Flesh firmness decreased gradually with maturity from a mean firmness of 40.54 N to 6.84 N. Tommy Atkins exhibited the lowest firmness levels at stage 4. Kent variety had the lowest ethylene at all stages while Tommy Atkins variety had the highest respiration rate of 21.40 ml/kg/hr at stage 1, which increased gradually to 32.10 ml/kg/hr at stage 4. The highest TSS: TTA values were reported in Kent variety. The results revealed significant differences in maturity indices of the three mango varieties despite similar physical indices. This study confirms the unreliability of physical maturity indices such as size and shape in establishing the right harvest stage of mango fruits. Computational, physiological and biochemical maturity indices should be incorporated in determination of accurate harvest maturity for mango. Key words: Ethylene, Harvest maturity, ‘Kent’, Maturity indices, Respiration, ‘Tommy Atkins’, ‘Van dyke’

Polyamines and ethylene interact in mediating the effect of nitrogen rates on synthesis of amino acids in rice grains

AbstractNitrogen (N) is one of the essential factors influencing amino acid synthesis in rice (Oryza sativa L.) grains. Polyamines (PAs) and ethylene (ETH) play vital roles in grain amino acid biosynthesis of rice. However, knowledge is limited about whether and how PAs and ETH mediate the effect of N rate on amino acid biosynthesis. Two rice cultivars were used with three N rates of low (LN), medium (MN), and high (HN) in the study. Levels of free PAs and ETH, activities/gene expressions of key enzymes related to amino acid synthesis in grains, and the amino acid contents in milled rice were investigated. Free spermidine (Spd) and spermine (Spm) concentrations, especially ratios of free PAs to 1‐aminocylopropane‐1‐carboxylic acid (ACC), and total amino acids (TAAs), essential amino acids (EAAs), and non‐essential amino acids (NEAAs) contents were increased with N rate, while ethylene evolution rate (EER) and ACC concentration were reduced with N increases. There was relatively little difference in the above parameters between MN and HN. Levels of free Spd and Spm, and their ratios to ACC exhibited significant and positive correlations with the activities/gene expressions of key enzymes related to amino acid biosynthesis, and TAAs, NEAAs, and EAAs contents, whereas ACC and EER levels had significantly negative correlations with those parameters. Exogenous Spd, Spm, or AVG (an ETH synthesis inhibitor) increased the enzymatic activities and gene expressions, whereas MGBG (a Spd or Spm synthesis inhibitor) or ethephon (an ETH‐releasing agent) exerted the opposite effect. These results demonstrated that free PAs and ETH antagonistically interact in mediating the effect of N rate on grain amino acid synthesis of rice. Higher ratios of free PAs to ACC could promote synthesis of amino acids in grains of rice.

Atypical Climacteric and Functional Ethylene Metabolism and Signaling During Fruit Ripening in Blueberry (Vaccinium sp.).

Climacteric fruits display an increase in respiration and ethylene production during the onset of ripening, while such changes are minimal in non-climacteric fruits. Ethylene is a primary regulator of ripening in climacteric fruits. The ripening behavior and role of ethylene in blueberry (Vaccinium sp.) ripening is controversial. This work aimed to clarify the fruit ripening behavior and the associated role of ethylene in blueberry. Southern highbush (Vaccinium corymbosum hybrids) and rabbiteye (Vaccinium ashei) blueberry displayed an increase in the rate of respiration and ethylene evolution, both reaching a maxima around the Pink and Ripe stages of fruit development, consistent with climacteric fruit ripening behavior. Increase in ethylene evolution was associated with increases in transcript abundance of its biosynthesis genes, AMINOCYCLOPROPANE CARBOXYLATE (ACC) SYNTHASE1 (ACS1) and ACC OXIDASE2 (ACO2), implicating them in developmental ethylene production during ripening. Blueberry fruit did not display autocatalytic system 2 ethylene during ripening as ACS transcript abundance and ACC concentration were not enhanced upon treatment with an ethylene-releasing compound (ethephon). However, ACO transcript abundance was enhanced in response to ethephon, suggesting that ACO was not rate-limiting. Transcript abundance of multiple genes associated with ethylene signal transduction was upregulated concomitant with developmental increase in ethylene evolution, and in response to exogenous ethylene. As these changes require ethylene signal transduction, fruit ripening in blueberry appears to involve functional ethylene signaling. Together, these data indicate that blueberry fruit display atypical climacteric ripening, characterized by a respiratory climacteric, developmentally regulated but non-autocatalytic increase in ethylene evolution, and functional ethylene signaling.

Effects of postharvest deastringency and 1-methylcyclopropene treatments on membrane permeability, membrane-degrading enzymes and their encoding genes in persimmon (Diospyros kaki, cv Mopanshi) fruit

Astringent persimmon fruit softens rapidly after harvest deastringency treatment. The purpose of this study was to understand the characteristics of membrane deterioration and its mechanism during rapid softening. The experiment included three treatments: (1) control, (2) CO2 treatment (≈100% CO2, 24 h), and (3) CO2 plus 1-methylcyclopropene (1-MCP, 1.5 μL∙L-1) treatment. CO2 treatment can effectively remove the astringency of persimmon fruit and cause a sharp drop in fruit firmness. The addition of 1-MCP was beneficial for firmness maintenance, but the process of astringency removal was delayed by one day. The fruit respiration rate and ethylene evolution rate were significantly increased by CO2 treatment, regardless of the presence or absence of 1-MCP, but the addition of 1-MCP could reduce the peak value and delay the occurrence of ethylene peaks by one day. The deastringency treatment resulted in a significant increase in membrane permeability and malondialdehyde content, and 1-MCP could significantly reduce membrane damage. CO2 treatment induced an enormous increase in LOX activity and the transcription of DkLOX3; however, 1-MCP significantly inhibited these increases. The PLD activity and DkPLDα1 expression level of the CO2-treated fruit were significantly promoted, and the addition of 1-MCP had less inhibition effect on the PLD activity and no significant inhibition on the DkPLDα1 expression. These results demonstrate that CO2 deastringency treatment could cause severe damage to the membrane integrity by promoting LOX and PLD activities and related gene expression. 1-MCP may ameliorate membrane damage mainly by inhibiting LOX activity and DkLOX3 gene expression and partly by suppressing PLDα1 expression.

Impact of chitosan on quality and storability of plums (Prunus salicina) under supermarket conditions

In the present study, effect of chitosan coating on storage quality of plum fruit (Prunus salicina Lindley. cv. Santa Rosa) was investigated under supermarket conditions during 2013 at ICAR-IARI. After coating the plum fruits with 2% chitosan and water, they were stored at 20±1°C and 90±2% RH for 15 days. Fruit firmness, colour characteristics (hue and chroma), respiration and ethylene evolution rate, physiological loss in weight, antioxidant activity and total phenols were measured along with the activities for pectin methylesterase and malondialdehyde content. Chitosan application resulted in better firmness of fruits, retarded ethylene evolution and respiration rates and least colour changes as compared with the control. Reduction of total phenolics and antioxidant activity were also significantly inhibited by chitosan. Furthermore, fruits coated with chitosan also exhibited a significantly lower pectin methylesterase activity throughout the storage period. Moreover, the production of malondialdehyde was significantly reduced in the coated samples. The results clearly demonstrate that dip treatment of fruits in 2% chitosan could be an effective means to enhance the shelf-life and maintain postharvest quality of Santa Rosa plums during storage.

DNA methylation of

In wheat (Triticum aestivum L.), S-type cytoplasmic male sterile (S-CMS) lines can mainly transform from sterility to fertility at the mononuclear pollen stage. Observations from microscopy revealed an inhibition of starch accumulation within the pollen grain, suggesting that an alteration in carbohydrate metabolism or assimilate supply may be involved in S-CMS pollen abortion. We measured levels of various carbohydrates and activities of key enzymes of sucrose metabolism at the mononuclear pollen stage in anthers collected from an S-CMS line and its maintainer line and found that nonreducing sugars increased in S-CMS anthers. Sucrose accounted for part of the nonreducing sugar accumulation. The activity of invertase declined significantly, whereas sucrose synthase activity during starch accumulation in pollen showed no significant change in S-CMS anthers at the mononuclear pollen stage. The results suggest that sucrose conversion and inhibition of invertase were probably responsible for the pollen abortion. Because there is a high correlation between the rate of ethylene evolution and sucrose content, ethylene anabolism was determined. TaACS2 regulates sucrose metabolism in pollen probably through catalysing the synthesis of ethylene precursor 1-aminocyclopropane-1-carboxylic acid in wheat. In this study, ethylene production of anthers underwent accumulation, revealed by gas chromatography, and expression levels of TaACS2 were upregulated in the S-CMS line, as determined by quantitative real-time PCR. We investigated the DNA methylation pattern of TaACS2 in the core promoter region using bisulfite genomic sequencing, and lower methylation was observed in the S-CMS line. These results suggest that DNA methylation of the TaACS2 gene may be involved in the sterility–fertility transition by regulating the synthesis of ethylene in S-CMS anthers.

The Influence of Rootstock on Fruit Ethylene, Respiration, Index of Absorbance Difference, Fruit Quality, and Production of ‘Aztec Fuji’ Apple under a Full-crop Condition

Selection of dwarfing rootstocks that facilitate optimum production of high-quality fruit is crucial in modern high-density apple orchards. In addition to tree growth and yield, rootstocks can influence fruit maturity of scion cultivars in apples. In this study, the impact of 17 rootstocks on fruit maturity, yield, and quality attributes of ‘Aztec Fuji’ apples (Malus domestica Borkh.) at harvest were evaluated in a season when all trees were in a “full-crop” condition. Keeping sealed fruit at room temperature, a typical climacteric pattern was observed in ethylene evolution, respiration, and oxygen consumption, peaking after 5–7 days in fruit from trees on all rootstocks. During the ripening period, ethylene evolution and respiration rates in fruit from trees on Supp.3, G.3001, and G.202 were often in the high-range category, whereas those on CG.4004, CG.4214, G.41N, and B.9 were in the midrange category and those on M.9Pajam2, M.26EMLA, and G.11 were in the low-range category. Evolved ethylene and respiration in fruit from trees on M9.T337 steadily and slowly increased from 7 days after harvest (7DAH) to 13 days after which harvest (13DAH) ethylene sharply increased, signaling occurrence of climacteric peak, while respiration declined after the peak of 13DAH. In fruit from trees on most rootstocks, the rates of oxygen consumption had inverse relationships with the rates of respiration, so that fruit from trees on M9.T337 had higher and those on G.41N and Supp.3 had lower rates of oxygen consumption. Trees on G.41N, CG.4004, and M.26EMLA had higher and those on CG.4003 had lower yield per tree than trees on other rootstocks. Trees on B.9 and M.9T337 were most yield efficient among trees on all rootstocks. Trees on CG.4004 had larger fruits than those on other rootstocks. Considering all fruit maturity, quality, and yield attributes, CG.4004 seems to be a good choice of rootstock for ‘Aztec Fuji’ under the conditions of this study.

Preharvest Application of Hexanal as a Surface Treatment Improved the Storage Life and Quality of Mango Fruits

Mango is a highly preferred seasonal tropical fruit with a maximum shelf-life of five to seven days. Hexanal is a plant volatile compound assayed in green tissues and showing significance in enhancing storage life and fruit quality attributes by preserving membrane integrity. This experiment explored the effect of the pre-harvest application of an aqueous hexanal composition (active ingredient: 0.02% hexanal) in altering the post-harvest storage behavior of four mango cultivars. The pre-harvest application of the hexanal formulation to the fruit surface twice before the harvest date drastically slowed down the physiological loss in weight by 70% to 80%, and reduced the ethylene evolution rate by two to three folds, respectively. The pre-harvest hexanal formulation spray combined with post-harvest cold storage prominently improved the storage life along with the total soluble solids, total sugars, ascorbic acid and carotenoid content compared to untreated fruits stored in ambient conditions. Though ripening coincides with the increased activity of enzymes, the hexanal formulation spray acts predominantly in bringing down the activities of fruit softening enzymes viz. pectinmethlyesterase (43%) and polygalacturonases (37%), and antioxidant enzymes viz. peroxidase (67%) and catalase (45%), respectively.

Pre-storage Exogenous Application of Hydrogen Sulphide Reduces Sugar spot, Decay loss and Preserves Quality of Banana Fruit

This research focuses on effect of hydrogen sulphide treatment (control, 0.5, 1.0, 1.5 mM) during ambient storage on sugar spot, decay loss and postharvest quality of banana fruit. Hydrogen sulphide (H 2 S) treated fruit were stored at ambient conditions (25±2oC and 60–65% of relative humidity) up to 9 days. In general, H 2 S treatment maintained higher values of lightness, peel firmness, reduce the respiration rate and ethylene evolution rate and extended shelf life of stored fruit by delaying progression of ripening. Moreover, H2S (1.0 mM) was found significantly better over other treatments in reducing sugar spot or peel browning spot and maintaining the desirable overall postharvest traits of the fruit. The findings indicated that H 2 S has a great potential for pre-storage application to preserve quality, reduce sugar spot and postharvest decay loss, possibly through the delayed onset of senescence, without any adverse effects on fruit quality.

How do elevated atmosphere CO2 and temperature alter the physiochemical properties of starch granules and rice taste?

Elevated atmospheric CO2 (EC) and temperature (ET) strongly affect agricultural production, but the mechanism through which EC and/or ET influence starch granules and their relationship to cooked rice taste remain largely unknown. Therefore, a field experiment using a popular japonica cultivar grown in a temperature/free-air CO2 enrichment environment was conducted to investigate the responses of volume and fine structure of starch granules and their formation physiology to EC (+200 ppm) and/or ET (+1 °C) in 2015–2016. EC markedly enhanced the activity of soluble-starch synthase and granule-bound starch synthase by 28.0% and 27.9% respectively, thereby increasing the long chains and the volume of starch granules. However, EC decreased the activity of starch-branch enzyme by 7.5% possibly via the pathway of ethylene signalling (EC prominently decreased the ethylene evolution rate of rice grains by 28.8%), resulting in a remarkable decrease in α-1′6 glucosidic bonds and significant increase in the iodine-binding capacity and double helix in starch molecules. These EC-induced changes in morphology and fine structure of starch granules synergistically altered the thermal properties of rice flour and eventually improved the cohesiveness and taste of cooked rice, as suggested by the significant relationships between them. ET partially offset the beneficial EC effects in most cases. However, few remarkable CO2 × temperature or CO2 × year effects were detected, indicating that the effects of EC on starch granules and rice taste less varied with meteorological conditions. These findings have important implications on rice palatability and for the development of adaptive strategies in the starch industry in future environment.

Physiological and biochemical attributes associated with jelly-seed disorder in mango (Mangifera indica L.)

‘Jelly-seed’ is considered as a serious disorder of mango which causes considerable postharvest losses. Due to the lack of clear understanding of jelly-seed disorder genesis and minuscule research work, a study was carried out to know the physiological and biochemical basis leading to the incidence of the jelly-seed disorder in ‘Langra’ and ‘Dashehari’ mango varieties. The results revealed that the respiration rate (143.32 and 149.32 mg kg−1 h−1 CO2) in the jelly-seed affected fruits was higher than the healthy fruits of both the varieties, while the ethylene evolution rate showed no significant difference. The biochemical attributes such as β-carotene (1.28 and 1.64 g kg−1) and total antioxidant capacity (607.78 and 563.25 mmol kg−1 Trolox) of jelly-seed affected pulp was significantly lower than the healthy pulp (HP) and pulp surrounding affected pulp (PSAP) in both the varieties, respectively. Ascorbic acid (66.76 and 33.70 g kg−1), TSS, reducing sugars (9.34 and 8.49%), total sugars and titratable acidity have been recorded to be higher in the jelly-seed affected pulp (AP) in both the varieties, respectively. This may be due to the higher activities of α-amylase (0.99 and 1.21 g kg−1 h−1 maltose liberated), pectin methylesterase (0.30 and 0.30 mmol min−1 kg−1 acid) and cellulase (0.0487 and 0.0564 U g−1) enzymes in the jelly-seed AP in both the varieties, respectively. Polyphenol oxidase enzyme activity was also significantly higher in jelly-seed affected pulp of both the varieties. The results of respiration rate suggested that the jelly-seed malady in mango may be a result of high seed activity rather than fruit pulp activity because the mesocarp tissue surrounding the vicinity of the seed is totally disintegrated and the seed might have entered into premature seed germination mode (vivipary nature). The affected fruits showed a higher respiration rate, reduced β-carotene content and total antioxidant capacity leading to loss of nutritional value.

Spermidine Increases the Sucrose Content in Inferior Grain of Wheat and Thereby Promotes Its Grain Filling.

The improvement of grain filling is the key issue for promoting wheat thousand grain weight and grain yield. The levels of polyamines (PAs) significantly affect grain filling in cereals, but the mechanism by which PAs affect grain filling in wheat is unclear. In the present study, six wheat cultivars whose grain filling differed were used, and their grain-filling characteristics and endogenous PA contents were measured. In addition, exogenous PAs were supplied during the wheat grain-filling period. The grain-filling characteristics, hormone levels, starch contents, and gene expression [based on RNA sequencing (RNA-seq)] in the grain were analyzed. The objective of the present study was to investigate the effects of PAs on grain filling in wheat. The results suggested that the direct synthetic pathway from putrescine (Put) to spermidine (Spd) in the grain was a key factor in promoting grain filling and thousand grain weight in wheat. Spd through regulates the grain-filling rate of inferior grain during the early grain-filling period to affecting the grain filling and thousand grain weight of wheat. The promotive effect of Spd on the grain filling of inferior wheat grain was notably related to carbohydrate metabolism in that grain. Spd significantly increased the zeatin (Z) + zeatin riboside (ZR) contents but reduced the ethylene (ETH) evolution rate in the inferior grain. In addition, Spd significantly increased the sucrose synthase (SS) and acid invertase (AI) activities in the inferior grain. These effects of Spd led to increased sucrose content in the inferior grain. These reasons might explain why Spd significantly promoted the filling and weight of inferior wheat grain.

Nutrient and planting modes strategies improves water use efficiency, grain-filling and hormonal changes of maize in semi-arid regions of China

A nutrient in combination of planting modes strategies has not been implemented on grain filling process, hormonal changes in seeds, water use efficiency (WUE) and maize yield. Field study was conducted during 2016–2017 to evaluate the performance to three cultivation techniques, (RF: ridge furrow precipitation harvesting technique with plastic mulching; PM: flat planting with plastic mulching; CP: flat planting without plastic mulching); with four nitrogen levels, (0: 0 kg N ha−1; 1: 100 kg N ha−1; 2: 200 kg N ha−1; 3: 300 kg N ha−1) in semi-arid areas. The results indicated that grain-filling rate, hormonal changes, dry matter per plant, yield components, WUE and ET of maize under the RF technique were significantly higher as compared with PM and CP cultivation techniques under different nutrient management strategies. Under the same cultivation techniques, as N amount increased up to 200 kg ha−1, the soil water storage, phytohormones such as IAA, Z+ZR, ABA content, were significantly improved and reducing GAs, Ethylene evolution rate, which led to improve maize production as compared with control plots. Nitrogen applications at 300 kg ha−1 have significantly reduced soil water storage and ET rate at different cultivation techniques. These results indicated that under the RF3 treatment improved grain filling process, WUE (55.5%) and grain yield (3.0 t ha−1). Nitrogen applications at the rate of 300 kg ha−1 with either RF or PM cultivation techniques significantly affected hormonal changes, therefore, regulating the Wmax, Gmax, Gmean, Tmax, and activity grain-filling period (AGP) of maize. It is concluded from our results that the RF3 treatment is an innovative cultivation technique to significantly improve the soil water storage, WUE, total dry mater accumulation (19.8%); grain filling rates thereby balance hormonal changes in maize seeds, as a result increase maize yields in semi-arid regions.

Salicylic acid influences lenticel discolouration and physiological and biochemical attributes of mango (Mangifera indica L.) fruits

Lenticel discolouration (LD) has now emerged as a leading postharvest threat in mango, which interferes with the face value of fruits, thereby affecting the trade and causing huge monetary losses to our country. For its management, we designed an experiment using salicylic acid at 200, 400 and 600 ppm concentration along with control fruits, as a dip treatment for 5 min. Our results revealed that salicylic acid at 200 ppm was not only effective in reducing LD significantly but also reduced the activities of polyphenol oxidase (PPO) (0.397 ∆A410 O.D min−1 g−1 FW), peroxidase (POD) (0.050 ∆ A470 O.D min−1 g−1 FW), and lipoxigenase (LOX) (3.227 µmol min−1 g−1 FW) enzymes and helped in increasing the total phenolics (15.46 mg gallic acid equivalent 100 g−1). This treatment also suppressed the rates of ethylene evolution (0.521 µL kg−1 h−1) and respiration (34.46 mL CO2 kg−1 h−1) over untreated mango fruits. With respect to quality parameters, the significant decrease in postharvest decay (23.3%) occurred without any adverse effect on soluble solids concentrates (16° B) and total carotenoids (4.1 mg 100 g−1pulp). Thus, keeping all parameters (physical, physiological, biochemical and quality) in view, salicylic acid at 200 ppm was most effective as a postharvest dip treatment for reducing LD in mango during storage or marketing without adversely affecting the fruit quality.

Effect of chitosan coating on postharvest life and quality of plum during storage at low temperature

Abstract The effect of chitosan coating on the storage life and quality of ‘Santa Rosa’ plum was investigated. The plum fruits were treated with 2% chitosan coating and stored at 1 ± 1 °C under 90 ± 5% RH. During storage, observations on weight loss, fruit firmness, colour, rates of respiration and ethylene evolution, biochemical and quality attributes were recorded at weekly interval. Our experiment yielded that chitosan had a significant effect in maintaining fruit firmness (∼78%), retarding weight loss (∼52%), respiration and ethylene evolution rates and delaying the colour change as compared to non-coated fruits. Furthermore, at the end of 35 days of storage at low temperature, a significant reduction in pectin methylesterase activity (∼44%) and malondialdehyde production (∼21%) was observed. Similarly, anthocyanin content (∼24%) was significantly retarded in chitosan-coated ‘Santa Rosa’ plums. Thus, postharvest application of chitosan as an edible coating can effectively maintain the quality and extend the storage life of plum up to 35 days under low temperature storage condition.

Effect of non-structural carbohydrate accumulation in the stem pre-anthesis on grain filling of wheat inferior grain

To promote the grain weight of wheat, the key is to improve the grain filling of inferior grain. The remobilization of non-structural carbohydrate (NSC) stored in reserve in the stem (sheath+culm) pre-anthesis is important for the grain filling of cereal. However, the mechanism that regulates the NSC reserve in the stem pre-anthesis on grain filling of inferior grains of wheat remains unclear. In the present study, six wheat cultivars with different grain weight were used. Additionally, different rates of nitrogen (N) fertilizer were examined. The objective of the present study was to investigate the relation between the NSC reserve in the stem pre-anthesis and grain filling of inferior grain of wheat and determine the mechanism of that relation. The results showed that the grain weight of inferior grain was significantly lower than that of superior grain, and the inferior grain was more affected by environmental factors than the superior grain. The superior grain had higher content of zeatin (Z)+zeatin riboside (ZR) and activities of synthase (SS) and ADP-glucose pyrophosphorylase (AGPP) and lower rate of ethylene (ETH) evolution than those of inferior grain. Because of these differences, the superior grain had higher sink strength and grain-filling rate and therefore had higher grain weight than that of inferior grain. With a high NSC reserve stored in the stem pre-anthesis, the Z+ZR content increased and the ETH evolution rate decreased in inferior grain significantly, which promoted the sink strength and grain-filling rate of inferior grain of wheat. Suitable nitrogen (N) fertilizer application notably increased the NSC reserve stored in the stem pre-anthesis, which promoted the sink strength and grain-filling rate of inferior grain. However, excess N fertilizer significantly decreased the NSC accumulation in the stem pre-anthesis and inhibited the sink strength and grain-filling rate of inferior grain of wheat.