Destruction Of Chlorophyll Research Articles

Plant Pigments in Bottom Sediment Cores as Indicators of the Trophic State in Large Shallow Lakes Vozhe and Lacha (Russia)

The first data on the content of plant pigments is presented for the cores of bottom sediments sampled in large shallow lakes Vozhe and Lacha located in the upper reaches of the Onega River. In the 1-m core of olive silts, the total concentration of chlorophyll a and pheopigments varied within 35–236 (94.2 ± 3.3) in Lake Vozhe and 58–118 (83.8 ± 1.3) μg/g dry sediment in Lake Lacha. The degree of chlorophyll destruction in the cores from Lake Lacha (98.7 ± 0.2%) was higher than in Lake Vozhe (85.2 ± 0.7%). Considering the average long-term sedimentation rate of 0.2 and 0.4 mm/year in Lakes Vozhe and Lacha, respectively, the annual vertical flux of chlorophyll a and pheopigments is 4.0 and 6.2 mg/(m2 · year) for the last 2500 years, respectively. Nowadays, the average annual rate of pigment accumulation is almost the same in the lakes (5.6 and 5.3 mg/(m2 · year)). Over the period under consideration until now, different patterns of long-term dynamics of pigment accumulation in the studied lakes have been revealed; in particular, there is a positive trend in Lake Vozhe and a negative trend in Lake Lacha.

Zinc Supplementation Enhances Glutathione-Mediated Antioxidant Defense and Glyoxalase Systems to Conferring Salt Tolerance in Soybean (Glycine max L.)

In this study, the role of zinc (Zn) in salt-affected soybean (Glycine max L.) was scrutinized by exposing plants to salt stress (150 mM NaCl) alone and in combination with exogenous Zn (priming and/or foliar spray with 1 mM ZnSO4.7H2O). Salt stress decreased plant growth and caused the destruction of chlorophyll and carotenoids. It also disrupted physiological processes and antioxidant defenses, resulting in an oxidative burst. The levels of the toxic metabolite methylglyoxal (MG) rose substantially under salinity. Salinity resulted in a high accumulation of Na+ and decreased K+ which decreased the K+/Na+ ratio. Zn supplementation decreased ion toxicity and improved ion homeostasis in soybean plants. Zn increased glutathione (GSH) levels, decreased glutathione disulfide levels, and increased their ratio in salt-treated soybean plants compared to salt-treated plants without Zn addition. Zn supplementation also upregulated the activities of the glutathione-dependent enzymes glutathione reductase, dehydroascorbate reductase, glutathione peroxidase, and glutathione S-transferase in salt-stressed plants. The enhanced GSH pool and increased activity of GSH-dependent enzymes decreased oxidative damage, as indicated by the reduced levels of H2O2 and malondialdehyde and lower electrolyte leakage. The increased GSH level and high activity of glyoxalase I and glyoxalase II conferred by Zn under salt stress helped to scavenge methylglyoxal. The restoration of photosynthetic pigment levels and increased proline accumulation, together with the recovery of leaf relative water content, were further signs of salt stress recovery and tolerance conferred by Zn supplementation. Our results showed that the antioxidant defense, glyoxalase system and some other physiological parameters were improved by Zn supplementation which contributed to mitigating the effects of salt stress in soybean.

Evaluation of Proline, Chlorophyll, and Carotenoid Contents of Two Globe Artichokes [Cynara cardunculus var. scolymus (L.) Fiori] Leaves Based on the Growing Season

Globe artichoke [Cynara cardunculus var. scolymus (L.) Fiori], a member of the Asteraceae family, has been known since ancient times. Edible parts of this valuable vegetable are rich in antioxidants and polyphenols as well as possessing healing properties against certain diseases. When the life cycle of plants is taken into consideration, the processes which are highly affected by environmental conditions are photosynthesis and cell growth. Chlorophyll level is known as a good indicator of the photosynthesis of plants. Carotenoids, one of the important functions of which protects chlorophyll from photo-oxidation, can prevent the destruction of chlorophyll. Therefore, chlorophyll and carotenoids play an important role in photosynthesis and the protection of photosynthetic pathways against harmful free radicals. The proline concentration present in various plants is increased in many different stress conditions, such as cold, temperature, salinity, drought, UV, and heavy metals, thus, providing better tolerance to stress conditions. The aim of the present study was to comparatively evaluate the proline, chlorophyll (a and b), and carotenoid contents of the young and mature leaves of two OP cultivars (Bayrampaşa and Sakız) based on different growing seasons. Obtained results demonstrated that there were differences between two OP artichoke cultivars based on the growing season and young and mature leaves with regards to proline, chlorophyll (a and b), and carotenoid contents. Findings revealed that proline and chlorophyll b levels in autumn were quite promising, while in terms of chlorophyll a and carotenoid levels winter was prominent. Regarding the young and mature leaves, high proline and chlorophyll a levels were found to be dominant in young leaves. On the other hand, chlorophyll b and carotenoid were more accumulated in mature leaves. Turkey has several other globe artichoke cultivars and the findings of the present study may play a supportive role in determining proline, chlorophyll (a and b), and carotenoid contents for combating several environmental stress factors.

Detergents are more harmful than COVID 19: Escaping or destruction of Chloroplasts and chlorophylls and methylation

Detergents are more harmful than COVID 19: Escaping or destruction of Chloroplasts and chlorophylls and methylation

The dynamics of pigments content in the leaves of Acer negundo L. in urban conditions of Barnaul

The article discusses the results of the study of dynamics of photosynthetic pigments content (chlorophyll a,chlorophyll b, carotenoids) in the leaves of Acer negundo L. in Barnaul. High contamination level causes a plant response,manifested in decreasing in amount of chlorophyll a and b and a changing in the chlorophyll a/b ratio. Carotenoids duringatmospheric air pollution act as a protective mechanism against the destruction of chlorophyll a molecules and organicsubstances. In urban ecosystems, their number increases during the growing season.

Impact of technogenic pollution on the pigment composition of birch leaves (Betula pendula Roth) in the urban conditions of Barnaul

The article considers the results of analysis of photosynthetic pigments сcontent (chlorophyll a, chlorophyll b, carotenoids) in birch leaves growing along the roads of Barnaul. High level of pollution causes decrease inamount of chlorophyll a and b and a change in chlorophyll a/b ratio. Carotenoids act as a protective mechanism againstthe destruction of chlorophyll a molecules and organic substances. Their number increases during the growing season.

Stabilization of the natural color of sweet pepper (Capsicum annuum L.) during its processing

The influence of various parameters of technological treatment on the degree of chlorophyll destruction and change in the green coloration of the sweet pepper (Capsicum annuum L.) has been investigated. It has been established that the temperature and duration of its effect on sweet pepper during primary heat treatment alter its natural green coloration to yellow with a brown tint. The paper presents experimental spectra of the intensity of light absorption by the samples of sweet pepper, which make it possible to define regularities in the influence of time and temperature on the color and the degree of chlorophyll destruction. During blanching, from 25.2 to 59.2 per cent of the total amount of chlorophylls of the starting value are destroyed, depending on the water temperature. It was established that the blanching process duration negatively affects the content of chlorophylls as well: depending on the process duration, 20.2‒61.7 % of the original content are degraded. The experimental diffuse reflection spectra for opaque objects, provided here, have made it possible to identify the dependence of color of the samples of pepper, treated in the Xanthium strumarium decoction, on various factors of the technological process. It is shown that the use of decoction of the natural plant raw material Xanthium strumarium for treating the samples leads to the stabilization of the green coloration of pepper compared to that blanched in water. The influence of the Xanthium strumarium concentration, temperature, and exposure time in the decoction, on the color of pepper samples has been investigated. Applying such color­parametric characteristics, calculated on the basis of spectral reflection coefficients using a CIE XYZ method, as dominant wavelength (λ, nm), color clarity (P, %), and brightness (T, %), has made it possible to compare the color of pepper samples with fresh samples (control­1), as well as with the samples blanched in water (control­2). The multivariate experiment, performed in this research, has made it possible to optimize parameters for the technological treatment of pepper samples in the Xanthium strumarium decoction. Basic parameters for treating sweet pepper are a 1­% Xanthium strumarium decoction, a treatment temperature of 75 °C, and a treatment duration of 15 minutes

Enhancement of Neuroprotective Effects of Spirulina platensis Extract from a High-Pressure Homogenization Process

This study is the first to show that a simple high-pressure homogenization process (HP) could extract very heat-sensitive chlorophyll from a marine alga, Spirulina platensis. Up to 9.85 mg/g was produced at an optimal input pressure of 650 bar with a shear stress of approximately 20,000 (1/s) compared to 5.27 mg/g from conventional 70% ethanol extraction (EE) at 40 °C for 24 h. However, a higher input pressure did not increase the extraction yield and in fact decreased it, possibly due to the destruction of chlorophyll a at a high shear stress of approximately 50,000 (1/s) under 1370 bar of input pressure. Chlorophyll a and other components of the extract had additive effects, showing higher antioxidant activities of ca. 56% of DPPH radical scavenging activities than 10 μg/mL chlorophyll a alone, which corresponded to the same chlorophyll a content that existed in the extract. It was also confirmed that the high antioxidant activities of the HP extract reduced the production of reactive oxygen species (ROS) from glutamate-induced HT22 cells, which resulted in increased neuroprotective activity compared to EE and even chlorophyll a alone, in addition to effectively reducing the release of Ca2+ from nerve cells.

S-nitrosoglutathione reductase (GSNOR) activity is down-regulated during pepper (Capsicum annuum L.) fruit ripening

Pepper (Capsicum annuum L.) is an annual plant species of great agronomic importance whose fruits undergo major metabolic changes through development and ripening. These changes include emission of volatile organic compounds associated with respiration, destruction of chlorophylls and synthesis of new pigments (red/yellow carotenoids plus xanthophylls and anthocyans) responsible for color shift, protein degradation/synthesis and changes in total soluble reducing equivalents. Previous data have shown that, during the ripening of pepper fruit, an enhancement of protein tyrosine nitration takes place. On the other hand, it is well known that S-nitrosoglutathione reductase (GSNOR) activity can modulate the transnitrosylation equilibrium between GSNO and S-nitrosylated proteins and, consequently, regulate cellular NO homeostasis. In this study, GSNOR activity, protein content and gene expression were analyzed in green and red pepper fruits. The content of S-nitrosylated proteins on diaminofluorescein (DAF) gels was also studied. The data show that, while GSNOR activity and protein expression diminished during fruit ripening, S-nitrosylated protein content increased. Some of the protein candidates for S-nitrosylation identified, such as cytochorme c oxidase and peroxiredoxin II E, have previously been described as targets of this posttranslational modification in other plant species. These findings corroborate the important role played by GSNOR activity in the NO metabolism during the process of pepper fruit ripening.

Nitric oxide protects carbon assimilation process of watermelon from boron-induced oxidative injury

Nitric oxide (NO) mediates plant response to a variety of abiotic stresses; however, limited information is available on its effect on boron (B)-stressed watermelon plants. The present study investigates the mechanism through which NO protects watermelon seedlings from B deficiency and toxicity stresses. Five days old watermelon seedlings were exposed to B (0, 0.5 and 10 mg L−1) alone or with 75 μmole of NO donor sodium nitroprusside (SNP) for 30 days. Both low and high B concentrations in the media altered nutrient accumulation and impaired various physiological processes of watermelon seedlings, leading to a significant reduction in biomass production. The plants exposed to B deficient or toxic concentrations had 66 and 69% lower shoot dry weight, respectively compared with optimum B levels. B toxicity-induced growth inhibition of watermelon seedlings was associated with high B translocation to shoot tissues, which caused lipid membrane peroxidation (12% increase) and chlorophyll destruction (25% reduction). In contrast, B deficiency accelerated generation of reactive oxygen species (ROS), specifically OH−1 and induced cellular oxidative injury. Exogenously applied SNP promoted leaf chlorophyll, photosynthesis and consequently biomass production in B-stressed watermelon seedlings by reducing B accumulation, lipid membrane peroxidation and ROS generation. It also activated antioxidant enzymes such as SOD, POD and APX, and protected the seedlings from ROS-induced cellular burst.

Pigments content in Сhlorella vulgaris under the influence of the sodium selenite and the ions of metals

We investigated the content of pigments in Chlorella vulgaris Beij. (Chlorophyta) under the influence of sodium selenite in concentrations based on Se4+ 0.5, 5.0, 10.0 and 20.0 mg/dm3 during one, three and seven days and under the influence of the simultaneous action of selenite in concentrations 10 mg Se4+/dm3 and ions of Zn2+, Mn2+, Co2+,Cu2+, Fe3+ in concentrations 5.00, 0.25, 0.05, 0.008 and 0.002 mg/dm3over seven days. This research was carried out to establish the conditions for obtaining algal lipidis substance enriched with selenium and biogenic metals in the aquaculture. The content of pigments was determined spectrophotometrically, the cellular walls were separatedby centrifuge in the percoll gradient and investigated microscopically. The pigments content in the Ch. vulgaris increased by 1.5–2.5 times in comparison with the control sample under the influence of 10 mg Se4+/dm3 with and without metal ions, in all variants of experimental influence due to binding of SeО32– with proteins and lipids. We found that selenium was included in all lipid fractions (triacylglycerols, dyacylglycerols, phospholipids, nonetherified fatty acids); the maximum amount of selenium-containing lipids wasrecorded in chloroplasts. The increase in the contents of carotenoids caused by the actions of experimental factors played an exceptional role in the mechanism of antioxidant protection that prevents destruction of chlorophyll and, accordingly, increases its amount in cells. Changes in the functioning of the photosynthetic apparatus of Ch. vulgaris affect the whole complex of metabolic transformation. Thus, the successful cultivation of chlorella, enriched with selenium and biogenic metals, is possible within seven days under the influence of 10 mg Se4+/dm3 and the above-mentioned concentration of metal ions.

Protective effect of exogenous nitric oxide on alleviation of oxidative damage induced by high salinity in rice (Oryza sativa L.) seedlings

To find the protective role of exogenous nitric oxide (NO) on salinity-stressed rice seedlings, a CRD-based factorial experiment with three replications was conducted in Agronomy Laboratory of the Faculty of Agricultural Sciences, University of Guilan, in 2012. The experimental design consisted of healthy and vigorous seedlings of two rice cultivars, Khazar and Goohar, the last already known as promising SA13 line, which were exposed to 0 (Control), 50 mM NaCl, 50 μM sodium nitroprusside (SNP) as NO donor solution supplemented with simultaneous 50 mM NaCl + 50 μM SNP for four days. After 4 days, electrolyte leakage and malondialdehyde (MDA) content, activities of antioxidant enzyme, destruction of chlorophyll and soluble protein content in leaves were measured in treated and control plants. The results showed that simultaneous treatment of rice leaves with SNP, suppressed the ion leakage content by 8.5% compared with the results of NaCl treatment. Furthermore, SNP increased the activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX) and catalase (CAT). Exogenous application of NO also reduced peroxidation of membrane lipids, whereas increased the soluble protein content and chlorophyll pigments in rice leaves under salinity stress. These results suggested that NO could effectively protect rice seedlings from salt stress damaged by enhancing activities of antioxidant enzymes to quench the excessive reactive oxygen species caused by salt stress.

Ripening of pepper (Capsicum annuum) fruit is characterized by an enhancement of protein tyrosine nitration

Pepper (Capsicum annuum, Solanaceae) fruits are consumed worldwide and are of great economic importance. In most species ripening is characterized by important visual and metabolic changes, the latter including emission of volatile organic compounds associated with respiration, destruction of chlorophylls, synthesis of new pigments (red/yellow carotenoids plus xanthophylls and anthocyanins), formation of pectins and protein synthesis. The involvement of nitric oxide (NO) in fruit ripening has been established, but more work is needed to detail the metabolic networks involving NO and other reactive nitrogen species (RNS) in the process. It has been reported that RNS can mediate post-translational modifications of proteins, which can modulate physiological processes through mechanisms of cellular signalling. This study therefore examined the potential role of NO in nitration of tyrosine during the ripening of California sweet pepper. The NO content of green and red pepper fruit was determined spectrofluorometrically. Fruits at the breaking point between green and red coloration were incubated in the presence of NO for 1 h and then left to ripen for 3 d. Profiles of nitrated proteins were determined using an antibody against nitro-tyrosine (NO2-Tyr), and profiles of nitrosothiols were determined by confocal laser scanning microscopy. Nitrated proteins were identified by 2-D electrophoresis and MALDI-TOF/TOF analysis. Treatment with NO delayed the ripening of fruit. An enhancement of nitrosothiols and nitroproteins was observed in fruit during ripening, and this was reversed by the addition of exogenous NO gas. Six nitrated proteins were identified and were characterized as being involved in redox, protein, carbohydrate and oxidative metabolism, and in glutamate biosynthesis. Catalase was the most abundant nitrated protein found in both green and red fruit. The RNS profile reported here indicates that ripening of pepper fruit is characterized by an enhancement of S-nitrosothiols and protein tyrosine nitration. The nitrated proteins identified have important functions in photosynthesis, generation of NADPH, proteolysis, amino acid biosynthesis and oxidative metabolism. The decrease of catalase in red fruit implies a lower capacity to scavenge H2O2, which would promote lipid peroxidation, as has already been reported in ripe pepper fruit.

Differences in gene expression between natural and artificially induced leaf senescence in barley

Senescence is the last step of leaf development in the life span of an annual plant. Senescence can be induced prematurely by treating leaf tissues with jasmonic acid methyl ester (methyl jasmonate, MeJA). During both senescence programmes, drastic changes occur at the biochemical, cellular and ultra-structural levels that were compared here for primary leaves of barley (Hordeum vulgare L.). Our findings indicate that both types of senescence are similar with respect to the morphological changes including the loss of chlorophyll, disintegration of thylakoids, and formation of plastoglobules. However, the time elapsed for reaching senescence completion was different and ranged from 7 to 8 days for artificially senescing, MeJA-treated plants to 7–8 weeks for naturally senescing plants. Pulse-labelling studies along with RNA and protein gel blot analyses showed differential changes in the expression of both plastid and nuclear genes coding for photosynthetic proteins. Several unique messenger products accumulated in naturally and artificially senescing, MeJA-treated leaves. Detailed expression and crosslinking studies revealed that pheophorbide a oxygenase (PAO), a previously implicated key enzyme of chlorophyll breakdown, is most likely not rate-limiting for chlorophyll destruction under both senescence conditions. Metabolite profiling identified differential changes in the composition of carotenoid derivatives and prenyl-lipids to occur in naturally senescing and artificially senescing plants that underscored the differences between both senescence programmes.

Color stabilization of green vegetables at storage

The effect of antioxidant preparations on color changes during storage of parsley, cucumbers and zucchini was investigated. The application of antioxidants is proposed to delay dissociation of chlorophylls, carotenoids and maintain high quality of green vegetables. Postharvest heat treatment by antioxidant solution which contains chlorophilipt for cucumbers and zucchini is recommended. The nutrient solution with antioxidants based on hydrogel may be used for parsley. It was established that the use of complex antioxidant composition of chlorophyllipt promotes certain stabilization of color during parsley, cucumbers and zucchini storage. It is shown that the application of nutrient solution with the addition of antioxidants can reduce the rate of chlorophyll destruction up to 1.1 ... 1.6 times and carotenoids destruction up to 1.2 ... 1.6 times according to the season of cultivation and varieties of parsley. After using the antioxidant composition for cucumber treatment there is a statistically significant decrease in the concentration of chlorophylls comparing with the initial value. It was detected after 21 days storage. The concentration of carotenoids in experimental cucumbers at the end of storage is 21 to 23 percent more than it is in the control ones. Antioxidant treatment also reduces the chlorophylls and carotenoids degradation in zucchini.

Resistance to paraquat in Mazus pumilus

SummaryMazus pumilus is an annual self‐pollinating weed that is commonly found in arable land, vegetable gardens and roadsides. This weed harbours insects and pathogens that attack vegetables. The mechanism of resistance to paraquat of M. pumilus found in Ohita, Japan, was studied. Whole plant bioassays revealed that the resistant (R) biotypes were four to six times less susceptible than controls. Chlorophyll destruction of leaf discs by paraquat treatment in R biotypes was 4–20 times lower than those of susceptible (S) biotypes. Ferric reducing antioxidant power (FRAP) values in R biotypes were higher than those of S biotypes before and after paraquat treatments. The activity of superoxide dismutase (SOD) was also higher in R biotypes than those of S biotypes before and after treatment with paraquat, but the activities of ascorbate peroxidase (APX) and catalase (CAT) were not different between R and S biotypes. Change of ascorbate (AsA) contents before and after paraquat treatment was equivalent in both biotypes. These results indicate that the increased SOD activity and antioxidant capacity in R biotypes contribute to the resistance to paraquat of M. pumilus.

3D-analysis of plant microstructures: advantages and limitations of synchrotron X-ray microtomography

Abstract Synchrotron X-ray computer microtomography was used to analyze the microstructure of rose peduncles. Samples from three rose cultivars, differing in anatomy, were scanned to study the relation between tissue structure and peduncles mechanical strength. Additionally, chlorophyll fluorescence imaging and conventional light microscopy was applied to quantify possible irradiation-induced damage to plant physiology and tissue structure. The spatial resolution of synchrotron X-ray computer microtomography was sufficiently high to investigate the complex tissues of intact rose peduncles without the necessity of any preparation. However, synchrotron X-radiation induces two different types of damage on irradiated tissues. First, within a few hours after first X-ray exposure, there is a direct physical destruction of cell walls. In addition, a slow and delayed destruction of chlorophyll and, consequently, of photosynthetic activity occurred within hours/ days after the exposure. The results indicate that synchrotron X-ray computer microtomography is well suited for three-dimensional visualization of the microstructure of rose peduncles. However, in its current technique, synchrotron X-ray computer microtomography is not really non-destructive but induce tissue damage. Hence, this technique needs further optimization before it can be applied for time-series investigations of living plant materials

Application of natural and synthetic polyamines as growth regulators to improve the freezing tolerance of winter wheat (Triticum aestivum L.)

Wheat cultivars were grown as soil culture under normal growth conditions. Twoweek- old seedlings were exposed to 4°C for 6 h and then transferred to −12°C for 24 h in the dark. Twenty-four hours before freezing stress, some of the plants were sprayed with aqueous solutions of spermine, spermidine, putrescine, 1,3-diaminopropane (1,3-DAP) and diethylenetriamine (DETA). The data showed that freezing stress caused a decrease in the fresh weight, chlorophyll content and plant survival rate, accompanied by a simultaneous accumulation of free proline and the enhanced leakage of electrolytes. Preliminary treatment with polyamines caused a decline in electrolyte leakage and a considerable augmentation in proline quantity, indicating that the compounds are capable of preventing frost injury. Additionally, the foliar application of polyamines retarded the destruction of chlorophyll, and lessened fresh weight losses due to freezing stress. The synthetic triamine DETA was the most effective, having the most pronounced action in all the experiments, followed by the tetraamine spermine. The application of polyamines to wheat crops could be a promising approach for improving plant growth under unfavourable growth conditions, including freezing temperatures. The results demonstrate that treatment with polyamines could protect winter wheat by reducing the stress injuries caused by subzero temperatures.

Effect of magnesium deficiency on antioxidant status and cadmium toxicity in rice seedlings

Cadmium (Cd) is one of the most toxic heavy metals and inhibits physiological processes of plants. Magnesium (Mg) is known as one of the essential nutrients for plants. Mg deficiency in plants affects metabolic processes. Plants grown in the field may encounter several abiotic stresses, rather than a single stress. Thus, the relationship between Mg nutrition and Cd toxicity is of ecological importance. In this study, effects of Mg deficiency on antioxidant systems and Cd toxicity in rice seedlings were investigated. Mg deficiency significantly decreased Mg concentrations in shoot and roots of rice seedlings. However, fresh weight and dry weight of rice seedlings were not affected by Mg deficiency. The contents of ascorbate and glutathione (GSH), the ratio of GSH/oxidized glutathione, and the activities of superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase in Mg-deficient leaves were higher than respective control leaves. Cd toxicity was judged by the decrease in biomass production, decrease in chlorophyll, and induction of oxidative stress. Based on these criteria, we demonstrated that Mg deficiency protected rice seedlings from Cd stress. Moreover, chlorophyll destruction by paraquat was higher in detached leaves from Mg-sufficient than Mg-deficient seedlings. Cd concentration was higher in Mg-deficient shoot and roots than their respective control shoot and roots, suggesting that the protective effect of Mg deficiency against Cd toxicity is not due to reduction of Cd uptake. Moreover, we observed that Cd-decreased Fe and Zn contents in Mg-deficient seedlings were more pronounced than that in Mg-sufficient seedlings. Of particular interest is the finding that the increase in OsIRT1, OsZIP1, and OsZIP3 transcripts caused by Cd in Mg-deficient roots was greater than that in control roots.

Peel Color and Blemishes in ‘Granny Smith’ Apples in Relation to Canopy Light Environment

The dark green apple cultivar, Granny Smith (GS), makes up 25% of the South African apple industry. However, production of GS is becoming unprofitable as a result of a high incidence of sunburn, red blush, and pale green fruit that decreases the proportion of Class 1 fruit that is suitable for export to more lucrative markets. This study was conducted to investigate the relationship between canopy position and external fruit quality with the ultimate aim to devise pruning and training strategies to maximize export yield. During early fruit development [26 days after full bloom (DAFB)], chlorophyll concentrations were the highest in fruit from higher light environments. Good green color at harvest relied on exposure of fruit to high irradiance at this stage because 50% shading between 14 and 56 DAFB significantly decreased dark green color at harvest. Exposed fruit from the northern side of east–west rows received the highest irradiance throughout the season [53% of full sun photosynthetic photon flux (PPF)] and had the highest fruit surface temperature (on average 5 °C above ambient). A high proportion of exposed fruit from either side of the row developed red blush. Only 22% to 39% of exposed fruit from the outer canopy did not develop sunburn or red blush. Partially shaded fruit from the southern side of east–west rows received ≈5% of full sunlight and had the highest chlorophyll concentrations and darkest green color at harvest. Deeply shaded inner canopy fruit received ≈2% of full sunlight, had low chlorophyll concentrations, and were lighter green in color. The 10% darkest green fruit received moderately high irradiance (25% to 45% of full sun PPF) during early fruit development (until ≈80 DAFB) but became progressively shaded (3% of full sun PPF) during the latter half of the season. Fruit that developed sunburn and the lightest green fruit were exposed to high (1300 μmol·m−2·s−1) and extremely low (50 μmol·m−2·s−1) light, respectively, throughout their development. In conclusion, maximum chlorophyll synthesis and dark green color require an open canopy during the first half of fruit development, whereas shading is necessary during the latter half of fruit development to avoid the occurrence of sunburn, red blush, and photothermal destruction of chlorophyll. GS may benefit significantly from the installation of shade netting if combined with rigorous pruning and vigor control.