Kaolin and Salicylic Acid Sprays Alleviate Sunburn Incidence and Improve Fruit Quality in Kinnow Mandarin

The quality of Kinnow mandarins (Citrus reticulate Blanco) is significantly influenced by the application of micronutrients, which play a crucial role in enhancing fruit attributes. This study evaluated the effect of foliar applications of 1.5% zinc sulfate, 0.6% boric acid and 0.5% potassium sulfate on various quality parameters of Kinnow mandarins cultivated in North India. Key quality metrics analyzed included juice content, peel content, rag content, peel thickness, total soluble solids (TSS), acidity, ascorbic acid and the TSS/acid ratio. Foliar nutrient treatments resulted in an increase in juice content and a reduction in peel and rag content, thereby improving the edible portion of the fruit. Peel thickness was minimized, contributing to better consumer acceptance. Additionally, significant improvements were observed in biochemical parameters: TSS, acidity, ascorbic acid levels and the TSS/acid ratio, enhancing the overall flavor and nutritional profile of the fruit. The study also examined leaf nutrient status (N, P, K, Zn and B), confirming improved uptake and utilization of essential nutrients under the foliar treatments. These findings underscore the importance of precise micronutrient management for achieving superior fruit quality in Kinnow mandarins.

The present study reports on the effect of humic and salicylic acids on the growth, yield, and fruit quality of three red sweet pepper ( Capsicum annuum ) cultivars: Barbero, Ferrari, and Imperio. The plants were grown in a greenhouse and the leaves were treated with humic or salicylic acids at 0, 0.5, 1.0, and 1.5 g·L −1 at 20, 40, and 60 days after transplanting. Foliar application of humic or salicylic acids significantly increased vegetative growth, fruit yield, and quality of the three cultivars as compared with the control plants. However, salicylic acid treatment proved more effective than humic acid treatment. Red sweet pepper plants of all three cultivars sprayed with 1.5 g·L −1 salicylic acid showed the greatest vegetative growth; fruit yield components, such as fruit number, diameter, and fresh and dry weights; and fruit quality traits, such as vitamin C content, total soluble solid content, titratable acidity, and total sugar content, than the plants in all other treatments. There were significant differences ( P ≤ 0.05) among cultivars in response to humic and salicylic acid foliar application; ‘Ferrari’ showed significantly higher yield and productivity than ‘Barbero’ or ‘Imperio’. ‘Ferrari’ plants sprayed with 1.5 g·L −1 salicylic acid showed the highest fruit weight (202.41 g) and flesh thickness (68 mm), both of which are preferred by consumers, and therefore, have increased market value. This treatment also increased total yield by 27.7% (16.03 t·ha −1 ), 15.9% (12.38 t·ha −1 ), and 17.9% (11.88 t·ha −1 ) in ‘Barbero’, ‘Ferrari’, and ‘Imperio’, respectively. Therefore, salicylic acid foliar application is recommended for enhancing fruit yield and quality of greenhouse-grown red sweet pepper.

Most of the researches on Salicylic acid (SA) have focused on postharvest application or acquiring stress resistance, while studies on its effect on plant growth, secondary metabolites and fruit quality are limited. SA as foliar application (0, 150, 300 and 450 mg/L) at different plant growth stages on fruit yield, secondary metabolites and quality features of tomato (Solanum lycopersicum L. cv. Kardelen) under greenhouse conditions were evaluated. The highest fruit yield per plant (about 1.3-fold greater than control) was obtained from 300 mg/L SA when applied three weeks after fruit set. Comparing to control plants, the highest fruit firmness, 10 days prolonged storability, highest total phenolics (22.6 mg gallic acid equivalent per 100 g fw); and highest antioxidant activity (65.11) were observed when 450 mg/L SA applied at fruiting stage and 3 weeks later. An increasing pattern in ascorbic acid content was observed with increasing SA concentration irrespective to application time. The same concentration effect was observed in flavonoid content when plants treated at 3 weeks after fruiting. The highest effect of flavonoids on antioxidant activity was calculated using Pearson correlation (r=0.82). SA concentrations greater than 450 mg/L showed significant adverse effects on all measured traits. The effect of exogenous SA on tomato plant depends on the developmental stage and SA concentrations tested. Improved fruit quality factors may happen in a certain concentration range, while over that may have negative or adverse effect.

مرکبات جزو میوه‌های نافرازگرا بوده و زمان برداشت و طول دوره انبارمانی می‌تواند تاثیر زیادی بر کیفیت میوه داشته باشد. این آزمایش به منظور بررسی خصوصیات کمی و کیفی میوه‌های برداشت شده نارنگی کینو در پانزدهم آذر، سی‌ام آذر، پانزدهم دی، سی‌ام دی و پانزدهم بهمن پس از 90-30 روز انبار خنک در دمای 6-4 درجه سانتیگراد در یکی از باغات شهرستان جیرفت اجرا گردید. نتایج نشان داد که برهمکنش زمان برداشت و مدت انبارمانی بر روی وزن میوه، گوشت، تفاله و عصاره و همچنین مواد جامد محلول (TSS)، اسید قابل تیتر (TA) و TSS/TA در سطح احتمال 1 درصد معنی‌دار گردید. تأخیر در برداشت باعث افزایش صفاتی از قبیل میزان وزن میوه، TSS و TSS/TA شد و بیشترین میزان TSS و TSS/TA مربوط به برداشت میوه‌ها در 15 بهمن بود. با افزایش دوره انبارمانی، درصد کاهش وزن میوه‌ها افزایش یافت. در مجموع، تاریخ برداشت پانزدهم‌ام بهمن بهترین زمان برداشت جهت انبارداری میوه نارنگی کینو در جیرفت می‌باشد.

The effect of salicylic acid (SA) treatment at different concentrations on fungal decay and some quality factors of kiwi fruit (Actinidia deliciosa var. Hayward) in postharvest conditions were studied. Results experiment showed that SA at all applied concentrations inhibited grey mould growth. The SA application significantly decreased weight loss percentage and increased life storage fruits. Also, SA positively affected on postharvest quality factors including total soluble solids (TSS), titratable acidity (TA), antioxidant, ascorbic acid and pH value. It was observed that treated fruits with SA at concentration 5 mM had the highest TSS, TA, ascorbic acid and antioxidant content and it had the lowest decay and acidity. Thus, these results showed that SA has strong impact on postharvest decay and fruit quality of kiwi fruit.

The main objective of this work was to assess the effectiveness of salicylic acid (SA), calcium chloride (CaCl2) or sodium bicarbonate (NaHCO3), and packaging on some qualitative properties of apricot fruit during cold storage. The experiments were conducted using a completely randomized design as factorial, with three replicates. Fruits were dipped in SA (0.1 or 0.5 mM), CaCl2 (1 or 2%) or NaHCO3 (0.2 or 0.5%) solutions for 3 min at 22°C. Then, fruits were placed into polyethylene trays and wrapped with cellophane films to create a passive modified atmosphere packaging, whilst the second group remained unwrapped. Fruits were stored in a cool room at 0.5 ± 0.5°C. Regardless of chemical treatments, total soluble solids (TSS), organoleptic characteristics, and shelf life were higher in packed fruit compare to unpacked fruit. The TSS, weight loss and firmness were lower in fruits covered with cellophane compared to unwrapped fruit. Fruits that treated with SA (0.5 mM) and covered with cellophane film had the lowest TSS while treated fruit with CaCl2 (1%) with no cover indicated the highest TSS. Generally, there was a significant decrease in fruit firmness under the cellophane layer compare to unpacked fruits while in treated fruit with CaCl2 (1%) firmness in packed fruit was obviously higher than unpacked fruits. The best visual quality and taste were obtained in treated fruit with CaCl2 (2%), followed by SA (0.5 mM) when they were packed with cellophane film. The highest shelf life obtained in treated fruit with SA (0.1 mM), followed by NaHCO3 (0.5%). Overall, a combination of chemical treatments and packaging with cellophane film improved fruit quality and extend shelf life significantly compared to the control.

During drought, chemical elements in a fertilizer go into solution in the soil with difficulty and nutrients are less available to plants. Foliar fertilization with water soluble Tecamin flower®, a product containing chemicals needed by plants, compensates for nutrient deficiency by roots due to water deficit. The study was undertaken to evaluate impacts of foliar application of Tecamin flower® at 0 or 2.5 ml/l and deficit irrigation (50 or 100% of field capacity) in tomato (Solanum lycopersicum L.) cvs. Bobcat, Finenss and Hadeer. The results showed that ‘Bobcat’ cultivar produced the highest vitamin C content, fruit firmness and total yield. ‘Finenss’ had the highest total soluble solids and water use efficiency (WUE). ‘Hadeer’ had the highest titratable acidity and the lowest pH. Plants irrigated at a 50% rate produced the highest vitamin C content, total soluble solids, fruit firmness and the lowest pH. 100% irrigation resulted with the highest yield and WUE. The plant treated with 2.5 ml/l Tecamin flower® produced the highest vitamin C content, total soluble solids, titratable acidity, fruit firmness, total yield, WUE and the lowest pH. Foliar application of Tecamin flower®, regardless of cultivar, improved production, fruit quality and WUE of tomato under normal and water deficit conditions and played a role in alleviating the negative impact of water deficit.

ENVIRONMENTAL STRESSES THAT CAUSE SUNBURN OF APPLE

Introduction. Arable regions often lack sufficient soil nutrients, which means that fertilizers must be used. However, using fertilizers excessively can harm the environment, human health and food safety. Natural growth regulators derived from plants are environmentally friendly and reasonably priced. The phytohormones methyl jasmonate (MeJA) and salicylic acid (SA) are crucial for enhancing plant biomass, quality, productivity and resistance to environmental stresses. Objective. To evaluate the foliar effect of MeJA and SA on fruit quality and production of colorful tomato cultivars under greenhouse conditions. Materials and methods. The trial was conducted at the University of Diyala, Iraq, from December 1, 2022, to June 5, 2023. Foliar applications of 0 mg/L, 200 mg/L SA and 200 mg/L MeJA were evaluated to determine their effects on fruit quality and production of colorful indeterminate cherry tomato cultivars: LA4013, LA353, LA2921, LA3899 and IQ2. A randomized complete block design was used, with each treatment having three replicates. Results. The cultivar IQ2 produced the heaviest fruit (82.13 g), the highest plant yield (4.56 kg/plant), the highest total yield (4.56 t/house) and the highest titratable acidity (0.62 %). The cultivar LA4013 had the highest fruit number (612.88 fruits/plant) and the highest total soluble solids (2.933 %). The foliar application of 200 mg/L SA resulted in the highest chlorophyll index (36.68 SPAD), the highest fruit number (373.73 fruits/plant), the highest plant yield (3.15 kg/plant) and the highest total yield (3.93 t/house). Conclusion. Considering all variables together, the best-performing genotypes were IQ2 and LA4013, which were superior to other genotypes in quality and yield trials. The foliar application of 200 mg/L SA improved both yield and quality of cherry tomatoes under greenhouse conditions.

Blue honeysuckle (Lonicera caerulea L.) is a novel, niche-market fruit because of its tart flavours, unique aroma profiles and abundant antioxidants. Commercial crop development requires improved biochemical traits to promote wide-spread market acceptance. Key foundation germplasm groups from Russia, Japan and the Kuril Islands were compared with three mainstream fruit crops (highbush blueberry, red raspberry and June-bearing strawberry) to characterize selected biochemical traits, including total soluble solids (TSS) and titratable acidity (TA), in a temperate climate over two years (2012, 2013) in the Fraser Valley, British Columbia, Canada. Biochemical diversity associated with commercially-desirable fruit quality varied across foundation groups, providing genetic resources required to improve several fruit quality traits. There was greater variability in dry matter and TSS:TA in the Russian and Japanese groups, respectively, and these groups had similar diversity in TSS, TA and pH. Blue honeysuckle possessed important variability in TSS:TA, meaning that overly tart fruit tastes are not an absolute limitation to wide-spread consumption. The Japanese group had low TSS:TA despite high TSS, and the Russian group had high TSS:TA despite low TSS. Diversity in TSS:TA is more directly related to differences in TA than TSS. Reducing TA will effectively improve TSS:TA, contributing to desirable fruit quality and market acceptance.

This study was conducted to evaluate the effects of exogenous polyamines, isopropyl ester, 2, 4D and naphthalene acetamide application on yield and quality of date palm of ‘Kabkab’ cultivar. The inflorescences sprayed with 2, 4-D isopropylester (0, 10, and 20 mg L -1 ), naphthalene acetamide (0, 80, and 120 mg L -1 ), putrescence and spermidine (0, 0.1, and 1.0 mM), three or six weeks after pollination. The highest rate of initial fruit drop (42.2%) was obtained when fruits were treated with naphthalene acetamide at a concentration of 120 mg L -1 , which was significantly higher than the control (32.0%). Fruit treated with polyamines had a higher yield than the control. The lowest total soluble solids (TSS) (21.5%) were found in spermidine 0.1 mM and the highest TSS (46%) was found in the control. Polyamines decreased fruit total soluble solids content (TSS) compared with untreated fruits, and also delayed fruit maturity for at least 17 days. In conclusion, polyamine application significantly affected yield, physical and chemical characteristics of date cultivar under the study and it may be recommended to be applied in cultural practices to enhance production and improve the fruit quality of date trees orchards.

Peel cracking and ostiole-end splitting (collectively termed cracking) are common disorders in ripe fig fruit, downgrading fruit quality and thus limiting marketability. This two-year field study addressed the possibility of alleviating cracking at harvest by two foliar salicylic acid (SA) sprays prior to harvest (8 and 5 d). Three SA concentrations (0, 1, and 2 mM) were employed in the first year, and based on the obtained results two (0 and 2 mM) in the second year. A local variety (‘Vasilika’) with excellent organoleptic profile, and high sensitivity to cracking was evaluated. Fruit was harvested at commercial maturity. Fruit marketability was mainly based on the incidence and severity of cracking. Fruit weight, peel color, flesh total soluble solids (TSS), titratable acidity (TA), and pH were estimated for fig quality. The contents of total anthocyanins (TAN), cyanidin-3-rutinoside (c-3-rut; the major anthocyanin in fig), and the expression of four genes coding for regulatory enzymes (phenylalanine ammonia lyase, anthocyanidin synthase, UDP-flavonoid glucosyl transferase 1, and UDP-flavonoid glucosyl transferase 2) of the phenylpropanoid biosynthetic pathway were also determined in the peel. Preharvest SA application (2 mM) increased the percentage of fruit without cracking (sound fruit) by 1.4–2.6-fold, and of marketable fruit (sound and slightly cracked) by 2-fold. SA application (2 mM) was associated with increased flesh TSS and TA, as well as with decreased flesh pH and peel red coloration in stripe. The treatment (2 mM SA) decreased both TAN and c-3-rut contents, which were highly associated (r = 0.978). Responses of transcription level of the four genes to SA application varied, and did not correlate with the other variables in the study. In conclusion, SA appears to be a low-cost and environmentally-safe agent for improving fig fruit quality and marketability, and facilitates harvesting and postharvest management of figs.

Improving fruit quality and reducing pre-harvest fruit drop are critical goals for Citrus reticulata production in Pakistan, where climatic and nutritional challenges affect yield and juice quality. This study evaluated the combined effects of plant growth regulators (salicylic acid and indole acetic acid) and nutrients (potassium and zinc) on fruit drop and juice volume in Citrus reticulata L. Field trials were conducted at three locations in Punjab, Pakistan (Layyah, Faisalabad, and Sargodha) using a randomized complete block design (RCBD) with five replications per treatment. Nutrients (K and Zn at 100 mg/L each) and growth regulators (SA at 100 mg/L and IAA at 5 mg/L) were applied individually or in combination at three growth stages. Statistical analyses, including PCA, ANOVA, and GGE biplot, were used to identify the most effective treatments for improving fruit juice quality and reducing fruit drop. The combined foliar application of SA + K + Zn was the most effective across all parameters, except fruit drop, juice citric acid contents, and juice pH, which were negatively affected. The highest juice potassium content was observed with K application. The PCA and GGE biplot analysis indicated that the Sargodha orchard performed best, with the SA + K treatment being the most effective there, while SA + K + Zn showed the best results at Layyah and Faisalabad for reducing fruit drop, enhancing juice volume, and improving fruit quality. However, individual fruit, juice, and juice nutrient contents traits analyses revealed that the most significant improvements in fruit and juice quality were observed at the Sargodha site instead of Layyah and Faisalabad. The treatment SA + K + Zn proved to be the most stable and consistent in enhancing citrus fruit and juice quality across all three selected locations. The findings suggest that adopting the SA + K + Zn treatment could be a practical approach for citrus farmers aiming to enhance crop yield and fruit quality, thereby supporting agricultural productivity and export potential in Pakistan.

Sunburn is a major problem caused by high temperature and direct solar radiation, which leads to significant economic losses in Balady mandarin yield. So, a field experiment was conducted during 2014 and 2015 seasons at a private orchard situated in Motobus, Kafr El-Sheikh governorate, Egypt, to study the effect of foliar spray of 0, 2, 3 and 4% kaolin, twice or three times at May, June and July on sunburn percentage and fruit quality of Balady mandarin trees. The obtained results showed that, kaolin foliar applications were effective to control fruit sunburn as well as reducing severity percentage of sunburned fruits as compared to untreated trees. Moreover, Kaolin foliar application at three times was decreased leaf and fruit surface temperature especially at the concentrations of 3 and 4%. In addition, kaolin treatments increased yield and improved fruit quality in terms of fruit size, diameter, weight, peel thickness and vitamin C. Kaolin foliar spray was raising fruit values of SSC%, acidity and SSC/acid ratio compared to control trees, whereas there is no significant variation among kaolin concentrations on this variables. Therefore, it could be recommended that, spraying kaolin at 3 or 4% three times in summer months, because it had a positive effect on preventing fruit sunburn damage and improvement yield and fruit quality of Balady mandarin trees.

Sweet cherry, which affects consumers’ preferences with its aroma, taste and sensory properties, is a significant fruit species for human health with its bioactive compounds such as organic acids, vitamins and anthocyanins. However, its post-harvest shelf life is very short due to its sensitive fruit structure. Thus, the significant economic losses occur. In the study, effects of pre-harvest Aminoethoxyvinylglycine (AVG), Salicylic acid (SA) and plant growth promoting rhizobacteria (PGPR) applications on fruit quality characteristics and biochemical content in sweet cherry were determined. SA and PGPR treatments increased fruit size, but AVG decreased (If the fruit weight is 4.51 in the control application, 4.49 in the SA application and 4.10 in the PGPR, how can it be said that SA and PGPR increase the fruit weight). The fruits treated with SA, AVG and PGPR had higher fruit firmness values than the control’-fruits. Salisylic acid treatmens did not affect the rate of soluble solids content(SSC) in fruit, SSC rate was higher in PGPR treated-fruit, but AVG decreased the SSC. Titratable acidity (TA) was lower in PGPR treated-fruit, but was higher in the AVG and SA treated-fruit. Fruits treated with the SA and AVG had higher fruit color values than control fruits, while the lowest color values was obtained with PGPR treatment. In general; PGPR, SA and AVG were effective in the concentration of organic acids, but their effects varied depending on the organic acid compounds. As a result, AVG and SA delayed fruit ripening and fruit softening while PGPR, AVG and SA improved fruit quality (It is not clear how this idea was reached). These applications can be considered as a promising method for improving fruit quality at harvest and maintaining post-harvest fruit quality of sweet cherry.