Calcium and Potassium Foliar Sprays Affect Fruit Skin Color,Quality Attributes,and Mineral Nutrient Concentrations of ‘Red Delicious’ Apples

This study was conducted to evaluate the influences of foliar spray of potassium (K), calcium (Ca), and their combination on the fruit red skin color and quality attributes of ‘Red Delicious’ apple under conditions of south central Iran with warm and dry summer, where low and high temperature differences are low. The trees were sprayed five times using 5 g L^–1 calcium chloride (CaCl₂) at 3-week intervals starting from 3 weeks after full bloom and three times (at 9, 12, and 15 weeks after full bloom) using 2.5 g L^–1 K sources [potassium chloride (KCl), potassium sulfate (K₂SO₄), and potassium nitrate (KNO₃)] during two growing seasons in 2013 and 2014. Anthocyanin, some physicochemical attributes, and fruit mineral concentrations were measured at harvest. Results showed that spraying with K, CaCl₂, and their combinations significantly increased fruit weight, sugar and anthocyanin concentrations, firmness, and K uptake. A combined foliar application of CaCl₂ and each of the K sources was more effective on the improvement of fruit color, firmness, fruit K and Ca uptake, and K/Ca ratio as compared to the case when either K or Ca was applied alone.     

Foliar Spray with Different Agrochemicals on Fruit Quality and Exportability of ‘Washington’ Navel Orange Fruit (Citrus sinensis L.)

The present study was carried out to improve fruit set, yield, quality, marketability, and exportability of ‘Washington’ Navel orange. Pre-harvest foliar sprays of GA₃, K, and Ca, either alone or combined, were applied at full bloom. The following treatments were applied: {control (T₁), 25 mg/L GA₃ (T₂), 2% K₂SO₄ (T₃), 25 mg/L GA₃ + 2% K₂SO₄ (T₄), 25 mg/L GA₃ + 2% Ca Cl₂ (T₅), 2% K₂SO₄ + 2% Ca Cl₂ (T₆), and 25 mg/L GA₃ + 2% K₂SO₄ + 2% Ca Cl₂ (T₇). All treatments improved fruit set, yield, physical and chemical characteristics, mineral content of leaves and fruit rind, and the percentage of exportable fruit in comparison to the control. Fruit set, fruit detachment force, peel firmness, and the mineral content of leaves and fruit rind were enhanced significantly with the combination of GA₃ + K₂SO₄ + Ca Cl₂ (T₇) in comparison to all other treatments and the control. Results indicated that all foliar combination treatments improved fruit quality and marketability, and increased the percentage of exportable fruit and reduced the defects of non-exportable fruit.     

Postharvest Quality Maintenance of Table Grapes cv. ’Alphonse Lavallée’ by Exogenous Applications of Salicylic Acid,Oxalic Acid and MAP

Treating the grape with elicitors such as jasmonic, oxalic or salicylic acid can reportedly activate several defense mechanisms, including the accelerated expression of defense genes, enhances in the cell wall composition, and the accumulation of antimicrobial compounds such as phytoalexins. Salicylic acid (SA) and oxalic acid (OA) with or without MAP (Modified Atmosphere Packaging) were tested for their effects on extending storage life of grapes cv. ’Alphonse Lavallée’. After treatments (control, MAP, 5?mM OA, 2?mM SA, SA + MAP, OA + MAP) grapes were stored at 1 °C, 90% R.H. up to 60 days. Overall, all the treatments had significant positive effects on postharvest quality of grapes. SA + MAP was the most effective treatment with the lowest weight loss and decay incidence, the greatest rachis chlorophyll content and berry detachment force at the end of 60?d storage. Effects of SA were also very close to those obtained by the combined treatment. SA alone or SA + MAP treatment may be recommended as an environmental friendly, healthy and sustainable method for extending postharvest quality of grapes up to 60?d, without significant adverse effect on produces. Considering the cost and ease of application, SA alone could be preferred as an effective alternative strategy for traditional chemical treatments.     

Grape Growth,Anthocyanin and Phenolic Compounds Content of Early Ripening Cv. Cardinal Table Grape (<Emphasis Type="Italic">V. vinifera</Emphasis> L.) as Affected by Various Doses of Foliar Biostimulant Applications with Gibberellic Acid

Uneven skin coloration of early ripening table grapes is characterized by a lack of coloring berries within a cluster and the failure of some berries to develop color even with an uncertain delay of harvest. Biostimulants and plant growth regulators are known to have considerable roles on skin color development in the course of grape maturation. This study was carried out to compare the effects of different biostimulant doses, including 0, 1000, 2000 and 4000?ppm (BSt 0, BSt 1, BSt 2 and BSt 4, respectively) with or without gibberellic acid (GA₃; 20?ppm) on grape characteristics and chemical composition of early ripening cv. Cardinal grape. Study results of cv. Cardinal grape revealed that alone effects of biostimulant doses had more effective on grape characteristics, total anthocyanin content and total phenolic compounds content from phytochemical characteristics. Although different foliar spray applications had varying effects on physical and chemical parameters; BSt 2 application had especially more superior effects on grape growth and phytochemical characteristics of cv. Cardinal grape.     

Seedless Berry Growth and Bioactive Compounds of cv. ‘Recel Uzümü’ (V. Vinifera L.) as Affected by Application Doses and Times of Pre-Harvest Thidiazuron

The purpose of this research was to appreciate the impact of the synthetic cytokinin, well known as thidiazuron (TDZ) on seedless berry quality of cv. ‘Recel Uzümü’. Three concentration levels including 0, 5 and 10 mg/L were applied on the grapevines during different phenological stages of grapevine such as Time 1: beginning of berry stetting, Time 2: berries pepper corn size and Time 3: berries pea size. While TDZ application times had no impacts on cultivar characteristics, it was determined that the application doses of TDZ had major impacts on yield and quality components of cv. ‘Recel Uzümü’.     

Variation in Total Phenolic Compounds,Anthocyanin and Monoterpene Content of ‘Muscat Hamburg’ Table Grape Variety (V. vinifera L.) as Affected by Cluster Thinning and Early and Late Period Basal Leaf Removal Treatments

Cluster thinning (CT) and basal leaf removal (BLR) are common canopy management practices used in grape growing. In recent years, novel viticultural techniques have been evolved all around the world to decrease costs of yield management, causing improvement in grape quality. The purpose of this study was to evaluate the effects of CT and early and late period BLR treatments on yield and quality components of cv. ‘Muscat Hamburg’. While BLR treatments were performing at pre-bloom (PB, early), berry set (BS), berries with pea size (PS), verasion (V), CT treatment was conducted at verasion period. Compared to Control, while the total phenolic compounds content, total anthocyanin content, free volatile terpenes content and potentially volatile terpenes content were made better by CT treatment and BLR treatments applied from berry set to verasion period gradually raised all these quality components.