Growing vegetables
Reza Najafi; Taher Barzegar
Abstract
Introduction
Cauliflower is one of the world’s most important vegetable crops. The edible head of the cauliflower is called curd, which is composed of many florets formed of aborted floral meristems. Curd has various components with high nutritional value including glucosinolates, vitamin ...
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Introduction
Cauliflower is one of the world’s most important vegetable crops. The edible head of the cauliflower is called curd, which is composed of many florets formed of aborted floral meristems. Curd has various components with high nutritional value including glucosinolates, vitamin A and C, phenolic compounds, and carotenoids, which exert beneficial effects on our health. Calcium is an essential macronutrient that plays a vital role in maintains cell wall stability, integrity and determining the fruit quality. Several researches have explored the effects of calcium salts on plant growth and quality in many horticulture crops. Various studies indicate that Ca2+ reduced peroxidation of lipid, increased activity of antioxidant enzyme and improve osmotic adjustment of cell membranes. Plant roots absorb calcium from the soil solution in the form of Ca2+ ions. The mobility of calcium in plant is low, and the root uptake from fertilized soils is poorly effective in increasing the calcium content in leaves and fruits. Deficiency of Ca will appear in younger leaves and in fruits, due to its low rate of transpiration. Thence, it is necessary to have a constant supply of calcium to continue growing. The direct application of liquid source of calcium on leaves and fruits may offer an alternative solution. The efficiency of foliar application with Ca depends on the source of Ca and applied dosage. To our knowledge, however, little information is available regarding the effect of different calcium sources on cauliflower. Thus, the aim of this study was to investigate the effect of foliar spray of calcium sources on quality and antioxidant properties of cauliflower cv. Romansco.
Material and Methods
In order to evaluate the effect of different sources of calcium on antioxidant properties and quality of cauliflower cv. Romansco, the field experiment was carried out as a randomized complete block design with three replication during 2018 at Research farm of faculty of Agriculture, at the University of Zanjan, Iran. Cauliflower plants (cv. Romanesco) were cultivated by applying conventional farming practice for growing in open air conditions. Different calcium sources including calcium nitrate (Ca(NO3)2, 0.5, 1 and 1.5 %), calcium chloride (CaCl2, 0.3, 0.6 and 0.9 %) and calcium lactate ( C6H10CaO6, 0.5, 1 and 1.5 g L-1) were sprayed in vegetative stage and 10 days after curd formation for 2 times onto the leaves and curd until runoff using a mechanical mist sprayer. Distilled water was used as a control. Potassium, phosphorus, total soluble content, titratable acidity, ascorbic acid content, total phenols and flavonoids, free radical scavenging activity (DPPH) were measured. Statistical analyses were performed with SPSS software package v. for Windows, and means comparison were separated by Duncan’s multiple range tests at p < 0.05.
Results and Discussion
The results showed that foliar spray of different Ca sources significantly increased K content and decreased P content. The highest amount of K (5.6 µg mg-1DW) was achieved in CaCl 0.9% treatment. The highest value of flavonoids (0.86 and 0.85 %) was found in plants treated with CaL 1.5 g L-1 and CaCl 0.9%, respectively. In this study, also it was found that foliar spray of CaN 1.5% and CaCl 0.9% increased respectively 49.3 and 40.4% vitamin C content compared to control plants. Ca application with increasing phenolic compound and vitamin C contents, improved antioxidant capacity and the maximum antioxidant capacity (26.19%) was found in CaL 1.5 g L-1 and CaN 1.5% treatments. Application of Ca sources increased TA and TSS content. The highest TSS content (12.5 and 13.3 ºB) was achievd in CaCl 0.9% and CaL 1.5 g L-1 and the maximum TA (28.8%) was found in plant treated with CaCl 0.9%. In this regard, foliar application of high level of calcium sources was more efficient than of lower levels on cauliflower quality. Therefore, the leaf application of calcium can be effective in improving the quality of vegetables, especially cauliflower.
Conclusion
Study results suggest that spraying different Ca source improved quality and antioxidant properties of cauliflower cv. Romanesco, so that with the application of Ca salts increase K, vitamin C, phenol and flavonoids contents. Among the calcium treatments used, higher levels of all three salts of CaCl, CaN and CaL had the most influence, so these calcium treatments are recommended to improve the quality and antioxidant properties of Romanesco cultivar.
Reza Najafi; Taher Barzegar; Farhang Razavi; Zahra Ghahremani
Abstract
Introduction: Eggplant (Solanum melongena L.) is an important non-climacteric fruit grown in tropical and subtropical regions. The total production in Iran and world for eggplants in 2018 were estimated 54077210 and 666838 tons, respectively, and Iran ranked fifth in the production of this product. The ...
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Introduction: Eggplant (Solanum melongena L.) is an important non-climacteric fruit grown in tropical and subtropical regions. The total production in Iran and world for eggplants in 2018 were estimated 54077210 and 666838 tons, respectively, and Iran ranked fifth in the production of this product. The health-promoting attributes of eggplant are derived from the phytochemicals with good source of antioxidants (anthocyanin and phenolic acids), dietary fiber and vitamins. Fruit deterioration during long term storage is associated with appearance quality reduction, calyx discoloration, softening and pulp browning caused by the oxidation of phenolic compounds. Hydrogen Sulfide (H2S) is a flammable and colorless gas, that similar to carbon monoxide and nitric oxide, is known as third leading signaling molecule. It has been reported that H2S play an imperative role in the postharvest physiology and chilling injury of various fruits and vegetables. In recent years, exogenous phenylalanine (PA) application has been employed as a beneficial procedure for enhancing quality in fruits and vegetables by promoting higher phenols and flavonoids accumulation arising from higher PAL enzyme activity and proline accumulation exhibiting higher ROS scavenging capacity. Thus, the aim of this study was to investigate the postharvest application of H2S and PA on quality and postharvest storage of eggplant fruit during storage at 7 °C for 21 days. Material and Methods: Eggplant fruits (Solanum melongena cv. Hadrian) were harvested at commercially maturity stage in Jun 2019 from a greenhouse in Hashtgerd city, Iran. Fruit selected for uniform size, shape, and color, and immediately transported to the laboratory. They were divided into seven parts for the following treatments: control (0), hydrogen Sulfide (H2S) at 0.1, 0.2 or 0.3 mM and phenylalanine (PA) at 2.5, 5 or 7.5 mM. Each treatment was done in three replicates, consists of 24 fruits from each replicate, and then randomly divided into four groups include six fruits. One group was analyzed 24 hrs. after harvesting and another groups stored at 7 ± 1 °C and 85% RH for 21 days. At 7-day intervals, one group was taken at random and transferred for one day at 20 °C (shelf-life), and subjected to physicochemical analysis. For H2S fumigation, fruit was placed at the bottom of a sealed 15 L container with different aqueous sodium hydrosulfide (NaHS) solution concentrations for 10 min, and for PA treatments, the fruits were immersed in 10 L of fresh phenylalanine solution for 10 min and in distilled water as a control. The fruits were allowed to completely dry at room temperature before storage. Results and Discussion: The results showed that fruits treated by PA and H2S exhibited higher fruit firmness, chlorophyll, anthocyanin, total soluble solids (TSS), vitamin C, pH and titratable acidity (TA) accompanied by lower weight loss and chilling indices during storage at 7 ºC for 21 days. In control eggplant fruits, fruit firmness (24.2%), chlorophyll (45.8%), vitamin C (34.1 %), anthocyanin content (66.2 %) and TA (44.8) decreased, and weight loss (7.5 %), TSS (8.2%) and chilling indices (4.5 %) increased during 21 storage time. The maximum fruit firmness (1.37 and 1.34 kg cm-2), anthocyanin content (5.02 and 4.2 mg L-1) and TA (18.67 and 1.37 %), and the lowest weight loss (3.67 and 3.7 %) and chilling index (1.6 and 1.3 %) was found in fruits treated with H2S at 3 mM and PA at 7.5 mM during storage at 7 °C for 21 days, respectively. It has been reported that texture correlates with firmness and higher firmness is a characteristic indicator of good texture during postharvest storage of fresh products. Soluble solid contents, titratable acidity (TA) and sugars have been known as important attributes contributing in overall sensory quality of fruits and vegetables. Development of the chilling injury disorder significantly reduces quality of fruits and vegetables due to diminished consumer’s acceptance. So, start of chilling injury symptoms eventually becomes economically critical postharvest constraint that defines the storage life potential of the products. Decline chilling injury in responses to H2S and PA treatments may resulted from higher ROS scavenging enzymes SOD, CAT, APX and POD activity and proline, phenols and flavonoids accumulation giving rise to conferring chilling tolerance. Conclusion: According to results, PA at 7.5 mM and H2S at 3 mM had the highest positive effect on maintain firmness and fruit quality and reducing weight loss and chilling, therefor postharvest treatment of PA and H2S can be proposed to improve fruit quality and postharvest life during storage period.
