Growing vegetables
Zahra Khalili; Fatemeh Nekounam; Taher Barzegar; Zahra Ghahremani; Maliheh Farhangpour
Abstract
Introduction: Tomato (Solanum lycopersicum L.) belongs to the Solanaceae family, which is one of the most widely cultivated and economically important vegetables in the world, which is an excellent source of ascorbic acid and has high antioxidant capacity against oxidative damage caused by free radicals. ...
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Introduction: Tomato (Solanum lycopersicum L.) belongs to the Solanaceae family, which is one of the most widely cultivated and economically important vegetables in the world, which is an excellent source of ascorbic acid and has high antioxidant capacity against oxidative damage caused by free radicals. Ascorbic acid (AsA) is a water-soluble vitamin that plays a key physiological role in scavenging reactive oxygen species (ROS), and enzyme cofactor. Ascorbic acid is antioxidant and antistress agent, and also acts as a signaling molecule in some plant physiological processes and defense mechanisms. Positive roles of such antioxidants in scavenging or chelating the free radicals and activating the natural resistance against different biotic and abiotic stresses have been reported in several fruit trees. Calcium has a vital role for normal growth and development of plants due to an important role in balancing membrane structures, increasing nutrient uptakes and activates of metabolic processes. Calcium plays a vital role in maintains cell wall stability, integrity and determining the fruit quality. To our knowledge, however, little information is available regarding the interaction effect of ascorbic acid and calcium chloride on tomato. Thus, the aim of this study was to investigate the foliar application of ascorbic acid and calcium chloride on quality and antioxidant capacity of tomato fruit.Materials and Methods: To study the effect of foliar application of calcium chloride (Ca) and Ascorbic acid (AsA) on growth, yield and fruit quality of tomato, the field experiment was carried out from June to September 2021 at Research farm of faculty of Agriculture, at the University of Zanjan, Iran. Each treatment was carried out with three replicates. Different concentrations of Ca (0, 0.3, 0.6 and 0.9 %) and AsA (0, 100, 200 and 300 mg L-1) were sprayed three times (0, 15, 30 days after full bloom). Fruits were harvested at two harvests stage (orange and red color) and transferred to the laboratory on the same day. Flesh firmness was determined with penetrometer (model Mc Cormic FT 32), using an 8 mm penetrating tip. Results were expressed in kg cm-2. The pH values of solutions were monitored with pH meter. TSS was measured in the extract obtained from three fruit of each replicate with a digital refractometer Atago PR-101 (Atago Co., Ltd., Tokyo, Japan) at 20◦C. Total ascorbic acid content was expressed as mg per 100 g of juice. Antioxidant activity was measured using the free radical scavenging activity (DPPH) and calculated according to the following formula: RSA%= 100(Ac-As)/Ac. Statistical analyses were performed with SPSS software package v. 20.0 for Windows, and means comparison were separated by Duncan’s multiple range tests at p <0.05.Results and Discussion: The results showed that fruit harvested at red color stage had the higher vitamin C, total soluble solid (TSS), total phenol, flavonoids contents and antioxidant capacity compared to fruit harvested at orange color stage. Foliar application of AsA and Ca had significantly improved tomat fruit quality. The highest value of TSS (4.9 °B), vitamin C (46.1 mg 100ml-1), total phenol and flavonoids contents and antioxidant capacity (36%) was achieved with application of 300 mg L-1 AsA and 0.9% Ca in fruit harvested at red color harvest time. The lowest value of pH and highest TA was observed in red color fruit treated with 300 mg L-1 AsA and all Ca levels. Ca had significant effect on fruit firmness, which the highest fruit firmness was obtained from 0.9% Ca. The fresh tomato is an important source of ascorbic acid for human consumption. AsA significantly increased the amount of vitamin C in the plum and sweet pepper fruits. Increasing vitamin C content in fruits after treatment with Ca could be related to inhibiting action of calcium on the activities of ascorbic acid oxidase that use ascorbate as a substrate. The results indicated that treatment of Ca produced fruits with higher firmness compared to control and other treatments. Firmness and resistance to softening can be increased by the addition of Ca, due to interaction of calcium with pectate acid in the cell wall to form calcium pectate and retarding polygalacturonase activity. Differences in the percentage of TSS content at the time of harvest indicated the AsA and Ca effects on carbohydrate accumulation in fruits, which had different potential on respiration rates and consequently storability of plants. The antioxidant activity has positive correlation with total phenolic content, flavonoids and content of ascorbic acid. Conclusion: The results of our research indicated that per-harvest foliar application of AsA and Ca improved fruit quality attributes including vitamin C, fruit firmness, TSS and antioxidant activity. These results suggest that AsA and Ca treatments, especially AsA 300 mg L-1 and Ca 0.9%, may be proposed to improve fruit quality.
Pomology
Fatemeh Nekounam; A. Salehi
Abstract
Introduction Apple (Malus damestica L.) is one of the most popular temperate fruits in the world as well as Iran. One of the challenges in managing apple orchards is excessive fruit formation or excessive fruit drop especially in the pre-harvest stage, which affects the performance and marketable product. ...
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Introduction Apple (Malus damestica L.) is one of the most popular temperate fruits in the world as well as Iran. One of the challenges in managing apple orchards is excessive fruit formation or excessive fruit drop especially in the pre-harvest stage, which affects the performance and marketable product. Therefore, the control fruit set is required to help regular fruit production. Currently, the application of synthetic auxins as plant growth regulators are successfully practiced and mainly used in various countries, including all aspects of modern apple production to control and manipulate vegetative growth and regulation of flowering, reduce immature fruit drop, fruit maturity, firmness, and manage apple harvest. Among the auxin-type growth regulators, NAA is a synthetic auxin analogue that may down-regulate abscission-related genes and reduce the sensitivity of the abscission zone to ethylene. It has long been used to reduce or totally prevent pre-harvest fruit drops, to preserve fruit flesh firmness, and to prevent starch degradation in apples. Therefore, this experiment was conducted to evaluate the effects of NAA foliar application at different days after full bloom on controlling fruit drop and improving physical and biochemical attributes of ‘Red Delicious’ apple fruits. Findings described here may help to understand the effects this PGR on apple quality and also help on the development of strategies to reduce post-harvest losses of apple fruits.
Materials and Methods In order to study the effect of NAA on controlling fruit drop, fruit yield and quality, a factorial experiment based on randomized complete blocks design with three replications was conducted under Zanjan climatic conditions during 2023. Ten year-old ‘Red Delicious’ Standard apple trees grafted on M.9 rootstock were used as plant material. Treatments consisted of different concentration of NAA (15, 30, 50 and 75 mg L-1) sprayed at different days after full bloom (10, 25 and 40 DAFB). The date of full bloom was 04/22/2023. The fruit growth pattern was based on fruit weight and diameter during DAFB. According to fruit growth pattern, fruit were harvested at physiological maturity stage. Fruit number per replicate, fruit weight, diameter and shape index, fruit firmness, total soluble solids content and taste index were measured. Also, fruit drop percentage, fruit yield as well as fruit efficiency was estimated.
Results and discussion Advanced knowledge of apple fruit development from fruitlet to maturity is crucial for optimal prediction of year-to-year yields and fruit quality. Apple fruit growth has been defined as sigmoidal increase in fruit diameter or fresh weight. Studying two fruit growth patterns based on fruit weight and diameter data showed that fruit weight is a more appropriate indicator for drawing fruit growth patterns, and according to that, the fruits were harvested at the physiological maturity stage. Foliar spray of NAA during different DAFB showed different significant effects on fruit drop and yield efficiency. The highest rate of fruit drop (95.7 % and 85.9 %) was observed with foliar application of NAA at 10 and 25 DAFB, respectively, but its application at 40 DAFB reduced fruit drop by 46.9% compared to the control, and correspondingly the fruit yield increased by 22% compared to the control treatment. The lowest number and weight of fruits per unit shoot cross sectional area was observed in trees treated with different concentrations of NAA at 10 DAFB. The maximum fruit length (72.3 mm), diameter (75.8 mm), weight (180 g) and fruit volume (240 cm3) were obtained with application of 75 mg L-1 NAA at 10 DAFB. The foliar spray of NAA at 10 DAFB significantly increased the fruit density, flash firmness and TSS. But their use in 25 and 40 DAFB had no significant effect on fruit density and flash firmness, and significantly decreased fruit TSS by 23.9% compared to the control trees. Unlike the TSS, the value of fruit titratable acidity showed a significant increase in all three times of naphthalene acetic acid treatment compared to the control, and as a result, the fruit taste index decreased.
Conclusions The present study concluded that the positive effects of NAA in controlling fruit drop and improving the yield and fruit quality will be different depending on the time of application and the weather conditions of the region under study. According to the results, the application of NAA at 40 DAFB reduced fruit drop and increased fruit yield efficiency.
Pomology
afsaneh Salehi; Fatemeh Nekounam; Farhang Razavi
Abstract
Introduction
Apple (Malus domestica) belongs to the Rosacea family and is one of the most important fruit trees in temperate regions. Apple fruit is a rich source of vitamins, sugars, organic acids, minerals, fibers, and bioactive compounds and is widely cultivated due to its pleasant taste, aroma, and ...
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Introduction
Apple (Malus domestica) belongs to the Rosacea family and is one of the most important fruit trees in temperate regions. Apple fruit is a rich source of vitamins, sugars, organic acids, minerals, fibers, and bioactive compounds and is widely cultivated due to its pleasant taste, aroma, and texture. Due to the rising need for food and fiber per unit of land area, chemical fertilizers are becoming increasingly popular to increase yields from small plots of land. Chemical fertilizers pose major health risks and harm the environment when they are used in excess. Because of this, research in this area is heavily focused on finding and evaluating the efficiency of new products. One such approach is using biostimulants that can enhance the effectiveness of conventional mineral fertilizers. Plant biostimulants contain some nutrients (marine plant extracts, humic acids, amino acids and other natural products such as saponins and compost teas) that stimulate plant growth, even when administered in small amounts. Foliar application of seaweed extracts at 0.2% recorded maximum no. of fruits/tree, fruit weight, and yield/tree in valencia orange.
Materials and methods
In order to investigate the effect of biofertilizers on growth, yield and leaf nutrient contents of apple under climatic conditions of Zanjan, the experiment was carried out in a completely randomized block design with three replicates in 2023. Different concentration of seaweed (Alg; 0.075 and 0.15%), amino acid (GF Amino; 0.1 and 0.2%), humic acid (HA; 0.3%), commercial fertilizer Homarang, (Homa fert; 0.5%), combined chemical fertilizer (nitrogen, zinc and boron (Combinate fert; 1% urea, 0.3% zinc chelate and 0.1% boric acid)) and distilled water as a control were sprayed on the trees at 40 days after full bloom stage until runoff using a mechanical mist sprayer, and repeated three times with an 30 days interval until the physiological ripening of fruits. The experiment was carried out on 10-year-old Red Delicious apple trees grafted on M9 rootstocks. Shoot length, chlorophyll index, fruit drop percentage, yield efficiency, leaf area, leaf dry matter, leaf macro and micro nutrient were measured. The analysis of variance (ANOVA) and least significant difference test (P≤ 0.05) used to compare means within each sampling date. The Statistical analysis and standard error calculation were carried out using SAS software (V. 9.3).
Results and Discussion
The results showed that the foliar application of bio and chemical fertilizers significantly increased growth and fruit yield. So that, the highest increase in shoot length (39%) and leaf area (74.30%) compared to the control was obtained with application of seaweed 0.075%. Also, seaweed 0.15%, amino acid 0.2%, humic acid and amino acid 0.1% caused a significant increase in leaf area (42.02, 35.57, 22.27 and 16.20%, respectively) compared to the control. Foliar spray of seaweed, amino acid and chemical fertilizer increased chlorophyll index. The highest increase in chlorophyll index (50%) compared to the control was obtained with application of combined chemical fertilizer at 130 days after full bloom. These results are in agreement with the outcomes of other experiments conducted with seaweed on apple and on other crops such as grapevine. Therefore, this represents a further evidence of a possible role of seaweed extracts in the reduction of chlorophyll degradation and in delaying leaf senescence. The highest amount of nitrogen (1.66%), potassium (1.03%) zinc (150 mg g-1DW) and boron (82.5 mg g-1DW) and the lowest amount of phosphorus (0.44%) were obtained with application of combined chemical fertilizer. The highest value of iron was observed in leaf of trees treated with seaweed 0.15%, humic acid and commercial biofertilizer. Based on the results, it was observed that the amino acid, seaweed and combined chemical fertilizer have the greatest effect in reducing fruit drop (36.97, 33.37, 29.07%, respectively) compared to control) and increasing yield efficiency (respectively 2.75, 2.73 and 2.8 compared to control with 0.22 fruits No. cm-2 SCSA). These results partially are in agreement with another research performed on apple, where the use of a similar seaweed extract (Ascophyllum nodosum) was found able to induce a higher final yield. The hormonal components found in the extracts, particularly cytokinins, are assumed to be responsible for the increased yield in plants treated with seaweed. Previous studies mentioned that the application of biological fertilizers alone or in combination with the mineral fertilizers had positive influences on the leaf plate area, mean fruit weight and fruit chemical composition.
Conclusions
According to the results of this research, the use of biofertilizers, especially seaweed (0.15%) and amino acid (0.1%), are suitable and nature-friendly substitutes for chemical fertilizers and can play a significant role in increasing growth indices and yield of apples.
Medicinal Plants
Seyyed Amir Hossein Mousavi; F. Nekounam; Taher Barzegar; Zahra Ghahremani; Jafar Nikbakht
Abstract
Introduction
Physalis peruviana L. is a short perennial shrub that is a member of the Solanaceae family. These fruits have many benefits for human health because of their nutritional and bioactive compounds (vitamins (A, B, C and K), essential fats and etc.) and reduced the risk of diseases such as ...
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Introduction
Physalis peruviana L. is a short perennial shrub that is a member of the Solanaceae family. These fruits have many benefits for human health because of their nutritional and bioactive compounds (vitamins (A, B, C and K), essential fats and etc.) and reduced the risk of diseases such as cancer, malaria, asthma, hepatitis, dermatitis and rheumatism. Therefore, it has received special attention for cultivation all over the world. Increasing crop production and mitigating abiotic stresses are major challenges under extreme climatic environments and intense farming activities. Crop management strategies such as deficit irrigation can decrease soil evaporation, runoff, and plant transpiration, and increase water use efficiency (WUE) and water conservation. In addition to these practices, organic input, which includes the application of organic materials such as compost and humic substances, is an additional strategy that increases soil water retention and can potentially improve plant WUE. Water is crucial for agriculture and needs to be used effectively due to climate change and drought in Iran. For this reason, to adapt to water deficit scenarios, deficit irrigation applications are increasing in importance. Water availability is expected to be a growth limiting factor that would affect fruit yield in Physalis peruviana due to reduced flower set and elevated floral abscission rate.
Materials and Methods
In order to investigate the effect of humic acid on physiological characteristics, yield and fruit quality of Physalis peruviana under deficit irrigation conditions, a split plot experiment based on randomized complete block design with three replications was conducted during 2021. Treatments consisted arrangement of three levels of irrigation (starting irrigation at 100, 80 and 60% ETc (crop evapotranspiration)) and three levels of humic acid (0, 1.5 and 3 kg ha-1). The seeds of Physalis peruviana were sown in seedling trays contain peat moss. The seedlings were grown under normal conditions (25±2 °C/day and 20±2 °C at night with 60-65% RH). Plant height, total chlorophyll, fruit yield per plant, total soluble solid content, titratable acidity, vitamin C content and water use efficiency were measured. Statistical analyses were performed with SAS V9.3, and means comparison were separated by Duncan’s multiple range tests at p < 0.05.
Results and Discussion
The results showed that deficit irrigation significantly reduced growth, fruit yield, vitamin C and increased water use efficiency (WUE) and Total soluble solid content of Physalis peruviana. The soil application of humic acid significantly increased total chlorophyll, fruit quality and yield, and decreased leaf electrolyte leakage under normal and deficit irrigation, thus, the deficit irrigation 60 ETc% decreased the plant height by 18.6% and the fruit yield by 22.2% compared to irrigation 100 ETc%. The maximum plant length (200.3 cm), total chlorophyll content (2.42 mg g-1FW) and fruit yield (4793.3 kg ha-1) were observed in plants treated with 3 kg ha-1 humic acid under 100% ETc irrigation. The highest value of total soluble solid (12.6 B°), antioxidant activity (90.06 %) and WUE (1.23 kg m-3) were obtained with 3 kg ha-1 soil application of humic acid under deficit irrigation 60% ETc. The application of 3 kg ha-1 humic acid under 100 and 80 %ETc irrigation increased the fruit yield by 25% and 4%, respectively, compared to the control plants (non treated with humic acid) under irrigation100 ETc% and under deficit irrigation 60 ETc%, with decreasing 11% fruit yield, water consumption was saved by 40%. Soil and crop management practices that alter plant water and nutrient availability could affect the processes of crop evapotranspiration and WUE, which can influence the yield and fruit quality by changing the internal nutrient and water balance. Incorporating organic matter within a crop growth system either as leaf spray or soil mix is a complementary strategy to improve crop growth and WUE. By inducing antioxidant enzyme activities, HS could assist plants in stomata functioning, thereby closing stomata more efficiently under drought stress, which results in plant water conservation. The reason of the difference between WUE values probably appeared due to the differences on Physalis peruviana yield. WUE showed an upward trend with an increasing in irrigation.
Conclusion
Study results suggest that soil application of humic acid with increasing vitamin C, TSS and TA, improved fruit quality. According to the results, application of 3 kg ha-1 humic acid is suggested to improve fruit yield and quality of Physalis peruviana under normal and deficit irrigation conditions.
Growing vegetables
Parastoo Molaei; Fatemeh Nekounam
Abstract
IntroductionLettuce (Lactuca sativa L.) from the Asteraceae family is one of the most important vegetables due to its rapid growth and commercial value. Currently, the market share of organic vegetables is constantly increasing due to customer demand for safer and healthier food. Excessive use of pesticides ...
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IntroductionLettuce (Lactuca sativa L.) from the Asteraceae family is one of the most important vegetables due to its rapid growth and commercial value. Currently, the market share of organic vegetables is constantly increasing due to customer demand for safer and healthier food. Excessive use of pesticides and chemical fertilizers threatens the environment and leads to the production of unsafe food products. Therefore, it is important to find alternatives instead of using pesticides chemical methods to manage powdery mildew. Generally, biotic and abiotic stresses are among the factors that have a destructive effect on growth and development, performance, and production of plant biomass. Fungicides can be the most effective method of controlling the powdery mildew disease, but this pathogen can develop resistance to fungicides. Rhizosphere bacteria are among the living agents that, by producing some allelochemicals, cause the dissolution of soil nutrients, increase the availability of nutrients, and induce plant resistance to biotic and abiotic stresses. In addition, they enhance host plant growth through an indirect mechanism, including the inhibition of disease-causing pathogens by releasing some allelochemical substances. The biological control of powdery mildew disease with the use of rhizospheric bacteria in lettuce and zucchini has been reported. Material and MethodsTo evaluate the biological control of powdery mildew fungus with plant growth promoting rhizobacteria (PGPR) and effects on yield and quality of New Red Fire greenhouse lettuce, an experiment was carried out in a completely randomized design with three replications in the Research greenhouse of University of Zanjan during 2020. Experiment treatments consisted of five levels of PGPR (Pseudomonas vancouverensis- VPM, Pseudomonas Koreensis- KPM, Pantoea agglomerans- PAPM, Pseudomonas putida- PPM, and one level of combined bacteria (Pantoea agglomerans+ Pseudomonas Koreensis+ Pseudomonas putida+ Pseudomonas vancouverensis- MBPM, one level of chemical fertilizer 100% N, P and, K according to soil test results- NPK, and two control treatment without powdery mildew condition (C) and under powdery mildew conditions (CPM).The “New Red Fire” lettuce seeds were surface sterilized with 0.5% (v/v) sodium hypochlorite for 10 min and germinated at 20ºC. After germination, seedlings with similar size were transplanted into pots. Plants were grown under greenhouse condition with 60/70 % (day/night) relative humidity, 15/18 °C (day/night) temperature. Inoculation of pathogenic fungi was done 40 days after seed germination. Plants were harvested after 75 days. The chlorosis and necrosis spots number on each plant, plant fresh weight, plant dry weight, leaf number, total chlorophyll, total phenol and flavonoids contents, antioxidant activity, anthocyanin content, and catalase and peroxidase enzyme activity were measured. ResultsThe results showed that the application of potassium and phosphorus solubilizing bacteria and NPK fertilizer significantly increased plant growth compared to control plants under the stress of powdery mildew fungus. The highest plant fresh weight, percentage of plant dry weight, and leaf number were obtained with the application of combined potassium and phosphorus solubilizing bacteria treatment and 100% N fertilizer under the biostress. The maximum total chlorophyll was obtained with the application of Pseudomonas koreensis and Pantoea agglomerans bacteria. 100% reduction of necrosis spots was obtained by using the Pantoea agglomerans bacteria. The maximum of chlorosis spots (increase of 55.8%) and necrosis spots (an increase of 88.8%), total phenol (an increase of 52%), total flavonoids (an increase of 39.3%), catalase (an increase of 28.4%) and peroxidase enzymes activity (49.1%) were obtained with application of NPK fertilizer. No significant effect on antioxidant activity was observed with the application of chemical fertilizer and rhizosphere bacteria under the Biostress. The maximum anthocyanin contents were obtained with the application of Pseudomonas koreensis. ConclusionAccording to the results, the application of NPK chemical fertilizer and seed pretreatment of lettuce with PGPR increased the value of antioxidant compounds including total phenol, flavonoid, and anthocyanin contents and catalase and peroxidase enzymes activity under powdery mildew conditions. Inoculation of lettuce seeds with PGPR, in addition to improve plant growth under biological stress conditions, increased anthocyanin contents and induced the resistance of lettuce plants to powdery mildew. Seed pretreatment with PGPR reduced chlorosis and necrosis spots in leaves. Therefore, pretreatment of lettuce seeds with PGPR instead of chemical compounds (fertilizers, pesticides and plant growth regulators) is recommended to improve the yield and quality of lettuce under powdery mildew conditions.
Growing vegetables
Parastoo Molaei; Taher Barzegar; Mohammad BabaAkbari Sari; Fatemeh Nekounam; Zahra Ghahremani
Abstract
Introduction
Excessive use of chemical fertilizers threatens the environment and leads to production of unsafe food products. Currently, the market share of organic vegetables is constantly increasing due to customer demand for safer and healthier food. Therefore, it is necessary to find alternatives ...
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Introduction
Excessive use of chemical fertilizers threatens the environment and leads to production of unsafe food products. Currently, the market share of organic vegetables is constantly increasing due to customer demand for safer and healthier food. Therefore, it is necessary to find alternatives instead of using chemical fertilizers in plant production.
Lettuce (Lactuca sativa L.), belongs to Asteraceae family is considered as one of the most popular salad vegetables as a cool season crop. It is also one of the most important vegetables due to its rapid growth and commercial value. Plant growth promoting bacteria promote plant growth directly by facilitating nutrient uptake through fixing nitrogen, solubiliszation of phosphorus, production of hormones and iron uptake. Arbuscular mycorrhizal fungi establish symbioses with plant roots which help to improve nutrient uptake by the host plant and alter its physiology to withstand external abiotic factors and pathogens. Arbuscular mycorrhizal fungi interactions with bacteria have been reported to enhance plant growth through phosphate solubilization, nitrogen fixation, increased AMF spore germination and colonization of plant roots. The potential of co-inoculation of these two organisms in promoting the growth of horticultural crops like tomato, strawberry, lettuce and spinach have also been reported.
Materials and Methods
In order to compare the effect of growth-promoting bacteria, mycorrhiza fungi and chemical fertilizers on morphological and physiological properties of lettuce (Lactuca sativa cv. New Red Fire), the experiment was carried out in a completely randomized design with three replications. Experiment treatments consisted of 14 treatments including three levels of potassium solubilizing bacteria (Pseudomonas vancouverensis, Pseudomonas koreensis, Pseudomonas vancouverensis + Pseudomonas koreensis) + 100% N and P, three levels of phosphorus solubilizing bacteria (Pantoea agglomerans, Pseudomonas putida and Pseudomonas putida + Pantoea agglomerans) + 100% N and K, and one level of potassium and phosphorus solubilizing combined bacteria (Pantoea agglomerans+ Pseudomonas koreensis+ Pseudomonas putida+ Pseudomonas vancouverensis) + 100% N, mycorrhiza fungi combination of three Glomus species (G. mosseae, G. etunicatum and G. intraradices) + 100% N and K and five chemical fertilizer levels (N100P100K100, N100P100K0, N100P0K100, N100P25K100 and N100P100K25) according to soil test results, and control treatment without bio-mineral fertilizers.
The “New Red Fire” lettuce seeds were surface sterilized with 0.5% (v/v) sodium hypochlorite for 10 min, and germinated at 20ºC. After germination, seedlings of similar size were transplanted singly into pots containing agricultural soil. Plants were grown under greenhouse condition of 60/70% (day/night) relative humidity, 15/18 °C (day/night) temperature. After a growth period of 75 days, plants were removed from the pots. The root system was separated from the shoot and washed to remove adhered soil. Root and shoot fresh weight, chlorophyll, vitamin C, anthocyanin, TA, TSS and nitrate contents were measured.
Results
The results showed that application of potassium and phosphorus solubilizing bacteria and mycorrhiza fungi significantly increased plant growth compared to control plant. The highest fresh shoot weight (increase of 42.3%) and crown diameter (increase of 14.4%) was obtained with application of combined potassium and phosphorus solubilizing bacteria treatment + 100% N fertilizer compared to control plants. Application of Pseudomonas koreensis + 100% N and P resulted in the maximum content of anthocyanin (increase of 62.2%) and total soluble solids (increase of 82.5%) compared to control plants. Ascorbic acid, a well-known antioxidant and organic compound, is an essential vitamin can be obtained from fruits and vegetables. The highest vitamin C content (32.3 mg 100 mL-1) was observed at plant treated with N100P100K100 fertilizer. The maximum titratable acidity content was obtained with application of Pseudomonas vancouverensis + 100% N and P, and combined potassium and phosphorus solubilizing bacteria treatment +100% N fertilizer. The nitrate content is an important quality index of leafy vegetables; low nitrate content is associated with enhanced quality. Application of chemical fertilizers significantly increased nitrate accumulation compared to biofertilizers and control plants, so that the minimum nitrate accumulation content was observed in control plant and combined potassium and phosphorus solubilizing bacteria treatment + 100% N fertilizer (21.14 µg g-1FW), respectively.
Conclusion
With continuous development of economy and society, people pay an increasing attention to the quality of fruits and vegetables. Improving the crop yield means that attention must also be given to improving vegetables quality, resulting in chemical fertilizer nutrition problem. To conclude, our study suggested that after the control treatment (without using any chemical fertilizers), which had the lowest accumulation of nitrate, application of growth-promoting bacteria and mycorrhizal fungi in combination with nitrogen fertilizer caused lower nitrate accumulation than chemical fertilizers treatments. So, the use of combined and pure bacteria treatments and mycorrhizal fungus treatment can be used to improve the growth, quality and antioxidant properties and increase the concentration of nutrients and also reducing nitrate accumulation in lettuce.
Growing vegetables
Moslem Ghoreyshi; Fatemeh Nekounam; Taher Barzegar; Jafar Nikbakht
Abstract
Introduction
Water stress is the most prominent abiotic stress limiting agricultural crop growth and productivity. Deficit irrigation stress as a consequence of the progressive decrease in water availability has been a hot topic regarding food security during the last two decades. Growth and development ...
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Introduction
Water stress is the most prominent abiotic stress limiting agricultural crop growth and productivity. Deficit irrigation stress as a consequence of the progressive decrease in water availability has been a hot topic regarding food security during the last two decades. Growth and development of plants is influenced by reduction in turgor that results in decreased nutrient acquisition from dry soil. When water supply is limited, plant growth and yield is reduced and plant structure is modified by decreasing in leaf size. The effect of deficit irrigation on fruit yield and quality has been reported by numerous researchers with different results. In melon, deficit irrigation reduced marketable fruit number and yield, average fruit weight, fruit diameter and did not affect rind thickness and seed cavity, but increased total soluble solids content. Although the effects of water stress have been studied on growth and yield of different crops during the last years, recent information on the response of African horned cucumber yield and quality to deficit irrigation remains limited, particularly about the results of restricted water distributions in arid and sub-arid environments. The main goal of this study was to evaluate the effect of controlled deficit irrigation on growth, physiological parameters and yield and fruit quality of African horned cucumber.
Material and Methods
Field experiment was performed based on a completely randomized block design with three irrigation regimes (60, 80 and 100 %ETc), whit three replications at Research Farm of University of Zanjan during the 2019. The African horned cucumber seeds were sown on 1th July 2020 at recommended spacing of 50 cm in row with 120 cm between rows. The irrigation system consisted of one drip line every crop row. The three irrigation levels were calculated based on actual evapotranspiration (ETc): (1) control, irrigated 100% crop water requirement, (2) deficit irrigation 80% ETc and (3) deficit irrigation 60% ETc. The Water requirement of the plant for control treatment was estimated using long-term average daily data of meteorological parameters recorded at Zanjan Meteorological Station and following relation. Before starting the differential irrigation at five-leaf stage, all treatments were supplied with similar amount of water to maximize stands and uniform crop establishment. During plant growth, the relative water content, proline content, electrolyte leakage, chlorophyll and carotenoids, P and K contents were measured. After fruit harvest, vine length of each plant, leaf dry weight and stem diameter were measured. The fruits were harvested when color changed from green to yellow. Fruit weight, fruit number per plant and fruit yield per plant was measured. Immediately after harvest, fruit firmness, total soluble solid, total phenols content, antioxidant capacity and vitamin C were determined.
Results and Discussion
As the results showed water deficit stress significantly reduced plant length, chlorophyll content, and increased carotenoids content. Based on the findings, deficit irrigation caused a significant reduction in leaf relative water content. According to the results, phosphorus and potassium contents in African horned cucumber leaves decreased with deficit irrigation treatments. The highest P and K contents were found under irrigation 100 %ETc treatment. Drought stress and associated reduction in soil moisture can decrease plant nutrient uptake by reducing nutrient supply through mineralization. The proline content increased with the deficit irrigation treatments; in particular with sever deficit irrigation (60 %ETc). Mean comparisons of data showed that deficit irrigation led to a significant increase in electrolyte leakage compared to control.
Water deficit stress caused significant reductions in yield. The highest fruit number per plant and yield were obtained under irrigation 100% ETc. The average fruit weigh significantly increased in response to increase water deficit stress. Deficit irrigation treatments significantly decreased vitamin C and fruit firmness. Significant differences among irrigation treatments were observed for total phenols and total soluble solid contents. The phenols and total soluble solid contents increased with the decrease of irrigation water applied. Antioxidant capacity was affected significantly by the irrigation treatments, and water deficit stress increased antioxidant capacity, which no significant difference was observed between irrigation 100 and 80 %ETc.
Conclusion
Water deficit has been shown to adversely affect plant growth, fruit yield, and leaf water status of African horned cucumber, but led to increase the TSS and antioxidant capacity. According to the results, fruit yield reduced 13.9 % under irrigation 80% ETc compared to irrigation 100% ETc, However, water consumption was saved by 20% and improved fruit weight and fruit quality with increasing soluble solids and antioxidant capacity.
