Evaluation of growth, yield and physiological responses of some watermelon accessions to water deficit stress

In order to evaluate the tolerance of watermelon (Citrullus lanatus L.) accessions to water deficit stress, an experiment was carried out in a split plot based on randomized complete block design with three replicates in research filed of university of Zanjan during 2016. Treatments consisted of three irrigation levels 100%, 70% and 50% Crop Evapotranspiration (ETc) and watermelon accessions (Ananasi, Sharif Abadi, Mahbubi and Charleston Gray commercial cultivar). The results showed that water deficit stress significantly decreased leaf area, plant length, fruit yield, stomata conductance and relative water content (RWC), and increased total soluble solids, peroxidase activity and electrolyte leakage. Amount accessions, the highest leaf area, plant length and yield (84.6 ton/ha) was obtained in Mahbubi accession. The lowest electrolyte leakage and the highest RWC was showed in Ananasi accession, and the highest peroxidase activity in Charleston Gray. Water deficit stress decreased fruit number per plant and fruit weight, although water deficit had no effects on fruit number in Mahbubi accession. The increase in water deficit stress, decreased water use efficiency in “Ananasi”, “Sharif Abadi” and “Charleston Gray”, but the highest WUE (54.85 kg.m -3 ) was obtained in “Mahbubi” under water deficit 50% ETc. water deficit had no significant effects on fruit pH. According to the results, “Mahbubi” with 46.9% reduction in fruit yield under water deficit 50% ETc had the lowest reduction in fruit yield compared to other accessions that was higher tolerance accession to water deficit stress

Yield, fruit quality and physiological responses of melon cv. Khatooni under deficit irrigation

To evaluate the effect of water deficit stress on growth, yield, fruit quality and physiological traits of melon cv. Khatooni, field experiments were conducted in split plot randomized complete block design with three replications. In 2014, irrigation treatments consisted of two deficit irrigation regimes, 33% and 66% of ETc (crop evapotranspiration), and 100% ETc as the control (DI33, DI66 and I100). In 2015, irrigation treatments applied were: 40, 70 and 100% ETc (DI40, DI70 and I100). The results showed that plant height and leaf area decreased from treatment I100 to DI40 and DI33. The highest average fruit weigh and yield were obtained from irrigation 100% ETc for both years. The water use efficiency (WUE) significantly increased in response to increase water deficit stress. Deficit irrigation treatments significantly decreased leaf relative water content, vitamin C and fruit firmness, whereas antioxidant enzymes activity, proline and total soluble solid contents increased. These results suggest that the crop is sensitive to water deficits, that moderate water stress (DI70 and DI66) reduced yield by about 28.5-38.2% and severe water stress (DI40 and DI33) had a much more marked effect, reducing yield by 48.1-61.4%

Evaluation of Growth, Yield and Vitamin C Content of Okra with Application of Putrescine and Humic Acid Under Deficit Irrigation Stress

In order to study the effects of putrescine (Put) and humic acid (HA) on growth, yield and pod quality of okra (Abelmoschus esculentus L. 'Kano') under deficit irrigation stress, the field experiment was conducted in split plot based on randomized complete block design with three replications. Three different irrigation regimes (33, 66 and 100% ETc) and foliar application of Put (0, 0.5, 1 and 2 mM) and HA (0, 150 and 300 mg.l-1) were conducted. The results showed that deficit irrigation significantly decreased growth, yield and vitamin C content. Significant (P>0.05) increase in growth and yield was observed with the application of both HA and Put. The highest plant growth was obtained whit application of HA 300 mg.l-1 and Put 1mM under irrigation 100% ETc. Also, the maximum yield was observed whit foliar application of HA 300 mg.l-1 and Put 1mM under irrigation 100% ETc. Application of Put and HA at irrigation 100% ETc and HA 150 and 300 mg.l-1 and Put 1mM under deficit irrigation 66% ETC had highest effects on vitamin C content. According to the results, application of HA 300 mg.l-1 and Put 1mM can be proposed to improve growth and yield of okra

The Effect of Different Cucurbit Rootstocks on Some Morphological and Physiological Traits of Cucumber (Cucumis sativus cv. Super Dominus)

Introduction: Cucumber is one of the most important vegetable crops for the local consumption and exportation. The use of grafted vegetable seedlings has been popular in many countries during recent years. Growing fruit-bearing vegetables, chiefly tomato, cucumber and watermelon through grafted seedlings become a widespread practice worldwide. Grafting is a valuable technique to avoid soil-borne diseases, provide biotic and abiotic stress tolerance, enhance nutrient uptake, optimize water use, and increase fruit yield and quality. Vegetable grafting is a new topic in Iran and there are a limited number of studies on grafted vegetable production. However, attention to grafting by researchers has recently increased. Suitable rootstocks should be identified and characterized for the effective utilization of grafting. The rootstock's vigorous root system increases the efficiency of water and nutrient absorption, and may also serve as a source of endogenous plant hormones, thus leading to increased growth and yield in addition to disease control. In the present study, we investigated the response of two Cucurbita sp. and an Iranian melon as rootstocks for cucumber. Materials and methods: In order to study the effect of cucurbit rootstocks and grafting method on growth, yield and fruit quality of cucumber (Cucumis sativus cv. Super Dominus), an experiment was conducted as a factorial design in the base of RCBD with three replications in the greenhouse and research farm, University of Zanjan. Treatments were included three rootstocks (Cucurbita moschata L., Lagenaria siceraria and Cucumis melo L.) and ungrafted plants (control) and two grafting method (hole insertion and splice grafting). Seeds were sown simultaneously in plastic pots. For obtaining the same stem diameter of scion and rootstocks, cucumber seeds were planted four days earlier than rootstocks seeds. The seedlings were grown in an environment-controlled greenhouse with 25/20 day/night temperatures. When seedlings reached the first true leaf stage (diameter of the leaf was about 2 cm) the grafting was performed. After grafting, grafted plants were transferred to a mist chamber for post-graft care (>95% RH, 27-30 °C) for 10 days, after which the relative humidity was reduced gradually for acclimatization. After 20 days of grafting, surviving grafted plants and ungrafted plants were transplanted to the field. Common agricultural practices like fertilizer application, insects and disease control were adopted. Vegetative growth, yield and fruit quality were measured. Data were analyzed using the SAS statistical program (SAS Institute Inc., Cary, NC, USA), and means were compared by Duncan’s multiple range tests at the 5% probability level. Results and Discussion : The result showed that rootstocks had a significant effect on growth indexes. Cucumber was grafted on cucurbita moschata L. rootstock had the highest stem length and leaf numbers, while, the lowest values of plant height, leaf area, leaf number and yield were recorded with grafted plant on melon rootstock. Fruit numbers were significantly influenced by rootstock. The highest fruit number per plant was observed in cucumber plants that were grafted on cucurbita moschata rootstock. The results of the study showed that cucumber grafting on suitable rootstocks had positive effects on the yield. But rootstock had no significant effects on fruit quality like flesh firmness and total soluble solid. The Soluble solid content of fruit was reported to decrease in tomato, cucumber and eggplant due to grafting. chlorophyll content of leaf showed significantly different between grafted and non-grafted plants. The highest amount of leaf area was obtained from non-grafted plants. Grafting methods had no significant difference in growth, yield and fruit quality. Nitrogen and potassium leaf contents of grafted cucumber and ungrafted plants had no significant difference. The interaction between rootstocks and grafting method had no significant effect on yield and the other growth indexes. Conclusion: Our findings showed that vegetative growth and yield of cucumber were affected by grafting. On the basis of these results, Cucurbita moschata rootstock had the highest effect on growth and yield of cucumber. It may also be concluded that the grafting method had relatively same growth response. Although the cost of a grafted seedling is surely one of the main concerns of growers, especially since grafted seedling costs from three to five times more than non-grafted seedling. However, investigation proved that, on-farm grafted cucumber transplant production can be successful and the results indicate that grafting of cucumber onto cucurbit rootstocks can increase on-farm net returns due to improve growth and yield

Effect of water deficit stress on yield, physiological and biochemical parameters of two Iranian cantaloupe accessions

Water deficit stress is one of the most important environmental factors limitting plant growth and crop production. In order to evaluate the tolerance of two Iranian melons to water deficit stress, an experiment in research filed of University of Zanjan was conducted. Treatments consisted of three Irrigation levels, starting irrigation at (100, 66 and 33 % Crop Evapotranspiration) and two accessions of Iranian cantaloupes (Tile-Zard and Tile-Sabz). In this experiment, total chlorophyll content, carotenoids, proline content, leaf relative water content (RWC), ascorbic acid, peroxidase and catalase activity, yield and water use efficiency (WUE) were evaluated. The results indicated that water deficit stress significantly increased proline content, peroxidase and catalase activity and WUE, but decreased RWC, yield and total chlorophyll content. The highest increase in proline content (34.8 %), catalase (18 %) and proxidase (42.3 %) activity and reduction in yield (61.6 %) and RWC (8 %) was obtained in 33 % ETc Irrigation. There has been significant difference between accesesions in relation to RWC, proline, total chlorophyll and peroxidase and catalase activity. The highest value of yield and WUE was observed in 'Tile-Zard'. According to the interaction results, both accessions, 'Tile-Sabz' and 'Tile-Zard' with 63.6 % and 59.7 % Reduction in fruit yield under deficit water stress, are

The mechanism of enhancing drought tolerance threshold of pepper plant treated with putrescine and salicylic acid

Pepper is a warm-season crop and water deficit is considered as dominant issue in pepper cultivation. Using plant growth regulators in different steps of plant growth and development could be as useful strategy to overcome adverse effects of abiotic stresses. In order to investigate the morpho-physiological responses of pepper plant to putrescine (Put) and salicylic acid (SA) foliar application and deficit irrigation (DI) strategy, the split plot experiments were laid out based on randomized complete blocks design at University of Zanjan. The highest values of leaf area and total yield were recorded in sprayed plants by Put at 1.5 mM under DI0% (5842 cm2 and 9.6 ton ha−1). SA at 1.5 mM was the best treatment to increase vitamin C content of pepper fruits. Free proline content increased by 41.34% in sprayed plants by Put at 1.5 mM (7.5 µm g−1 FW) compared to control. SA treatment increased number of pepper fruits, size of harvested fruits and total produced yield by regulation of stomatal conductance and increasing leaf chlorophyll content of pepper plants under drought stress conditions. Also, Put foliar treatment increased drought tolerance rate of pepper plant by increasing free proline content, peroxidase enzyme activity and water use efficiency and also applying this treatment could significantly reduce electrolyte leakage rate. So, SA and Put foliar application at 1.5 mM concentration could be recommended as widely used technique to overcome adverse effects of drought stress on pepper plants cultivated in arid and semi-arid regions

Common Causes of Anaphylaxis in Children

Background Anaphylaxis is an acute, systemic, and potentially fatal allergic reaction. Many things can cause anaphylaxis potentially but some agents are more common like some foods (milk, egg, soy, wheat, peanut, tree nut, shellfish, and fish), insect stings, medications, latex, and food-dependent exercise-induced anaphylaxis. The goal of this study is to show the common causes of anaphylaxis among the children with anaphylaxis history who were referred to the Immunology, Asthma and Allergy Research Institute (IAARI) during a 4-year period (2005-2009).Methods and Materials During those 4 years, we registered all children (<14 years old) with a history of anaphylactic reaction. To prove the cause of anaphylaxis, we performed skin prick tests with suspected agents according to their history and measured specific IgE against them by the ImmunoCAP test. Recognition of common allergens was based on having a positive history for 1 allergen and positive skin prick test or specific IgE for that at the same time, or having positive results from both tests when the allergen was unclear. Idiopathic anaphylaxis was a reaction when any known allergen and positive tests were not obtained.Results One hundred ninety-three nonfatal anaphylactic attacks among 63 children were recognized. In total, the most current cause of anaphylaxis in children was food (89.7%). Milk (49.3%) and wheat (26.1%) were the most common. Other foods were egg (8.7%), nuts (2.8%), and spices (2.8%). Six children (8.7%) were sensitive to multiple food allergens like milk, egg, and wheat. Five (7.1%) of 63 patients had anaphylactic attack because of stinging. Wasp was the trigger in 3 (4.3%) of them and honeybee was the cause in 1 (1.4%). The last one was because of unknown hymenoptera. There were 2 idiopathic cases of all 63 patients.Conclusions Food allergens, especially milk and wheat, are the most common cause of anaphylaxis in children. Because anaphylaxis can be fatal, it is advisable to recognize its causes in different communities to prevent recurrent attacks. Keywords: anaphylaxis, common causes, childre