maryam haghighi; Bahareh Naghavi
Abstract
Introduction: Salinity has deleterious effect through ion toxicity and changes nutrient balance on plant growth parameter. For decreasing the hazardous effect of salinity stress, some effort has done to reduce uptake and accumulation of Na. Adding of Ca decreased these deleterious effect of salinity. ...
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Introduction: Salinity has deleterious effect through ion toxicity and changes nutrient balance on plant growth parameter. For decreasing the hazardous effect of salinity stress, some effort has done to reduce uptake and accumulation of Na. Adding of Ca decreased these deleterious effect of salinity. Calcium ions have significant effects on the physiological processes of plants and improve the morphological and biochemical factors of plants under salinity stress. The effect of calcium on reducing the harmful impacts of salinity from sodium depends on the plant type, calcium concentration and sodium source. Recently, the addition of nanoparticles to plants as fertilizers has attracted the attention of researchers because of its unpredictable effects, such as faster and easier penetration into the membrane of the cell. A few studies have examined the effect of different nanoparticles on the growth and physiology of plants. So, a research was conducted to investigate the effects of salinity and supplemental calcium in the form of spraying into two metal and nano-metal forms on vegetative growth of tomato plants under crop cultivation conditions.
Materials and Methods: To study the effect of CaCl2 and Nano-Ca on tomato (Lycopersicon escuhentum var. Falcato), a factorial experiment based on completely randomized design (CRD) with 4 replicates was designed with NaCl (0, 25 and 50 mM) and Ca and N-Ca (0, 150 and 200 mg/l) in Isfahan University of Technology greenhouse. Indicators include chlorophyll index, relative water content, ion leakage, leaf water potential, root and shoot dry weights, root and shoot length and root volume were measured. Finally, the analysis of the results was done by statistical statistic software and comparing the meanings by LSD test at 5% level.
Result and Discussion: Results showed that Ca and Nano-Ca was effective on decreasing hazardous effect of salinity on fresh and dry weight of shoot and root volume and Ca was more effective than Nano-Ca. In high salinity level (50mM NaCl), application of 150 mg/l Ca increased fresh and dry weight of root, fresh weigh of shoot and root volume by 60, 63, 50 and 70 % compare to control ,respectively. As well as, the highest root length and shoot was observed in this treatment. Application of 200 mg/l calcium and 150 mg/l of nano-calcium significantly improved chlorophyll content in 50 mM sodium chloride treatment. The plant's compatibility mechanism is very complex in the salinity conditions, from reasons for the growth of the plant under saline conditions are the accumulation of toxic ions, chlorine and sodium in plant tissues, which reduces enzyme activity and changes the pattern of carbohydrate distribution. Loss of the fresh and dry weight shoots and root of tomato has been reported in salinity conditions, which can be attributed to reduce plant growth due to the decrease in leaf area growth and thus the reduction of photosynthesis and the production of proteins. There is little research on the use of nanoparticles in plant growth and the use of nano-calcium has been used to reduce salinity stress for the first time, but the beneficial effects of some nano-materials on plants have been proven. With the use of titanium and nano-titanium in spinach, nano-titanium increases the fresh and dry weight of the plant relative to the use of titanium. In this study, the effects of calcium salinity stress were observed, but nano-calcium had less effects than calcium, and probably due to the fact that the concentrations of nano-calcium were used, using less concentrations in future research to achieve possible concentrations are suggested.
Conclusions: The use of nano-calcium to reduce salt stress was used for the first time in this experiment. The results of this experiment showed that the application of 150 mg calcium per liter on many tomato traits such as root and shoot fresh weight, root length shoots and root volume were effective under salinity stress, especially intense salinity (50 mM sodium chloride). The comparison of the effects of calcium and nano-calcium showed that the particle size reduction hadn’t shown a significant effect on calcium salt modification and may be due to the concentrations of nano-calcium. Therefore, nanotechnology needs more research in the application of nano-calcium and other nano-materials. Ca also alleviated the hazardous effects of salinity but comparing Ca and nano-Ca showed that nano-Ca has not significant alleviating effect on salinity stress.
L. Shekari; M. M. Kamelmanesh; M. Mozafarian; F. Sadeghi
Abstract
Introduction: Aluminum (Al), cobalt (Co), sodium (Na), selenium (Se), and silicon (Si) are considered as beneficial elements for plants. They are not required for all plants but they can improve the growth and development of some plant species. Selenium is an essential element for human with antioxidant ...
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Introduction: Aluminum (Al), cobalt (Co), sodium (Na), selenium (Se), and silicon (Si) are considered as beneficial elements for plants. They are not required for all plants but they can improve the growth and development of some plant species. Selenium is an essential element for human with antioxidant and antivirus functions but is not considered essential for higher plants. Selenium is reported to be protective against cancer and more than 40 types of diseases are associated with Se deficiency. The amounts of selenium in food also depend on the amount of the element in the soil. However, its beneficial role in improving plant growth and stress tolerances is well established. Plants revealed different physiological reactions into the Se levels, some specious accumulate it unlike some which are sensitive and Se is a toxic element for them. Some studies showed that Se can reduce adverse effects of salinity, drought, high and low temperatures and also heavy metal stress by enhancing antioxidant defense and MG detoxification systems. Pepper is one of the most important vegetable crops which have strong antioxidant properties. The effect of Se on vegetable especially on hot pepper is not well documented.
Materials and Methods: Present experiment was designed in order to study the effects of different concentrations of selenium on vegetative growth and physiological trait of hot pepper (Capsicum annum cv. kenya) in hydroponic conditions in the greenhouse at the Department of Horticulture Science, Islamic Azad University of Shiraz (Iran) under natural light with a day/night average temperature of 25/17 °C, relative humidity of 50±8.5% and photoperiod 14/10 (day/night). This experiment was carried out based on completed randomized design (CRD) with 5 Se levels at (0 as control, 3, 5, 7 and 10 µM) with 3 replications. 30 days old seedling with uniform size were selected and transplanted into 4 L pot containing a mixture of peat moss and perlite (1:1). The nutrient solution was a modified Hoagland’s solution and each plant received 400 mL nutrient daily. Selenium concentrations were added by 0, 3, 7 µM Na2SeO3 (Merck, Germany) 10 days after transplanting. Leaf number (by counting), leaf area (with leaf area meter), relative water content (RWC), membrane stability index (MSI), chlorophyll and carotenoids content were determined one month after treatment applications. All data were subjected to one-way ANOVA by Statistix 8 (Tallahassee FL, USA) and the means were compared for significance by the least significant difference (LSD) test at p < 0.05.
Results and Discussion: The results showed that selenium supplement at 5 µM significantly increased relative water content by 12.8% compared to control. Se increased root growth and thus absorbed more water and increased RWC in present experiment. Selenium at 7 and 10 µM Se increased membrane stability index by 33.61 and 80.06, respectively, compared to control which may be due to increasing potassium by Se application. Selenium at 3 and 5 µM increased leaf area by 24.6% and 25.1% relation to plants which were grown without Se supplementation. Leaf number increased by application of 5 µM Se about 15.14% and chlorophyll a, b and total increased by 64.67%, 38.5% and, 55.8%, respectively, in comparison with plants grown without Se application. Carotenoid content was not affected by different Se concentrations. Se increase chlorophyll content by increasing Mg and Fe absorption, or protect of chlorophyll content against chloroplast enzymes. The highest leaf area was observed at 3 µM Se in comparison with other treatments. Se at 5 µM is beneficial for growth, photosynthesis pigments, and leaf area and leaf number. Se application had no beneficial influence on lateral shoot. The highest starch concentration was observed at 5 µM Se in comparison with other treatments and control (by about 60% in comparison with plants were grown without Se application).
Conclusion: In general, the result of present study indicated that selenium at low concentrations improved plant growth (such as leaf area and leaf number), physiological trait (relative water content and membrane stability index) and photosynthesis pigments (chlorophyll a and b) of hot pepper in hydroponic conditions. Also, it is suggested that this experiment should be repeated on some other important vegetable during growth and reproductive stages in hydroponic and soil condition and also on hot pepper quality and quantity of fruit.
