Mohammad Rahmnpourazar; Seyyed Jalal Tabatabaie; Sahebali Bolandnazar
Abstract
Nitrate is an essential component for plants and vegetables are of the most important source of nitrate for human being. It is estimated that vegetables provide 92 % of nitrate for human nutrition. The positive and negative effects of elevated root zone CO2 on growth and yield of some plants have been ...
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Nitrate is an essential component for plants and vegetables are of the most important source of nitrate for human being. It is estimated that vegetables provide 92 % of nitrate for human nutrition. The positive and negative effects of elevated root zone CO2 on growth and yield of some plants have been reported. This study has been conducted in order to examine the effect of root zone CO2 on growth and nitrate accumulation in lettuce. The experiment was conducted as a completely randomized design with four levels of CO2 (0, 200, 400 and 600 ml per minute) and with five replication on two cultivars of lettuce (Sativa and Capitata). The study performed in floating system and aeration was supplied by air pump. The results showed that injection of CO2 had significant effect on the fresh and dry weight of leaves, stems and roots of plants. By increasing the concentration of CO2 fresh and dry weight of leaves, stems and roots increased in both cultivars. Photosynthesis efficiency increased in both cultivars in the treatment of 400 ml/min root zone CO2. The influence root zone CO2 significantly decreased nitrate content in leaves of lettuce. Nitrate concentration in the leaves of lettuce was decreased by injection of root zone CO2 in L.sativa. var. Capitata in the treatment of 400 ml/min and in L.sativa. var Sativa in the treatment 600 ml/min. respectively by 27% and 47.6%. With increasing input root zone CO2 increased activity of nitrate reductase enzyme in both cultivars that showed highest content in treatment 400 ml/min.
Maryam Haghighi; Mohsen Kafi
Abstract
Information of heavy metal toxicity about physiological aspect of lettuce is limited. Therefore an experiment was conducted in CRD designed with 7 replications on lettuce (Lactuca sativa L.). Treatments were cadmium in 3 concentration (0, 2 and 4 mg/L) added to Hoagland solution. Results were shown that ...
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Information of heavy metal toxicity about physiological aspect of lettuce is limited. Therefore an experiment was conducted in CRD designed with 7 replications on lettuce (Lactuca sativa L.). Treatments were cadmium in 3 concentration (0, 2 and 4 mg/L) added to Hoagland solution. Results were shown that increasing in cadmium of nutrient solution caused increasing in SOD, POD antioxidant and proline contents of leaf tissues, in addition, cadmium decreased the amount of fresh weight and organic acid. Applying 2 and 4 mg/L cadmium in nutrient solution produced POD, SOD and Proline around 8 and 53%, 55 and 106%, 39 and 119% in 2 and 4 mg/L cadmium, respectively. Whereas in the same concentrations of cadmium protein decreased 25 and 5 %, respectively. Under cadmium stress, toxic effects decline photosynthesis more than chlorophyll content.
Mohammad Hassan Bagheri; Hamid Reza Roosta
Abstract
In this study the effect of nitrogen form and different oxygen levels on growth and development and macronutrients concentrations in lettuce plants was investigated. This investigation showed that sole ammonium application caused fresh and dry weight reduction of shoot and root in lettuce plant. But ...
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In this study the effect of nitrogen form and different oxygen levels on growth and development and macronutrients concentrations in lettuce plants was investigated. This investigation showed that sole ammonium application caused fresh and dry weight reduction of shoot and root in lettuce plant. But different oxygen levels had no effect on them. Nitrogen concentration of shoot was higher in ammonium treatments compared to nitrate treatment and with increasing of oxygen levels in the presence of ammonium, nitrogen content also increased, although it was not the same in nitrate treatment. Phosphorous concentrations in shoot and root were not affected by any of treatments and their interaction. Ammonium also caused reduction of potassium concentration in shoots, but different oxygen levels and its interaction with nitrogen form had no significant effect on it. Magnesium content of shoot also decreased in the presence of ammonium, although it was not the same in root. With increase of dissolved oxygen level, magnesium content of shoot decreased in ammonium treatment, but in nitrate treatment the concentration of this element was not affected by oxygen levels. It is concluded that probably reduction of potassium and magnesium in ammonium-fed plants has a role in plant growth reduction, and it was also observed that in spite of increase in the concentration of shoot nitrogen and root magnesium with increase of dissolved oxygen level in ammonium treated plants, lettuce growth was not affected by oxygen levels.
