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Atena Sheibani

Grade: 
Graduated

The Effect of Root Zone Temperature on N Metabolism, Growth and Physiological Characteristics of Lettuce and Sweet Pepper in 3 N Withholding Levels in Early Growth Stage

Abstract Considering increasing world population vegetables cultivation also increased. So that, plants faced with different temperature, nutritional and climatic situation which can induced various stresses for plants. Stress intensity related to the plant’s type and recovery ability under unfavorable condition. In order to evaluate the effect of of plants unfavorable root temperature and nitrogen starvation lettuce and sweet pepper plants selected and this study conducted in factorial experiment based on control randomized design (CRD) with five replications for each treatment in greenhouse of Isfahan University of Technology with 3 nutrient treatment (100, 75 and 50) precent of Johnson nutrient solution and 3 root zone temperature (±15°C, ±25°C and ±35°C). Results demonstrated that by reducing nitrogen concentration in both plants under 35°C root temperature nitrogen absorbtion and urea and nitrate concentration increased. Furthermore, in 25°C and 15°C root temperature higher amount of phosphorous and potassium with reduce of nitrogen observed. The highest plant biomass was in optimum root temperature and 100% Johnson nutrient nitrogen concentration. By nitrogen diminishing, plants growth decreased. Phenolic compound of root exudate and shoot extract increased in 25°C root temperature and 15°C root temperature by reducing although only in lettuce only in 15°C root temperature an acceptable amount of phenolic compound produced in lettuce. Chlorophyll value by decreasing nitrogen concentration decreased in all root temperature and this reduction was more obvious in 35°C root temperature treatments. Photosynthesis rate in all nitrogen concentratin of 15°C root temperature in sweet pepper and 35°C root temperature in lettuce were higher than other treatments. The highest transpiration of lettuce in 50% Johnson nutrient nitrogen concentration in all root temperature and in 15°C root temperature in all N levels in sweet pepper observed. Eventually concluded that nitrogen metabolism limited less under nitrogen deprivation and high root zone temperature and low root zone temperature has more destructive effect in both evaluated plants. Although both unfavorable temperature and nitrogen deficiency reduced yield

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