Showing 3 results for Nitrate
Hamidreza Nassery, Zahra Kayhomayon, Mohammad Nakhaei,
Volume 16, Issue 42 (5-2015)
Abstract
The present study aimed at identifying the nitrate transport in the groundwater of Lenjanat plain, Isfahan. Nitrate concentrations were measured seasonally and groundwater flow was modeled for nitrate transport simulation using MODFLOW and MT3DMS codes. The nitrate concentrations were compared with the human and livestock drinking water and irrigation water standards. The results show that nitrate concentrations are higher than the guidelines limits in groundwaters. The flow modeling reveals that the groundwater flow system of the study aquifer has been influenced by the aquifer hydrogeological characteristics. The falling watertable and reduce aquifer storage are due to the anthropogenic stresses on flow system. The transport model calibration and sensitivity analysis shows that nitrate leaching from agricultural land, first–order irreversible rate reaction, effective porosity and precipitation are the major factors affecting the entry and retention of nitrate in Lenjanat groundwater. Denitrification rate in the aquifer has been decreased due to high concentration of dissolved oxygen in groundwater and low extent of organic carbon. Half-life of nitrate in Lenjanat aquifer is more than 2.5 years. Nitrate transport in the aquifer is mainly by convection. Considering the calculated mass with transport model, the nitrogen leaching to groundwater of study area is 108 kg N ha-1 yr-1.
Volume 18, Issue 44 (10-2009)
Abstract
Hyoscyamus is one of the medicinal plants, rich in tropane alkaloids. In this research the effects of nitrate and ammonium on production of secondry metabolites and other physiological parameters, were investigated. The results indicated that when nitrate and ammonium were both present in nutrient solution and ammonium concentration was lower than nitrate, dry and fresh weight of root and shoot increased. However, by increasing ammonium concentration, plant growth decreased. With increased concentra-tions of ammonium, root/shoot ratios were decreased. Nitrate reductase activity increased in both nitrate and ammonium fed plants. However, the higher ratio of ammonium to nitrate led to a decreased NRA. Alkaloid content (sum of hyoscyamine and scopolamine) increased in both nitrate and ammonium fed plants. However, the higher the ratio of ammonium to nitrate, the lower the alkaloid content.
Volume 18, Issue 56 (9-2006)
Abstract
The mechanism of soybean(Glycine max L.cv.Gorgan 3) response to drought stress was evaluated. The plants were grown in pots under 23 ± 2°C temperature and 14000 lux light intensity and 14hr photoperiod. When first leaf appeard, three irrigation treatments occurred that consisted as one every day(control), once in three(mild stress) and in five days(sever stress).During 15 days the plants were irrigated an amount of 150 ml. The effect of irrigation treatment on the soluble sugar, total protein, proline, phenolic compound, chlorophyll content and nitrate reductase activity was studied.The results showed that in the root soluble sugar and proline content in mild and sever stress significantly increased while in the stem and the leaf these compound considarably increased under sever stress the total protein ,chlorophyll a,b and nitrate reductase activity in leaf especially decreased in sever stress. Also the decrease phenolic compound in leaf under this condition was significant
