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The response of photosynthesis parameters, catalase, superoxide dismutase and peroxidase activity, malondialdehyde, proline, chlorophyll, yield and yield components to foliar application of calcium and simulated acid rain in wheat were investigated. Foliar treatment of calcium led to significant increases in the photosynthesis rate, transpiration rate, stomatal conductance, proline, chlorophyll, yield and yield components in plants subjected to acid rain. Antioxidant enzyme activity and lipid peroxidation in the wheat leaves decreased because of calcium foliar application. Calcium hindered degradation of the rubisco subunits under acid rain treatment compared with water-treated plants. Results suggest that acid rain induces the production of free radicals resulting in lipid peroxidation of the cell membrane so that significant increase in antioxidant enzyme activity was observed. In addition, photosynthetic parameters i.e. photosynthesis rate, transpiration rate and stomatal conductance were drastically suppressed by acid rain. The cellular damage caused by free radicals might be reduced or prevented by a protective metabolism including antioxidative enzymes and calcium. We report that foliar application of calcium before acid rain may ameliorate the adverse effects of acid rain in wheat plants.

Selection of an appropriate forage species is an important fi rst step in successful forage production. Among forage species, canola (Brassica napus L.) can be cut for hay or silage to cover certain costs of growing the crop. Because forage production is largely controlled by the environment and management, this experiment was conducted in a semiarid region of Iran during the 2006-2007 and 2008-2009 growing seasons to investigate whether canola forage yield and its nutritive value aff ected by diff erent rates of N and natural zeolite. Th e experimental treatments were arranged in randomized complete blocks with three replications and comprised a factorial combination of three N levels (90, 180, and 270 kg N ha -1 ) and four zeolite rates (0, 3, 6, and 9 t zeolite ha -1 ). Th e results showed that the enhanced N application from 90 to 270 kg N ha -1 resulted in a 49% rise in forage yield for the fi rst year and a 39% increase for the second year. Th e converse eff ects from N and zeolite yielded a signifi cant interaction on the forage nitrogen concentration (FNC) so that the N and zeolite application enhancement led to an increase and decrease, respectively, in the FNC. Th e integration of the minimum N level with the maximum zeolite application generated the highest forage calcium concentration (FCC) (1.13% in dry matter). In contrast, N 270 Z 0 treatment yielded the lowest FCC (0.54% in dry matter). Th ere was a linear response between N application rate and its leaching loss whereas in the zeolite treatments, minimum N leaching was observed aft er the Z 9 treatment. A combined application of zeolite and chemical N for canola production in a poor sandy soil is recommended to ensure an acceptable forage yield and for soil protection from excess N leaching loss.