مرتضی شلالوند

The main objective of this study was to determine an optimal cropping pattern in a productive unit located in Pishva County based on regional and national comparative advantage analysis. In order to achieve this goal, the physical indices of the comparative advantage of production including scale advantage, efficiency advantage, and aggregative advantage with the export advantage of both agronomic and greenhouse crops were calculated. The research was an empirical study based on field survey. Data were gathered through a questionnaire, interview with experts from Varamin Agricultural unit and statistical reports from the Ministry of Jihad-Iran Agriculture and FAO. The results of the study showed that the current cropping pattern of Varamin production unit has scale, efficiency and aggregative advantage and therefore the current farming pattern should be continued. These crops also had efficiency advantage in regional level according to Pishva County cropping pattern Analysis. The analysis of the comparative advantage of greenhouse products at the regional level showed that cucumber, colored pepper and tomatoes had comparative advantage in the province of Tehran. The revealed comparative advantage also showed that cucumbers, colored peppers and greenhouse tomatoes, along with cabbage (leaves, flowers and broccoli), have an export advantage at the national level. Therefore, the optimal cropping pattern of the agricultural unit can be reached through continuing the current cropping pattern along with the addition of greenhouse products with regional advantage and cabbage crop with national and export advantage.

In order to evaluate the suitability of maize hybrids in different planting dates, an experiment was conducted as split plot in JalilAbad, Varamin, Iran in 2015. Main and sub plots were planting date (D1: April 4, D2: April 19, D3: May 5, D4: May 20) and maize hybrids (H1: Gazda, H2: Maxima, H3: KSC 701, H4: AS160) respectively. Results indicated that there was variation between hybrids in terms of leaf area index (LAI), dry matter, crop growth rate (CGR), relative growth rate (RGR) and net assimilation rate (NAR) in different planting dates. Also results showed that the effects of planting date, hybrid and planting date × hybrid interaction on plant height, plant weight, ear weight, ear/plant weight ratio, silage yield and water use efficiency were significant. Among the qualitative traits examined, the effects of hybrid on protein and neutral detergent soluble fiber were significant. The best planting date for achieving the highest silage yield of hybrids Maxima and AS160 were May 5 and 20, but for KSC 701 was April 19 and May 5. However hybrid Gazda had a similar yield in all planting dates. It was concluded that even though cultivation of KSC701 and Maxima seems preferable in terms of silage yield but repeating this experiment in further years is necessary for a solid recommendation.

In order to investigate the effects of different irrigation methods on yield and some physiological characteristics and activity of antioxidant enzymes of milk thistle (Silybum marianum L.) under using of vermicompost and salicylic acid, a field experiment was conducted as split-factorial based on randomized complete block design (RCBD) with three replicates on Shahr-e-Rey station during 2014-15 growing seasons. Irrigation methods as the main factor were conducted on four levels (including drip irrigation, basin irrigation, furrow irrigation, and alternate middle irrigation) and using of vermicompost on two levels (0 and 15 ton/ha) and application of salicylic acid on two levels (0 and 1 mM) were performed as minor factors. The results showed the highest activity of antioxidant enzymes including catalase, superoxide dismutase, peroxidase, ascorbate peroxidase, and glutathione peroxidase were observed in alternate middle irrigation with the combined consumption of vermicompost and salicylic acid and the lowest them activity in drip irrigation. The amount of malondialdehyde was higher in alternate middle irrigation than drop irrigation and application of vermicompost and salicylic acid simultaneously was decreased amount of malondialdehyde. Also, the highest seed yield and chlorophyll content were observed in drip irrigation with the combined consumption of vermicompost and salicylic acid. The results of this study showed that consumption of vermicompost and salicylic acid has a role in eliminating the negative effects of stress, and can improve the activity of antioxidant enzymes and increase the yield of milk thistle plant.