In order to study the effects level of nitrogen fertilizer on yield and physiological traits of rice cultivars (Oryza sativa L.), an experiment as factorial in RCBD with three replications was conducted during 2009 year in the Rice Research Institute, Iran, Rasht, central of Guilan and Rudsar, East of Guilan. Factors were cultivar (Khazar, Ali Kazemi and Hashemi), and nitrogen fertilizer levels (0, 30, 60, and 90 Kg N/ha). Characters measured were: leaf area index (LAI), Total of dry weight (TDW), leaf dry weight (LDW), Crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), leaf area duration (LAD), leaf area ratio (LAR), leaf weight rate (LWR), specific leaf area (SLA), grain yield. Growth parameters were calculated during six growth stages by harvesting samples from leaf area index, leaf dry and total weight dry weight in all treatments. The comparison of calculated and measured amounts of growth indexes with use determination of regression coefficients (R 2 ).Results of growth analysis indicated that, nitrogen increasing rates of fertilizer caused the increment of growth indexes. Khazar and Ali Kazemi Hashemi showed higher growth indices rather than Hashemi. Results indicated that cultivar and nitrogen fertilizer significantly effected on grain yield. Khazar and Ali Kazemi have the highest grain yield among cultivars. Also, Results indicated with increasing nitrogen fertilizer application, grain yield increased significantly (17،13 and 57 %).
The objectives of this study was to analyze greenhouse gases (GHG) emissions for watermelon production under watered and rain fed farming in north of Iran. Data were collected from 72 farms in guilan province with face to face questionnaire method. GHG emissions can be calculated and represented per unit of the land used in crop production, per unit weight of the produced grain and per unit of the energy input or output. Results showed that, total green house gases emissions for watermelon production under watered farming was calculated as 895.16 kgCO2eqha -1 . Results showed that, total green house gases emissions for watermelon production under rain fed farming was calculated as 777.16 kgCO2eqha -1 .
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