An experiment was performed in the Seed and Plant Improvement Institute, Karaj, Iran to study the influence of plant densities on physiological traits of six canola cultivars. Treatment conditions included three different plant densities (40, 60, and 80 plants m-2) for triplicates of six canola cultivars, namely, Ahamadi, Opera, Okapi, L72, Karaj1, and Sw102. Results indicated that L72 cultivar exhibited the highest yield at the lowest plant density (40 plants m-2). For all cultivars, both plant densities of 60 and 80 plants m-2 resulted in lower relative water content than 40 plants m-2. Proline and carbohydrate content significantly increased with increasing plant densities. The highest proline content was obtained from L72 under the highest plant density, whereas the lowest was also detected in this cultivar at the lowest plant density. All cultivars grown at the lowest density showed higher amounts of photosynthetic pigments chlorophylls a and b than those at the highest density. Glucosinolate increased with increasing plant densities, with L72 yielding the highest quantity when grown at the highest density. In conclusion, a density of 40 plants m-2 is recommended for growing L72 in this region.

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The aim of present study was to determine the relationship between grain yield and important agricultural characteristics for six lines of rice and Shiroodi cultivar as control in rice research station (Tonekabon) in west of Mazandaran Province in 2015. The experiment was conducted in a randomized complete block design with three replicates. Analysis of variance showed that there was a significant difference between genotypes for all studied traits except flag leaf width, which indicates the appropriate variation among the studied genotypes. Results of mean comparison test showed that the highest and the lowest grain yield were belong to line No. 5 (7831.7 kg.ha-1) and No. 204 (6884.3 kg.ha-1) respectively. Results showed that there were positive and significant correlation between grain yield and number of tiller, 1000-grain weight, filled grain number and number of total grains per panicle. Using stepwise regression method showed that 1000-grain weight, filled grain number and number a tillers had the maximum effect on grain yield. Results of path analysis showed that 1000-grain weight an important and effective trait can be used for selection of high yielding rice lines in breeding programs.