Effect of seed pretreatment and foliar application of Origanum majorana extract on some growth traits and photosynthetic pigments of soybean

In order to study the effects of marjoram extract on soybean (Glycine max), an experiment was conducted in research field of Shahroud University as factorial based on completely randomized blocks in 3 replications. Experimental treatments included marjoram extract in 5 levels (no pretreatment, pretreatment with extract of 40 and 60 percent each for 6 and 9 hours) as the first factor and foliar application of extract in 3 levels (distilled water spraying, extract spraying of 40 and 60 percent) as the second factor. The highest dry weight of leaf (253.3 g.m-2) and stem (279.0 g.m-2) was obtained in pre-treatment with concentration of 40% for 6 hours with foliar application of 40% extract. The maximum leaf area index and number of secondary lateral branches, was obtained with foliar application of 40% marjoram extract that caused a significant increase by 8.8 and 18.3 percent compared with control respectively. The maximum carotenoid (0.029 mg.g-1 dry weight) and total chlorophyll (1.12 mg.g-1 dry weight) was observed in pre-treatment with concentration of 60% for 9 hours in combination with foliar application of 60% extract. In general, it can be said that the use of marjoram extract, while increasing the growth characteristics and yield of crops, can also reduce the environmental pollution.