The effect of seed rate of alfalfa (Medicago sativa L.) and efficiency of plant growth promoting bacteria (PGPR) that facilitates phosphorus uptake with different doses of phosphate fertilizer was evaluated on seed quality. For this purpose, the germination and seed vigor tests before and after accelerated aging were performed in a split split plot experiment based on randomized complete block design with three replications in 2010 in the field of education and research in the College of Agriculture and Natural Resources, Tehran University, Karaj. Phosphorus factor at 4 levels (0, 30, 60 and 90 kg Phosphorus.ha-1) in main plots, PGPR (Pseudomonas) in three levels (no bacteria, bacterial strains, No. 9 and bacterial strains No. 41) in subplots and rate of seed factors on three levels (2, 6, and 10 kg of seed per hectare) were the sub-subplots. The results showed the highest rate of germination and seed vigor obtained by use of 6 kg seeds per hectare, PGPR No.41 strains with 30 kg Phosphorus per hectare and after accelerated aging. The highest rate of germination and seed vigor at 10 kg of seed per hectare were found for PGPR No.41 strains, with 60 kg Phosphorus ha-1 treatments. After accelerated aging practices to achieve maximum germination index and vigor, seed rates and phosphorus requirement were more than standard conditions. Based on obtained results for the storage conditions, bacterial strains No. 41 had a better effect on increasing seed vigor than bacterial strains No. 9. To produce alfalfa seed with high vigor and obtain better results, use of optimum seed rates and phosphorus (6 and 30 kg.ha-1, respectively) along with PGPR (strain No. 41) could be considered in crop plants.
In order to investigate the effect of an electromagnetic field and ultrasonic waves on the seed germination of Cuminum cyminum that two separate experiments using a completely randomized design with four replications was conducted at Seed Science and Technology Laboratory of Faculty Agricultural Sciences, the Shahed University of Tehran in 2012. In the first experiment, for the seeds of zero, 10 and 30 min exposure to electromagnetic field intensity was 88 microTesla. In the second test (ultrasonic waves), seeds for zero, 2, 4, 6, 8 and 10 min exposure ultrasonic waves’ intensity were 40 and 59 kHz. The interaction between the electromagnetic field and the length had a significant effect on the traits of length, fresh weight and dry weight of root and shoot, length and weight of root to shoot ratio, percent and rate germination and mean germination time. In most of the studied traits showed that electromagnetic field causes a significant decrease in the number of traits so that the control (zero M.T) had the highest value. The interaction of Ultrasonic waves at the time had a significant effect of on the most traits. Maximum germination percentage (100%) for the treatment of 40 kHz with duration of 4 and 6 minutes and mean germination time was highest in control (10.76 days) and 59 kHz treatment duration of 2 and 4 min (respectively 11.01 and 10.75 days). Generally, Cuminum cyminum seeds responded positively to the use of ultrasonic waves (In contrast field) and germination index was significantly increased in this case.
The present study was conducted to investigate the efficiency of hormonal pretreatment on increasing germination and early growth of seedling in the Seed Technology Laboratory of Shahed University in 2015 as a factorial experiment, adopting a completely randomized design with 4 replications. The treatments were: 5 levels of IAA (indole-3-acetic acid) namely, zero, 0.1, 0.5, 1 and 1.5 mg/L and 5 levels of PBA (Tetrahydro pyranyl benzyl adenine), which were zero, 0.5, 1, 1.5 and 2 mg/L. Analysis of variance showed that the use of the two hormones and their interactions had a significant effect on all traits such as seed germination, biomass, leaf relative water content and photosynthetic pigments. The highest percentage of germination (66.66%) was obtained in 1.5 mg/L IAA with 1 mg/L PBA. 0.5 mg/L PBA and in 0.1 mg/L IAA the longest shoot (1.28 and 1.17 cm, respectively) was obtained. Germination coefficient decreased by about 12.5% by increasing IAA from 0.1 to 1.5 mg/L. The greatest relative water content (42.73% and 37.38%) was obtained with 0.5 mg/L PBA and 1.5 mg/L IAA, respectively. Combination of IAA+PBA (0.1+0 mg/L) had a positive effect on both the length of the root and seedling. The high concentration of PBA and the lowest amount of IAA had similar results in terms of plant biomass. The highest plant biomass (4.33 mg) was obtained in seeds treated with 2 mg/L of cytokinin and 0.1 mg/L of auxin. Photosynthetic pigments were also affected by these two hormones through the IAA was more effective than PBA. The finding was that auxin and cytokinin increase germination and improve the morpho-physiological indicators and thus increase the yield of Stevia.
For the purpose of evaluating the effect of chitosan on seed germination and some biochemical characteristics of the milk thistle herb in the conditions of salinity, an experiment was conducted as factorial in a completely randomized design (CRD) with three replications in the Laboratory of Seed Science and Technology of Shahed University, Tehran in 2015. Experimental factors comprised salinity levels (0, 4, 8 and 12 dS.m-1) and different levels of Chitosan (0, 0.25, 0.5, 0.75 and 1 percent). The results showed that salt stress reduced germination percentage, germination coefficient, germination speed, weight and length vigor index, radical, plumule and seedling length and total biomass and increased mean germination time. Seed priming with chitosan up to 0.5% concentration increased germination coefficient, weighted index vigor and plumule length. The highest amounts of total chlorophyll and total protein were obtained in seed priming with 0.5% chitosan levels in zero salinity level (control). By increasing salinity levels, the activity level of catalase and peroxidase increased, so that the highest level of the activity of these two enzymes was obtained in the salinity level of 12 dS.m-1 in pre-treatment with 0.5% Chitosan. The results showed that seed priming with chitosan of 0.5% could reduce harmful effects of salt stress on some traits of milk thistle seedlings and could even improve their growth.
In order to investigate the effect of pretreatment of chitosan biological compounds on seeds of soybean (Glycine max L. cv. Williams) under salt stress conditions, a factorial experiment was conducted, adopting a completely randomized design with three replications at Shahed University in 2015. Factors examined included the combination of chitosan at three levels (0, 0.25 and 0.5 the weight-volume) and salinity at 4 levels (0, 5, 5.7 and 10 dS/m). The results showed that the interaction of chitosan and salinity had a significant impact on seed germination characteristics such as germination percentage, germination rate, mean germination time, normal seedling and physiological characteristics such as proline and soluble sugars of shoots. In contrast to salt stress increase of 30%, and an increase of 24 and 35% of proline and soluble sugars of the shoot, pretreatment of chitosan (0.25%) improves seedling germination characteristics of soybeans. Given the impact of the treatments of chitosan on seed germination and seedling growth of soybean, it is possible to introduce 0.25% W/V chitosan as a treatment to deal with conditions of salinity.
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