جستجوی مقالات مرتبط با کلیدواژه « germination rate » در نشریات گروه « زیست شناسی »

In order to study the effect of seaweed extract and nano-ZnO on germination characteristics of tomato seed, a factorial experiment was conducted based on a randomized complete block design. Preliminary germination and seedling growth tests were performed to determine the best concentration of seaweed extract and nano-ZnO. Experimental treatments included three levels of drought stress (0, 2- and 3-bar), four levels of application of nano-ZnO and seaweed extract (control, seaweed extract 4%, nano-ZnO 1200 ppm, and a combination of seaweed extract and nano-ZnO). The results showed that by decreasing the water potential standard germination percentage, seed germination rate, seedling length and dry weight, length and weight vigor indices decreased, whereas mean germination time increased. As the drought stress intensified, the amount of hydrogen peroxide accumulation was increased and also the activity of peroxidase and catalase enzymes in tomato seedlings increased. As well, application of seaweed extract and nano-ZnO at different levels of drought stress significantly reduced the negative effects of this stress on seed germination and the early growth of seedlings. Application of these compounds at different drought stress levels significantly increased the standard germination percentage, seed germination rate, seedling length and dry weight, length and weight vigor indices, but reduced seed germination time. Also, the use of seaweed extract and nano-ZnO under drought stress conditions increased the activity of peroxidase and catalase enzymes but reduced the accumulation of hydrogen peroxide in tomato seedlings.

In order to investigate the pre-harvest and priming application effects of gibberellic acid, salicylic acid and nitrogen on seed germination indices of Echinacea purpurea, this experiment was designed on factorial experiment in base completely randomized design with three replications at 2018 in field conditions and laboratory in the department of horticultural science of Ilam University. Experimental factors included gibberellic acid at two concentrations (100 and 200 mg/L), salicylic acid at two concentrations (100 and 200 mg/L) and nitrogen (from urea sorce) at two concentrations (3 and 6 g/L) that were investigated separately and in combination with each other. Treatments were applied with control samples as pre-planting (before maturity and seed harvesting) and seed priming (after seed harvesting). The results showed that the highest germination percentage, vigor index and shoot length were obtained in pre-harvest interaction with gibberellic acid 200 mg/L and nitrogen 6 g/L. The highest germination rate was observed in gibberellic acid 200 mg/L and the highest seed dry weight was obtained in gibberellic acid 100 mg/L. The highest root length was observed in pre-harvest treatment with 200 mg/L of gibberellic acid and 200 mg/L of salicylic acid. Also, pre-harvest nitrogen treatment had significantly higher germination percentage, germination rate, vigor index, shoot length and dry weight than their priming. Therefore, in present study, preharvest treatments of gibberellic acid in combination with nitrogen or salicylic acid were introduced for improving the seed germination of Echinacea purpurea.

In order to study the effect of seed priming with salicylic acid (SA) and jasmonic acid (JA) on emergence and early growth of pumpkin (Cucurbita pepo L.) seedlings  under drought stress condition, a factorial experiment based on randomized complete block design (RCBD) with four replications was conducted at the greenhouse of Malayer university. Experimental treatments were seed priming with salicylic acid (0, 100 and 200 ppm) and jasmonic acid (0, 50 and 100 ppm) and three levels of drought stress (100, 60 and 30% of field capacity). Based on results, drought stress significantly (P≤0.05) affected the percentage and rate of seedling emergence. In the severe drought stress (30% of field capacity) percentage and rate of seedling emergence were decreased 10% and 54%, respectively. Furthermore, seedling length, seedling dry weight and seedling length vigor index were decreased 11%, 9% and 25%, respectively, whereas at the same condition malondialdehyde and proline content increased 84% and 13%, respectively. Severe drought stress also increased the activity of catalase and proxidase enzymes in pumpkin seedlings up to 39 and 57 percent, respectively. Seed priming with salicylic acid and jasmonic acid significantly (P≤0.05) decreased the negative effect of drought stress on all of the studied traits except seedling emergence percentage. Simultaneous priming with highest level of salicylic acid and jasmonic acid resulted in highest drought tolerance in pumpkin seedlings

TRR14 is a small protein which is located in chloroplast. This protein was first identified in screening of trehalose resistant (TRR14) Arabidopsis seedlings. The aim of present study was physiological and molecular investigation of TRR14 re-transformed (T17) seedlings under salt stress, compared to wild type Arabidopsis seedlings (WT). For this purpose, WT and T17 seeds were grown on MS medium complemented with 0, 75, 100 and 150 mM NaCl. The results showed that under salt stress, the germination rate and trehalase activity in T17 seedlings were higher than WT. Meanwhile the results showed that anthocyanin level in WT seedlings was higher than T17 under salt stress. The Na level was highly increased in WT seedlings under 75 mM NaCl treatment, compared to T17 seedlings. The K measurements revealed that the K level in T17 seedling was 3 times more than WT seedling when grown on MS medium. But K level was decreased under 75 mM NaCl treatment in both WT and T17 seedlings. On the other hand, by adding NaCl to medium culture, the shape and size of epidermal cells were changed in both WT and T17 seedlings. While stomata numbers increased in WT leaves under NaCl treatment, it remained unchanged in T17 seedlings. The gene expression pattern showed that trehalase and TRR14 expression were increased under salt stress.