SEED RESEARCH (JOURNAL OF SEED SCIENCE AND TECHNOLOGY)
Year:2013 | Volume:3 | Issue:1|Papers Count:8

A factorial experiment was conducted as a complete randomized block design with 2 factors at the laboratory of the College of Agriculture, Islamic Azad University of Guaemshahr in 2010 to evaluate the effect of different seed priming techniques on germination and morphological characteristics of wheat. Seeds were primed for 15, 30 and 45 h in seven priming media (PEG 5%, PEG 10%, KNO3 1%, KNO3 2%, KCl 4% and KCl2% as well as distilled water as control). Maximum seed germination percentage was observed when seed primed by PEG 10% for 45 h. The most stem and radical lengths were observed in the seeds primed by KCl 2% and KCl 4% for 45 h. Rate of germination was improved when the seed soaked in water and PEG 10%. The interaction effect between the seed priming media´priming duration showed the beneficial effects of priming techniques on germination percentage and stem length.

Coldness is the most important factor reducing the percentage of seed germination and seedling emergence of alfalfa. Seed priming is a technique that can improve seed germination and growth under environmental stresses. In this study, the effects of seed priming were investigated on the germination and seedling growth of alfalfa. Seed priming treatments included: Gibberellic acid (20 and 40 ppm), Salicylic acid (0.1 and 0.2 mM), distilled water (8 and 16 h), Biomatis grow fertilizer (30% P and 20% K, two and four per thousands) and Hiumix (68% Humic acid, 12% Folic acid and 80% Humic acid, 15% Folic acid) 2 g/L (8 and 12 h). Temperature treatments were; low (0 and 10oC, at night and day, respectively), semi-optimal (5 and 15oC, at night and day, respectively) and optimal (10 and 20oC, at night and day, respectively). The experimental design was completely randomized with four replications. The results showed a significant difference in germination rate at low, semi-optimal and optimal temperatures. Priming with 0.2 mM salicylic acid over 16 h resulted in a 42% increase in the germination rate and a 59% decrease in time to 50% germination compared to the control group. The greatest effect on the seedling growth traits was observed in the seeds primed by distilled water over 8 h, which showed 27.3 % increase in root length, compared to the control group. The seedling components traits showed 100% increased at the optimum germination temperature compared to the low temperature. Overall, priming with 40 ppm Gibberellic acid for 8 h had the greatest improving effect on seedling components at different temperatures.

The effects of priming by salicylic acid and sowing dates were investigated on wheat, cv. Alvand, yield and its components under field conditions. The factors were including priming levels [control (untreated seed), 400, 800, 1200, 1600, 2000 and 2400 mM salicylic acid) and planting dates (23 Oct. and 22 Nov.). Results showed that salicylic acid effectively increased number of tiller, plant height, neck length, number of spike per plant, number of seed per spike, 1000 kernel weight, biological and seed yield and harvest index. There was no correlation between seed yield and seed weight, thus, it seems that yield was affected mainly through the number of spike and seed per spike rather than seed weight. Since the variation of spike number was small, this increase was mainly related to seeds increment per area. Among the priming levels, 1200 mM salicylic acid treatment had better performance compared to others, especially at late planting. In general, priming by salicylic acid had ameliorative effects on the examined characteristics in the late-sowed plants and even improved the mentioned traits compared to the control group, at normal sowing date.

Crop canopies development (in the terms of dry matter and leaf area index) at the early growth season is exponential, before canopy closure, in which seedling growth rate is limited by leaf area and light reception. Varieties with high early vigor and relative growth rate are able to pass faster this early growth phase. Thus, the present study was investigated early growth differences among canola cultivars. This experiment was conducted on the 9 canola cultivars with 3 replications. Results indicated that there were some differences in early vigor and relative growth rate among cultivars. Option (cv.) had lower seedling dry weight, leaf number, leaf area and plant height, whereas, it had more leaf expansion rate and seedling growth rate. Peace (cv.) had a high leaf development rate as well as the maximum leaf number. PF and excel were kept higher seedling dry weight at all harvests. Cluster analysis indicated that it is possible to grouping the cultivars. It was concluded that it is possible to use genotype differences to improve early vigor in canola.

Vigor of seed often decreases under aging conditions. This experiment aimed to evaluate germination indices and enzyme activity under accelerated aging condition in canola (Brassica napus). To accelerate aging, seeds were imposed to different aging periods of 0, 2, 4, 6 and 8 d at 41oC in sealed aging boxes. Standard germination test was carried out at 20oC for 7 d in three replications of 50 seeds. Results showed that germination of deteriorated seed was reduced. Eight days deterioration had the most influence on the germination indices. The highest germination indices were attained under 0 d aging. Also our results showed that catalase and ascorbate peroxidase activities decreased under accelerated aging.

This experiment was carried out in order to study the effects of salinity stress on germination components of 3 different chamomile (Matricaria chamomilla) ecotypes. The effect of the 6 levels (0, 2, 4, 6, 8 and 10 ds/m) of salt (NaCl) stress on 3 chamomile ecotypes (Gorgan, Semnan and German) was studied as a factorial design in the basis of completely randomized design with 4 replications. The measured and calculated traits were the percentage and rate of germination, the length of radical and plumule, dry weight of radicles and plumules, vigor index and salt tolerance index. The effect of salt stress was significant on all traits. By increasing the salinity a significant decrease was observed in the traits and most of the traits showed significant decrease in their values compared to the control group, even at the lower levels of salinity stress, indicating the high sensitivity of chamomile seeds to salt stress. The percentage and rate of germination were, respectively, 74.67 percent and 4.64 in control group, and these values decreased significantly to respectively, 65 percent and 3.7 at the lowest level of salinity stress, which showed further decrement by increasing the salinity stress. The effect of ecotype was also significant on all traits except the length of plumule and salinity tolerance index. The percentage and rate of germination, the dry weight of plumule and radicle and seed vigor, with respective values of 75.83%, 4.12, 0.617 mg, 2.088 mg and 10.91, were significantly higher in Semnan ecotype compared to the other ecotypes. The percentage and rate of germination and seeds vigor were significantly lower in Gorgan ecotype compared to the other ecotypes.

Sugar beet production correlates closely to production conditions and seed qualitative characteristics. This experiment was conducted in Agricultural Research Station of Ardebil in 2003 based on split plot based on completely randomized blocks with 4 replications in order to evaluate the effects of different planting dates (PDs) and harvesting dates (HDs) on qualitative and quantitative characteristics of sugar beet seed. PDs were 10 March, 25 March, 9 April and 24 April as main plots and HDs included 15, 30, 45 and 60 d after flowering as sub-main factor. It was found that the PD significantly affected emergence, seed stalk formation (SSF), flowering, viable seed percent (VSP) and normal germs percent. HD had a significant effect on main branch number/plant, leaf dry weight, seed yield/plant, total dry weight (TDW), germination rate, VSP and normal germ percent. Flowering also was significantly affected by planting´harvesting interaction. The highest seed yield was obtained in the third and second harvest, respectively. Among qualitative characteristics of the seed, the highest VSP, germinating rate, normal germ percent were obtained in fourth HD.

Knowledge on sunflower seed physical characteristics can play an important role in the proper procedures during harvesting, transport, drying, sorting, seed peeling and storage. In order to study the effect of removing leaf and seed in different plant densities on seed physical and chemical properties of sunflower hybrids, an experiment was conducted as a factorial split plot based on completely randomized block design with three replications in 2009 at Aboureihan Research Field of University of Tehran. Azargol and new Iranian hybrid SHF81-90 and three plant densities 60000, 80000 and 100000 plants/ha were main plots and five levels of change in source and sink size (removed 50% lower leaves, removed 50% upper leaves, removed 50% seeds, removed 25% seeds) and control (without removing leaf and seed) were sub plots. Photographs were taken from the seeds, by a digital camera, and analyzed using MATLAB programming language. Some morphological features were extracted by this software. Results indicated that the hybrids had significant difference in Perimeter and Area, Major and Minor Axis, Elongation, Compactness, Roundness, Solidity, seed weight and seed coat to seed ratio at 5% and 1% probability levels. Also the effects of plant density and source and sink manipulation were significant on all traits. Oil percent increased along with the plant density increase. Correlation between oil percent with seed weight (r=+0.53) and seed coat to seed ratio (r=-0.27) was significant at 1% probability level. Also the results of this study showed that using image processing technique, which is the new technique in agricultural researches, the physical properties of seed cultivars in different environmental conditions can be identified more accurately and this will be helpful in management of different planting, harvesting and postharvest stages.