SEED RESEARCH (JOURNAL OF SEED SCIENCE AND TECHNOLOGY)
Year:2013 | Volume:3 | Issue:2|Papers Count:8

Low germination percentage, seedling emergence and germination rate, are of the important problems of sowing in arable lands in Iran, especially in arid regions. This problem increases costs and decreases the exploitation of agricultural lands. A factorial experiment was conducted based on a completely randomized design with three replications at College of Agriculture, Qaemshahr Azad University in 2009. Priming solutions included polyethylene glycol (PEG 6000) with the concentrations of 5 and 10%, potassium nitrate (KNO3) with the concentrations of 1 and 2%, potassium chloride (KCl) with the concentrations of 2 and 4%, whereas the time of priming was 4, 8 and 16 h. Analysis of variance showed that the maximum (12.61 mm) stem length was observed in the seed primed with 4% KCl over 16 h. The maximum number of normal germination (24.11) and germination rate (12.37 seed per day) were observed in the seeds primed with 4% KCl over 16 h. Generally, seeds of Kimia cultivar of sorghum had a better response to salinity, when pre-primed with 4% KCl over 16 h.

Germination is one of the most important plant growth stages, which has a drastic effect on other growth activities. This stage is very sensitive to environmental stresses, particularly salinity and drought, and improvement of germination under unfavorable environmental conditions causes increasing resistance to these conditions. Priming is a method to facilitate germination and increase seed resistance under unfavorable environmental conditions. This research was performed in order to investigate the hydropriming effect on green onion seed germination under salinity stress condition. A factorial experiment was performed as a completely randomized design. Treatments were combination of five levels of salinity (concentration of 0, 50, 100, 150 and 200 mg NaCl) and 3 levels of priming [without soaking (control), 24 and 48 h soaking]. Daily germination, final germination percentage and final germination rate of the green onion seeds were calculated. Results showed that interaction between priming treatments and salinity levels was not significant. Along with salinity increment, control group (without NaCl treatment) had a significantly better germination characteristics compared to the other treatments. The germination rate of the seeds primed over 24 h was significantly different compared to the non-primed seeds. However, priming over 48 h led to a significant decease in the germination characteristics.

An experiment was carried out to investigate the effect of seed size on yield and yield components of three soybean (Glycin max. L) cultivars. The experiment conducted as factorial based on a completely randomized block design with four replications at the Islamic Azad University of Gorgan in 2011. Treatments were combination of two factors cultivar and seed size. The first factor included three soybean cultivars (Sahar, Wilimaz and Katul) and the second factor included three levels of seed sizes (Small, medium and large).  Analysis of variance showed a significant difference in total number of fertile and unfertile pods, the number of grains in the pods, the number of pods per plant, weight of one hundred grains, harvest index of plant, economical yield and biological yield among the treatments (seed size and cultivar). Wiliamz cultivar had the most economical yield and number of grains in the pods, Katul cultivar had the most one hundred grain weight, and Sahar cultivar had the most number of fertile and unfertile pods. Interaction effect of Sahar and Williams cultivars with large seed size had the most effect on economical yield.

Soybean seed is susceptible to cracking, and its final quality dependents on storage condition and processing methods. Therefore, preventing of mechanical damage during seed processing and storage is an important management in maintaining high quality seeds. A factorial experiment based on completely randomized design with 3 replications was conducted to determine the number of seed bags can be stacked in each part without affecting soybean seed quality. The experimental treatments included rows of bags (8, 10 and 12 rows) and cultivars (Sari, 032 and 033). The seed of such parts were stored for 4 months in Sari, and then sampled seeds from stored parts were studied. Results showed that more variation of temperature and humidity along with more relative humidity in first year of study significantly decreased soybean seeds quality compared to the second year. 033 Line has more germination percentage and better field emergence as compared with Sari cultivar and 032 Line. Probably 033 Line could tolerate storage condition with the respect of the other cultivars. Increased number of bag rows in each seed part negatively affected soybean seeds properties. Mean of germination percentage and seedling length in 8 row parts (81.5% and 17.89 cm respectively) was higher than 10 row (79.3% and 11.83 cm respectively) and 12 row (79% and 11.52 cm respectively) parts. Electrical conductivity of solution from seeds of 8 row parts was significantly lower than that of seeds of 10 and 12 row parts. Therefore, it is recommended to store soybean seeds in 8 row parts.

In order to study the effects of hydropriming and osmopriming on germination indices in lentil (Lens culinaris Melik.) seeds under salt stress, a factorial experiment based on a completely randomized design was conducted with three replications. This investigation conducted at Seed Science and Technology laboratory of Faculty of Agricultural of Islamic Azad University – Mashhad Branch in 2011. Factors included two cultivars of lentil (Robat and Kimia), three levels of seed priming (hydropriming, osmopriming by NaCl and KCl in osmotic potential -12 bar) and five levels of salt (NaCl) stress (0, 2, 4, 6 and 8 ds/m). Results showed that all indices decreased when salt stress increased. Hydropriming improved all germination indices in both cultivars Robat and Kimia under salt stress.

Soybean seed size is a key component of the crop performance and can affect the adaptation of the crop varieties to different environmental conditions and also affect the early vigor. To investigate the effect of seed size on yield, harvest index, seed germination and seed vigor of soybean cultivars two experiments were conducted in the field (completely randomized blocks design, four replications) and at Seed Technology Laboratory  Islamic Azad University of Tabriz (completely randomized design, three replications)  in 2008. The treatments were cultivars at 2 levels (Williams and TMS) and seed size at three levels (small, medium and large). Results showed that increase in the seed size resulted in the seed yield and harvest index increment. The maximum grain yield per unit area (with 518.5 kilograms per square meter) was observed in the large seeds of TMS cultivar, whereas, the lowest value (418.1 kilograms per square meter) was related to the small seeds of TMS cultivar. The large seeds harvest index was 11.94% higher than small seeds. The laboratory results showed that germination percentage increased along with the increase in the seed size. The large seeds had 39.06 % higher germination compared to the than small ones, however, the effect of seed size on germination rate was not significant. The highest and lowest seedling lengths belonged to Williams' medium and small seeds, respectively.

In order to identify and classify the seeds of three species of genus Amaranthus including Amaranthus albus, Amaranthus retroflexus and Amaranthus viridis an experiment was conducted using machine vision and artificial neural network in 2011. Quantified information about the characteristics of each seed was extracted, after taking images of the seeds. After that neural networks were constructed using original and normalized data. Results showed that the Multilayer Perceptron neural networks with the transfer function of TanhAxon and Momentum learning rule were the best neural networks. Overall accuracy of identification of neural networks constructed from the original data of the fifteen predictor variables were 74.75%. The values for the neural network which constructed form predictor variable that suggested by stepwise were 76.26%. Overall accuracy of identification of neural networks constructed from the normal data of the fifteen predictor variables were 82.00%. The values for the neural network which constructed form normal data of the predictor variable that suggested by stepwise regression were 79.81%. In general, using morphological characteristics of seeds for classifying Amaranthus species was relatively acceptable. Using other morphological, color and texture characteristics of the seeds were advised to increase identification and classification accuracy.

Nowadays, non-linear regression models are used to estimate germination indices. In this study, the four-parameter Hill model (4-PHM) is introduced to estimate the germination indices. For this purpose, the germination data of 3 wheat seed lots at 20oC, ray response to germination at three water potential levels (0, -10 and -18 bar) in 20oC and yellow sweet germination data at four different temperature (5, 15, 25 and 30oC) were used. Wheat seed lots vigor were evaluated by measuring maximum emergence in field. In each treatment, the maximum germination percentage, germination speed, germination uniformity and time to germination onset were calculated using 4-PHM. Results of the field emergence of the wheat seed lots showed vigor differences. The time difference between the start of the germination and the time required for 50% of viable seeds to germinate determined wheat seed lots vigor difference. 4-PHM parameters showed that in ray with reducing water potential, the maximum percentage of germination, germination rate and time to germination start significantly reduced. Highest value of germination percentage, germination rate and time to start germination were observed close to the optimum temperature in yellow sweet according to 4-PHM parameters for this plant germination in different temperatures. The results indicated that the great flexibility of the 4-PHM in fitting data, due to the model's parameters significantly varied in different environmental conditions also it was shown that this model's all parameters have biological meaning.