Shayesteh Salehi; Ghorban Noormohammadi
Abstract
In order to quantify the germination characteristics and determine the cardinal temperature of germination of Euphorbia maculata, seeds were placed at constant temperatures (2- 45 °C). Results showed that seed of E.maculata had no germination at temperatures of 2, 5, 10 and 45 ° C, and the temperature ...
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In order to quantify the germination characteristics and determine the cardinal temperature of germination of Euphorbia maculata, seeds were placed at constant temperatures (2- 45 °C). Results showed that seed of E.maculata had no germination at temperatures of 2, 5, 10 and 45 ° C, and the temperature of 30° C was the best temperature for germination seeds (91% Germination percentage). Three models of intersected-line, dent-like segmented and quadratic polynomials were used to estimate the cardinal temperatures. The best model for estimating the cardinal temperatures in E.maculata was intersected-line model with respect to coefficient of determination and mean square error. According to the intersected-line the minimum, optimum and maximum temperatures were calculated 9.8, 28.33 and 43.16 °C. In order to investigate water potential on germination percentage, seeds treated with water potentials (0, -0.2, -0.4, -0.6 and -0.8 MPa) at optimum temperature of 28°C. Baesd on the three-parameter sigmoid method, the value of speed, root length, stem length, seedling fresh weight and dry weight were estimated to be -0.53, -0.48, -0.51, -0.48, -0.52Mpa respectively. According to the hydro-time model based on normal distribution, the hydro-time constant and the base-water potential (which is a threshold for germination beginning) of E.maculata degree were 291.32 (MPa/h) and -1/2 (MPa) at 28 °C, respectively. Thus, this weed species has a great potential for distribution to other areas such as provinces with a dryer climate than Golestan, and the necessary measures to prevent its distribution is necessary.
Batool Mahdavi
Abstract
This study was conducted to study germination two species of vetch (Vicia sativa; Vicia pannonica) under temperatures (5, 10, 15, 20, 25, and 30 °C) and different water potentials (0, -2, -4, -6, -8 and -10 bar) at the Vali Asr Rafsanjan University laboratory in completely randomized design ...
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This study was conducted to study germination two species of vetch (Vicia sativa; Vicia pannonica) under temperatures (5, 10, 15, 20, 25, and 30 °C) and different water potentials (0, -2, -4, -6, -8 and -10 bar) at the Vali Asr Rafsanjan University laboratory in completely randomized design arranged as a factorial with four replications. The segmented function was evaluated to describe the relationship between germination rate and temperature. Results showed base temperature for germination of Vicia pannonica was -3.65 to 1.39, optimum temperature 23.99 to 25.57 and ceiling temperature 30 to 58.54 under different water potentials. The biological hours for germination of this specie were 32.29 to 74.97 hours under different water potentials. Also, base temperature for germination of Vicia sativa was -3.54 to 1.39, optimum temperature 22.70 to 25.64 and ceiling temperature 30 to 42.28 under different water potentials. The biological hour requirements for germination of this specie were between 33.10 to 83.54 hours under different water potentials. The results of germination rate in both species showed that with increasing water potential, germination rate decreased. In all of water potentials germination rate increased to 25°C and then decrease. Estimated parameters and the relations can be used to prediction time to germination or emergence in two species of vetch under different water potentials.
Esmaeil Yasari; Mousa Miri; Sadegh Atashi; mohsen jamali
Abstract
This study was evaluated the ability of a hydrothermal time model (HTT) to describe the kinetics of seed germination in crops and also to determine the cardinal temperatures for germination (as a case study; velvetleaf). For this purpose, the experiment was carried out at eight constant temperature regimes ...
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This study was evaluated the ability of a hydrothermal time model (HTT) to describe the kinetics of seed germination in crops and also to determine the cardinal temperatures for germination (as a case study; velvetleaf). For this purpose, the experiment was carried out at eight constant temperature regimes (T; 15, 20, 25, 30, 35, 37, 40 and 42°C) at each of the following water potential (ψs; 0, –0.18, –0.36, –0.54 and –0.72 MPa; using PEG 6000). The results indicated that ψ influenced germination rate and germination percentage (P < 0.0001). For this seed lot, cardinal temperatures were 11.8°C for Tb, 35.4°C for To and 45.2°C for Tc in the control (0 MPa) treatment. There was a decrease in hydrotime constant (θH) when T was increased to To and then remained constant at supra-optimal Ts (24 MPa h-1). At the Ts above To, ψb(50) values increased linearly with T. The kT value (the slope of the relationship between ψb(50) and T exceeds To) of this seed lot was calculated as 0.1011 MPa°Ch-1. Moreover, the ψb(50) was estimated to be –0.91 MPa based on this model. Our results show that when the HTT model is applied, it can accurately describe germination response of velvetleaf around Ts and ψs.
R. Ostadian Bidgoly; H.R. Balouchi; E. Soltani; A. Moradi
Abstract
There is a little information about the effects of temperature and water potential on safflower. In order to study the effects of temperature and water potential on seed germination characteristics of safflower (Carthamus tinctorius L.), an experiment as combined analysis was conducted base on a completely ...
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There is a little information about the effects of temperature and water potential on safflower. In order to study the effects of temperature and water potential on seed germination characteristics of safflower (Carthamus tinctorius L.), an experiment as combined analysis was conducted base on a completely randomized design with 4 replications by 25 seeds in laboratory of seed technology at Yasouj University in 2015. The factors included temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 oC) and water potential (0, -0.2, -0.4, -0.6, -0.8, -1, -1.2, -1.4 and -1.6 MPa). The percentage and rate of germination, root length, shoot length, ratio of root length to shoot length and seedling vigor index were measured in this experiment. The results of analysis of variance showed that main effects of temperature and water potential and interactions were significant on all indicators of germination at 1% probability level. Also, by decreased water potential, germination percentage and germination rate reduced. At 5 oC and at zero potential germination percentage was 98% while the potential of -1.6 MPa germination percentage dropped to zero. At 35 oC and at zero potential germination percentage was 95% while the using potential of -1.6 MPa germination percentage decreased to 1%. By increasing the temperature up to 20oC increasing germination percentage and germination rate detected and afterwards reduced.
A. Nezami; H.R. Khazaie; A.R. Barjasteh
Abstract
Because of the importance of the role of maternal environment during seed development on germination of produced seed and seedling establishment an experiment in a randomized complete block design base as a factorial was conducted to evaluate effects of drought stress (0.0, -0.2, -0.4, -0.8 and -1 MPa) ...
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Because of the importance of the role of maternal environment during seed development on germination of produced seed and seedling establishment an experiment in a randomized complete block design base as a factorial was conducted to evaluate effects of drought stress (0.0, -0.2, -0.4, -0.8 and -1 MPa) on germination and seedling growth characteristics of wild oat seed production under different irrigation regime (100,80 and 60 percentage of water requirement of wheat from stem elongation stage to the end of growth season) in Shahrood Agriculture research center. According to the results, maternal irrigation regime, drought stress and interaction effects between them had significant effect on germination and seedling characteristics of wild oat. The results showed that germination characteristics were decreased significantly with decrease of water potential to -1 MPa. The highest rate and percentage of germination and radicle length in this water potential was related to irrigation regime of 60% water requirement and the least of plumule dry weight was related to irrigation regime of 60 and 80% water requirement. Length and dry weight of plumule decreased more than those of radicle under drought stress conditions and showed greater sensitivity to reduced water potential. Lower dry weight and green area was observed in seedling that germinated at water potential more than -0.4 MPa. The results showed that drought stress during the seed formation caused significant changes in response of wild oat germination under stress condition.
