جستجوی مقالات مرتبط با کلیدواژه « مدل بتا » در نشریات گروه « منابع طبیعی »

To study the relationship between seed size and aging on cardinal temperatures of canola cv. Hyola 50, seed germination an experiment was conducted based on a randomized complete design with three replications. Seeds were classified in to four groups based on their diameter (1.4, 1.8, 2 and 2.2 mm) and considered as the first experimental factor. The Second factor was various durations of accelerated aging treatment (0, 24, 48, 72, 96 and 120 hours (40oC, RH=100%) and the third factor was nine constant temperatures in which seeds were germinated (0, 5, 10, 15, 20, 25, 30, 35 and 40 ˚C). Cardinal temperatures were quantified for germination fraction of 50% using four nonlinear model: beta, beta modify, dent-like and segmented. The result indicted beta model better described responses germination rate to temperature compared with others models and accelerated aging and sizes did not affect the change model base temperature was about 1.15 OC in sizes 1.4 mm and increase in size to 2.2 mm deceased to 0.11 OC. The optimal temperature range was about 21.37 to 21.58 OC and the maximum temperature was 40.2 to 40.8 OC. it was also found that different seed sizes did not have a significant difference in terms of thermal time and deterioration increased the basal germination temperature and thermal time coefficient and reduced the optimal and maximum temperature, that it can show necessity delay in planting date in cold areas or early planting in tropical areas in these types of seeds.

Safflower (Carthamus tinctorius L.) is an important industrial plant, which classified in the category of oil plants. The tolerance of plants to drought is different, as well as Plants have different temperature and water requirements, and understanding this requirement helps them survive and reproduce. Therefore, the purpose of this study was to evaluate the germination characteristics of safflower seeds at different temperatures and humidity and the adaptation power of this plant under these conditions. For this purpose, germination of safflower seed (Faraman cultivar) was investigated in incubator at constant temperatures of 5, 10, 15, 20, 25, 30, 35 and 40 ° C. in this study, 3 regression model including, Beta model, Dent like model and segmented model were used to determine cardinal safflower temperatures. Then, to investigate germination and seedling growth response of Carthamus tinctorius toward different levels of Water Deficite Stress at an optimum temperature, another test was conducted. in this experiment, seed germination was assessed in six levels of Water Deficite Stress with the osmotic potential of 0, -3, - 5, -7 and -9 bar (in temperatures of 20 ° C). Based on Beta model, Dent like model and segmented model, the cardinal temperatures of Carthamus tinctorius seeds germination including, (Tbase, Topt and Tmax) were: (4.6, 4.1, 4.1), (22.02, 20 – 24.3, 22.5) and (43.3, 50.3, 50.3) °C, respectively.

In order to quantifying cardinal temperature and hydro time germination of Cuminum cyminum seeds, an experiment was conducted as completely randomized design with three replications in laboratory of Faculty of Agriculture and Natural Resources of University of Mohaghegh Ardabili in 2017. Experimental treatments were included: temperatures as, 0, 5, 10, 15, 20, 25, 30, 35 and 40 ˚C and osmotic potential as 0, -0.2, -0.4, -0.6, -0.8, -1 and -1.2 MPa. Quantifying of cardinal temperature for germination fraction of 10, 50 and 90 % were evaluated from four models as: beta, modified beta, dent-like and segmented. In this study, RMSE and R2 and AICc were used for comparison between models. Result indicted that beta model showed better responses description for germination rate of Cuminum cyminum to temperature compared with others models. However basic temperature of Cuminum cyminum was between 0.7 to 0.9 ˚C, optimum temperature about 20 to 21 ˚C and maximum temperature was 35 ˚C. In addition based on hydro time models results, θH and Ψb(50) of Cuminum cyminum were estimated 97.5 and -0.46 MPa respectively.

To determine the specific temperature of Medicinal Cannabis sativa, the effects of different temperatures on germination, in a laboratory study in a completely randomized design with three replications were studied. Germination response assessment at constant temperatures (3, 5, 10, 15, 20, 25, 30, 35, 40 and 45ºC) was conducted. The germinated seeds were counted every day and the rate of germination percentage, cumulative germination and cardinal temperatures diagram of Cannabis sativa seed germination based on 3 regression model including segmented model, Beta model and Dent like model. The results showed that the temperature increase of 3 to 25°C significantly increases the germination rate, while the germination rate did not differ at 25 to 40°C. Also with increasing temperature over 25°C, germination was reduced. Dent like model such as higher accuracy in determining the cardinal temperatures hemp seed germination was compared with other models, Base, optimum and maximum temperature of seed germination of Cannabis sativa based on Dent like model was determined 1, 26-39.3 and 48°C respectively.

In order to evaluate different nonlinear regression models for estimating cardinal temperatures of Lepyrodiclis holosteoides as an invasive weed, an experiment was carried out at Biodiversity Laboratory of Environmental Sciences Research Institute at Shahid Beheshti University. 8 germination temperatures (0, 5, 10, 15, 20, 25, 30 and 35 °C) and humidity potential (0, -0.2, -0.4, -0.6 and -0.8 MPa) with four replications. Were arranged in a completely randomized design with for replications. Then, germination rate and percentage of seeds were measured. To predict the response of germination rate to temperature in Lepyrodiclis holosteoides, some regression models including dent-like, segmented, beta (four and five parameters) were applied. Some statistical estimators like Root Mean Squared of Error (RMSE), Akaike Information Criterion (AIC) and coefficient of determination (R2) were used to evaluate goodness of fit for different regression models. Results showed that the highest germination percentage (72%) was obtained at 20 °C. Results also indicated that beta four and five-parameter models were amongst the superior functions in describing the response of germination rate to temperature in Lepyrodiclis holosteoides largely due to their higher R2 (0.99 for both beta models), lower AIC (-73.16 and -73.27) and RMSE (0.0092 and 0.0091). Generally, base, optimum and ceiling cardinal temperatures for Lepyrodiclis holosteoides were estimated 4.29, 19.76 and 37.55 °C for beta four-parameter models and 4.22, 19.72 and 37.83 °C for beta five-parameter model. The findings of the current study (i.e. cardinal temperatures) could be used in prediction of Lepyrodiclis holosteoides germination and emergenceunder various temperatures.