جستجوی مقالات مرتبط با کلیدواژه "مدل های رگرسیونی" در نشریات گروه "زراعت"

Reports indicate the invasion of two species of Ivy-leaved morning-glory (Ipomoea hederaceae Jacq) and Asian spider flower (Cleome viscosa L.) to summer crops fields such as soybeans in Golestan province. Considering the importance of knowing the cardinal temperatures of germination in the models for predicting the presence of weeds and consequently designing correct management strategies on these plants, this experiment was conducted to study the germination behavior and to compare the cardinal temperatures of germination for two species of Ivy-leaved morning-glory and Asian spider flower under two conditions of constant and alternating temperatures.

In order to study the effects of constant and alternating temperature on the percent, rate and estimating cardinal temperature of germination for Ivy-leaved morning glory and Asian spider flower, two separate experiments as a Completely Randomized Design with four replications were carried out at the seed laboratory of Gorgan University of Agricultural Sciences and Natural Resources. Studied temperature treatments on Ivy-leaved morning glory included the constant temperatures of 10,15,17,20,25,30,35 and 40 oC and alternating temperatures of 12.5:7.5,10:15, 12.5:20, 15:25, 20:30, 25:37.5, 30:42.5 and 35:45 oC. Temperature treatments on Asian spider flower included the constant temperatures of 15, 20, 23, 25, 28, 30, 35, 40, 45 and 50 o C and alternating temperatures of 15:20, 20:25, 20:30, 25:30, 25:35, 30:40, 30:45, 30:50 and 40:50 oC.

Results indicated that alternating temperatures had a positive effect on the germination of Ivy-leaved morning glory, which increased from 78% at constant temperatures to 94% at alternative temperatures. However, the maximum germination percentage of Asian spiderflower at the alternative temperature of 20:30 was 79%, which had no significant difference with a constant temperature of 30 with 84% germination. The base temperature for seed germination of Ivy-leaved morning glory at alternating temperatures (10.09 oC) was a little lower than that of constant temperatures (11.25 oC). But in Asian spider flower, the base temperature at alternating temperatures (17.57 oC) was more than that of constant temperatures (15.43 o C).

The most important factor in the occurrence of such different responses to constant and alternating temperatures in Ivy-leaved morning glory and Asian spider flower is their adaptation to environmental conditions and their survival in highly degraded agricultural environments. These two weeds are warm-season plants and their seeds enter the soil seed bank in autumn. The presence of dormancy (regardless of its type) in the seeds of these two plants prevents the germination of their seeds in winter; and the experience of alternating temperatures at this time prepares the seeds for germination in the spring. The base temperature of Ivy-leaved morning glory was not much different under the constant and alternating temperature conditions. But the base temperature of Asian spider flower was higher under alternating temperatures compared with constant temperatures.

Leaf area is a key indicator for the growth and production of plant products and also determines the efficiency of light consumption. Therefore, the study of diversity and also the estimation of leaf area in different mint ecotypes is particular importance. One of the common methods for estimating leaf area is regression analysis, the leaf area as independent variable, and leaf length and width as dependent variable. In this study, leaf area of ​​18 mint ecotypes with different models of ANFIS, artificial neural network (MLP and RBF), linear and nonlinear regressions using two inputs of leaf length and width in four levels of salinity stress (control, 2.5, 5 and 7.5 dS/m) were estimated in two levels of harvesting. The results showed that there is a high correlation between length and width with leaf area, so that the width correlation with leaf area was greater than leaf length. Among the regression models in both harvest levels and at all levels of salinity stress, the NLR model is presented as the best and most accurate model. ANFIS model was harvested in both stages and at all levels of stress was more accurate than other models and less error rate was obtained. Also, the results of cluster analysis showed that there is a good variation between ecotypes. In addition, the mean comparison between different cluster analysis groups showed that the highest amount of length, width and leaf area was taken in both stages and at all levels of salinity stress was related to E18.

Safflower (Carthamus tinctoriusL.) is annual and oil crop belong to Aster-aceae family that planted all over the world (Isigigure et al., 1995). Seed germination is a complex physiological process and one of the most important part of plant life cycle that affected by environmental factors. Temperature and moisture are the most important of these factors. Seed planting in optimum temperature resulted in maximum germination, uniformity and seedling establishment. Knowing minimum, maximum and optimum tem-perature of seed germination is necessary to appointment suitable planting date. In the oth-er way, environmental factors for seeding are not always favorable for seed germination. Osmotic stress is the most important factor that reduces growth and crop yield. Most re-ports showed that decline of osmotic potential cause a change cardinal temperature of seed germination. Hence the aim of this study is determination of cardinal temperature of safflower and the effects of different levels of temperature and osmotic potential on seed germination characteristics. The experiment was conducted as factorial in a completely ran-domized design with four replications, in agronomy laboratory, agricultural college, the University of Guilan in 2015. Experimental factors were including temperature (5, 10, 15, 20, 25, 30 and 35 ̊C) and osmotic potential (0, -0.2, -0.4, -0.6 and -0.8 MPa). Different osmotic potential prepared based on Michael and Kaufman (1973) method using with PEG 6000 and double distilled water. Germination percentage, germination rate and vigor index was calculated in the end of germination period (14 days). To estimation the cardinal tem-perature and needed biological hours for germination, five nonlinear regression models (polynomial quadratic, segmented, beta, dent like and curvelinear) were used. RMSe, R2, r and coefficient regression (a, b) related to amount of observed and predicted germination rate were used for finding the best model. Choosing the best model was conducted in two stages. At First, a model selected that amounts of parameters a, b were not significant dif-ferences with zero and one respectively. In the second stage, the model that had maximum R2 and minimum RMSe introduced as the selected model. The results showed that, minimum (%4) and maximum (%92) germination per-centage were observed in interactions of -0.8 MPa with 30 ̊C and 15 ̊C with control (dis-tilled water) respectively. Overall, the seed germination rate decreased with declining os-motic potential. The temperature levels of 25 and 35 ̊C had maximum and minimum ger-mination rate in all osmotic potential levels respectively. The treatment of osmotic poten-tial in comparison to the temperature on vigor index had the worse effect, nonetheless in all temperature levels reducing osmotic potential, was showed significant decrease. Based on model parameters measurement, only segmented and quadratic models had suitable fitness. Although segmented model had better fitness than quadratic model for safflower germination rate to temperature response. The preferable regression model estimated min-imum seed germination temperature (2.2 to 4.2 ̊C) optimum temperature (23.12 to 23.98 C) and maximum temperature (42.2 to 43.89 C). Decreasing in osmotic potential from control until -0.8 MPa causes decreasing minimum temperature in both models. The opti-mum temperature in -0.8 MPa osmotic potential increased nearly one degree in segmented model but in quadratic model this temperature is declined 3.25 ̊C degree. Also the effect of decreasing osmotic potential on maximum temperature was much observable than its effects on minimum and optimum temperature. So that maximum temperature in -0.8 MPa osmotic potential comparison control (zero MPa) in segmented model 9 ̊C and in quadratic model 6.3 ̊C was decreased. Overall, safflower seeds, protected their germination parame-ters suitably in sub optimal temperature in comparison with supra optimal temperature (in the same osmotic potential levels). Extreme decreasing of these parameters in high tem-perature (35 ̊C) expression the susceptibility of this crop to high temperature. Expect preferable regression models and estimated parameters (minimum, maximum and optimum temperature) in preparation and assessment of seedling appear-ance models in field and determination of planting date in every area are used. Safflower is a tolerant plant to drought stress under suboptimal temperature, but is very sensitive at higher than 30̊C temperature. Therefore, it is a good candidate to be planted in suitable planting date even relatively low soil moisture condition.

Evolution of resistance in weeds leads to induction of fitness cost. Five winter wild oat biotypes resistant to haloxyfop R methyl ester collected from Kalaleh Township located in Golestan province were evaluated along with the susceptible biotype in terms of variation in cardinal temperatures in the following study. The experiment was conducted at laboratories of Gorgan University of Agricultural Sciences and Natural Resources as completely randomized design with 4 replications each consisting of 25 seeds. Petri dishes containing seeds were incubated and monitored continuously at temperatures 5-40 °C (at 5°C intervals) following a 72 hours vernalization at 4°C. Non-linear regression models were used to quantify germination response to temperature. No notable difference was observed among winter wild oat biotypes and beta model at 50 percentile was the most suitable model to describe cardinal temperatures. Base, optimum and ceiling temperatures were estimated between -4.21 to -5.91, 23.37-23.94 and 36.99-37.54 °C, respectively. Thermal tolerance range of susceptible and resistant biotypes were not significantly different. Susceptible and resistant biotypes showed similar response. Lack of fitness cost regarding cardinal temperatures demonstrates that similar non-chemical management practices including early sowing may be implemented to control resistant and susceptible biotypes germination and emergence

This study aimed to evaluate the non-linear regression model (Beta-original, Beta-modified, Segmented and Dent-like Models) to describe the germination rate of Arugula (Eruca sativa Mill.), temperature and water potential factorial a completely randomized design with four replications in Gorgan University of Agricultural Sciences and Natural Resources was performed in 1392. Treatments were temperature to 9 levels (2.5, 5, 10, 15, 20, 25, 30, 35 and 38 ° C) and water potential to 8 levels (0, -0.2, -0.4, -0.6, -0.8, -1.0, -1.2- and -1.4 Mpa). To quantify the response of germination rate to temperature and to determine cardinal temperatures for germination, Beta-original, and Beta-modified, Segmented and Dent-like models were used. The Beta-original model descript germination rate to temperature better than the others. According to this model the base temperature, optimum temperature and ceiling temperatures were 0.0, 30.13 and 38.50 0C respectively in non-stress conditions (zero potential). Changes of water potential had significantly effect on optimum and ceiling temperature but had no significantly effect on base temperature and biological hours.

Access to weed distribution maps can be very useful in planning their management. Locating areas prone to infection with new entrant weeds is needy to knowledge of ecological characteristics of these plants such as cardinal temperatures, EC and pH. In order to investigate the effects of temperature on germination and determine the main germination temperatures (base temperature, optimum and ceiling for germination) of ivy-leaved morning glory, seeds incubated at 10, 15, 17, 20, 25, 30, 35 and 40 0C. To determine the cardinal temperatures, Original beta, Modified beta, segmented and dent like models were used. The results indicated that the original beta model was superior than the other models and base, optimum and ceiling temperatures for seed germination were 10, 25.91 and 41.22 0C respectively. The results showed that ivy-leaved morning glory has high tolerance ability to soil salinity. So, germination percent of this plant can be reduced by 50% in salinity of 45dS.m-1. In addition, germination present of these plants in acidic pH was higher than the alkaline pH. Distribution maps indicated that there were no limitations regarding temperatures and EC for germination and establishment of this weed through the Golestan Province. But regarding pH, there is a major in increasing distribution extent in the province. So that only a small section of Kalaleh and Galikesh lands are suitable in this regard.

Walnut is one of the most important nut crops in Iran. Because of its sexual propagation in Iran, the tree shows a high genetic diversity. In this study, the correlations between trunk cross-sectional area, scaffold cross area, crop density per trunk cross-sectional area and scaffold cross area, number of leaves and leaf area per nut, nut number to branch cross-sectional area, leaf number to branch cross-sectional area, leaf area to branch cross-sectional area and alternate bearing in eight terminal and lateral nutting genotypes were studied in walnut collection of Seed and Plant Improvement Institute of Iran in two years. Number of nuts to trunk cross sectional area and number of nuts to scaffold cross area were 1.68 (nuts/cm2) and 19.43 (nuts/m2), respectively. The average number of leaves and leaf area per nut were 4.42 (leaf/nut) and 1346.33 (cm2 leaf/nut), respectively. The lowest nut density (number of nut/cm2 branch cross sectional area) was found to be in genotype H1-1 (2.74) and the highest value was found in ‘Pedro’ (4.36). The correlation coefficient between nut density and leaf area per nut was -0.7. The highest alternate bearing was detected in ‘Hartley’ (15.38 %). This study showed that nut number and branch cross sectional area, nut number and branch leaf area, and branch leaf area and branch cross sectional area had very high correlations, and the polynomial regression model was appropriate for studying the relationship between the evaluated traits with high determination coefficients.