Relationship between thermal properties of canola pods (without seed) with moisture content, porosity and chemical composition of pods

Thermal properties of canola pods including coefficients of thermal conductivity, thermal diffusivity and specific heat and chemical composition of rapeseed pods were measured at three levels of conventional canola varieties cultivated in the north of Iran (Hyola 50, Hyola 401 and Hyola 420) and in three times before harvest, while harvest and post-harvest. Then the relationship between the thermal properties of canola pods with chemicals, moisture and porosity were investigated. Conductivity coefficient was resulted from linear thermal method, the specific heat was obtained from mixing method and diffusion coefficients were calculated by the formula. The results showed that changes of variety and time of sampling were significant on thermal conductivity coefficient and diffusion coefficient at the probability level of 1%. Changes of variety at the level of 1% and time changes of sampling at the level of 5% were significant on specific heat. As well as the interaction between the variety and time was effective on conductivity coefficient and thermal diffusivity coefficient at 1% level. It was also observed between thermal properties and porosity, the relationship was significant at 5% level. As well as the relationship between the thermal properties and chemical composition was significant at 5% level

Physiological Fitness Associated to ACCase Target-Site Resistance Enhances Growth and Reproduction in Phalaris brachystachys

Short-spike canarygrass (Phalaris brachystachys (Link.)) from Iranian wheat fields has developed resistance to acetyl-coenzyme A carboxylase (ACCase) inhibitors due to a target-site mutation (Ile-1781-Thr). Target-site resistance mutations may confer pleiotropic effects in weeds. In this paper, the possible effect of the Ile-1781-Thr mutation on the ecological fitness during life cycles in P. brachystachys plants was investigated. ACCase genes of P. brachystachys populations resistant (R) and susceptible (S) to ACCase inhibitors were sequenced and the vegetative growth and reproductive characteristics of the plants were assessed. In the final growth stage (217 days after planting—DAP), R sub-population plants were 30 cm taller than the S plants. Additionally, the R sub-population produced up to 12 leaves and 2.8 tillers more per plant, and accumulated double the dry weight (2850 g m−2) compared to the S sub-population. The leaf area index (LAI) of the R sub-population was 1.1 times higher than that of the S sub-population. In addition, the net assimilation rate (NAR) and plant growth rate (PGR) between 114 and 182 DAP of the R sub-population were 0.11 and 13 g m−2 d−1 higher than the S sub-population, but the relative growth rate (RGR) was similar between R and S sub-populations. The number of spikes (6 vs. 3.8), the spike length (8.4 vs. 5.5), and number of seeds per plant (1276 vs. 751 seed plant−1) of the R sub-population were higher than the S ones, but the weight (3.25 g) and size (11.6 mm2) of 1000 seeds were similar between populations. The R sub-population of P. brachystachys exhibited higher plant growth and reproductive parameters than the S one, which may increase the frequency of resistance in the population in the absence of adequate weed-control methods

The First Case of Short-Spiked Canarygrass (Phalaris brachystachys) with Cross-Resistance to ACCase-Inhibiting Herbicides in Iran

The weed Phalaris brachystachys Link. severely affects winter cereal production. Acetyle-CoA Carboxylase (ACCase)-inhibiting herbicides are commonly used to control this weed in wheat fields. Thirty-six populations with suspected resistance to ACCase-inhibiting herbicides were collected from wheat fields in the Golestan Province in Iran. A rapid test performed in Petri dishes and whole-plant dose–response experiments were conducted to confirm and investigate the resistance level of P. brachystachys to ACCase-inhibiting herbicides. The seed bioassay results showed that 0.02 mg ai L−1 clodinafop-propargyl (CP) and 1.36 mg ai L−1 of the diclofop-methyl (DM) solution were the optimal amounts for reliably screening resistant and susceptible P. brachystachys populations. In the whole plant bioassay, all populations were found to be resistant to CP, resistance ratios ranging from 2.7 to 11.6, and all of the CP-resistant populations exhibited resistance to DM. Fourteen populations showed low resistance to cycloxydim, and thirteen of these populations were also 2-fold resistant to pinoxaden. The results showed that DM resistance in some P. brachystachys populations is likely due to their enhanced herbicide metabolism, which involves Cytochrome P450 monooxygenases, as demonstrated by the indirect assay. This is the first report confirming the cross-resistance of ACCase-inhibiting herbicides in P. brachystachys in Iran

Base temperatures for germination of selected weed species in Iran

Weed emergence models require the estimation of base temperature for germination (T-b) that was estimated for Abutilon theophrasti, Echinochloa crus-galli, Amaranthus retroflexus, Sorghum halepense, Amaranthus albus, and Amaranthus hybridus in Iran, to calibrate an existing model called AlertInf. Two statistical procedures were adopted: Model 1 - linear regression of germination rate and Model 2 - probit analysis. Model 1 provided lower T-b values. Abutilon theophrasti and A. hybridus presented lower T-b values (about 4 and 8 degrees C), while the remaining species had values above 10 degrees C. Since the estimated values of T-b were in agreement with those adopted for the Alertinf model in Italy, the first step was achieved to adapt AlertInf to Iranian conditions

Effect of osmotic potential on germination cardinal temperatures of tall mallow (Malva sylvestris L.)

Introduction Seed germination is a complex biological process that is influenced by various environmental and genetic factors. Temperature and water potential are two primary environmental regulators of seed germination. Quantification of germination response to osmotic potential and temperature is possible using non-liner regression models. Tall mallow (Malva sylvestris) is an important invasive weed in southwest Iran and also a medicinal plant. ). Tall mallow is native home in Western Europe, North Africa and Asia. This plant frequently found in cultivated fields, orchards, gardens, farmyards near manure piles, along roadsides, in towns, and in waste places and, can grow anywhere from 60 to 120 cm in length. Not published information exists concerning effect of osmotic potential on cardinal temperatures, Therefore, the objective of this research was to evaluate the effect of osmotic potential and different temperatures on germination and determination cardinal temperatures (base, optimum and maximum) of Malva sylvestris under osmotic stress. Material and methods In this study germination response to water potential in different temperature were studied. Treatments included osmotic levels (0, -0.2, -0.4, -0.6 and -0.8 MPa) and temperature (5, 10, 15, 20, 30, 35 and 40 °C). Cumulative germination response of seeds to differential water potential and temperature were quantified using three-parameter sigmoidal model. For quantifying response of germination rate to temperature for different osmotic potential were used of 3 non-linear regression models (segmented, dent-like and beta). The root mean square of errors (RMSE), coefficient of determination (R2), CV and SE for relationship between the observed and the predicted germination percentage were used to select the superior model from among the employed methods. Germination percentage and time to 50% maximum seed germination of Malva sylvestris were calculated for the different temperatures and osmotic potential by fitting 3-parameter sigmoidal functions to cumulative germination data. Results Results indicated that temperature in addition to germination percentage also on germination rate was effective. Also results showed that germination percentage and germination rate increased with increasing temperature, while germination percentage and germination rate reduced as a result of water potential increment. Results indicated that under different osmotic potential as 0, -0.2, -0.4, -0.6 and -0.8 MPa, the segmented model estimated base temperature as 1.46, 1.82, 1.29, 0.43 and 4.06 °C, the dent model estimated base temperature as 1.23, 1.82, 3.04, 2.63 and 4.07 °C, the beta model estimated base temperature as -4.32, 4.46, 1.86, 1.61 and 4.13 °C, the segmented model estimated optimum temperature as 28.29, 27.58, 22.24, 22.51 and19.69 °C, the optimum temperature using beta model as 27.89, 25.41, 23.18 and 21.05 °C, the dent-like model estimated lower limit of optimum temperature and upper limit of optimum temperature as 23.16 and 33.58, 16.86 and 30, 16.1 and 25, 15.81 and 25, 19.51 and 1987 °C, ceiling temperature using segmented model were 42.9, 40, 40, 40 and 34.96 °C, using dent-like model were 42, 40, 40, 40 and 34.96 °C, using beta model were 42.01, 40.02, 39.96, 39.98 and 34.83 °C, the segmented model estimated fo as 13.87, 18.45, 19.43, 25.24 and 36.13 h, the dent-like model estimated as 16.65, 23.28, 23.43, 30.48 and 36.56 h and using beta model were 16.06, 21.34, 22.21, 28.92 and 42.89 h, respectively. In compared 3 models according to the root mean square of errors (RMSE) of germination time, the coefficient of determination (R2), CV and SE the best model for determination of cardinal temperatures of Malva sylvestris for 0 to -0.6 MPa was dent-like model and for -0.8 MPa was segmented model. In general, results indicated that lower limit of optimum temperature and upper limit of optimum temperature and ceiling temperature reduced but fo increased as a result of water potential increment. Conclusion Germination of Malva sylvestris response to different temperatures and osmotic potentials, led to acceptable results. Utilizing the output of non-liner models at different temperatures can be useful in prediction of germination rate in different water potential

Biochemical changes during ageing in medicinal pumpkin: lipid peroxidation and membrane damage

Seeds gradually lose their viability during storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seed. The lipid peroxidation through the production of free radical plays an important role in the loss of seed viability during seed storage. In the present study, we examined the relationship between the activity of free radical detoxifying enzymes, lipid peroxidation and seed deterioration in medicinal pumpkin (Cucurbita pepo subsp. Pepo. Convar. Pepo var. styriaca Greb) during storage. The seeds were incubated at different storage temperatures (35 and 5oC) and seed moisture content (5, 8 and 14%) for 2 and 4 days. Malondialdehyde content in seed was increased during storage with increasing moisture content and temperature, suggesting that seed deterioration was associated with lipid peroxidation. The increase in lipid peroxidation was related with increased electrical conductivity, which suggested membrane damage during deterioration. The decrease in germination was also associated with a decrease in catalase and peroxidase activity and as a result, the antioxidant system was not sufficient to protect seeds against free radical damage. Thus, medicinal pumpkin seed deterioration was closely related to decrease in the activities of free radical detoxifying enzymes and increased lipid peroxidation

Comparison of Different Models for Determining Time up to 50% Maximum Germination: A Case Study of Cottonseeds (Gossypium hirsutum)

DOR: 98.1000/2383-1251.1397.5. 1.10.2.1605.41 Extended abstract Introduction: Germination speed is one of the most important germination indices, used in most studies to compare the effects of different treatments on seed germination. Researchers use the reverse time up to 50% maximum germination (1/D50) to calculate the germination rate. One of the methods used for calculating the D50 is the utilization of nonlinear regression models such as Logestic, Gompertz, Richard, Weibull and Hill. In addition, for the purpose of calculating this parameter, simple empirical models such as the model presented by Farooq et al. and Ellis and Roberts are used. The question which arises is which of these methods has more precision predicting D50. The purpose of this study was to calculate D50, using different methods in seed germination of cotton. Material and Methods: In this experiment, cottonseeds were placed at three temperatures of 15, 25 and 40°C with three replications, and germinated seeds were counted daily several times. To calculate D50, several nonlinear regression models including Gompertze, Logestic, Hill (the four-parameter), Richard and Weibull models were used. Moreover, for the purpose of calculating D50, the models presented by Farooq et al. and Ellis and Roberts were used. Results: The results showed that all nonlinear regression models exhibited suitable fit to germination data. However, logestic, Hill and Weibull showed better predictability of D50, compared with other models. Besides, D50 calculated by the Farooq model was similar to that estimated by nonlinear regression models, whereas D50 estimated by the Ellis and Roberts model was higher than that estimated by other models. Conclusions: The results of this study showed that both non-linear regression models and the model developed by Farooq could be used to calculate D50 of cottonseed. In general, the results of this study showed that nonlinear regression models could be used to calculate D50. In this research, Logestic, Hill, and Weibull showed good fit for cumulative seed germination data of cotton seeds versus time at different temperatures. These models have coefficients that have a biological concept that includes maximum germination percentage, time to 50% maximum germination and time to start germination. Moreover, when researchers only seek to measure D50 and are not familiar with the statistical software, they can use the empirical formula presented in this research.   Highlights: Calculating D50 in cottonseeds, using different methods. Using nonlinear regression models to calculate D50 in cottonseeds. Developing a proper method which is more accurate, and better lends itself to calculating D50 of cottonseeds

Seed Priming Improves Enzymatic and Biochemical Performances of Rice During Seed Germination under Low and High Temperatures

As an abiotic stress, adverse germination temperatures cause serious disruptions in physiological and biochemical processes involved in seed germination. Using a factorial experiment, we examined the effects of different seed priming treatments on enzymatic and biochemical performances of rice seed germination under different temperatures. Each of the rice genotypes (Hashemi, Sadry-domsefid, IRON-70-7053-7 and NORIN-22) was primed with hydro-hardening, KCl, CaCl2 and ascorbic acid (AsA) and without a priming agent as a control at low (15 ºC), optimum (25 ºC) and high (35 ºC) germination temperatures. The results showed that the enzymatic and biochemical performances of all the rice genotypes were affected by the seed priming agents, especially under the low germination temperature. At 15 ºC, seed priming with AsA was found to be the best agent for the activities of amylase, α-amylase, catalase (CAT), peroxidase (POX), ascorbate peroxidase (APOX) and superoxide dismutase (SOD) as well as the content of soluble sugars in the NORIN-22 genotype, and for protease activity and soluble protein content in the IRON-70-7053-7 genotype. SOD at the low germination temperature and CAT, POX and protease at the optimum and high germination temperatures were the most important enzymes in occurrence of germination potential in terms of seedling length, vigor index, normal seedling rate and germination rate. Under the priming agents, the highest changes in normal seedling rate were observed at the low and optimum germination temperatures by AsA priming in the Hashemi and NORIN-22 genotypes, and at the high germination temperature under KCl priming in the Hashemi genotype

A quantitative analysis of seed dormancy and germination in the winter annual weed Sinapis arvensis (Brassicaceae)

The aims of this study were to determine the effects of burial on germination and longevity and of water stress and temperature on germination and dormancy induction of the weed Sinapis arvensis. During exposure to the high temperatures of summer seeds buried in the field became nondormant, but low water potential and supra-optimal temperatures (constant not alternating) induced them into secondary dormancy. The threshold temperature for dormancy induction (TTDI) was about 19 oC when water was not limiting germination, and it decreased with a slope of 10ºC per MPa as water potential decreased. Seeds had minimum dormancy (Dmin) when TThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author