Parvin Salehi Shanjani; Hamideh Javadi; Leila Rasoulzadeh; Leila Falah Hoseini; Arash Mamedi
Abstract
To investigate the cardinal temperature of three medicinal species of Nepata haussknechtii, N. pogonosperma and N. glomerulosa subsp. staffina and determining the appropriate temperature and time conditions for their planting, a factorial experiment was carried out in the form of a completely randomized ...
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To investigate the cardinal temperature of three medicinal species of Nepata haussknechtii, N. pogonosperma and N. glomerulosa subsp. staffina and determining the appropriate temperature and time conditions for their planting, a factorial experiment was carried out in the form of a completely randomized design in three replications in 2023 in the Seed Technology Research Laboratory of the Gene Bank of Natural Resources of Iran. Three non-linear regression models, including dent-like, segmented and beta, were evaluated at eight temperature levels (5, 10, 15, 20, 25, 30, 35 and 40°C) to describe the response of the seed germination rate of three Nepeta species to temperature. Statistical indices such as root mean square (RMSE) and coefficient of explanation (R2) were used to compare the models.The results showed that the parameters estimated using the dent-like model in N. haussknechtii include base temperature, optimal lower temperature, optimal upper temperature, ceiling temperature, R2 and RMSE values were 9.01°C, 20°C, 25°C, 36.21°C, 0.94 and 0.11, respectively; segmented model in the N. pogonosperma include base temperature, optimal temperature, ceiling temperature, R2 and RMSE values were 9°C, 23°C, 36.14°C, 0.95 and 0.31, respectively; and beta model in the N. glomerulosa subsp. staffina include base temperature, optimal temperature, ceiling temperature, R2 and RMSE values were 9.84°C, 24.95°C, 37°C, 0.99 and 0.03, respectively had more confidence. The results of this experiment showed that in the different studied species of Nepeta, due to the similar initial growth rate, they have the same germination peak.
Arash Mamedi; F. Sharifzadeh; Reza Maali Amiri
Abstract
Quinoa has attracted a lot of attention in recent years due to its low ecological needs and rich nutritional value. Therefore, the variability of germination components to temperature and determination of cardinal temperatures were performed by seed germination test at different constant temperatures ...
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Quinoa has attracted a lot of attention in recent years due to its low ecological needs and rich nutritional value. Therefore, the variability of germination components to temperature and determination of cardinal temperatures were performed by seed germination test at different constant temperatures from -1 to 45°C.The results of the dent-like model showed that the base temperature and ceiling temperature of quinoa were -03.04 and 45.45°C, respectively, and the optimum temperature was from 20 to 35°C. To investigation the effect of salinity and drought stress on germination at 25°C, the seeds were exposed to osmotic potentials from 0 to -28 bar, which were made of sodium chloride (NaCl) and polyethylene glycol (PEG), respectively, to induce stresses. The results showed that the reduction of osmotic potential up to -12 bar was not able to significantly reduce the germination components compared to normal conditions. However, with decreasing osmotic potential to -18 and -24 bar, the germination percentage decreased significantly. The germination was completely stopped at -24 bar of drought-induced, while 24% germination was observed at the same point of the salinity-induced osmotic potential. Therefore, seed germination capacity under salinity-induced stress was more tolerant than drought-induced stress at all levels of osmotic potentials. Most likely, due to the fact that quinoa is halophyte, by absorbing the ionic elements of salt, required for the maintenance of the cell turgor, which concurrent increase in cytosolic osmolality. Thus, this species has a great potential for distribution to other areas such as provinces with dry climate.
vahid amiri monfared; Reza Tavakkol afshari; arash mamedi
Abstract
The prediction of seed viability is important for seed producers, and its prediction in storage depends on the understanding of the quantitative relationships between seed loss, seed moisture and storage temperature. In order to study the effect of temperature, seed and time on the deterioration of the ...
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The prediction of seed viability is important for seed producers, and its prediction in storage depends on the understanding of the quantitative relationships between seed loss, seed moisture and storage temperature. In order to study the effect of temperature, seed and time on the deterioration of the anise seed, and also quantitative characterization of this effect and determining the coefficients of life, this study was carried out in a randomized complete block design in a factorial experiment in the Agricultural Laboratory of Tehran University. The temperature was measured at 4 levels (5, 15, 25 and 35 o C), soil moisture contents in 4 levels (5, 9, 13 and 17%) and six times (one, two, three, four, five and six months) as the factors were this test. The results of analysis of variance showed that the effect of temperature on seed moisture content was significant for germination indices at 1% level. With increasing temperature and humidity, germination declined over time. Life coefficients after six months of storage showed that survival curves can be plotted with a single source. Also, the results showed that by increasing the moisture content at any temperature, especially at higher temperatures, the life expectancy decreases with increasing moisture content. Using the life-time equation, the coefficients KE=4/21, CW =1-66, CH =0 038/0 and CQ =0,00039 were calculated.
A. Mamedi; R. Tavakkol Afshari
Abstract
Quinoa (Chenepodium quinoa Willd.) is a grain-like crop which has a high grown potential in Iran. Due to it's seed have high nutritional value, therefore, compared to milk nutrition by the FAO. This study aims to determine the seed dormancy and pre-harvest sprouting three cultivars of quinoa. This plant ...
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Quinoa (Chenepodium quinoa Willd.) is a grain-like crop which has a high grown potential in Iran. Due to it's seed have high nutritional value, therefore, compared to milk nutrition by the FAO. This study aims to determine the seed dormancy and pre-harvest sprouting three cultivars of quinoa. This plant was planted in a randomized complete block design at the research farm of university of Tehran and, phonological traits were recorded. Then the related studies such as seed dormancy and pre-harvest evaluation resistance were conducted in two 15 and 25°C constant temperatures in seed laboratory. The results shown that there is significant genetic variation for pre-harvest sprouting and other traits. The results demonstrate that Titicaca and Santamaria have lowest and highest germination in cluster, respectively. Also, Titicaca cultivar related to the other cultivars have had high percentage of seed dormancy. The results shown that it is possible to handle the quinoa crop in such areas which have frequent risk of PHS.
V. Amiri Monfared; A. Hashemi; A. Mamedi; R. Tavakkol Afshari
Abstract
The aim of this study was to quantify the response of germination rate to temperature and to find cardinal temperatures required for different germination percentiles in Papaver somniferum. Four models of non-linear regression [Quadratic, Segmented, Beta and Dent-like] were evaluated to describe the ...
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The aim of this study was to quantify the response of germination rate to temperature and to find cardinal temperatures required for different germination percentiles in Papaver somniferum. Four models of non-linear regression [Quadratic, Segmented, Beta and Dent-like] were evaluated to describe the relationships between germination rate and temperature of P. somniferum over 7 constant temperatures (3, 5, 10, 15, 20, 25 and 30 ˚C). Different statistical indices [Root Mean Squares of Error (RMSE) and coefficient of determination (R2)] were used to compare models performance. The Dent-like was found to be the best model to predict germination rate (RMSE=000.35, R2=0.87). The base, sub optimum, supra optimum and the ceiling temperatures for P.somniferum seed germination were estimated 3, 7, 20 and 31˚C, respectively. The cardinal temperatures depended on the model used for their estimation. Overall, Dent-like was better suited than the other models to estimate the cardinal temperatures for germination of P. somniferum seed. The highest germination percentage (72) and germination rate (0.86) was observed in 10 and 15 ˚C, respectively.
