جستجوی مقالات مرتبط با کلیدواژه "سبزشدن" در نشریات گروه "کشاورزی"

 Storage potential is an important characteristic for onion. Annually, a large quantity of worldwide onion production deteriorated during storage. The storage ability of onion is influenced by various endo- and exogenous factors including cultivar and storage conditions specially, temperature. Based on literature, there is considerable genetic variation for onion storability in onion germplasms from different origins. Rivera Martínez et al. (2005) evaluated the storability of 18 local and 4 commercial onion cultivars in Spain. Their results showed that there was significant variation for storability among different onion cultivars, and interstingly the local cultivars had more storability than commercial ones. Onion storage could also affected by environmental conditions such as temperature. Benkeblia et al. (2000) studied the effects of various temperatures on respiratory parameters of onion. Their finding showed onion respiration were raised by increasing temperature. Likewise, the positive effect of higher temperature on enhancing the growth of sprouts and elevating transpiration has been reported (Miedema, 1998; Yoo et al., 1997). Although, Afghanistan is considered to be one of the origins of onion (Brewster, 1994) there are no reports on estimating the storability of Afghan local cultivars under different temperature conditions. So this research has been conducted to study the effects of various temperatures on storability of native onion cultivars of Afghanistan.

 In this research, the plant materials consisted of 10 onion cultivars consisting eight local varieties “Hanaaie Harat”, “Zard-e-Harat”, “Ghermrz-e-Harat”, “Mazar-e-Sharif”, “Kabul”, “Sar-e-Pul”, “Ghonduz” and “Balkhaab” originated from Afghanistan, an Iranian cultivar (“Ghermez-e-Azarshahr”), and a commercial cultivar “Sweet Grano”. The cultivars were stored at two different temperature regimes (5 ºC and ambient temperature), during six-time intervals of 20 days. The average temperature of ambient storage was 13 °C ranging from 8-18 °C. The experiment lasted from November 6th, 2011 to March 5th, 2012. This research was performed in a completely randomized design based on split factorial design, with three replications. For each replication, 50 healthy non-sprouted bulbs were packaged in plastic nets. Storage potential related characteristics such as sprouting percentage, weight loss percentage, sprout length, and sprout weight/bulb weight ratio in 20 days intervals were measured. All data were subjected to analysis of variance (ANOVA) using SAS statistical software. Mean comparisons were calculated at 5% probability level using LSD when the F-value was significant (Fisher’s protected LSD).

 The results showed that there were significant differences among cultivars for storage characteristics (weight loss percentage, sprouting percentage, length of sprouts and sprout weight/bulb weight ratio). “Ghonduz” and “Ghermrz-e-Harat” local cultivars had the most and least storage ability, 50% of bulb sprouting after 105 and 35 days, respectively. Rivera Martínez et al. (2005) and Ramin (1999) also reported Spanish and Iranian local cultivars had more storability compared to commercial cultivars. In 5 °C, weight loss of onion bulbs followed a linear model during storage period. But, in ambient storage, it was higher at the beginning and the end of storage period, showing the adverse effects of high temperatures on bulbs weight loss during storage. The interaction between cultivar and time was also significant. It showed onion weight loss differs in various intervals.  It could be attributed to the genetic variation and morphological difference such as number and thickness of dry scales of onion bulbs. In ambient storage condition, onion sprouting percentage showed a sharp increase in early storage intervals and became stable in the late intervals. Under 5 °C treatment, it raised as a linear model with very slow slope. It seems that weight loss and sprouting of onion bulbs in ambient storage is dependent on temperature and relative humidity of environment. This finding is in agreement with previous reports (Baninasab and Rahemi, 2006; Forudi, 2005). The sprout length and the ratio of sprout weight to bulb weight was lower in 5 ºC than ambient temperature. Abdalla and Mann (1963) and Yoo et al. (1997) also reported that smaller sprouts were observed in lower temperatures. 

 In this experiment, the effects of temperature on storability of some local cultivars of onion originated from Afghanistan were studied in different intervals. It was found that the storage potential of onion bulbs could be influenced by genetic factors and environment conditions such as temperature. Findings of this research showed that sprouting percentage, weight loss percentage and onion sprout growth were less under 5 °C treatment than ambient temperature. Therefore, it was concluded that storing onion bulbs in low temperature conditions can reduce the onion spoilage and improve their storage life. Additionally, cultivars showed highly significant variations for all characteristics related to storage ability. Our findings showed that some local cultivars are more storable than commercial cultivars. Among the cultivars, “Ghonduz” cultivar has more storage potent as compared to all studied cultivars. Our results confirmed that local cultivars can be a good source of desirable genes related to storability. Subsequently, they can exploited to broaden the genetic base of breeding matreials.

The purpose of this study was to quantification the effect of secondary dormancy inducing on emergence rapeseed using Chapman-Richards model under field conditions. This experiment was carried out using 20 rapeseed genotypes cultivated in Iran under field conditions. Seeds were tested for secondary dormancy according to the Hohenheim standard dormancy test. Seedling emergence trial was carried out using a randomized complete block as a factorial arrangement with four replications in a research farm of Abourahian Campus, University of Tehran for 122 days. Emerged seedlings were removed after counting. The results of this study showed that both genotype and drought stress factors are effective on seedling emergence percentage and rate of rapeseed under field conditions. However, potential secondary dormancy inducing was different among the cultivars, and in Karaj2, H50 and SLM046 genotypes emergence rate before inducing secondary dormancy was 0.407, 0.143 and 0.355 which increased to 0.411, 0.228 and 0.364 after inducing secondary dormancy, respectively. the results of the mean comparison showed that the maximum percentage of emergence in nondormant seed was related to Ahmadi cultivar, but this cultivar was not significantly different with other varieties of Hayola, Moghan, SLM046, RGS003, Opera and Karaj. When secondary dormany induced to seeds, Ahmadi cultivar had the highest percentage of emergence and the lowest percentage of emergence after dormancy inducing was related to Talayeh cultivar.

To evaluate the effect of rimsulfuron and oxadiargil and also rimsulfuron and metribuzin combinations on weed biomass and tuber yield of potato, a factorial experiment based on a randomized complete block design with 3 replications performed in 2016. Factors consisted of herbicide mixture ratio (0:100, 25:75, 50:50, 75:25 and 100:0), herbicides time of applications (pre-plant and potato emergence stages) and herbicide mixture of rimsulfuron and oxadiargyl and also rimsulfuron and metribuzin. In all treatments, a weedy plot as semi control and a weed free plot as control were considered. Results showed that the maximum reduction percentage of total dry weight of weeds obtained in 25% oxadiargyl + 75% rimsulfuron and also 25% metribuzin + 75% rimsulruron at potato emerge stage. Also, after weed free treatment which increased total potato tuber yield compared to herbicide mixtures by 1.33%, the maximum total potato tuber yield obtained from 25% oxadiargyl + 75% rimsulfuron at pre-plant stage witch increased 69/16% total tuber yield of potato compared to weedy control.

To evaluate the effects of two herbicides mixures, of Oxadiargyl and Rimsulfuron on weed control and potato yield and its components, a randomized complete block design experiment with 3 replications was conducted at the Research Field of Mohaghegh Ardabili University. The factors include Rimsulfuron in 0, 12.5, 25, 37.5 and 50 gr a.i/ha and the Oxadiargyl in 0, 0.2, 0.4, 0.6 and 0.8 lit a.i/ha in 5 herbicide mixture percentage two by two (include: 0:0.8, 12.5:0.6, 25:0.4, 37.5: 0.2 and 50:0) and the second factor is different time of application of these herbicides include (preplant and potato emergence). The statistical analysis showed that interaction effect of two herbicides mixture percentage and time of application had significant effect on reduction percentage of density of Commen Lambsquare, Redroot Pigweed and Field Bindweed. In order to results herbicide mixture application improved the efficacy of each herbicide on weed control, wherby these herbicide mixture percentages reduce density of Commen Lambsquare in 75% Oxadiargyl + 25% Rimsulfuron, Redroot Pigweed in 25% Oxadiargyl + 75% Rimsulfuron  and Field Bindweed  in 100% Rimsulfuron lonely recpectively 100%, 94.67% and 59.67% in preplant stage. Interaction effect of herbicide mixture percentage on time of application had significant effect on mean of tuber weight, yield of per plant and total tuber weight. The results of total yield showed that treatment of 25% Oxadiargyl + 75% Rimsulfuron in potato emergence application by 69.16% increasment in comparison to weedy was the best recommended treatment of experiment. Also the results showed that despite increasment in enzyme activity of Catalase, this increasment hadn’t destructive effect on yield of potato, so conclude application of this herbicide mixture hadn’t any destructive effect on potato.

Because of small and low quality seeds, St Johns wort (Hypericum perforatum L.) have not favorable establishment in the field. In these study effects of different seed enhancement treatments were applied on the seeds and relationship of emergence with germination characteristics and amylase activity were evaluated. A factorial experiment was conducted in randomized ccompletely design with four replications. Osmopriming with Polyethylene glycol 6000 in five levels (0, -3, -6, -9 and -12 bar) were conducted as first factor and application of Gibberellic acid at four concentration (0, 500, 1000 and 1500 ppm) as second factor. Analysis of variance showed that polyethylene glycol, gibberellin and their interaction had significant effects on germination and emergence of St Johns wort seeds. Continuous application of PEG and GA had most favorable effect on germination, emergence, vigor and Amylase activity compared to the control and separate application of them. Concentration of 1000 ppm of gibberellin in -12 bar of osmotic potential caused to highest germination (91.5 %), emergence (80.5 %), seed vigor (32.08) and amylase activity (25.21 starch breakage percentage). While the control showed lowest performance in all measured traits. Correlation analysis showed a positive and significant correlation between seedling emergence of and germination percentage (r=0.89**), seed vigor (r=0.95**) and amylase activity (r=0.92**) of St Johns wort seeds. Based on the results, it is seems that application of priming techniques improve establishment of St Johns wort seeds via increasing germination, seed vigor and amylase activity.

Milky thistle (Silybum marianum) is an annual or biennial plant of the Asteraceae family. Possibly native near the coast of southeast England, it has been widely introduced outside its natural range, for example into North America, Iran, Australia and New Zealand where it is considered an invasive weed.
Seed is an important stage of plant life history. Most invasive plants primarily rely on seedling recruitment for population establishment and persistence. The rapid spread of many invasive plants is frequently correlated with special seed traits. Seed trait variations exist not only among species but also within species. Seed traits variations within a species are essential for the seedling establishment at different habitats.
Environmental factors, such as temperature, soil solution osmotic potential, solution pH, light quality, management practices and seed location in the soil seedbank, affect weed seed germination and emergence.
Fluctuations in temperature can influence seed germination differently than those under constant temperatures; however, such information is not available on Milky thistle. A light requirement for germination is the principal means by which germination can be restricted to an area close to the soil surface, and species requiring light for germination are potentially more likely to be prevalent in no-till and pasture systems. Soil pH affects the development and competitiveness of crops and weeds by affecting the availability of essential minerals, nutrients, the solubility of toxic elements, and soil microflora. Seed burial depth (buried by tillage or other means) also affects germination and seedling emergence of several weed species.
Better knowledge of the factors that influence seed germination and seedling emergence of Milky thistle could contribute to the development of control measures and help determine its potential for invasion into new areas. The objectives of this study, therefore, were to determine the effect of various environmental factors on seed germination and seedling emergence of Milky thistle.
Material and Germination of Milky thistle was determined by placing 25 seed in a 9-cm-diam Petri dish containing two layers of Whatman No. 1 filter paper and moistened with 5 ml of distilled water or a treatment solution.
Temperature: Germination of freshly harvested seed was determined in growth chambers under fluctuating day/night temperatures (15/5, 20/10, 15/25, 15/30 and 20/35˚ C).
Salinity: In this experiment, seeds were exposed to seven levels of increasing salinity using NaCl solutions including 0, 10, 20, 40, 80, 160 and 320 mM. Petri dishes were incubated as described in the general protocol under the light⁄dark regime.
pH: To examine the effects of pH on seed germination, buffered solutions of pH 5 to 9 were prepared.
Seed burial depth: The effect of different burial depths on seedling emergence was investigated in a growth chamber. Seeds were buried at six different depths (0, 0.5, 1, 2, 4, and 8 cm) in 15-cm-diam plastic pots.
Statistical analysis: Data were subjected to two-way analysis of variance (ANOVA) and the difference between treatment means was separated using FLSD test. A significance level of 5% was applied by SAS 9.2.
The results showed that effect of different temperature regimes on germination percentage and rate, plumule length and seedling dry weight were significant (P

Various species of Satureja genus are growing in different regions of Iran. The drought stress is one of the most unfavorable factors for plant establishment and growth in main parts of the Iran. Germination and emergence of the most plants is affected by environmental stresses including drought and disturbed evnironments. One way to improve seeds and seedlings to cope with stress is seed priming. This research was conducted in order to study the effects of osmo and hydro priming at different temperatures on improving seed and seedling performance of Satureja khuzestanica Jamzad under drought stress conditions. A greenhouse research was carried out as a factorial experiment on the base of a randomized completely block design with three factors and four replications. The factors were including drought stress (50% and 25% of field capacity) with control (75% of FC), osmotic potential of priming (0, -4, -8 bar using PEG 6000) and priming temperatures (15 and 25 ºC). The percentage and rate of emergence, seedling fresh and dry weights, seedling height, vigor index, and leaf area decreased by increasing drought stress but the essential oil content and root length increased. The highest percentage of essential oil observed under 25% FC. Interaction of drought stress and osmotic potential of priming solution was significant on percentage and rate of emergence and vigor index. The interaction of priming temperatures and osmotic potential of priming was significant on the percentage and rate of emergence, vigor index, and shoot dry weight. Hydro-priming at 15 ºC had the most positive effect on the percentage and rate of emergence, fresh and dry weight of seedling, root length, plant height, leaf area, and vigor index. Overall, seed quality was better when priming temperature was lower (15 ºC).

Trittipyrum is an important annual grass plant for forage production in arid and semiarid regions. The effects of drought stress on Trittipyrum lines were evaluated in the field experiment in a randomized complete block design with factorial experiment involving three replications in 2012. Treatments were water stress (field capacity (FC), 75% of FC, 50% of FC and 25% of FC throughout the experimental period and 13 primary Trittipyrum lines ((St/b)(Cr/b)F4, (Ma/b)(Cr/b)F4, (Ma/b)(Cr/b)F3, (Ka/b)(Cr/b)F2, (Ka/b)(Cr/b)F3, (Ka/b)(Cr/b)F5, (Ka/b)(Cr/b)F6, La(4b,4d)/b, St/b, Cr/b, La/b, Ka/b, Az/b). The results showed that drought stress had significant effects on seedling traits. Drought stress significantly decreased shoot length, root length, shoot dry weight, root dry weight, seedling dry weight, seedling length vigor index and seedling weight vigor index. The results of mean comparison revealed that (az/b)(cr/b)F5 and Kz/b lines were the most sensitive and the most tolerant lines to drought stress in early vigor stage, respectively. Although the response of Trittipyrum lines were different to drought stress, but the result indicated that Trittipyrum lines are sensitive to drought at emergence stage.

In order to investigate the early growth response and sodium and potassium ions concentration in ten barley (Hordeum vulgare L.) cultivars under effect of salinity tension¡ an experiment was conducted at a controlled environment at Agriculture collage of Shiraz University. In this greenhouse research ten barley cultivars including Eram¡ Karoon¡ Kavir¡ Jonoob¡ Makoei¡ Afzal¡ Shirin¡ Gohar¡ Nosrat and Reyhan were investigated in two irrigation regimes by tap water (0.62 dS m-1¡ as control) and salt water by electrical conduct 20 dS m-1 in a sand culture system. The results showed that salinity significantly decreased emergence percentage and rate¡ leaf area¡ shoot and root dry weight¡ potassium concentration and the ratio of potassium to sodium and increasing sodium concentration. The response of cultivars to salinity was different. The ratio of potassium to sodium (40.7 percentage reduction) and root length (4.6 percentage reduction) showed the most and the least reactions to salinity. On average¡ salinity tension decreased 24.3 percentage shoot dry weight of barley cultivars that the most and the least reduction percentage were observed in Shirnin (31.6 percentage) and Afzal (16.3 percentage) cultivars¡ respectively. The traits of mergence percentage¡ potassium concentration and root dry weight in optimum conditions and root dry weight and the ratio of potassium to sodium in salty conditions were identified as the most effective traits on shoot dry weight. According to this¡ Afzal and Kavir cultivars can be associated as the tolerant cultivars and Shirnin and Reyhane cultivars as sensitive cultivars to salinity. The results of this research showed that although emergence rate and percentage traits appeared to be essential for better plant growth¡ but has no direct effect on salinity tolerance.

Priming is one of the seed enhancement methods that might be resulted in increased seed performance (germination and emergence). The objective of this research was to evaluate effect of priming on seed emergence and yield under wide ranges sowing dates in cotton. Treatments were combinations of 6 sowing dates and 2 seed treatments (control and primed seeds). Hydropriming method was used; seeds of Siokra 324 were moistened in water for 16 h at 25oC. Results indicated that priming affects seed emergence components. Primed seeds had faster and more uniform emergence at all sowing dates. Priming also affected germination response to temperature; primed seeds “emerged” at lower base temperature. Base temperature was 15.4oC for control seeds, but was 13.5oC for primed seeds. Primed seeds had high yield than unprimed seeds (control) at all the sowing dates.

Ceratocarpus arenarius L. is one of the problematic and noxious weeds in dryland farming of wheat, barley, lentil and peas in north of Khorasan. In order to determine the effects of temperature, light, salinity and drought stress and burial depth on seed germination and seedling emergence of this species, experiments were conducted in the Research Laboratory of Birjand Faculty of Agriculture. Ceratocarpus seeds had identical germination in either light/dark and continuous dark regimes, indicating this weed species is non-photoblastic. Seeds germinated over 85% in the range of alternating day/night temperatures (20/10, 25/15 and 30/20ºC) and the maximum germinability (96%) was observed at 25/15ºC. Ceratocarpus arenarius seeds maintained their germinability at high levels of salinity and drought stress, so that at NaCl concentration of 800 mM and osmotic potential of -1 MPa seed germination was 20 and 25%, respectively, indicating this species is tolerant to salinity and drought stress. Seedlings could emerge from a range of burial depth from 0 to 6cm and maximum emergence (94%) was observed from seeds planted on the soil surface covered with 3 layers of filter paper. This shows that minimum- and no-till systems would increase seedling emergence of this species through keeping crop residues on the soil surface.

Emergence of crops is affected by environmental factors such as soil water, salinity and sowing and seed quality. The present study was conducted to evaluate the effect of seed aging (seed quality) on emergence of wheat under optimum (control) and stressful conditions including salinity (2 levels), drought (2 levels) and deep sowing depth (physical stress). Seeds (cv. ‘Zagros’) were kept at a high temperature (43°C) and high relative humidity (90-95%) to create different classes of seed aging. Factorial combinations of 5 seed aging treatments (0, 48, 72, 96 and 144 h accelerated aging periods) and 6 levels of environmental factor were treatments of the experiment. Results indicated that maximum and rate of emergence reduced significantly with increase in the duration of accelerated aging in all environmental factors. Decreasing slope of maximum emergence for control, medium drought, severe drought, sowing depth, medium salinity, severe salinity were 0.192, 0.304, 0.152, 0.296, 0.221 and 0.184, respectively. Decreased percent of emergence in 0 h compared with 48, 72, 96 and 144 h at control environment condition were 9.10, 5.68, 21.59 and 27.27 respectively. But, this decreased percent of emergence increased in stress conditions. Overall, seeds of high vigor had better emergence than low vigor seeds in stress and they had higher maximum emergence and rate.

The main objective of this study was using of canonical correlation analysis (CCA) to find relations between 15 different variables of seed emergence and seedling growth related characteristics of seven important crop that were classified in three groups. The studied groups of variables were included physical characteristics (seed weight, seed length, seed density, water absorption and water content), seed germination characteristics (germination percentage, germination rate, uniformity of germination, wet and dry weight of petridish grown seedling) and seed emergence characteristics (emergence percentage, emergence rate, uniformity of emergence, wet and dry weight of field grown seedlings) and crops were included of wheat, barley, soybean, cotton, rapeseed, sunflower and safflower. The CCA revealed two considerable associations between physical characteristics and seed and seedling characteristics grown in petridish. The first pair of canonical variables had a correlation coefficient of 0.99. The physical and growth related characteristics of seedlings grown in petridish most consistently correlated with the first pair of canonical variables respectively were seed density, water absorption, water content, germination percentage, wet and dry weight of petridish grown seedlings. The second pair of canonical variables between physical characteristics and seed and seedling characteristics grown in petridish had a correlation coefficient of 0.73. The CCA indicated that there are three important pairs of canonical variables between physical characteristics and seed and seedling characteristics grown in field with correlations of 0.92, 0.86 and 0.8, respectively. Also there was one considerable pair of canonical variables between seed and seedling characteristics grown in field and grown in petridish with correlation of 0.78. Careful evaluation of distribution of each measured variables in the obtained canonical variables revealed that there was considerable relationship between seedling weight and germination with water content or absorption of seeds; seed size with seedling weight; and biomass production with growth in petridish. Finally, the results showed that CCA could be use for evaluation of association between seed physical characteristics, germination and seedling growth.