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

In order to identify different landraces of onion seeds in terms of germination characteristics, an experiment was conducted in a completely randomized design with four replications in the Biology Laboratory of the Faculty of Agriculture, Ferdowsi University of Mashhad in 2020. The experimental treatments were 29 native landraces of onion seeds from different regions of Iran and two improved cultivars as control. The results showed a significant difference for all measured indices amongst landraces. Also, the clustering results of the landraces, based on the apparent characteristics, showed that among the 4 clusters, the third cluster, which includes 9 landraces (Harsin, Kavar, Azarshahr, Bonab, Yasuj, Qorveh, Kashan white, Neishabour white and Qoli Qeseh) has better appearance characteristics in terms of 1000-grain weight (average 4.54 g), grain length (average 3.08 mm) and grain diameter (1.9 mm). Also, it was shown based on germination characteristics that among the six indivisual clusters, the fourth cluster with 7 landraces including Yasuj, Kashan white, Dorcheh Yellow, Turkey, Tarom, Neishabour white and Qorveh has better germination characteristics. In general, it can be concluded that based on the appearance and germination characteristics, Yasuj, Kashan white and Neishabour white landraces showed a better seed quality.

Introduction

Planting onion sets instead of seeds or seedlings in situations where factors such as physical and chemical quality of soil and water are very limiting, is the safest planting method to achieve maximum plant establishment in the ground. In order to determine the appropriate planting date and density (in the treasury), storage conditions of bulbs in storage and the response of cultivars belonging to the long day type to this method of onion production, the present plan was implemented to optimize the conditions of production and storage of anions. Appropriate means, it is possible to compare the agricultural problems of this production method with common methods such as direct seeding and planting seedlings in the present study.

In order to determine the optimazation of dry onion sets production and to examine the storage capacity of produced dryonion sets, a field experiment was carried out in Kabutar Abad Research Station in Isfahan during 2015-2016 in a split- split plot experiment based on RCBD with three replication.The effects of nursery planting date (30 March, 30 April, 30 May), plant density (15 and 30 g m-2) and variety (Dorche, White Kashan and Sweet spanish) on dry onion sets pruduction in long day condition, this experiment. In a separate experiment, three planting date (9 May, 9 June and 10 July) and two plant density (15 and 30 g m-2) in a short variaty was examinated. Also, in order to investigate the possibility of using heat treatment to reduce or stop bolting, another experiment was conducted in a completely randomized design with three replications for the three cultivars. In each repetition, 400 anions (randomly with a size of 10 to 20 mm) are distributed in plastic nets and in a warehouse whose temperature is supplied by a gas heater and between 28 and 32°C was, for a period of two months (from February 10 to April 10) and the number of surviving onion sets was calculated after removing those that were rotten, green and hollow. Experimental data were analyzed by SAS software version 9.4 and the means were compared based on Duncan's multiple range test.

According to the results, the best planting date was 30 April by the mean 616 onion sets pruduction for all three variety in long day types and 9 may by the mean 311 inion sets in short day types and the effect of seed weight (15 and 30 g m-2) was nonsignificant. In two separate experiments, storability of onion sets was examinated in ambient storage (6-28 °C) after 118 days and warm storage (> 30 °C) after 60 days. The cause of this phenomenon can be traced to the reaction of the onion plant to the length of the day, so that the cultivar in question, due to its short day, in the face of long and hot days, without being able to develop and produce enough leaves, enters the production stage. They are fried and of course their size will be very small. Results indicated that 84%, 64% and 61% of onion sets survied in the first condition for three population (Dorche, kashan and Sweet Spanish). What was evident in this experiment was that most of the surviving onion sets were those who had completed the maturation process in the field, and conversely, the higher storage losses were in those that had leaves and leaves at harvest. Growth has been observed. Such a phenomenon was also observed in edible bulbs, so that bulbs with thick necks and green leaves are more susceptible to the entry and establishment of pathogens during storage during harvest. An observational estimate in this experiment indicates that the percentage of green onion sets is not more than normal storage and the main losses are due to depletion and water loss. As reported in the storage of edible onions, very high temperatures (about 38 °C) and very low temperatures (about 0 °C) both prevent flowering and sprouting of bulbs.

Based on the results obtained from the four experiments, in the first planting date, due to the existence of sufficient time (from emergence to harvest) and coincidence of leaf production with favorable environmental conditions (high temperature and long day length), a larger share of total yield to shoots Coarse was allocated and as a result the number of onion sets was reduced. Finally, they did not enter the phase of coagulation and anion production. In summary, spring sowing of long-day onion cultivars by onion sets with a treasury date of 10 May and a seed density of 15 g m-2 is recommended.

Cytotoxic and genotoxic effects of extract and essential oil of medicinal plants are evaluated by cytogenetic experiments and parameters like mitotic index and chromosomal aberrations. Evaluation of cytotoxicity and genotoxicity of aqueous extracts of Securigera cecuridaca seeds, Adiantum capillus-veneris leaves, and Trachyspermum ammi fruits on meristem cells of Allium cepa root and its growth was the aims of this study. Twenty gram of powdered samples were poured in to separate Erlenmeyer flask and 100 ml of distillated water were added. The flasks were covered by aluminum foil and shacked for 24 hours. Then extracts were filtered and centrifuged. In order to determine percentage of mitotic index and chromosomal aberrations 3000 cells were countered for each treatment and by division of mitotic cells and chromosomal aberrations numbers to total cells multiply to 100 were calculated. The results showed that the reduction of mitotic index and root growth of onion are related to extract concentration. The highest cytotoxicity and genotoxicity are related to aqueous extracts of A. capillus-veneris leaves and S. securodaca seeds, respectively. The extracts of three plants induced chromosomal aberrations such as C-mitosis, chromosomal stickiness, loss and laggard chromosome, chromosomal bridge, micronucleus and also cell death in the root meristematic cells of onion. The extract of S. cecuridaca seeds had the highest genotoxicity. Root of Allium cepa test is a rapid and efficient method for evaluation of cytotoxicity and genotoxicity of aqueous extracts of medicinal plants. This study shows that consumption of medicinal plants must be with precaution.

In order to study the effect of priming on onion seed germination of Zangan Cultivar in different temperature conditions, this study was carried out with 6 levels of temperature of 5 to 30 ° C and three seed pretreatment, include control, hydro-priming and halo-priming with 0.5% potassium nitrate with three replicate. The results showed that priming treatment with potassium nitrate (0.5%) could be effective on germination components. Primed seeds with potassium nitrate (0.5%) showed more germination at all temperatures. Potassium nitrate (0.5%) treatment also affected the germination reaction to temperature. These seeds showed 33.6% more germination than the other two treatments at 5°c. The results showed that germination percentage at 20°c in all treatments reaches its maximum and then remained relatively constant. In evaluating the segmented model for predicting cardinal temperatures, seed germination at base, optimum and ceiling temperatures was 1.7, 27.38, 46.09°c(in potassium nitrate (0.5%) treatment), 1, 25, 43°c (in hydro-priming treatment) and 1.9, 27.6, 46.12°c (in control treatment). For predicting time of germination at different constant temperatures used Thermal-time that constant coefficient of Thermal-time was 1872.79(°Ch).

About one third of the onion harvesting time and cost is consumed for removing of leaves from onion bulbs. Accordingly, the use of appropriate topping technologies is one of the main objectives for development of onion harvesting mechanization. In this study, a rolling onion topper was modified in such a way that to be mounted on a tractor. Then, the effect of two rotational speeds of leaf remover blades namely, 2950 and 1800 rpm on remaining leaves of onion bulb after cutting, and also, the percentage of topped onions and percentage of damaged bulbs were measured to determine the suitable speed. Necessary modifications were made on the machine to enable it to be run and transported by a tractor. In the next step, the machine's field capacity was calculated and economical comparison between conventional topping method by labor and the device was carried out. The results showed that both 2950 and 1800 rpm rotational speeds of the topping blades do not have significant effect on remaining leaves after cutting, percentage of topped onions and percentage of damaged bulbs. According to the design requirements and energy reduction of leaves removing, the rotational speed of 1800 rpm was proved to be the appropriate speed. Economic evaluations showed that replacing of conventional topping method by topping machine reduces work force by 43 workers and saves 53% of the costs per hectare.

One method for digging onions up during harvest operation is using a rod cultivator in which, combination of rotational and linear movements of the rod underneath the bulbs, dig the onions out. Total power consumed by rod cultivator comprises two parts; one for driving the rod, and the other, for pulling the rod along the field. Travel speed as well as operation depth (depth to width ratio) of onion rod digger are both important factors that affect the total power consumption. In the present research, the effect of travel speed as well as operation depth on power demand of an onion rod digger was studied using a split plot in randomized complete block design with three replications. The treatments were operation depth in two levels, namely, 5-7 and 10-12 cm as the main plots and travel speed in three levels, namely, 0.3, 0.4 and 0.5 m/s as the subplots. During each treatment, draft force, drawbar power, torque and rotational power were measured. Based on results, draft force and drawbar power were between 4865 and 6400N, and, 1857.5 and 3125.5 W per meter of work width, respectively. In addition, the measured torque and rotational power were between 25.2 and 35.1 N.m, and, 1079 and 1814.5 W per meter of work width, respectively. Considering 2 m of work width for onion digger, tractors capable of delivering about 6.5 kW of drawbar power and about 4 kW of PTO power, are able to run onion digger. Most of the tractors currently used by farmers in Iran, fall within this category.