جستجوی مقالات مرتبط با کلیدواژه "تنش خشکی" در نشریات گروه "مکانیزاسیون کشاورزی"

The majority of volume in a plant cell is water, therefore changes in water content drastically affect the growth and metabolism of plants. To handle plants growth in water limited and drought stress conditions numerous mechanisms are considered to be used. In this study it was shown that the automated irrigation system could measure and determine the morphological and color parameters of plant as well as the plant wilting condition. Moreover, the required water for plants has been detected through automated irrigation system, and finally it performs necessary actions in order to improve plant condition. To check the system, in this study, an ornamental shrub with the scientific name of Plectranthus scutellarioides was chosen. According to statistical analysis, there were significant differences between the measured parameters of the wilting and fresh plants (p

Drought stress in germination stage is one of most important factor that limit yield and growth of lentil in Iran. The heterotrophic seedling growth can be considered as the product of three components: initial seed weight، the fraction of seed reserves which are mobilized، and the conversion efficiency of mobilized seed reserves to seedling tissues. In order to investigate the effect of drought stress on percentage and rate of germination and seedling growth components، a factorial experiment was conducted based on randomized completely design (RCD) with three replications. The experimental factors were included three lentil cultivars (Robat، Kimia، Gachsaran) and five levels of drought stress (0، -3، -6، -9، -12 bar of polyethylene glycol 6000). The results showed that with increasing drought stress، percentage and rate of germination percentage was decreased to zero in the osmotic potential of -12 bar. Although significant difference was not observed in germination percentage in drought stress levels between different cultivars، but difference in germination rate was significant. The rank of cultivars was Robat> Gachsaran> Kimia in germination rate. The inverse linear relationship was made between drought stress levels and seedling growth components. More seed reserve depletion in Robat and Gachsaran lead to more seedling dry weight of two cultivars in compare to Kimia cultivar that had more conversion efficiency. Thus efforts to improve germination and seedling growth in lentil breeding programs should focus on improvement of component of mobilized seed reserves.

In order to determine the efficiency and appropriate levels of two biofertilizers including municipal solid waste compost and vermicompost on improving nutrient availability, growth and yield of canola under drought stress conditions, an experiment was conducted as factorial arrangement based on randomized complete block design with four replications. Treatments consisted of three levels of drought stress, including no stress, mild stress and severe stress conditions, and biofertilizer combination in five levels including control, application of municipal solid waste compost at two and four percent levels and application of vermicompost at two and four percent. Results showed that the effect of stress and biofertilizer levels on nutrient uptake, growth, and yield was significant. The interaction of drought stress and biofertilizer had significantly affected all traits except nitrogen and zinc percent. The results of mean comparison indicated that the mild and severe stress significantly reduced nitrogen, phosphorous, iron percentage and grain yield of canola and increased potassium and sodium percentage in shoot in comparison with the control group. Application of four percent vermicompost resulted in an increase in biomass, yield and nutrient uptake except zinc, under no stress, mild and severe drought stress compared to other biofertilizer treatments. Overall, it could be concluded that biofertilizers, especially vermicompost, positively affected plant growth under drought stress conditions.

In order to study the effect of drought stress on qualitative and quantitative traits of sunflower cultivars and use of drought tolerance stress to determine the most tolerant cultivar to drought stress، this experiment was conducted on six cultivars of sunflower under two irrigation regimes (normal irrigation and drought stress) at agricultural and natural resources center of Yazd in 2010. The experiment was carried out in split plot in randomized complete block design with three replications. Results showed that effect of drought stress was significant on all of the characteristics and cultivars. The highest seed yield was produced by Azargol cultivar (1874 kg/ha) and lowest seed yield was produced by super grows (757 kg/ha) in drought stress condition. Therefore results indicated that Azargol is the most resistant cultivar to drought stress and Supergrow is the most sensitive cultivar to drought stress.

Priming is an effective method to improve seed viability that might be resulted to increase of seed germination percent and germination rate under stress conditions، such as drought stress. So، in this research the effect of seed priming on seed germination characteristics of safflower were evaluated under drought stress. A factorial experiment based on completely randomized design (CRD) with three replications was carried out at faculty of Agriculture، Bu-Ali Sina University. Treatments were priming at two levels (non priming and hydro-priming) and drought stress at seven levels (0، -2، -4، -6، -8، -10 and -12 bar). Results showed that with increasing drought stress from 0 to -12 bar، germination properties such as germination percent، germination rate and weight of seedling decreased. But، this decrease in non seed priming treatment was more than priming treatment. Therefore، at all levels of drought stress، germination rate and seedling fresh weight of safflower in control treatment was less than hydro-priming treatment. This reduction for germination percent at control treatment in compare to hydro-priming treatment was 70%. In general، hydro-priming improved germination characteristics of safflower under drought stress conditions and increased the resistance of safflower to drought stress in germination phase.

To evaluate the effects of Glycine Betaine (GB) on yield and seed quality of some cotton (Gossypium hirsutum L.) cultivars in response to drought stress, a field experiment was conducted in northern part of Iran, Gorgan. The experiment was a factorial on the basis of a randomized complete block design with four replications. Field research survey consisted of two factors; GB concentration and cotton cultivars. Glycine Betaine was applied to filed-grown cotton at three rates: 0 kg/ha foliar application of GB at the first flowering + application at one and two weeks later, 3 kg/ha foliar application of GB at the first flowering + application at one and two weeks later (two times GB application) and 6 kg/ha foliar application of GB at the first flowering + application at one, two, three and four weeks later (four times GB application). Four cotton cultivars were selected based on their proportional susceptibility to drought stress including Tabladilla and Nazili, considered as drought tolerant, and Varamin and Sahel, considered as drought sensitive cultivars. The results showed that spraying with GB at different levels (3 and 6 Kg/ha) enhanced cotton yield, boll numbers, sympodia branch numbers, early maturity, plant height, final node on main stem, boll retention at 2nd position and boll abortion, seed bulk density, but had no significant effect on monopodia branch numbers. This research could ultimately result in higher yield production and improved tolerance to water deficit condition with applying following treatments: Tabladilla and Nazili with 3 kg/ha foliar application of GB at the first flowering + application at one and two weeks later for tolerant cultivars and Varamin and Sahel with 6 kg/ha foliar application of GB at the first flowering + application at one, two, three and four weeks after first flower.