PLANT AND ECOSYSTEM
Year:2011 | Volume:7 | Issue:26 (SUPPLEMENT)|Papers Count:9

In the arid and semiarid regions of the world, drought stress is the most important factor that decreases growth and development of crops such as safflower. In order to investigate the effect of drought stress on some traits of autumn safflower cultivars a field experiment was conducted during 2009 in research farm of the Islamic Azad University, Shre-rey branch. The experimental design was split plot on the basis of randomized complete block design with four replications. Main plots consisted of two irrigation levels (irrigation throughout the growing period and withholding of irrigation at the heading stage) and sub plots were also allocated to three genotypes (Goldasht, Padideh and KW). Results showed that drought stress reduced number of heads plant, number of seeds pod, 1000-seed weight and grain yield. In control conditions, Goldasht cultivar had maximum grain yield as compared with other cultivars but in drought stress conditions difference between all cultivars was not significant.

This research was conducted to investigate the effect of supplementary irrigation and frequency of irrigation (S) on yeild of three dryland wheat varities including Sardari, Sabalan and Glenson (V) on three replications at Tajrak Dryland Agriculture Research Center in Hamedan province, using Split Plot statistical plan. A non-irrigation treatment was considered as control one. Results of variance analysis indicated that supplementary irrigation had a significant effect on grain yield, 1000 kernel weight, harvest index and spike number per plant. The variety type had a significant effect on the 1000 kernel weight and the spike number per plant. Supplementary irrigation in combination with variety type also had only a significant effect on the spike number per plant. The results of comparison of averages on the effects of supplementary irrigation (S) at 5% level showed that S7 had a significant difference with the other treatments viewpoint the effect on various properties of yield. The results of comparison of averages on the effects of supplementary irrigation in combination with variety (S×V) at 5 % level showed that S5V2, S7V2, S2V2 and S7V1 had the maximum of grain yield, straw yield, the spike number per plant and harvest index, respectively. Economical comparison showed that S2V1 treatment had maximum income, and so it is suggested to be used in similar conditions.

In order to investigate the effect of drought stress and delay sowing date on percent and yield of Oil and Protein of advanced Rapeseed cultivars, a field experiment was conducted as Factorial split-plot arranged in a Randomized Complete Block Design with three replications in 2004/06 in karaj seed improvement institute. There were two factors: Irrigation at two levels: 80% of evaporation as control(I1), drought stress started from stem elongation stage(I2), and planting date: normal planting date as fall (D1) and delay planting date as winter(D2), as main plots, cultivars were: RGS003, Sarigol, Hyola401, Hyola420, Hyola330, RGS006, RG4403, RG405.03, RGAS0324, RG405.02, as sub factors. Results showed that there were significant differences on percent and yield of edible Oil and Protein percent at most treatment (1%level). At second sowing date (D2) and water stress (I2) condition, Hyola330 c.v. with 40%; and in normal irrigation (I1) at the same planting date (D2), RG4403 c.v. with 978 kg/ha oil, were the highest cultivars in this conditions.

Agropyron genus is the important grass for forage production and soil and water conservation in Iran rangelands. There are differences among various species of this genus for salt tolerance. In order to study the salinity effects, an experiment was conducted using four levels of 0, 100, 200 and 300 mM NaCl and CaCl2 on Ag.intermedium and Ag.trichophorum seed characteristics.The research was performed for germination characteristics in Laboratory conditions. Data were recorded and analyzed for percentage and speed of germination, length of root and shoot, length of plantlet, Ratio of S/R, Vigour index and Plantlet dry weight.The results in the higher stress values showed that there wasn’t any germination in the two species and most of the germinaton particulars in 100 mmol level had significant decrease (P<0.01). In the other hand, the results of mean comparison of simple effects and salinity levels on the germination particulars showed, Ag. inter medium had higher percent of germination. Also, the another of characteristics except Plantlet dry weight, in Ag. intermedium also had higher growth than the other species.

To evaluate the different Water Deficit levels on yield, yield components and water use efficiency of forage millet (Pennisetum americanum) and sorghum (Sorghum bicolor); an experiment was conducted in agricultural research station of Miyaneh branch, at Islamic Azad University in 2010. Experimental design was split plot based on Randomized Complete Block in three replications. The main plots were three irrigation levels (33.67 and 100 percent of water requirement), sub plots were species (forage sorghum and millet).The results showed that the effect of irrigation, plant and their interactions were significant in %1 level on total fresh and dry yield and water use efficiency. The results showed that the total fresh and dry yield for without stress treatment, was 27.1 and 7.0 ton/ha per each harvest, respectively. In moderate water stress, yield reduction was 20% but in severe stress we showed 63% yield reduction, which showed that high resistance to plants against drought stress was moderate. The highest water use efficiency (0.98 kg dry matter per kg water) related to moderate stress treatment and CV. Notrifeed millet. Treatment of severe stress in sorghum had the lowest water use efficiency (0.65 kg dry matter per cubic meter of water) with about 34 percent lower compared to superior treatments. Ability of millet in water utilization for dry matter production was higher than sorghum. The results also showed that the water use efficiency and fresh and dry forage yield had significant and positive correlation in %1 probablity level. In addition there was a significant and positive correlation between fresh and dry forage yield, Plant height, leaf number, stem diameter and number of tillers as well as total fresh and dry yield of forage and WUE in millet was greater than sorghum.

In order to determine the response of Agropyron desertorom, Bromus tomentellus, Secale montanum to drought stress, an experiment was conducted in a factorial experimentbased on randomized complete block design with four replications in 1387 in shahr-e-rey branch of Islamic Azad University. Drought levels were made by polyethylene glycol 6000 (PEG) solutions in five drought levels (0, -2, -4, -8 and -12 Bar). Germination percentage, rate germination, height of radicle and hypocotyle, length of seedling, raiteof S/R, seed vigor, total dried weight of seedlings of control and stressed seedlings were analysed.The results showed that the effect of water stress was significant in 1% level on all traits. There were significant differences between species. In general, it could be concluded that Secale was the most resistant species to the water stress.

In this study the effects of NaCl, 50 mM, and osmotic stress caused by polyethylenglycol (PEG) 6000, 64 g/l, wich is isotonic with the salt solution, with or without gibberellin (GA3, 10 mg/ml) in germinating soybean (Glycine max L.cv.Pershing) seeds have been investigated. Seeds were exposed to the above mentioned solutions, or distilled water as control, for 48 hours. In every 8 hours, seed germination percent content of proline and glycinebetain, was measured based on the results of the present work, salt and PEG treatments, were able to make significant delay in seed germination, and GA could compensate such a delay. It seemed that the salt treatment was responsible for delay, by making delays in increasing content of proline and glycinebetain Slow and continuous increase in the content of proline and glycinebetain, in salt treatment might be considered as the possible mechanism for decreasing the negative effects of these stresses during seed germination. Gibberellin alone or with the salt or PEG solutions, could maintain or increase the content of the measured solute. The physiological response of seeds, in different time sections of germination during 48 hours was not essentially similar.

To investigate the effects of different irrigation regimes, and chickpea cultivars on chickpea production an experiment was carried out in the Agricultural Research Station, college of Agriculture, Islamic Azad University, Kermanshah Branch in 2007. The experiment was split-plot in a randomized complete block design with three replications. Supplementary irrigation at three levels including no irrigation (control), one time irrigation at 50%- flowering stage and one time at pod- filling stage, was allocated to main plots and the variety (Arman, Hashem and ILC-482) was allotted to sub plots. A significant difference was observed between irrigation treatments in terms of plant height, number of axillary branches, distance to the first pod from soil surface, number of grain per plant, number of pod per plant, grain yield, biological yield, harvest index and 100- grain weight; such a difference was observed between test varieties in terms of all traits rather than 100- grain weight. The grain yield mean was significantly higher for Arman than that of Hashem and for Hashem was significantly higher than that of ILC-482. The highest values of the number of grain per plant relate to Arman and of pod per plant related to Arman and Hashem, respectively. High rate of grain yield in irrigation treatment at pod- filling stage was associated with yield components, especially with the number of pod per plant and 100- grain weight. The results showed that grain formation and pod- filling stages were the most sensitive ones to water-deficit and under water limitation conditions, we can considerably increase grain yield at this stage by irrigation, especially for Arman.

This experiment was carried out in fall in 2006 to study the effect of selenium on yield and yield components of two varieties of wheat (Azar2 & Pishtaz). The seeds of both varieties of wheat planted in normal and drought stress (Stopping the irrigation) conditions. Sodium Selenate (Na2SeO35H2O) was sprayed in 3 levels (b1=withness, b2=20mg/lit and b3=25mg/lit) on booting stage. The experimental design was arranged on Factorial split plot with 4 replications. Drought stress (Stopping the irrigation) and selenium used as factorial in main plot and wheat varieties in sub plot. In this experiment, factor (a) was named for irrigation treatment, factor (b) for Selenium treatment and factor(c) for wheat varieties. The most important assessed traits in the field were measuring of the Spike weight, Grain yield, Harvest Index(HI), Thousand grain weight, Mean of the number of total tillers- fertile tillers and Mean of the Spike length. We also assessed the RWC in the lab. The results of the field experiments showed that the traits as Spike weight and Grain yield had significant differences in various condition of irrigation. In well water condition, Spike weight and Grain yield were more than lack of the water condition. The results also showed the significant differences between the Spike weight and the Grain yield in varieties of wheat. Pishtaz variety had more Spike weight and Grain yield than Azar2. In Harvest Index (HI), there was no significant difference in various levels of Irrigation and Selenium spraying but we observed significant difference in varieties. Azar2 variety had more HI than Pishtaz variety. In thousand grain weight trait, there was significant difference in the different levels of watering. We had more thousand grain weight in well water condition than lack of the water condition. The various levels of Selenium spraying was not effective on thousand grain weight and showed no significant difference. Also Azar2 variety had more thousand grain weight than Pishtaz. In the Mean of the number of total tillers- fertile tillers traits different levels of watering and selenium spraying showed no significant difference but these traits had significant difference between the varieties of wheat. The Pishtaz variety was superior about Mean of the number of total tillers and fertile tillers traits than Azar2. The Spike length trait had not significant difference in none of the various levels of watering, selenium spraying and varieties of wheat treatments. The separate assessed trait in the laboratory was measuring the percentage of relative water content of the leaf. Experimental results showed that the RWC had significant differences between the levels of watering in statistical analyses. In well water condition, the RWC was obviously more than lack of the water condition. The RWC showed no significant difference in various treatments of selenium spraying and wheat varieties.