مجله علوم گیاهان زراعی ایران
سال چهل و هفتم شماره 2 (تابستان 1395)

To study the effects of mycorrhiza fungi and humic substances on yield and yield components of corn (Zea mays L. var. s.c. 704) under limited irrigation condition, an experiment was conducted in split plot arrangement based on RCBD in four replications at the research farm of University of Tehran (Karaj-Iran) in 2011. The main factor consisted of three irrigation levels i.e. normal (irrigation every 7days); mild water stress (irrigation every 10days) and severs water stress (irrigation every 14days). Fertilizer treatments comprised of zero (control); application of phosphorus 50% (based on soil testing result); application of phosphorus 100%; phosphorus 50% plus mycorrhiza; phosphorus 50% plus humic substance; and phosphorus 50% with humic substance plus mycorrhiza. The results showed that water stress significantly decreased yield. The fertilizer treatments had significant effects on grain yield, biological yield, and plant height, grain protein, grain nitrogen and phosphorus; but had no significant effect on seed weight, and harvest index. Comparison of treatment means for different traits showed that the greatest change compared to the control, was for the treatment of 50% humic compounds plus phosphorus fertilizer with mycorrhizal fungi.

Mechanisms of tolerance to water deficiency stress for introducing sunflower hybrid was investigated by a two-factor experiment as a split plot design based on RCBD was at the research station in Alborz province, Hashtgerd region, Iran in 2013. Irrigation rates (irrigation after 50, 100 and 150 mm cumulative evaporation from class A evaporation pan) were considered in the main plots and sunflower hybrids (Farokh, Allstar, Ghasem, Hysun 25) as sub plots. In this study, the amount of soluble sugars, proline, protein, chlorophyll content, oil content and yield, protein yield and some agronomic characteristics were determined. Based on the results, the amount of total soluble sugars, proline and chlorophyll-b contents as mechanisms to resist water deficit stress significantly increased with increased water deficit stress. Allstar hybrid had the highest amount of total soluble sugars (176.05 mg/g f. w), proline (45.43 mg/lit) and chlorophyll-b (12.52 mg/g f. w). Also, Allstar produced the highest grain yield and oil content in both mean water deficit stress conditions with values 2121 and 956.90 kg/ha, and in severe water deficit stress condition with values 829 and 315.10 kg/ha, respectively. However, with normal irrigation, Farokh hybrid had highest grain yield and oil yield.

In this research, we studied polyamines including putrescine (put), spermidine (spd) and spermine (spm) changes in three common bean (Phaseolus vulgaris) genotypes, K-S-31167, GE-288 and NAZ under drought stress. Our result showed steadily increase in putrescine (put) and spermine (spm) in all three genotypes. GE-288 genotype showed decrease and then increasing in spermidine (spd) content but K-S-31167 and NAZ genotypes showed steadily increasing in spermidine (spd). NAZ genotype accumulated putrescine more than other polyamines and showed the highest amount of putrescine in compare with other genotypes. K-S-31167 genotype accumulated the highest spermine content in compared with other genotypes. Our result showed significant increase in electrolyte leakage (EL) in all three genotypes. K-S-31167 as drought tolerant genotype and ZAZ as drought sensitive genotypes showed the lowest and the highest increase in EL, respectively.

To study the effects of carbon dioxide enrichment on morphological, nutrient absorption and yield of wheat (Triticum aestivum L. cv. Pishtaz) under weed competitive pressure of wild oat (Avena ludovicianaL.), an experiment was conducted as a split plot based on a randomized completely block design during the 2013-2014 growing season at the Research field of Tarbiat Modares University, Iran. Carbon dioxide concentrations (400, 700 and 1000 ppm) and weed densities (0, 25, 50, 75 and 100 plants/m2) were arranged in the main- and sub-plots. Open top chambers were used for CO2 concentration adjustments. Results indicated that, increasing the concentration of carbon dioxide caused an increasing in yield and yield components of wheat. The highest and the lowest yield and yield components were observed in maximum and minimum concentration of carbon dioxide, respectively. Also, increasing in weed density significantly decreased yield and yield components of wheat in all CO2 concentrations. In addition, under all CO2 concentrations, the density of 100 plants per square meter of wild oat compared to control caused decreases in wheat yield and yield components. The value of these decreases were 76.5, 78.26 and 88.80 percent in 400, 700 and 1000 ppm CO2 concentrations, respectively.

Salinization of crop lands is one of the most important reasons for reduction in productivity and threats food security. Activation of signaling process in plants is the first step during sense environmental cues and stress signals. Identification of the components of plant intracellular signaling mechanisms, pathways, and networks in response to salt stress in Aegilops tauschii (the D genome donor of bread wheat) by transcriptome analysis tools such as RNA Seq method is very worthwhile. RNA Seq method and functional annotation of data by MapMan suite is an efficient strategy to functional genomics analyses. In order to identify and evaluate some genes involved in signaling process, we performed library construction for two cDNA libraries from leaves of seedlings treated with 200 mM NaCl and control. Results of differential expression showed that out of 4506 differentially expressed genes, 603 (11/59%) BINs assigned to signaling process. It also became clear that receptor kinases are the largest number (222 transcripts) of differentially expressed genes in signaling process components. This study is a fundamental research that provide worthwhile functional sequences for gene transferring study to improve salinity tolerant in bread wheat.

Understanding the physiological processes associated with drought stress lead to an understanding of the basic mechanisms of resistance, maintaining yield potential and contribute to the identification of drought tolerant cultivars. For this purpose, the effects of drought stress in cowpea genotypes was evaluated using five different genotypes with different yield potential in a pot experiment in split plot in a randomized complete block design with three replications under drought stress levels (35, 65 and 100% of field capacity) in the College of Agriculture, University of Tehran in 2014. Drought stress decreased RWC of cells and increase antioxidant enzyme and MDA content. Drought stress decreased RWC and increase MDA content and antioxidant enzyme activities by increasing levels of stress, but for catalase enzyme in stress levels the highest activity was 65%. With increasing stress and the stress level of 35% of field capacity, catalase activity exhibited higher reduction. Genotypes 210 and 313 had the lowest MDA level at 35% of field capacity and in these two genotypes enzymes CAT, GPX and APX 210 had the highest value. High levels of antioxidant enzyme activity in genotypes 210 and 291 associated with lower levels of MDA content in these genotypes, probably indicates the high potential of these genotypes to eliminate oxygen species production and yield stability compared with other genotypes.

In many studies, the medicinal properties and impact of blond plantain on mechanisms of human physical activities has been proven. Salinity is an important abiotic stresses with detrimental effects on seed germination. An experiment was conducted to study germination characteristics of blond plantain under water and salinity stress conditions at different temperatures. The experiment was conducted at the University of Tehran Seed lab, Karaj, in 2015. Temperatures regimes included 5, 10, 15, 20, 25, 30, and 35°C. For each temperature, the treatment forsalinity and water stress was four water potentials (zero, -4, -8 and -12 bar) using sodium chloride. The effects of salt stress on seed germination of blond plantain at different temperatures showed the highest resistance to salinity at 20ºC. Salt stress at different temperatures reduced germination parameters. Increased temperatures resulted in better conditions for seed germination and increase the salinity stress tolerance. Increased severity of salinity causes the reduction of temperature range in which the seed can germinate.

Investigation of various irrigation methods and intercropping are effective strategies for increasing water use efficiency and improve crop production. A field experiment conducted to study the effects of alternate furrow irrigation on quantitative and qualitative characteristics of forage corn with annual alfalfa cropping under its canopy in Ilam climate conditions. Experiment carried out as a split plot based on a randomized complete blocks design with three replications at research farm of Ilam University. Irrigation (alternate furrow irrigation and common furrow irrigation) as main plots and planting methods (Control without nitrogen fertilizer and alfalfa, nitrogen fertilizer and intercropping) as sub plots. The results showed that alternate furrow irrigation decreased significantly total dry weight and total produced forage dry weight (dry forage of corn and dry forage of alfalfa, total fresh weight and total produced forage fresh weight (fresh forage of corn and fresh forage of alfalfa), and protein content. According to the results, the most quantity of forage obtained from corn plots with nitrogen which commonly irrigated, also the best quality was in cropping alfalfa under corn canopy without fertilizer. Therefore, intercropping of corn and alfalfa with alternate furrow irrigation is suggested to produce high quality forage with considering water use efficiency.

Because of importance of morphological characteristics, canopy temperature and their relationship with grain yield in rice varieties, an experiment was conducted based on split plot in a randomized complete block design with three replications in two years (2013-2014) at the College of Agriculture, University of Guilan. The experiment consisted of three transplanting times (5, 20 May and 5 June) as main plot and six cultivars of rice (Hashemi, Sange jo, Ali Kazemi, Dorfak, Khazar and Gouhar) as sub plots. The results showed that with delaying of transplanting time, number of fertilized tillers decreased up to 6.4 and 6.1 fertilized tillers at first and second year, respectively. With delaying in transplanting time, leaf area index decreased up to 1.6 and 1.51 in first and second year, respectively, and reduced tillering rate up to 0.08 tillers. Comparison of the temperature difference between canopy and environmental showed that Khazar cultivar had the highest temperature difference between canopies and environmental in amount of 2.69 and 3.11˚C in the first and second year, respectively, and exhibited lower temperature of canopy compared to environment. The results showed that grain yield of rice cultivars except Khazar significantly reduced with delaying in transplanting time. So it should be noted that the Khazar, with the number of fertilized tillers and lower canopy temperature than other cultivars at different times, could be maintained their functional stability in front of unfavorable conditions such as the high average temperature, lower intake cumulative temperature and radiation during the growing season, especially during the grain filling stage.

A field experiment was conducted at research station of Zabol university in 2012. The experiment carried out as split plot on basis of a randomized complete block design with three replications. The main and sub factors included tillage systems (No, reduced, and Conventional tillage) and planting ratios of intercropping (pure culture of roselle, pure culture of green gram, 25% roselle 75% green gram, 50% roselle 50% green gram and 75% roselle 25% green gram), respectively. For roselle, the results showed that the effects of tillage systems and planting ratio was significant on plant height, diameter of stem, lateral branch, number of fruit and sepal yield. For green gram the results showed that the effects of tillage systems and planting ratio was significant on plant height, number of pods in plant, number of seed in pod and economical yield. Tillage systems had not significant different on land equivalent ratio but comparison of means showed that the maximum and minimum of LER was obtained in conventional and reduce tillage, respectively. The maximum of LER was obtained at 75% green gram plus 25% roselle (1.36). In general, more useful intercropping confirmed than a pure culture of roselle and green gram.

In order to study the effects of conventional and conservation tillage with management residue on wheat physiological properties, a field experiment was conducted in 2013-2014 at Mashhad Agricultural and Natural Resources Research Center of Razavi Khorasan province. This experiment was carried out as split plot design based on a randomized complete block design with three replications. Main plots included tillage systems: 1) conventional tillage, 2) reduced tillage and 3) no tillage; subplots were management residue: 1) 0%, 2) 30% and 3) 60% residue. The results showed that tillage systems had significant effect on relative water content (RWC), the difference between canopy temperature and air temperature (∆t), SPAD reading, Flag leaf area (FLA), Leaf water potential (ΨW) and Radiation interception (RI). The highest RWC (83%), ∆t (-7.36 cº), SPAD (47.35), FLA (26.3 cm2), ΨW (-11.19 bar) and RI (90.22%) were detected in no-tillage method. Residue management had significantly different on RWC, ∆t and RI traits, but no significant effect on SPAD reading, Flag leaf area (FLA), leaf water potential (ΨW) was detected. The highest grain yields were obtained under no-till (6912.2 kg/ha) and 60% residue treatment (6980.8 kg/ha). It is concluded that conservation tillage with more aboveground residue could improve wheat yield and some of physiological properties (RWC, ∆t, SPAD reading, FLA, ΨW and RI).

In order to study the effect of planting pattern and nitrogen application on barley and faba bean yield and quality of forage in intercropping, an experiment was conducted on farm of agricultural and natural resources faculty of Gonbad Kavous University as factorial based on RCBD with three replications in 2012-2013. Planting pattern consisted of five levels, i.e. sole barley, intercropping of barley with faba bean at 75:25, 50:50, 25:75 rations and sole faba bean and nitrogen fertilizer factor was comprised of four levels of 0, 25, 50 and 75 Kg N ha-1. The results showed that effect of planting pattern on forage yield, height, percentage of dry matter digestibility, crude protein and acid detergent fiber at 1% probability level were significant. Nitrogen fertilizer had additive effect on forage yield, height, percentage of dry matter digestibility and crude protein. Sole barley produced the highest yield with13.38 ton ha-1 and sole faba bean produced the lowest forage yield with 7.4 ton ha-1. With increasing of faba bean in intercropping treatments, total yield decreased compared to sole barley. The highest and lowest crude protein percentage with 25.37 and 8.81 and dry matter digestibility with 69.96 and 58.96 percent was obtained from sole faba bean and sole barley, respectively. Although forage yield in sole crop of barley was high but its quality was low.

The present study was conducted to investigate the yield and some morphological characteristics of Echinacea Purpurea. The experiment was conducted in Research Farm of the Ramin Agriculture and Natural Resources University of Khuzestan during 2013- 2014. The experiment was performed as a split plot factorial based on a randomized complete block design (RCBD) with four replications. The foliar application of vermicompost tea (control and vermicompost tea) was applied in the main plot and other factors include organic fertilizer (control, vermicompost and cow manure) and biofertilizer (control and of Azospir biofertilizer) were used in the sub-plots. Results showed that maximum diameter of the flower was obtained by vermicompost application. The maximum root dry weight, stem dry weight, leaf dry weight, number of flowers per plant and lateral shoot number were obtained by mixed application of vermicompost and Azospir biofertilizer. It was also found that vermicompost with Azospir biofertilizer treatment caused the highest flower, dry weight, biological yield and root diameter. Most collar diameter was created by the integrated treatment of manure and bio-fertilizer. The highest LAI value was obtained by combined Azospir biofertilizer and vermicompost tea. The foliar application of vermicompost tea and Azospir biofertilizer caused the highest plant height. However, the highest harvest index was observed in control treatment. As a result, it was found that integrated treatment of vermicompost and vermicompost tea was remarkably recognized better than other treatments which could improve the yield of Echinacea Purpurea.

The growing demand for animal products has made importance of the utilization of biotechnological techniques in improvement of forage crops such as sainfoin. In this research, the effects of different levels of auxin (NAA and IBA) and cytokinin (BAP, Zeatin and TDZ) on in vitro growth response of shoot apex explants of Shahrkord and Khansar cultivars of sainfoin were investigated. For this, shoot apex explants were prepared from 4-7 days old seedling grown and cultured on solidified MS medium containing different levels of auxin and cytokinin. The results indicated that the percentage of multiple shoots, number of shoots per explants and shoot length were significantly influenced by cultivar, plant growth regulators combination and its interaction. The percentage of multiple shoots and number of shoots per explants were varied from 0 to 89.7% and 1 to 5.03, respectively. Generally, the percentage of callus induction, multiple shoots and number of shoots per explant in the Khansar cultivar was significantly higher than those of Shahrkord cultivar. The highest percentage of shoots (98.15%), multiple shoots (89.17%) and number of shoots per explant (4.3) were obtained in the Khansar cultivar with MS medium containing 0.1 mgL-1 IBA and 3 mgL-1 BAP. Root induction and appropriate growth of roots were observed on MS medium without plant growth regulators. These results are highly valuable for in vitro culture and micropropagation of sainfoin as well as in breeding programs and transformation of this plant.

In order to evaluate the relationship between grain yield and agronomic characteristics in bread wheat genotypes in different planting dates under rainfed conditions, a factorial experiment was conducted based on RCBD with four replications at Gonbad-e Qabus region, Iran, during 2012-2014 growing seasons. Number of spikes per unit area, grain filling rate, effective grain filling period, number of grain per spike, 1000KW, grain weight, grain yield, biological yield and harvest index were measured. Planting dates including Dec. 2nd, Dec. 21st, Jan. 9th, Jan. 28th and Feb. 17th were considered as first and five wheat genotypes: Gonbad, Karim, Koohdasht, line 7 and line 16, as second factor, respectively. Combined analysis of variance revealed that the mean grain yield decreased from 4956 in the first year to 2833 kg.ha-1 in the second year (43% reduction). Grain yield had the highest and positive significant correlation with biological yield (r= 0.97**) and grain filling duration (r= 0.97**). The stepwise regression analysis showed that biological yield and harvest index justified more than 99% of grain yield variation, indicating their considerable importance in grain yield. Grain filling duration was the first variable to enter to the model and showed more important role in grain yield justification. The grain filling duration and biological yield had effective role in grain yield that could be used for selecting the suitable genotypes of wheat for rainfed conditions.