فهرست مطالب آرمین اسکوییان

Low yield and instability, is one of the most important issues in chickpea cultivation. The adverse environmental conditions have affected the crop yield; in this regard, one of the most important factors is salinity stress that reduces crop yield. Meanwhile, microorganisms have a high ability to mitigation the adverse effects of salinity. In addition, the coexistence of beneficial bacteria and fungi creates a potential for a decrease of salinity stress impacts on plants. Mycorrhizal fungi belonging to the branch Glomeromycota, one of the oldest living organisms introduced to coexist with plants on land and in salinity. These fungi are widely found in saline soils. Research has shown that mycorrhizal arbuscular fungi increase salinity tolerance and prevent yield loss. Studies have shown that the coexistence of mycorrhizal arbuscular fungi with crop roots increases the activity of antioxidant enzymes and this expansion of activity to the plant helps to reduce the effects of salinity stress. With regard to the beneficial effects of mycorrhizal fungi on reducing salinity effects in crops, this study aimed to evaluate salt tolerance in chickpea using native mycorrhizal fungi to improve soil properties and its sustainable production under saline conditions.

This study was performed in 2016 as factorial based on completely randomized block design with three replications in the research glasshouse of the College of Agriculture, Ferdowsi University of Mashhad. Salinity stress treatments included four levels (tap water [control], 6, 6 and 9 dS.m-1 sodium chloride) and mycorrhiza species at three levels (native mass, Piriformospora indica as endophyte, and Gigospera margareta). Four weeks after applying salt stress, maximum quantum efficiency of PSII photochemistry (F'v/F'm) II, stomatal conductance, SPAD index, relative water content (RWC) of leaves, and membrane stability index in the youngest fully expanded leaf were measured. In addition, morphological traits, including plant height, lowest branch height, number of branch number, and number of leaves per plant were measured. At the end of the experiment, the shoot fresh and dry weight, length, volume and dry weight of root were measured, finally root colonization was assessed.

The maximum quantum efficiency of PSII photochemistry (F'v/F'm) affected by different levels of salinity and mycorrhiza application. The highest and lowest maximum quantum efficiency of PSII photochemistry (F'v/F'm) levels were related to 9 dS.m-1 salinity treatment with mycorrhiza Piriformospora indica and control treatment with Gigospera margareta species, the difference between which was 4.5 times. In addition, the highest amount of gas exchange was observed in the Piriformospora indica species. The highest SPAD index was related to treatment with Piriformospora indica fungi in non-stress conditions and the highest salinity stress level. Moreover, application of Piriformospora indica fungal species increased RWC by 4.54% and 9.20%, compared to the use of mycorrhiza native mass and Gigospera margareta species, respectively. Application of Piriformospora indica showed superiority in membrane stability index relative to Gigaspora margareta in all treatments of salinity stress, with the exception of 9 dS.m-1 treatment. However, no significant difference was observed between mycorrhiza treatments in 9 dS.m-1 of salinity stress. Root inoculation with Piriformospora indica increased plant height by 12.7%, compared to mycorrhiza native mass. At all levels of salinity stress, Piriformospora indica increased shoot fresh weight, compared to native mass and Gigospera margareta treatments. Furthermore, the least and highest decrease in root length was observed in Piriformospora indica and Gigospera margareta treatments, respectively. Among mycorrhiza fungi treatments, Piriformospora indica produced the highest root volume, compared to native mass and Gigospera margareta treatments with a difference of 10.9% and 36.4% between them. In addition, in non saline treatment with Piriformospora indica had the highest percentage of root colonization (54.66).

According to the results of the study, most traits evaluated in the study were affected by increased intensity of salinity stress. In addition, increased salinity had a negative impact on root development due to increased soil osmotic potential and toxicity, which ultimately reduced plant growth. Moreover, mycorrhiza inoculation had a significant, positive effect on the photosynthetic system of photosystem II, shoot and root dry weight, ratio of shoot to root, root length and percentage of colonization, root volume, root fresh weight, RWC and membrane stability index. Inoculation of commercial species of mycorrhiza under salt stress increased plant salinity tolerance.

 Leaf area index, radiation absorption and radiation use efficiency are important ecophysiological characteristics, which is useful in assessing the amount of light absorbed for dry matter production. Understanding how and managing the effects of ecological factors on plant reproduction is essential for achieving sustainability in agricultural production systems. On the other hand, the use of efficient crops in utilization of resources, especially solar radiation, is one of the fundamental approaches towards achieving this goal. The purpose of this study was to investigate the effect of sulfur and biofertilizers applications on growth indices, radiation absorption and use efficiency of chickpea.

 In order to determine the growth indices, radiation absorption, and radiation use efficiency (RUE) of chickpea, a field experiment was conducted in 2019 at the Agricultural Research Station of Ferdowsi University of Mashhad based on a completely randomized block design with ten treatments and three replications. The experimental treatments including: 1-Spa, 2-Spo, 3-Spa+SOB, 4-Spa+SOB+NFB+PSB+KSB, 5-Spo+SOB 6-Spo+SOB+NFB+PSB+KSB, 7-SOB+NFB+PSB+KSB, 8- NFB+PSB+KSB, 9-SOB and 10-Control. Sampling was started 20 days after planting by taking six destructive samples. The plant was sampled two weekly intervals to determine the growth parameters of chickpea including leaf area index (LAI), dry matter accumulation (DM), crop growth rate (CGR) and radiation use efficiency (RUE). For calculations of radiation use efficiency, it was necessary to estimate daily LAI and daily absorbed, the RUE was calculated based on g MJ-1 through the slope of a linear regression between total dry weight accumulations (g m-2), and cumulative absorbed the total daily solar radiation.

 The results showed that the highest leaf area index was obtained in Spa + SOB + NFB + PSB + KSB and Spo + SOB + NFB + PSB + KSB treatment which was 29 and 26 %  more than control, respectively. The application of pa + SOB and Spo + SOB treatment, which increased 12 and 7 % compared to control, respectively. In this study, sulfur was more important than other fertilizer treatments. The highest dry matter accumulation was obtained in Spo + SOB + NFB + PSB + KSB and Spa + SOB + NFB + PSB + KSB treatment which was 31 and 27% more than control. SOB and NFB + PSB + KSB treatments had the lowest amount of dry matter after control. The results showed that the highest crop growth rate observed in Spo + SOB + NFB + PSB + KSB treatment, which increased by 14% compared to control. The maximum absorbed radiation coincided with the highest leaf area index of chickpea. Then, Due to the decrease in leaf area index until the end of the growth period, the absorbed fraction of light absorbed a decreasing trend. The estimated RUE levels in different treatments were significantly different (P≤0.01). The highest radiation use efficiency was in Spa + SOB + NFB + PSB + KSB treatment (R2 = 0.91**) which was 18% more than control. Also, increasing leaf area can increase the plant's photosynthetic potential and increase dry matter, at finally to increased RUE.

The results showed that treatments (Spo + SOB + NFB + PSB + KSB) and (Spa + SOB + NFB + PSB + KSB) with higher leaf area index resulted in more efficient use of canopy light absorbed by chickpea leaves as a result of increased radiation and dry matter efficiency. High slope radiation use efficiency indicates the high efficiency of a plant using sunlight and converting it to dry matter. Giving attention to a more frequent application of biological fertilizers could be considered as an essential agro-ecological approach, which results in healthier soil and water resources.

Using biofertilizers and weed control can be effective on improving of chickpea yield. In this study, a factorial experiment was conducted in a RCBD with three replications at Ferdowsi University of Mashhad. Experimental Factors included the application of biofertilizers in six levels (phosphate solubilizing bacteria (Bacillus +Pseudomonas), potassium solubilizing bacteria (Thiobacillus sp.), pseudo-mycorrhizae (Piriformospora indica),  Bacillus + Pseudomonas + Thiobacillus , Bacillus + Pseudomonas + Thiobacillus + Piriformospora, and control treatment) and weeds control at three levels (weed control with combination of pyridate and cletodim herbicides, two and three times weeding). Results showed that the distance of the first branch from the soil surface was not affected by biological fertilizers and weed control treatments although it was increased with application of biological fertilizers. The highest pod distance from the soil surface was observed in phosphate solubilizing bacteria + two weeding treatment. The maximum number of main branches per plant was obtained in phosphate solubilizing + two weeding treatment. The highest number of lateral branches per plant was observed in potassium solubilizing bacteria treatment + phosphate solubilizing bacteria + weed control using combination of pyridate and cletodim herbicides. Concomitant using of potassium solubilizing bacteria with phosphate solubilizing bacteria increased the number of pods per plant by 30% compared to the control treatment.There were no significant differences between chemical and weeding of weed control treatments in terms of number of pods per plant. Concomitant consumption of potassium + phosphate solubilizing bacteria and concomitant application of potassium + phosphate solubilizing bacteria along with endophytic fungi mycorrhiza produced the highest chichpea biomass and seed yield. The application of pyridate + cletodim herbicides reduced seed yield to 29 and 24 percent, respectively, compared with two and three times weeding. The highest concentration of shoot phosphorus was obtained in the treatment of endophytic fungi and chemical control of weeds and the highest concentration of potassium was obtained in the combination treatment of potassium and phosphate solubilizing bacteria and endophytic fungi. Generally, in this study biological fertilizers had a positive effect on yield and yield components of chickpea, although the application of combination of pyridate and cletodim herbicides had a negative effect on chickpea yield.

Potatoes producers in Iran are widely use nitrogen, phosphorus and potash fertilizers for tuber production, but the tuber yield is less than the potential in desirable conditions. In this high cost and low efficiency farming system, soil microorganisms can play an important role in improving fertilizer efficiency and reducing costs. In addition to physical and chemical properties, soil quality has a close relationship with biological aspects. The aim of the present work was to evaluate the positive effects of potassium, phosphate solubilizing bacteria and nitrogen-fixing bacteria on potato growth, tubers yield and its dry matter, as well as saving the chemical fertilizers for healthier crop production. Materials and Methods This study was conducted as a split plot experiment in a randomized complete block design with three replications at Research Farm of Ferdowsi University of Mashhad, Iran in the 2016 cropping season. Treatments included nine fertilizer programs including; phosphate solubilizing bacteria (Phospho-powerbacter dayan), potassium solubilizing bacteria (Peta-powerbacter dayan), free-living nitrogen-fixing bacteria (Nitro-bacter dayan), phosphate solubilizing bacteria + Triple super phosphate fertilizer, potassium solubilizing bacteria + potassium sulfate fertilizer, free-living nitrogen-fixing bacteria+ nitrogen fertilizer with a source of urea 46%, phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria, phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria + triple super phosphate + potassium sulfate + nitrogen and control (without biological and chemical fertilizer) as main plots and two potato cultivars (Fontane and Sante) as subplots.

The highest leaf area index observed in Fontane cultivar and phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria. In Sante cultivar, tow treatments including free-living nitrogen-fixing bacteria alone and phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria showed the highest leaf area index. The highest Fontane shoot biomass was produced in phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria treatment and in Sante cultivar was observed in free-living nitrogen-fixing bacteria + Nitrogen fertilizer treatments. Application of phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria simultaneously caused an increase in the number of tubers per plant in both cultivars. Fontane in potassium solubilizing bacteria + potassium sulfate fertilizer produced the highest tuber yield, which it was 37% more than control treatment. The highest tuber yield in Sante cultivar was obtained by application of phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria + triple super phosphate + potassium sulfate + nitrogen, which was 36% more than control treatment. The highest of dry matter percentage, specific gravity and starch content in both cultivars were obtained in treatment of all bacteria with chemical fertilizers and the lowest of these characteristics was observed in control treatment. The lowest reducing sugars was obtained in the phosphate solubilizing bacteria + Triple super phosphate and phosphate solubilizing bacteria in Fontaneh and Sante cultivars, respectively. The best DPPH radical scavenging activity in Fontaneh was observed in treatment of all bacterias and in Sante cultivar in applying free-living nitrogen-fixing bacteria. The highest and lowest total phenol content was observed in control treatment and application of potassium solubilizing bacteria + potassium sulfate fertilizer with 75% difference, respectively.

In the present study, the application of bio fertilizers in potatoes showed that these fertilizers could improve physiological, yield and quality characteristics of potato cultivars by using less chemical fertilizers. Generally, application of phosphate solubilizing bacteria + potassium solubilizing bacteria + free-living nitrogen-fixing bacteria + triple super phosphate + potassium sulfate + nitrogen produced the highest potato tuber yield.