mohammad esmailpour

In this research, wheat, rice, and corn residue were used as a substrate for biogas production. Due to the high amount of lignin in all three substrates (> 9.9) and in order to increase the degradability of these substrates, an ultrasonic pretreatment with a power of 150 w at 15 min was used prior to initiating enzymatic digestion process. Some physical and chemical properties including solid and volatile particles and contents of lignin, cellulose and hemicellulose were measured before and after digesting the substances; and in addition, the biogas compounds including hydrogen, methane, hydrogen sulfide and carbon monoxide was measured during digestion. The metabolic pathways of converting glucose as the main constituent of all three waste types into biogas were studied to determine the factors affecting biogas compounds. The results showed that use of ultrasonic pretreatment in all three wastes increased the breakdown of lignin structures, which decreased the content of these structures in the feedstock compared to the substrate. The amount of solid and volatile particles of the feedstock obtained from the substrate of wheat residue was 35.1% and 95.3%, respectively, which was more than that of the other substrates. The highest amounts of reduction of solid particles (19.6%), volatile particles (18%), cellulose (12.6%), hemicellulose (4.4%) and lignin (3.6%) were related to the feedstock obtained from wheat residue. Analyses of biogas compounds showed that the highest biohydrogen production obtained for wheat substrate (ppm 18000), but its biomethane production was lower than the other substrates. The highest amounts of biohydrogen production of all the substrates occurred after seven days, which was related to the butyrate acidification stage. With increasing digestion time, hydrogen production decreased while the other biogas compounds increased. One of the probable reasons was the consumption of hydrogen produced in the stages of hydrolysis, acidification and acetate formation in the stages of alcoholization and methanation. The highest amount of hydrogen production was related to the stage of butyrate formation and then acetate formation. The higher production of biohydrogen by wheat residue is most likely due to its high volume of volatile, hydrocarbon and hemicellulose compounds. While the low production of hydrogen by corn residue was due to driving the reactions towards the production of ethanol and consuming hydrogen.

Wheat is the most important source of carbohydrates in a majority of countries. It provides more nourishment for people than any other food source. Limited rainfall and drought stress occur frequently during the grain filling stage of wheat in many areas. Accumulation of photoasimilates in the stem of wheat and remobilization of theses storages could be considered as important adaptive traits to environmental stresses and are important in breeding cultivars with improved grain yield. Previous published researches on carbohydrates accumulation and remobilization in wheat were studied. The results of these articles were summarized systematically and then critically analyzed. Approaches for future works in terms of carbon accumulation and remobilization were also presented. Water-soluble carbohydrates (glucose, fructose, sucrose, and fructans) accumulate in the stem of wheat plants. The accumulation of reserves in the different internodes started near the end of extension growth. That is to say, the accumulation of reserves in the lower internodes takes place over long periods of time compared to the upper internodes. Accumulation of stem reserves, depend on environmental conditions and cultivars, continues until 10-25 days after anthesis when maximal amounts are reached. Wheat cultivars with optimum stem length and stem specific weight (stem dry weight per unit stem length) have higher potential for stem storages. Under optimal conditions, where photosynthesis takes place over long periods of time, storage of assimilates is high. In contrast, stress conditions such as drought reduce the amount of accumulated carbohydrates. Typically, remobilizations of stem reserves are started at the second half of linear grain growth when the current photosynthesis is declined. Physiological bases for remobilization initiation have not been understood well. It is probable that sucrose level as well as abscisic acid (ABA) concentration in the stem are involved in this process. The amount of remobilization in each cultivar is determined by stem reserves and remobilization efficiency. The later factor is affected, in turn, by grain number and grain weight (sink strength). That is to say, cultivars with higher stem storage do not necessarily show higher carbohydrates remobilization. Abiotic stresses (such as drought, salinity and heat stress) have pronounced effects on the amount and initiation of carbohydrate remobilization. However, wheat cultivars respond to such conditions differently. Researches on 81 Iranian wheat cultivars showed that drought stress increased stem dry matter remobilization from 2 to 45% whereas this trait was decreased from 1 to 72 percent in the remaining cultivars. Interestingly, the response of each stem segment (internode) to imposed stress conditions may be different with respect to remobilization amount. The flow of carbon (carbohydrates) to the grain from stored stem materials has been classified to pre- (All the carbon in the grain which is derived from photosynthesis prior to anthesis) and post-anthesis (All the carbon in the grain which is derived from photosynthesis after anthesis) remobilization. The contribution of stem dry matter to grain growth is not consistent and varies depends on the cultivar, environmental conditions, and grain weight changes. Clear association is not found between grain yield and remobilization. No clear relation was found between stem reserve mobilization and year of cultivar release. Weather conditions have pronounced effects on carbohydrates accumulation and its subsequent remobilization in wheat stem. Therefore, when breeding for these traits are considered, special attention should be paid to the environmental conditions. Typically, the lower internodes of wheat stem have higher potential for carbohydrates accumulation and remobilization when compared with the upper internodes (peduncle and penultimate). Clear relations were not found between grain yield and remobilization. This suggests that manipulating of this trait (remobilization) in wheat breeding program is a challenging task.

Soil salinity is one of the largest global challenges especially in the arid and semi-arid regions. It adversely and severely affected agricultural production and consequently food security. The new cereal, tritipyrum, is an artificial hexaploeid wheat (2n=6x=42, AABBEbEb) derived from crossing between Triticum durum (2n=4x=28, AABB) and Thinopyrum bessarabicum (2n=2x=14, EbEb) species that has good potential to be used as a seed or forage plant. The aim of present research was evaluating saline tolerance of new primary different tritipyrum lines through assessing some agronomical traits and ion distribution in plant under mild and severe salinity stress conditions.  

Materials and Methods:

A split-plot hydroponic experiment based on completely randomized block design with two factors and three replications was carried out at Shahrekord University in 2020. The NaCl salinity stress was considered as the main factor with 3 levels (0, 100, 200 Mm) and the genotypes were considered as sub plots with 8 levels. Genotypes included three primary tritipyrum lines (Ka/b, La/b, St/b), three combined tritipyrum lines (i.e. F4, F5 and F6 generations of a combined (Ka/b) (Cr/b) lines), as well as one durum wheat (cv. Creso) and a promising triticale line (Ma45). Different salinity stress levels were imposed from three leaf stage till maturity via irrigating the plants by appropriate saline water. The leaf surface area, fertile florets per spike, 1000-grain weight, grain yield, biological yield as well as concentration of Na+ and K+ and Ca++ ions in both root and aerial parts of genotypes were measured. 

Results and Discussion:

There were significant differences between genotypes in the case of all measured traits. Regardless of salinity levels, tritipyrum line (ka/b) (cr/b) (F6) had the highest amount of biological yield, grain yield, concentration of K+ and Ca++ and K+/Na+ ratio in shoot and the least amount of Na+ in shoot. With increase in salinity level from 0 to 200 mM, flag leaf area, number of fertile florets, 1000 grain weight, biological yield, grain yield and amount of K+ and Ca++ in both root and shoot were significantly reduced in almost all genotypes and concentration of Na+ was increased. At 200 mM salinity, all of the three combined tritipyrum lines had significantly higher amount of biological yield and K+ concentration in shoot and less amount of Na+ in shoot than durum wheat and triticale. Shoot Na+ concentration had negative significant correlation with flag leaf area and 1000 grain weight. In the other hand, positive correlation was observed between shoot K+ concentration and flag leaf area, number of fertile florets, 1000 grain weight and grain yield. At 200 mM salinity, the highest and lowest shoot K+/Na+ ratio were observed in tritipyrum line F5 and durum wheat, respectively. On average, root sodium concentration in tritipyrum lines was higher than that of wheat and triticale while shoot sodium concentration in tritipyrum lines was less than that of the two other genotypes. 

Conclusion:

Results of our experiment suggest that hindrance in the transfer of Na+ from root to the aerial parts is probably one of the mechanisms that used by tritipyrum lines to cope with the high NaCl concentrations.

In this paper, the electrical transport of graphene and silicene nanostructures connected to two semi-infinite graphene and silicene electrodes have been investigated. In these structures, we created nanopores and passed the DNA molecule through the nanopore. Using the Green's Function method and Tight binding approximation, two types of systems with zigzag edges in graphene and silicene have been investigated. By connecting the nanoribbons to the metal electrodes, the created current passes from the nanopore and DNA, from the left to the right. This electric current flow increases the system's sensitivity to the organic DNA bases. We have introduced a new scheme for DNA sequencing.