جستجوی مقالات مرتبط با کلیدواژه « peduncle » در نشریات گروه « زراعت »

Among cereals, durum wheat (Triticum turgidum L. var. durum) is one of the most important protein and energy sources after bread wheat. It has a significant role in human nutrition in most countries.

In this study, in order to identify and localization of QTLs controlling traits related to flag leaf and peduncle, 118 durum wheat recombinant inbred lines obtained from the cross between the local genotype of Iran-249 originated from the west of Iran and the local cultivar of Zardak from Kermanshah were evaluated in three environments under rainfall conditions using randomized complete block design along with parents in three replications. QTL analysis for each trait was performed using the inclusive composite interval mapping method to identify genomic regions that significantly affected the studied traits.

Based on the analysis of variance, the effect of genotype (recombinant inbred line) was significant in terms of traits related to flag leaf and peduncle in three environments, which indicates the existence of appropriate levels of genetic diversity in the studied population for measured traits. The results of QTL analysis using the inclusive composite interval mapping method led to the identification of 33 QTL for the measured traits. The common and stable QTLs were located in at least two environments on chromosomes 1A, 1B.1, 2B.1 and 5A for peduncle length and diameter traits and on chromosomes 2A, 5A and 7A for flag leaf length, flag leaf width and flag leaf area. Identification of repeatable QTLs in the different environments can indicate the existence of stable genomic regions related to flag leaf and peduncle. On the other hand, a positive and significant correlation was observed between the traits, probably due to the linkage or pleiotropic effect of their controlling QTLs. Also, based on QTL analysis using the two-locus method, the additive main effect, as well as the interaction effect of the QTL× environment, was significant for all traits except for the middle and bottom peduncle diameter. In total, six gene loci with significant additive× additive epistasis effects were identified for the flag leaf area-related traits and top peduncle diameter.

Identification and localization of stable QTLs in different environments for some traits related to flag leaf and peduncle can assist in understanding better the genetic basis of these traits to be used in breeding programs, especially in MAS projects.

Available water is an important factor for plant growth in arid regions and dry matter remobilization from different parts of the plant stem has an effective role in drought tolerance. In order to assess the effect of drought stress in flowering stage of barley, a field experiment was carried out in a split-plot based on randomized complete block design with three replications in Ahar in 2018-2019. Irrigation treatments included normal irrigation and irrigation up to the flowering stage in main plots and barley cultivars (Sahand, Bahman, Makui and Valfajr) were placed in subplots. The results showed that weight of thousand grains of cultivars decreased under stress conditions by 21.45% compared to normal irrigation. Makoei cultivar had the highest decrease in grain yield with 23.55% reduction compared to other cultivars. The highest decrease was belonged to Bahman and Makoei in biological yield. The highest amount of biological yield was observed in Bahman under normal irrigation conditions. The rate of remobilization increased in different stem internods and different cultivars. Penultimate remobilization was higher than peduncle in Valfajr and Sahand cultivars. Bahman and Makui cultivars had high remobilization rate from peduncle and lower stem internodes. The remobilization efficiency of different stem internods had a significant increase under stress condition and the highest contribution of peduncle remobilization was related to Sahand under drought stress conditions.

Short periods of heat stress in spring under Mediterranean climate (e.g. southern vast areas of Iran) are common and cereal crops often exposed to short periods of elevated temperatures which can have large effects on crop yields. Stem water-soluble carbohydrate (WSC) could be an important carbon bank for supporting grain filling in wheat especially when carbon assimilation is hampered by heat stress. In Iran, a large number of studies have been done on the effects of heat stress on grain yield of wheat and its components, based mainly on the change in planting date, and data from the effect of short-term heat wave on yield and grain growth and the role of WSC in developing grains do not exist under field conditions. The aim of this study was to determine the effects of short-term heat stress before flowering and the beginning of grain filling on peduncle WSC and grain filling pattern as well as determination of the contribution of peduncle WSC in genotypes with different amounts of carbohydrates in grain growth under short-term stress conditions.

This research was carried out at Research Farm of Khuzestan Agricultural Sciences and Natural Resources University, located 35 km northeast of Ahwaz, in 2014. Four wheat genotypes (Chamran. Maroon, Arvand and Atrak) were exposed to heat stress (maximum 35 °C) for a three-day in the field with a portable heat chamber at two different stages, near flowering (H1) and early grain set (H2). to investigate the changes in individual grain weight (IGW) during grain development, the total WSC changes in the peduncle of the main stem after exposure to short-term heat stress during the development of grain, three plants marked from day zero after flowering. The grains were harvested at intervals of seven days until the time of maturity. The total WSC were measured by anthrone method. When the dry weight of peduncles was maximized in each genotype, the concentration of peduncle carbohydrates (WSC-C) was considered as the maximum WSC-C. To calculate the maximum peduncle WSC content, the maximum WSC-C was multiplied by the maximum peduncle weight. The difference between peduncle WSC-C at maximum time and at maturity time was considered as the mobilized WSC from peduncle to grain. The ratio (%) of peduncle mobilized WSC to maximum peduncle WSC-C was calculated as the efficiency of peduncle in mobilized WSC. The analysis of variance of the measured traits in this study was performed using SAS 9.4 software. Duncan's test was done for means comparison.

The results of analysis of variance showed that there were significant differences between heat stress levels and the traits of genotypes. Short term heat stress (H1 or H2) caused a significant reduction in individual grain weight (IGW) and grain number of main spike. There was no detectable change in IGW until 14 days post-anthesis, after which time grain growth in the heat-stressed plants was reduced from 4.5% to 17%. Based on number of grain per spike and IGW, Atrak, Chamran and Arvand genotypes were recognized as tolerant gynotypes. Heat stress (average of H1 and H2) reduced maximum peduncle water soluble carbohydrate (WSC) content by 26% and mobilized WSC by 15%. The reduction of peduncle WSC content by the heat stress treatments appeared to start at 21 days post-anthesis Reductions in IGW and among genotypes were negatively correlated to the maximum peduncle WSC content.

In order to investigate the effect of drought tension after flowering on dry matter remobilization in 56 wheat genotype, the present experiment was conducted as rectangular lattice 8x7 with two replications during 2010-11 cropping year at research farm of the Campus of Agriculture and Natural Resources of Kermanshah Razi University. Results showed that there was a significant difference at one percent level among genotypes in terms of grain yield and about 27.2 percent reduction in grain yield was observed in response to drought tension after flowering. Mean comparison of yield in different wheat genotypes showed that under humidity control conditions, Darab 2, Navid and UN-11 genotypes (760, 690 and 662 gram per meter square, respectively) had the highest and Rasad cultivar (419 gram per meter square) had the lowest grain yield and also under drought tension conditions after flowering, 330 and Moghan1 genotypes by 542 and 510 gram per meter square, respectively, had the highest and Shiroudi cultivar by 187 gram per meter square had the lowest grain yield. In terms of dry matter remobilization and remobilization efficiency, lower stem internodes compared to peduncle and penultimate internode, showed superiority. Under studied genotypes had a significant difference in remobilization and dry matter remobilization efficacy. According to the obtained results, it appears that remobilization efficiency has been affected under genetic and environment and probably higher production of dry matter at flowering stage would be resulted to higher dry matter remobilization to the grain.

This experiment was carried out to determine the effects of heat stress, due to different planting dates, on the peduncle anatomy of rice cultivars and their grain yields. It was performed in a split-plot experiment using randomized complete blocks design with three replications in 2006 and 2007 cropping seasons at the Shavoor Agricultural and Natural Resources Research Center of Khuzestan. Three planting dates (May 5th. with 20 days intervals), to expose rice cultivars to different tempratures, were assigned to main plots and cultivars (Hoveizeh, Hamar, heat tolerant, Ghermez Anbori, Champa, heat sensitive, and Danial, relatively heat tolerant) to sub-plots. The results of combined analysis showed that the effects of planting date× variety interactions were significant for all of traits, including air channel surface, large vascular bundles surface, xylem and phloem. This indicates that cultivars reacted differently to planting dates. Lowest and highest airchannels surface levels were related to 1st and 2nd planting dates (15492.23 and 21144.38 µm2) and to Hoveizeh and Champa cultivars (15492.23 and 23411.18 µm2) respectively. Lowest and highest xylem surface obtained in 3rd and 1st planting dates (741.37 and 898.03 µm2) respectively. But, lowest and highest level of large vascular bundles were optained in 2nd and 3rd planting dates (15514.20 and 15983.93 µm2)and for phloem (3121.68 and 3437.55 µm2)respectively. Based on these results it can be said that the reduction of large vascular bundles surface and phloem in 1st and 2nd planting date are mechanisms of water conservation and maintaining cell turgor pressure. Increasing xylem vascular bundle surface also, would facilitate availability of water to plant under drought stress conditions.

In order to investigate the effect of drought tension after flowering on dry matter remobilization in 56 wheat genotype, the present experiment was conducted as rectangular lattice 8x7 with two replications during 2010-11 cropping year at research farm of the Campus of Agriculture and Natural Resources of Kermanshah Razi University. Results showed that there was a significant difference at one percent level among genotypes in terms of grain yield and about 27.2 percent reduction in grain yield was observed in response to drought tension after flowering. Mean comparison of yield in different wheat genotypes showed that under humidity control conditions, Darab 2, Navid and UN-11 genotypes (760, 690 and 662 gram per meter square, respectively) had the highest and Rasad cultivar (419 gram per meter square) had the lowest grain yield and also under drought tension conditions after flowering, 330 and Moghan1 genotypes by 542 and 510 gram per meter square, respectively, had the highest and Shiroudi cultivar by 187 gram per meter square had the lowest grain yield. In terms of dry matter remobilization and remobilization efficiency, lower stem internodes compared to peduncle and penultimate internode, showed superiority. Under studied genotypes had a significant difference in remobilization and dry matter remobilization efficacy. According to the obtained results, it appears that remobilization efficiency has been affected under genetic and environment and probably higher production of dry matter at flowering stage would be resulted to higher dry matter remobilization to the grain.

In order to evaluate the accumulation of dry matter and soluble sugars and their remobilization to the growing grains of wheat cultivars under terminal drought stress, a field experiment was carried out in a split-plot arrangement based on randomized complete block design with three replications during 2009-2010 in Razi University, Kermanshah, Iran. Water regime (includes: complete irrigation (control) and withholding irrigation from starting grain-filling stage till maturity) and wheat genotype (includes: Marvdasht and Pishtaz cultivars and DN-11 and 336 lines) were placed in main and sub-plots, respectively. Under control and drought stress treatments, DN-11 line and Marvdasht cultivar had the highest and the lowest grain yield. Drought stress significantly increased dry mater and soluble sugars remobilization of peduncle and penultimate internode in all genotypes and in 336 and DN-11 lines respectively. 336 and DN-11 lines significantly had higher capacity of stem reserves for remobilization from stem to the growing grains than Marvdasht cultivar (sensitive to drought stress). Among studied internodes, lower internodes in addition to having higher potential for accumulation of photosynthetic material also had higher remobilization rate than penultimate and the peduncle internodes. The evidence from this study suggests that DN-11 line with lower grain loss under terminal drought stress then had the highest drought stress resistance.

In order to study the effect of integrated chemical and biological fertilizer in competition with weeds on accumulation and remobilization of dry matter, a field study was conducted at 2010-2011 in Agricultural Faculty of Shahid Chamran University of Ahwaz. The experimental design was split-plot based on randomized complete block with 3 replications. The main plot included 5 integrated nutrient managements and the sub-plot also included 3 competitions intensity. Lengths and dry weight of main stem internodes and dry matter remobilization efficiency were calculated. Our results showed dry matter accumulation and translocation efficiency was changed by changing the chemical fertilizer ratio in integrated treatments. The treatment of 50% chemical fertilizer with biological fertilizer had the highest translocation efficiency (43/30), percent of dry matter translocation (51/10), and also, dry matter translocation (2/09). Different integrated nutrient management treatments had higher effect on dry matters translocation efficiency than weed competition treatments. In addition, weight changed more than length in all 3 types of stem internodes. Finally, our results showed that integrated VS. biological methods had more consisted sitvation for wheat in ternods characters.

Among different cereal crops, wheat has the most cultivation areas and yield in the world. Also, wheat is the major crops grown in arid and semi-arid regions. The occurrence of drought stress during grain filling is the prominent and inevitable characteristic of these areas. The objectives of this research were to determine the effect of water deficiency and the role of current and storage sources of assimilates on grain filling, grain yield and carbohydrates remobilization. Therefore, an experiment was carried out in a split-plot factorial arranged in a randomized complete block design with three replications during 2010-2011 cropping season at the Research Farm of Razi University in Iran. The main factor was the irrigation treatments including control or non-stressed treatment (irrigating plants at all growing stages based on crop water requirement and climatic conditions) and water deficit stress (irrigation cessation after anthesis). The combination of eight wheat cultivars including Bahar, Parsi, Pishtaz, Pishgam, Chamran, Zarin, Sivand, Marvdasht and one line DN-11 along with the photosynthetic sources limiting treatments including control (no limitation of photosynthetic sources), defoliation of the flag leaf, defoliation of all leaves except the flag leaf), de-awning and shading over the ear were considered as the sub plots. The results showed that post-anthesis water deficiency significantly decreased grain yield (22.2%) and removal of photosynthetic sources reduced grain yield through reducing the grain weight. In this case the role of spike photosynthesis in grain filling (35.4%) was greater than the flag leaf and lower leaves roles (18.6 and 18.5%, respectively) and awns had the lowest role in grain filling (3.3%). Under removing of assimilate sources, remobilization of stored material from the different parts of stem internodes was increased, suggesting the compensatory role of them in yield loss prevention. Water deficit stress could not increase the remobilization efficiency, but in terms of mentioned traits, there were differences amongst cultivars and different removing photosynthetic sources. In both control and water deficiency stresses treatments, the amounts of remobilization from different parts of stem and spike to the growing grains were similar. Under well water condition, the grain yield increased due to higher photosynthesis rate compared to water deficiency stress conditions.

A trial study was set to assess the influence of the plant residue management in conjuction with application of different nitrogen sources on accumulation and translocation of wheat stem reserves، at the Agricultural Faculty of Shahid Chamran University of Ahvaz during 2011-2012. The experimental design was split plot at randomized completed block design arrangement. The main plot were different wheat residue management at three levels (residue moving، residue incorporated to the soil and burning) and the subplot were different nitrogen resources (control، 75 & 150 kg/ha urea، Supernitroplus biological fertilizer) SNBF and 75 kg/ha urea fertilizer+ SNBF. Plant characteristic such as main stem internode length، weight and specific weight of internodes and dry matter accumulation and translocation were measured to learn about their growth behavior under plant residue and nitrogen treatments. The result showed that the plant residues are able to inhibit the growth of the internode length in particular those in which developed at the lower internodes of the plant stem. While، various nitrogen application have been shown more striking in term of growth of internode length as compared to the plant residues treatment and the majority of internode lengths on the plants were able to develop maximum growth at the 150 kg/ha urea. Similar growth for the internode length were obtained at the75 kg/ha urea+ SNBF، except for the peduncle length. The present study reveales information that the lower internodes are capable of conserving the most remobilization (307 mg) while peduncle holding the least remobilization (95 mg).

To study the trend of changes in grain yield، growth indices، stem soluble carbohydrates and canopy temperature in 15 spring bread wheat cultivars released between 1951-2008 in Iran، a field experiment was carried out using randomized complete block design with three replications in Research Field Station of Seed and Plant Improvement Institute in Karaj، Iran، in 2011-2012 cropping cycle. Results showed that grain yield has increased by 35 kg ha-1 year-1 from 1951 to 2008. The highest grain yield (5. 38 kg ha-1) belonged to Parsi a recently released cultivar and the lowest grain yield (2. 81 kg ha-1) obtained from Sholeh an old cultivar. Analysis of variance showed that the growth indices; crop growth rate (CGR)، relative growth rate (RGR) and leaf area index (LAI) were significantly different (P ≤ 0. 01) among spring bread wheat cultivars. The modern cultivars research to maximum LAI earlier than older cultivars. The leaf area duration (LAD) was also longer in modern cultivars. Most of cultivars reserved carbohydrates in pedunde and penultimate internode in 14 days after anthesis and then remobilized it to developing grains. The quantity of reserved stem soluble carbohydrates was greater in penultimate internode. Canopy temperature at anthesis stage was cooler in modern cultivars.