جستجوی مقالات مرتبط با کلیدواژه "صفات مورفولوژیکی" در نشریات گروه "منابع طبیعی"

Wheat (Triticum aestivum L.) is the main staple food in many parts of the world including Iran. This crop is one of the most cold stress tolerant crops amongst domesticated plants. Still, Severe freezing in winter and early spring may influence the growth and survival of wheat plants and decrease its growth and seed yield. The absolute minimum temperature in North Khorasan reach to -20°C in many years and if a cold tolerant cultivar is not choose or if wheat field in not hardened properly then the freezing stress might be injurious. Therefore each new cultivar that introduced to the region should firstly test to chilling and freezing stress. This experiment was carried out to explore freezing tolerance of two wheat cultivars (Mihan and Pishtaz) under controlled and field conditions with spraying paclobutrazol (PBZ) and non-spray.

 Seeds of two wheat cultivar Mihan and Pishtaz were sown in plastic pots in 20th of September in Bojnord and kept them in open space until third leaf stage in order to grow in the same climatic conditions as they will grow in the future. All plants could receive the enough temperature for winter hardening then they transfer to Mashhad to apply freezing stress in controllable freezer. After applying freezing stress all pots transferred into research greenhouse at Ferdowsi University of Mashhad with light density of 500±50 μmol m-2 s-1 and light/dark cycle of 14/10.   Sampling and measurement were arranged after four weeks that plants grown in the greenhouse.  Measured parameters included electrolyte leakage, plant height, green leaf area, plant survival rate and number of tiller and leaves per plant. Field experiment was arranged in the Kohnekand Agricultural research center in Bojnord. Both experiments conducted as a split-split plots based on a completely randomized design with three replications. The main plots in green house were six freezing temperatures (zero,-4, -8, -12, -16, and -20°C), the sub-plots were three paclobutrazol (PBZ) concentrations (foliar application of zero as control, 30 and 60 mg L-1) and the sub-sub-plots were wheat cultivars (‘Mihan’ and ‘Pishtaz’) with three replication. In the field experiment main plots were three sowing dates (16th Oct., 13th Nov. and 5th Dec.), and the sub-plots and sub-sub-plots were the same as controlled experiment. Data were statistically analyzed using the SAS software (SAS version 9.2). The LSD test (p=0.05) was used to determine which treatment is statistically different from the others.

The results showed that, Mihan cultivar produced more leaves but lower tiller per plant compare to pishtaz, Up to -16°C but at and -20°C the tiller number was also not significant. But reduced to -20°C, the electrolyte leakage of membrane increased significantly by 71.5%. The electrolyte leakage in Mihan cultivar was significantly lower than that of Pishtaz cultivar when freezing temperature was decreased lower than -16°C.  PBZ also caused shorter plants but less leaf lost observed due to freezing stress in both cultivars. Delay in sowing date from 16th Oct. to 13th Nov. and to 5th of Dec. caused 19% and 31% seed yield reduction in two wheat cultivars, respectively. While the average seed yield of Mihan was 17% higher than pishtaz cultivar. Biological yield also followed the same trend of grain yield. PBZ application did not show any significant effect on seed yield, this result might be due to ABA production after PBZ spraying, which can negatively affect yield component formation.  Based on our results temperatures below -12°C is much more injurious that higher temperatures, and the advantage of freezing tolerance wheat cultivars appears in lower temperatures.

Based on our results, Mihan cultivar has higher freezing tolerance capacity and in temperature below -12°C and PBZ application this cultivar can alleviate negative effects of freezing stress. Therefore, introduction and extension of this cultivar in mountain regions and those areas that the risk of freezing stress is high might reduce the risk of freezing damage in Bojnord area and at the same time produce reliable grain yield.

To evaluate the morphological diversity of some almond cultivars and genotypes, an experiment was carried out on 35 Iranian and foreign almond genotypes. Thirty-eight quantitative and qualitative characteristics of nuts and kernels of almond trees were evaluated. Analysis of variance and means comparisons showed that all of the characteristics in examined cultivars were significant, showing high variability in these cultivars and their characteristics. Results of simple correlation analysis indicated the existence of significant, positive and negative correlations among some important traits. Cluster analysis showed that, in Euclidean distance of 15, all cultivars and genotypes divided in to 2 main branches. With decrease in Euclidean distance from 25 to 5, the cultivars and genotypes were divided to 8 main subclusters. Cluster analysis showed that nut length, kernel length, kernel weight, nut weight, shell thickness and hardness, dispermous kernel percentage, patterns of outer shell and suture opening of shell were the main characteristics that separated the genotypes. According to results, ‘Shahrood 13’ ,‘Shahrood 21,‘Shahrood 6’, ‘Sefied’, ‘Premorski’, ‘Yalda’, ‘Shahrood 10’, ‘Shahrood 12’, ‘Mamaei’, ‘Shahrood  7’, cultivars, and also ‘AIM2’, ‘AIM1’, ‘GM1‘, AHN2’,‘AHN1’, and ‘AHYU’ genotypes were better than other cultivars and genotypes.

In order to study biomass yield in flowing stage and morphological traits, 12 populations M. pulegium were evaluated in a field experiment in the Alborz research station, Karaj Iran in 2014. Seeds of  the accessions were sown as spaced planet using complete randomized block in two replications. Each plot contains 20 spaced plants with 50×50 cm distance. The drip irrigation system was used for irrigation. In The first year, due to poor establishment no data were collrvted. In the second year, data were collected for fresh and dry matter yield, plant height, stems number, flower number per plant, the canopy diameter and infloescence length. Result showed significant differences between accessions for all of the traits (p < 0.01). Mean comparisons between populations showed that, Marivan and, 22381-Arak with values of 824 and 375.6 g/p had the highest aerial fresh and dry weight. In terms of plant height, the populations of 22381 and 22391-Arak with average values of 82.6 and 81.8 cm had the highest stem length, respectively. The highest inflorescence length with average values of 11.6 and 10.7 cm were observed in 22391-Arak and Gorgan, respectively. For flower number, Miandoab with 60 flowers per plant had the highest number. Using cluster analysis, the populations were split into two groups with 8 and 4 populations in cluster 1 and 2, respectively. The overall mean values in populations of cluster 1 were higher than cluster 2. It was concluded that the populations of Marivan and 22381-Arak had the highest aerial fresh and dry weight and can be used for improved breeding varieties.

Inter and intra-specific crossing is a useful technique to introduce characteristics from wild plants to commercial cultivars of asparagus. In this research, Inter and intraspecific crosses between Iranian wild asparagus and European commercial asparagus was carried out at university of Cordoba (Spain) during 2015-2018. Specific allele for each parental species and accessions was detected with help of molecular markers. The genetic nature of hybrid plants was then confirmed by detecting of parental specific alleles in progeny. Thereafter, some of the most important morphological properties were evaluated in parental and progeny plants populations. Successful interspecific hybridization was obtained between Asparagus breslerianus and A. officinalis. Specific allele (1086 bp in length) was detected by TC6 primer in A. persicus. Morphological analysis showed that the highest coefficient of variation (CV %) was related to number of spear, main stem diameter, length of primary and secondary branches and number of cladode. The number of spear, number of secondary branch and number of cladode were higher in hybrids obtained by crossing between A. persicus × A. officinalis than parental plants. Diameter and height of main stem, number of primary branch, diameter and length of primary and secondary branches, width and length of spear scale, leaf diameter and internode length of primary and secondary branches played an important role to create morphological variability in parental and hybrid asparagus populations.