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Showing 24 results for Stress
Mozhgan Shirinpour, Ehsan Atazadeh, Ahmad Bybordi, Saeid Aharizad, Ali Asghari, Ashkboos Amini,
Volume 10, Issue 1 (9-2023)
Abstract
Considering the importance of maize production and the impact of water deficit stress on reducing the yield of maize, estimating the genetic components and heritability of traits for determine the breeding method under water deficit stress is essential in breeding programs. The generations drived from a cross between two inbred lines of maize including B73 (maternal line) and MO17 (paternal line), SC704 (F1) as well as F2, BC1, BC2 and F3 generations in order to estimate the genetic effects and heritability of yield, yield components and morphological traits were studied. Seven maize generations using the generations mean analysis under the full irrigation, mild and severe water deficit conditions were evaluated. The experiment was conducted in the form of randomized complete block design with 20 replications per experimental unit during two cropping seasons (2018-2019) at the Agricultural Research Station of University of Tabriz. The results of two-year combined analysis of variance and mean comparisons under three different irrigation regimes showed that water deficit stress significantly reduced all of the studied traits (except root/shoot ratio). The generations mean analysis showed the high contribution of non-additive gene effects for the genetic control of grain yield, ear diameter, number of kernel row, ear weight (in full irrigation conditions), 100 grain weight, plant height, fresh shoot weight and biological yield traits. According to these results, selection in the advanced generations and the breeding method based on hybridization can be effective to improve these traits. Also, the significant contribution of additive gene effects in controlling the inheritance of ear length, ear weight (in both stress conditions) and root/shoot ratio traits indicated that selection in early segregating generations and inbred parents can be effective for breeding of these traits and taking advantage of additive variance. Hybrid SC704 and inbred MO17 compared with the inbred B73 showed the lowest variation percentage under the water deficit stress conditions, which indicated their high yield potential and stability in the stress conditions.
Maryam Ebrahimi, Reza Darvishzadeh, Amir Fayaz Moghaddam,
Volume 10, Issue 1 (9-2023)
Abstract
Protection of food security is one of the basic priorities of any country, which is achieved through the development and introduction of new, high-yielding and stress-resistant crop varieties. Considering the wide range of usage; human nutrition, livestock and poultry nutrition as well as use in industrial products production, maize is of special importance in agricultural development programs. To improve a trait with complex behavior and low heritability, indirect selection by other traits or a suitable index developed based on several traits can be used. In this research, 86 maize genotypes were cultivated in the form of randomized complete block design with three replications in the field in the Faculty of Agriculture, Urmia University under two normal and salt stress conditions. The measurement of the traits was done from the tassel appearance to kernel physiological maturity. In order to speed up genotype selection and increase the acuracy of selecting high yielding genotypes, four selection indices including Smith- Hazel, Pasek- Baker, Brim and Robinson were used and calculated. The results of present study revealed that selection based on the Smith- Hazel index with the highest selection efficiency (∆H) will increase the grain yield in normal and grain yield and plant height in salt stress conditions. This index, with its high correlation with the breeding value is introduced as a superior index. Based on this index, R59 and 6*/88 genotypes were introduced as the superior genotypes under normal and salt stress conditions, respectively. Nonetheless, these genotypes were recognized as the best genotypes considering the results of all other investigated indices. Identifying and introducing genotypes tolerant to salinity stress is of particular importance due to the expansion of saline lands and the limitation of access to water suitable for irrigation. Based on the above results, 6*/88 genotype is recommended for the development of promising hybrids for cultivation in areas with water or saline soil.
Seyede Maryam Seyed Seyed Hassan Pour, Leila Nejadsadeghi, Zahra Sadat Shobbar, Danial Kahrizi,
Volume 10, Issue 2 (2-2024)
Abstract
Camelina )Camelina sativa (is an annual, self-pollinating, allohexaploid plant with diploid inheritance belonging to the Brassicaceae family. Camelina exhibits a remarkable degree of similarity to the model plant Arabidopsis thaliana. WRKY transcription factors are among important gene families in plants that play crucial roles in regulating growth and development and in response to diverse stresses. In this research, using bioinformatics analysis and databases, members of the WRKY gene family were identified and their various characteristics were investigated. Overall, the genome of the Camelina plant was found to harbor 214 members of the WRKY gene family. All 214 WRKY genes were found to possess the conserved WRKY functional domain, along with a variety of motifs within their structural composition. Phylogenetic analysis divided the identified members of Camelina WRKY genes into four main groups. Examination of the chromosomal positions revealed that the 214 identified WRKY genes exhibited an uneven distribution across the chromosomes. In order to validate the identified genes, the expression of two genes (Csa11g065620 and Csa07g035970) orthologs of two genes involved in drought stress in Arabidopsis (WRKY8 and WRKY57), were investigated in a drought tolerant (DH 91) and a drought sensitive (DH 101) lines. The results of the gene expression analysis showed that both genes had high expression in drought stress conditions in tolerant line in comparison to normal conditions, whereas no significant expression was found in drought sensitive line. The findings of the present study offer valuable insights for evolutionary investigations and enhance our understanding of the functional roles of the WRKY gene family in Camelina, thereby laying a foundation for future research endeavors in this field.
Nasrin Akbari, Reza Darvishzadeh,
Volume 11, Issue 1 (9-2024)
Abstract
Sunflower, one of the important oilseed plants, is affected by drought stress, consequently leading to yield decreases. Direct selection for improving seed yield, as the end result of multiple traits, is often ineffective due to the significant impact of environmental conditions. For many years, indirect selection through other traits or selection indices has been proposed to improve seed yield. In the present experiment, 100 oilseed sunflower genotypes were evaluated in terms of some agro-morphological traits using a simple 10 × 10 lattice design under normal and drought stress conditions during two consecutive croping seasons. In drought stress conditions, irrigation was done after 180 mm of evaporation from class A evaporation pan, compared to 90 mm in normal irrigation conditions. Brim, Smith-Hazel, Robinson and Pesek-Baker selection indices were calculated to select genotypes under two environmental conditions. In order to evaluate and compare the efficiency of selection indices and select the best index, the genetic gain of traits (∆G), expected gain (∆H) and relative efficiency of selection index (RE) were calculated. The results of this study showed that the direct response to selection for the traits including seed oil content, days to maturity and leaf length under both environmental conditions was more favorable compared to the correlated response. However, for head and stem diameter traits, the lowest efficiency of direct selection was observed under both environmental conditions compared to other investigated traits. Considering the two criteria; the genetic gain of traits (∆G) and expected gain (∆H) under normal and drought stress conditions, the two indexes of Brim and Smith-Hazel were introduced as the best index and the genotype ENSAT-254 was introduced as the superior genotype. The selected ENSAT-254 genotype can be considered in developing hybrid cultivars for cultivation under drought stress conditions, provided it is validated at the molecular level by analyzing the expression of genes related to water deficit stress tolerance.
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