Adaptation of cotton to different watering regimes

Many physiological functions and morphological properties determining yield of cotton plant may inhibited by different water regimes. The aim of the present study was to investigate morpho-physiological adaptation of cotton plants to different irrigation regimes. For this purpose, a pot experiment was conducted under fully controlled growth chamber. Cotton plants (Gossypium hirsutum L.) were exposed three irrigation regimes. Plants were irrigated when water holding capacity reach 20%, 40% and 60% to field capacity in I20, I40 and I60 treatments respectively. Physiological parameters such as transpiration, canopy temperature depression (CTD) and SPAD values and morphological parameters such as adaxial and abaxial stomatal density were determined. Lowest transpiration found in I20 treatments than I40 and I60 treatments. SPAD value remained lower level in I20 treatment whereas higher in I60 treatments during different irrigation regimes. Stomatal density was higher in adaxial surface than abaxial surface of leaves. On the other hand, increasing stoma number per unit leaf area in adaxial surface with lower irrigation frequency was recorded. Our results suggested that cotton plants adapt to different water regimes via regulating transpiring organs and their functions

Genetic Diversity and Population Structure Analysis of Triticum aestivum L. Landrace Panel from Afghanistan

Landraces are a potential source of genetic diversity and provide useful genetic resources to cope with the current and future challenges in crop breeding. Afghanistan is located close to the centre of origin of hexaploid wheat. Therefore, understanding the population structure and genetic diversity of Afghan wheat landraces is of enormous importance in breeding programmes for the development of high-yielding cultivars as well as broadening the genetic base of bread wheat. Here, a panel of 363 bread wheat landraces collected from seven north and north-eastern provinces of Afghanistan were evaluated for population structure and genetic diversity using single nucleotide polymorphic markers (SNPs). The genotyping-by-sequencing of studied landraces after quality control provided 4897 high-quality SNPs distributed across the genomes A (33.75%), B (38.73%), and D (27.50%). The population structure analysis was carried out by two methods using model-based STRUCTURE analysis and cluster-based discriminant analysis of principal components (DAPC). The analysis of molecular variance showed a higher proportion of variation within the sub-populations compared with the variation observed as a whole between sub-populations. STRUCTURE and DAPC analysis grouped the majority of the landraces from Badakhshan and Takhar together in one cluster and the landraces from Baghlan and Kunduz in a second cluster, which is in accordance with the micro-climatic conditions prevalent within the north-eastern agro-ecological zone. Genetic distance analysis was also studied to identify differences among the Afghan regions; the strongest correlation was observed for the Badakhshan and Takhar (0.003), whereas Samangan and Konarha (0.399) showed the highest genetic distance. The population structure and genetic diversity analysis highlighted the complex genetic variation present in the landraces which were highly correlated to the geographic origin and micro-climatic conditions within the agro-climatic zones of the landraces. The higher proportions of admixture could be attributed to historical unsupervised exchanges of seeds between the farmers of the central and north-eastern provinces of Afghanistan. The results of this study will provide useful information for genetic improvement in wheat and is essential for association mapping and genomic prediction studies to identify novel sources for resistance to abiotic and biotic stresses.info:eu-repo/semantics/publishedVersio

Exploring the genetic diversity and population structure of wheat landrace population conserved at ICARDA genebank

Landraces are considered a valuable source of potential genetic diversity that could be used in the selection process in any plant breeding program. Here, we assembled a population of 600 bread wheat landraces collected from eight different countries, conserved at the ICARDA's genebank, and evaluated the genetic diversity and the population structure of the landraces using single nucleotide polymorphism (SNP) markers. A total of 11,830 high-quality SNPs distributed across the genomes A (40.5%), B (45.9%), and D (13.6%) were used for the final analysis. The population structure analysis was evaluated using the model-based method (STRUCTURE) and distance-based methods [discriminant analysis of principal components (DAPC) and principal component analysis (PCA)]. The STRUCTURE method grouped the landraces into two major clusters, with the landraces from Syria and Turkey forming two clusters with high proportions of admixture, whereas the DAPC and PCA analysis grouped the population into three subpopulations mostly according to the geographical information of the landraces, i.e., Syria, Iran, and Turkey with admixture. The analysis of molecular variance revealed that the majority of the variation was due to genetic differences within the populations as compared with between subpopulations, and it was the same for both the cluster-based and distance-based methods. Genetic distance analysis was also studied to estimate the differences between the landraces from different countries, and it was observed that the maximum genetic distance (0.389) was between the landraces from Spain and Palestine, whereas the minimum genetic distance (0.013) was observed between the landraces from Syria and Turkey. It was concluded from the study that the model-based methods (DAPC and PCA) could dissect the population structure more precisely when compared with the STRUCTURE method. The population structure and genetic diversity analysis of the bread wheat landraces presented here highlight the complex genetic architecture of the landraces native to the Fertile Crescent region. The results of this study provide useful information for the genetic improvement of hexaploid wheat and facilitate the use of landraces in wheat breeding programs

MITIGATE GRAIN YIELD LOSSES OF WHEAT UNDER TERMINAL DROUGHT STRESS BY DIFFERENT NITROGEN APPLICATIONS

WOS: 000413647600045Water and nitrogen are both most limiting factors for plant growth and productivity. Effects of different nitrogen applications on grain yield of wheat under terminal drought stress were investigated in the present study. A field experiment was conducted with a bread wheat cultivar Gonen in two experimental sites characterized by loamy-sand (Menemen) and clay-loam (Bornova) soils. Rainout shelters were used to exclude rain from drought imposed plots during grain filling stage. Gradually decrease in soil moisture content caused significant decrease in grain yield in both experimental sites. However, higher yield were recorded in loamy-sand soils (LSs) than clay-loam soils (CLs) in all treatments. Thousand grain yield and grain number per spike were also decreased due to drought conditions. Similar to grain yield, both parameters were also significantly lower in CLs than LSs. Split nitrogen treatment included flowering stage caused a significant decrease in grain yield because of lower biomass production during earlier development stages. Our findings suggested that higher biomass which could be obtained by high earlier nitrogen application may provide an advantage in wheat production for later drought conditions.Ege University (Scientific Research Project)Ege University [2009ZRF064]The data presented in this paper is the part of PhD. Thesis of Ozgur Tatar. This study financially supported by Ege University (Scientific Research Project No: 2009ZRF064)

EFFECT OF DROUGHT STRESS ON YIELD AND QUALITY TRAITS OF COMMON WHEAT DURING GRAIN FILLING STAGE

Wheat (T. aestivum) has a crucial role for human diet especially in developing countries. Changes in precipitation intensity, amounts and patterns restrict wheat growth and productivity under rainfed conditions. Thus, assessment of drought effects during growth stages of wheat on grain yield and quality traits has substantial importance. Grain filling stage, coincides with early spring when the rainfall pattern highly variable, was considered in this study to evaluate effects of drought conditions on yield and quality of 16 wheat genotypes and determine superior varieties. Drought treatment inhibited plant height (5.5 %), 1000 grain weight (9.2 %) and grain yield (17.7 %) while harvest index increased (8.5 %). However, there was no significant effect of drought conditions on grains number spike(-1) and spike numbers m(-2). Protein content increased (31.6 %) in all genotypes, while the Zeleny sedimentation significantly decreased (8.2 %) with drought treatments during both growing seasons. Cultivars Pandas and Meta had higher grain yield under drought stress in both years whereas Line-28 and Pandas had better quality properties.Research Fund of TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [113O893]The authors thank the Research Fund of TUBITAK (The Scientific and Technological Research Council of Turkey) for their financial support (Project No. 113O893)

Dwarfing gene Rht4 and its effects on key agronomic and coleoptile traits in bread wheat

The gibberellin sensitive gene Rht4 is a single recessive factor and reduces plant height in wheat. To reveal its potential use in wheat breeding, the effects of Rht4 gene on plant height and other key agronomic and coleoptile traits were investigated and compared using a bi-parental population from a cross between BSJ-14 (semi-dwarf, Rht4) and Scholar (tall, no known dwarfing alleles) under the rainfed conditions. The presence of Rht4 gene was controlled at the molecular level using SSR marker of Rht4. It was found that 25 out of 72 F4 lines carried Rht4 gene while 36 lines did not possess the gene and 11 lines were heterozygous. Rht4 gene reduced plant height and peduncle length by 5.2% and 5.3%, respectively. Spike length, spikelet number and kernel number per spike were decreased but thousand kernels weight increased in lines with Rht4 gene as compared to tall lines. Reduction in coleoptile length, coleoptile diameter and first leaf length was observed in lines with Rht4 gene by 5.5%, 2.1% and 6.6%, respectively. The increase in thousand kernels weight in plants carrying Rht4, especially in heterozygotes, shows that this gene should be put emphasis on in wheat breeding programs, particularly in the development of hybrid varieties