Koua, Ahossi Patrice: Breeding progress for drought tolerance and nitrogen use efficiency in winter wheat (Triticum aestivum L.). - Bonn, 2022. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-65091
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-65091,
author = {{Ahossi Patrice Koua}},
title = {Breeding progress for drought tolerance and nitrogen use efficiency in winter wheat (Triticum aestivum L.)},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2022,
month = mar,

note = {Drought is the major abiotic stress factor limiting agricultural production in arid, semi-arid as well as in temperate regions around the world, whereas nitrogen (N) is one of the most important nutrients for crop production. With the current threat of climate change, drought-prone land is predicted to increase in the four corners of the planet. The development of drought-tolerant genotypes is seen as the most efficient and economical approach to curb the problem of drought and increase crop productivity. In this study, we employed a forward genetic approach to understanding the genetic basis of traits related to drought tolerance and nitrogen use efficiency, with the ultimate goal to find genetic variants that can be used to improve drought tolerance and N use efficiency in wheat.
A number of 200 winter wheat genotypes released from 1946 to 2013 were used to screen the genotypic variation in agronomic, photosynthetic-related and grain quality traits under different water regimes. The evaluated genetic variation was used to identify traits with higher contribution to grain yield (GY) and highlighted the role played by breeding to enhance drought tolerance, photosynthesis efficiency and GY in the last seven decades. Results indicated significant effects of genotype, water regime, and their interactions for agronomic and photosynthesis-related traits. Kernels number per square meter was the yield-component with highest contribution to GY. Breeding has increased GY over years through improving the kernels number per area and the harvest index, which were due to improvement in the photosynthesis efficiency in modern cultivars. Genome wide association study (GWAS) and haplotypes effects analysis confirm that major haplotypes favorable for higher GY, and higher photosynthesis efficiency, especially under drought conditions were selected through breeding.
The effect of drought on plant nitrogen uptake and use efficiency was examined to uncover genomic regions that simultaneously contributed to drought tolerance and N use efficiency. The results indicated a total of 27 potential QTL with main effects on evaluated traits, while 10 QTL regions were interacting with N availability. The transcript abundance analysis showed that the cold shock protein gene in the vicinity of a pleiotropic QTL region was highly expressed under drought stress conditions. Our result from the experiment conducted to assess the effect of fungicide and nitrogen supply on wheat grain productivity revealed a synergistic effect of nitrogen and fungicide on GY. Forty-six high-yielding cultivars showed different stability levels under three cropping systems (CS) including low N, high N and high N plus fungicide, suggesting that resource use efficiency can be improved via cultivar selection for targeted CS.
The breeding progress in the wheat panel for most traits including GY was consistent across all three CS. The present study demonstrated that breeding has improved genotypes performance not only under optimum conditions but also under various stress conditions such as drought and N deprivation. This improvement could be explained by the increment of favorable alleles for photosynthesis efficiency. Upon validation of the genomic regions harboring the favorable alleles highlighted in this study, they can be exploited to improve drought tolerance and N use efficiency in wheat.},

url = {https://hdl.handle.net/20.500.11811/9706}

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