Abstract:The purpose of this study was to monitor population fluctuations of various species of Diptera during the growing season of durum wheat, in years 2009 and 2010. The most abundant Hymenoptera species was also included in the study as a control species. The species studied were Cephus pygmaeus, Haplodiplosis marginata, Mayetiola destructor, and Chlorops pumilionis. Samplings of insects were taken in eight periods to cover the late stages of durum wheat. Measurements were made every about 100 m in the field, with… Show more
“…Also, for the TKW trait in the wheat breeding, the numbers of favourable alleles in the modern cultivars indicate that there is still considerable genetic potential (variability) for use in genome selection (Wang et al 2012) and, thus, this trait needs more investigation. These positive results were realised although the presence of various insects was apparent and the possible damages were described previously in the same region (Deligeorgidis et al 2012). They also referred to the fact that the yield losses are usually about 5% or more.…”
The objective of this study was to explore the internal variability in six established F7 commercial wheat cultivars for breeding purposes. They are sown traditionally in the region of Western Macedonia, Greece. Spikes of the six cultivars were sown in 2008 in separate rows. A head to row selection scheme was applied for two growing periods in order to select lines within the cultivars, based on various traits such as: the total spike number, the spike weight per row, the 1000-kernel weight and the specific weight . The final selection was based on the specific weight and the four best rows from each cultivar were selected. All selected lines were tested in a field trial with a randomised complete block design (RCB). The original seed of the cultivars were used as controls. Statistically significant differences were found for all the studied traits. The line selections differed from the original cultivars, sometimes highly significantly. In conclusion, commercial cultivars that are sown traditionally for many years may contain exploitable variability, which reveals, that the continuous selection within cultivars is necessary to avoid cultivar deterioration and to improve the yield and other traits. The results indicate a degeneration of grain yield from 8% to 20%. Although eye-selection restricts off-types, our results mainly indicate new variability and cultivar performance deterioration under extreme biotic and abiotic stress.
“…Also, for the TKW trait in the wheat breeding, the numbers of favourable alleles in the modern cultivars indicate that there is still considerable genetic potential (variability) for use in genome selection (Wang et al 2012) and, thus, this trait needs more investigation. These positive results were realised although the presence of various insects was apparent and the possible damages were described previously in the same region (Deligeorgidis et al 2012). They also referred to the fact that the yield losses are usually about 5% or more.…”
The objective of this study was to explore the internal variability in six established F7 commercial wheat cultivars for breeding purposes. They are sown traditionally in the region of Western Macedonia, Greece. Spikes of the six cultivars were sown in 2008 in separate rows. A head to row selection scheme was applied for two growing periods in order to select lines within the cultivars, based on various traits such as: the total spike number, the spike weight per row, the 1000-kernel weight and the specific weight . The final selection was based on the specific weight and the four best rows from each cultivar were selected. All selected lines were tested in a field trial with a randomised complete block design (RCB). The original seed of the cultivars were used as controls. Statistically significant differences were found for all the studied traits. The line selections differed from the original cultivars, sometimes highly significantly. In conclusion, commercial cultivars that are sown traditionally for many years may contain exploitable variability, which reveals, that the continuous selection within cultivars is necessary to avoid cultivar deterioration and to improve the yield and other traits. The results indicate a degeneration of grain yield from 8% to 20%. Although eye-selection restricts off-types, our results mainly indicate new variability and cultivar performance deterioration under extreme biotic and abiotic stress.
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