An increase of 3–4☌ of seasonal temperature has been shown to decrease wheat yield by 15–35% in Africa and Asia and by 25–35% in the Middle East during the grain-filling period. The impact of extreme heat waves has been analyzed in wheat. Continual and terminal high temperature stresses are the two major impediments to wheat production. Heat intensity remarkably influences flowering, pollination, and grain filling and is a serious challenge to sustain high production. The difference between wheat production and consumption has been bridged by targeting breeding efforts toward increasing wheat productivity by using high-yielding and early-maturing cultivars for use in intensive cropping systems and to avoid hot winds at the end of the agricultural season during grain filling. Wheat production needs to be continually increased by 2% each year to meet the basic needs of the increasing human population. In particular, the steady rise in population, loss of agricultural lands to sustainable urbanization, and decrease in resource availability owing to climate change pose serious threats to the safe production of wheat. Decreased wheat productivity has caused devastating economic and sociological impacts. All these negative influences threaten the sustainability of grain crop production. In addition to these, the incidence of diseases and pest infestation is increasing with global warming. Multiple challenges such as high temperature stress and reduced water availability are the major concerns for all countries in the Arab region. Agricultural productivity is remarkably affected by extreme weather events. In addition, wheat straw is an important component of animal feed. It represents 17% of the global crop area, feeding about 40% of world’s population and providing 20% of the total diet calories. Wheat ( Triticum aestivum L.), one of the most prominent food crops worldwide, is one of the most essential sources of protein in humans. Multivariate analysis (stepwise regression and path coefficient) suggested that GFD, hundred kernel weight, days to maturity, and number of kernels per spike had the highest influence on GY. These correlations indicate that the performance of wheat hybrids with high GY and earliness could be predicted by determining the GD of the parents by using SSR markers. Correlation between GD and each of BPH and SCA effects based on SSR markers was significantly positive for GFD, hundred kernel weight, number of kernels per spike, harvest index, GY, and grain filling rate and was significantly negative for DH. Two hybrids (P2 × P4) and (P2 × P5), which showed the highest performance of days to heading (DH), grain filling duration (GFD), and GY, and had large genetic diversity among themselves (0.883 and 0.911, respectively), were deemed as promising heat-tolerant hybrids.
The combined data indicated that five hybrids showed 20% greater yield than mid-parent or better-parent. Cluster analysis based on the GD estimated using SSRs classified the genotypes into three major groups and six sub-groups, almost consistent with the results of principal coordinate analysis. The GD varied from 0.235 to 0.911 across the 16 genotypes. Eight parental genotypes with greater genetic diversity and their 28 F 1 hybrids generated using diallel crossing were evaluated for 12 measured traits in two seasons. This study evaluated the GD between 16 wheat genotypes by using 60 simple sequence repeat (SSR) markers to classify them according to their relationships and select those with greater genetic diversity, evaluate the correlation of the SSR marker distance with heterotic performance and specific combining ability (SCA) for heat stress tolerance, and identify traits that most influence grain yield (GY). Hybrid performance during wheat breeding can be improved by analyzing genetic distance (GD) among wheat genotypes and determining its correlation with heterosis.
0 kommentar(er)
