Genetic evaluation of seedling heat tolerance in sorghum

Surface temperatures of tropical soils at planting time, where sorghum (Sorghum bicolor) is a traditional crop, can exceed 50 oC for hours. Seedling heat tolerance is critical for adequate crop establishment in the semi-arid tropics. Improvement of seedlings heat tolerant genotypes would reduce crop losses due to sufficient plant populations. The objectives of this study were to estimate seedling tolerance to heat, determine individual parental contribution and estimate additive, dominance and epistatic effects for seedling tolerance. In our experiments, seedling heat tolerance termed heat tolerance index (HTI) was defined as a ratio of resumed coleoptile growth after a controlled heat shock, compared to normal growth. Genetic parameters of HTI were determined by crossing four lines with varying HTI, with three tester lines, and deriving F1, F2, F3, BC1 and BC11 families forgeneration means analysis. Line IS20969 from Egypt showed the highest HTI of 0.71, while 290R, an experimental line from the University of Nebraska was the lowest at 0.51. Additive and dominance effects contributed to coleoptile elongation under normal conditions, but only additive effects were significant in recovery growth. Epistatic effects were present in both conditions. General combining ability (GCA) effects for HTI were highly significant in both conditions, but specific combining ability effects were negligible. These results indicate that it is possible to improve seedling heat tolerance and, thus, improve sorghum variety and hybrid plant populations in tropical areas where hot soil temperatures occur

Current warming will reduce yields unless maize breeding and seed systems adapt immediately

The development of crop varieties that are better suited to new climatic conditions is vital for future food production1, 2. Increases in mean temperature accelerate crop development, resulting in shorter crop durations and reduced time to accumulate biomass and yield3, 4. The process of breeding, delivery and adoption (BDA) of new maize varieties can take up to 30 years. Here, we assess for the first time the implications of warming during the BDA process by using five bias-corrected global climate models and four representative concentration pathways with realistic scenarios of maize BDA times in Africa. The results show that the projected difference in temperature between the start and end of the maize BDA cycle results in shorter crop durations that are outside current variability. Both adaptation and mitigation can reduce duration loss. In particular, climate projections have the potential to provide target elevated temperatures for breeding. Whilst options for reducing BDA time are highly context dependent, common threads include improved recording and sharing of data across regions for the whole BDA cycle, streamlining of regulation, and capacity building. Finally, we show that the results have implications for maize across the tropics, where similar shortening of duration is projected

Genotype x environment interactions in eggplant for fruit phenolic acid content

Eggplant fruit are a rich source of phenolic acids that influence fruit culinary quality and antioxidant content. We evaluated the influence of production environments and stability of diverse genotypes across environments for eggplant fruit phenolic acid content. Ten Solanum melongena accessions consisting of five F-1 hybrid cultivars, three open-pollinated cultivars and two land race accessions, plus one S. macrocarpon and one S. aethiopicum accession, were grown at two locations under greenhouse and open field environments. Twenty phenolic acid conjugates were identified in fruit flesh and assigned to six classes that included hydroxycinnamic acid amides, caffeoylquinic acid esters, hydroxycinnamoylquinic acid esters, malonylcaffeoylquinic acid esters, di-hydroxycinnamoylquinic acid esters, and other hydroxycinnamic acid conjugates. There were significant differences among accessions for total phenolic acid conjugate content and for all six classes. There were no significant differences detected among the environments for any of the variables. However, the environment x accession interaction was highly significant for all phenolic acid classes. Broad-sense heritability estimates for all six phenolic acid classes were high, ranging from 0.64 to 0.96. Stability analysis demonstrated widespread instability for phenolic acid content across environments. Stability of the predominant caffeoylquinic acid esters class positively influenced stability of total phenolic acid content for some but not all genotypes. High heritability, coupled with highly significant genotype x environment interactions suggests that stability estimates may improve the efficiency of breeding new genotypes with predictable performance across environments.Stommel, JR.; Whitaker, B.; Haynes, K.; Prohens Tomás, J. (2015). Genotype x environment interactions in eggplant for fruit phenolic acid content. 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