Africa RISING genetic intensification in Central Tanzania and Zambia

United States Agency for International Developmen

Exploiting Grain-Filling Rate and Effective Grain-Filling Duration to Improve Grain Yield of Early-Maturing Maize

Early-maturing maize (Zea mays L.) genotypes yield 15 to 30% less than late-maturing genotypes. One strategy for improving grain yield in the early-maturing group involves assessment of grain-filling traits as secondary traits for selection for high grain yield. In this study, we investigated the possibility of using grain-filling rate and duration for improving grain yield in early-maturing tropical maize. Forty-four hybrids generated using North Carolina design II were evaluated at CIMMYT-Zimbabwe during the 2011/2012 season under irrigated and nonirrigated environments. Although grain-filling rate and effective grain-filling duration were negatively correlated, several hybrids were distinctly above the trend line. The earliest-maturing hybrid took 127 d to reach physiological maturity and produced grain yields comparable to those of the medium-maturing genotypes (7 t ha−1). It had a high grain-filling rate of 2.40 g per plant d−1 (18% higher than those of the low-yielding hybrids) and a relatively longer effective grain-filling duration. Grain-filling rate and effective grain-filling duration had high coefficients of genetic determination, positive correlations with grain yield, low error terms, and low genotype × environment interactions, making them appropriate selection traits for improved grain yield. The study shows that it is possible to develop high-yielding early- to medium-maturing maize hybrids based on favorable combining ability values for grain-filling rate and duration

Variability of Grain-filling Traits in Early Maturing CIMMYT Tropical Maize Inbred Lines

Grain-filling rate (GFR), effective grain-filling duration (EGFD) and total grain-filling duration (TGFD) are important physiological traits of maize (Zea mays L.) grain yeild (GY) formation. To devise effective breeding strategies, the genetic nature of these traits is pre-requisite for improvement in early maturing maize

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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