Heat stress adversely affects wheat production in many regions of the world and is particularly detrimental during reproductive development and grainfilling. The objective of this study was to identify quantitative trait loci (QTL) associated with heat susceptibility index (HSI) of yield components in response to a short-term heat shock during early grainfilling in wheat. The HSI was used as an indicator of yield stability and a proxy for heat tolerance. A recombinant inbred line (RIL) population derived from the heat tolerant cultivar 'Halberd' and heat sensitive cultivar 'Cutter' was evaluated for heat tolerance over 2 years in a controlled environment. The RILs and parental lines were grown in the greenhouse and at 10 days after pollination (DAP) half the plants for each RIL received a three-day heat stress treatment at 38°C/ 18°C day/night, while half were kept at control conditions of 20°C/18°C day/night. At maturity, the main spike was harvested and used to determine yield components. A significant treatment effect was observed for most yield components and a HSI was calculated for individual components and used for QTL mapping. QTL analysis identified 15 and 12 QTL associated with HSI in 2005 and 2006, respectively. Five QTL regions were detected in both years, including QTL on chromosomes 1A, 2A, 2B, and 3B. These same regions were commonly associated with QTL for flag leaf length, width, and visual wax content, but not with days to flowering. Pleiotropic trade-offs between the maintenance of kernel number versus increasing single kernel weight under heat stress were present at some QTL regions. The results of this study validate the use of the main spike for detection of QTL for heat tolerance and identify genomic regions associated with improved heat tolerance that can be targeted for future studies.

We tested 13 sorghum entries (lines and hybrids) with different endosperm matrices for ethanol production using a laboratory dry grind process. Waxy and heterowaxy samples had the highest efficiencies. Free amino nitrogen (FAN) contents in sorghum samples were positively related to the fermentation rate during fermentation (R2=0.8618). Dried distiller's grain with solubles (DDGS) from different sorghums had significantly different crude protein and crude fat contents. Residual starch content in DDGS ranged from 0.60% for the most efficient sample to 2.66% for the least efficient sample. This study showed that the HD lines (TX1, TX3, TX5, TX7, and TX9) with modified endosperm protein matrix have several attributes desirable for ethanol production: easily pasted starch granules, significantly higher FAN content in finished mashes, 30-45% faster ethanol fermentation rate during early stages, and 50-60% higher lysine content in DDGS.

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