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Quality of Hard Red Winter Wheat Grown Under High Temperature Conditions During Maturation and Ripening¹

¹Contribution 97-455-J from the Kansas Agricultural Experiment Station, Manhattan, KS 66502. ²Department of Crop Science, Box 7620, North Carolina State University, Raleigh, NC 27695-7620 ³Corresponding author. E-mail: Lance_Gibson@ncsu.edu ⁴Department of Grain Science, Shellenberger Hall, Kansas State University, Manhattan, KS 66506. ⁵Department of Agronomy, 2004 Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS 66506-5501.

High temperature during grain filling has been identified as a major factor in the end-use properties of bread wheat (Triticum aestivum L.). Our objectives were to assess the effect of high temperature during maturation on the grain characteristics, milling quality, and flour quality of hard red winter wheat. In three separate experiments, plants of wheat cultivar Karl 92 were subjected to regimes (day-night) of 20–20, 25–20, 30–20, and 35–20°C from 10 and 15 days after anthesis (DAA) until ripeness, and 25–20, 30–20, and 35–20°C from 20 DAA until ripeness. In other experiments, plants of wheat cultivars Karl 92 and TAM 107 were dried at 20 and 40°C, and spikes of Karl 92 were dried at different temperature and humidity conditions to asses the effects on quality of high temperature and drying rates during grain ripening. Flour yield correlated positively with kernel weight and diameter, test weight, and proportion of large kernels. Flour yield decreased as temperature increased and correlated negatively with hardness index and proportion of small grains. High growth temperatures and rapid grain desiccation decreased mixing time and tolerance of the flours. The greatest damage occurred when high temperature was maintained continuously from early grain filling until ripeness. Weakening of dough properties by rapid desiccation during ripening suggest that temperature, humidity, and possibly soil moisture all contribute to the final quality of bread wheat.