Delayed Harvest Effect on Soft Red Winter Wheat in the Southeastern USA

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Abstract
Harvest of soft red winter wheat (Triticum aestivum L.) in the southeastern USA can be delayed because of inclement weather or other unforeseen problems. Our objectives were to determine the impact of delaying harvest beyond grain ripeness (135 g kg−1 grain moisture content) on yield, test weight, grain protein, and 20 milling and baking quality parameters, and to determine if these impacts were correlated with environmental conditions occurring between grain ripeness and harvest. In 2001 and 2002, a total of six trials were conducted where treatments consisted of a timely harvest at grain ripeness and a delayed harvest, 8 to 19 d later. Yield was reduced by up to ∼900 kg ha−1 due to delayed harvest, with yield losses negatively related to total precipitation and positively related to minimum daily temperatures (R2 = 0.99) during the delay interval, indicating that dry and warm environments increased yield losses. Test weight reductions up to ∼115 kg m−3 were seen and were linearly related to the number of precipitation events (r2 = 0.93) between harvests. Grain protein was not affected by delayed harvest. Of the milling and baking quality parameters measured, grain and flour falling number, clear flour percentage, grain deoxynivalenol (DON), and farinograph breakdown times were negatively affected by delayed harvest. Lower falling numbers and higher levels of DON are consistent with the high humidity and rainfall typical of the southeastern USA wheat harvest and are problematic for millers. Decreased farinograph breakdown times can be a problem for bakers.