Date of Award

Spring 2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Agronomy

First Advisor

Shaun Casteel

Committee Member 1

Jeffrey Volenec

Committee Member 2

Kiersten Wise

Abstract

Bread wheat (Triticum aestivum L.) is a cereal crop of global importance. As global demand increases, it is essential to increase the quality and efficiency of crop production. Harvesting wheat early provides an opportunity for increased grain quality, and it may also allow the grower to double-crop soybean ( Glycine max L.) after wheat more effectively. Our objectives were to determine if harvesting grain early, at high moisture would, 1) increase milling and baking quality and 2) improve germination potential. As a result of these objectives, we will develop a model to predict dry-down of wheat. Five soft red and five soft white winter wheat cultivars were grown at West Lafayette, IN, over two years using a randomized complete block design. Grain was sampled by hand as drying progressed from approximately 40 to 10% moisture. Milling and baking quality of the samples was tested at the USDA-ARS Soft Wheat Quality Laboratory in Wooster, OH. Parameters tested included flour yield, whole grain hardness, whole grain protein, flour protein, softness equivalent, lactic acid solvent retention capacity (SRC), sucrose SRC, estimated cookie diameter, and modified milling, baking, and softness equivalent scores. Germination was evaluated by the Indiana Crop Improvement Association. Additionally, grain moisture loss was compared with growing degree days (GDD) accumulated from heading date to harvest date to discern the relationship between grain dry-down and thermal time.

Overall, harvesting grain early at high moisture maintained, if not increased, milling and baking quality. Flour yield, one of the most important quality parameters, did not change as a result grain moisture across the two years and the cultivars of both wheat types (means ranging 64.8 to 68.4). Protein quality, as measured by lactic acid SRC, was not detrimentally affected by grain moisture in either year in both wheat types. In general, grain at 22 to 24% moisture displayed favorable milling and baking quality for most parameters. Cultivar response differed only in one quality parameter with soft red wheat in 2013. The remaining effects of harvest grain moisture were consistent within wheat types and years. Germination was unaffected by high grain moisture at harvest except for soft red wheat in 2013, in which germination increased as grain moisture decreased. Both wheat types showed a strong linear decrease in grain moisture with accumulation of GDDs after heading, but differed between years due to opposing weather patterns. While the drought conditions in 2012 caused a grain moisture loss of 2.1% per 10 accumulated GDD, relatively cooler, wetter conditions in 2013 caused a grain moisture loss of 1.4% per 10 accumulated GDD. These findings are important to growers who may want to increase the quality of their wheat as well as predicting the time to harvest the wheat early in order to plant double-crop soybean.

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