Impact of Tillage and Crop Rotation on Wheat Grain Quality.

Use of field pea (Pisum sativum L.) can enhance grain yield of spring wheat (Triticum aestivum L.) in a wheat-pea (WP) rotation compared with continuous wheat (WW) monoculture. The pea rotation benefits to wheat grain quality are uncertain. A 6-yr study was conducted to determine if: (1) grain protein content, kernel density, and volume weight of wheat were enhanced in a WP rotation compared with a WW monoculture, and; (2) an interaction between cropping and tillage systems existed for these grain quality traits. The WP and WW systems were maintained in subplots across clean-till (CT), reduced-till (RT), and no-till (NT) whole plots arranged in a randomized complete block as a split plot in southwestern North Dakota, USA.  Grain protein content of wheat averaged 160 g kg^-1 and was unaffected by cropping system (P > 0.05). However, grain protein content was 10 to 30 g kg^-1 lower under NT compared with CT, depending on the year.  Kernels were heavier in two of six years in the WP rotation compared with WW monoculture.  Differences in kernel weight were not detected between cropping systems in other years.  A consistent trend in kernel density was not detected across tillage systems, and interactions between cropping and tillage systems were not observed for either grain protein content or kernel weight. A three-way interaction among cropping systems, tillage systems, and environments was detected for grain volume weight.  These results failed to demonstrate a consistent pea rotation benefit to wheat grain quality.