Uncontrolled environmental factors can affect DM yield and composition of corn whole-plant for silage. The spring and summer drought of 2012 reduced corn yields substantially when compared to 2011. In Virginia, drought stress affected DM yields and composition differently, depending on the region. The extremely low DM yield observed for the Southern Piedmont region in 2012 (2.0 ton DM/acre) could be attributed to the severe drought suffered that year. However, from the perspective of water status, the Southern Piedmont region had similar water status at the same fenological state than the Shenandoah Valley region, suggesting that factors other than drought stress also affected DM yield in the Southern Piedmont in 2012. Analysis of maximum temperatures showed that heat stress had a major effect on kernel development in the Southern Piedmont but not in the Shenandoah Valley. Therefore, in the Southern Piedmont region, heat stress exacerbated the effects of drought, reducing substantially DM yields and kernel development. Crop management practices, such as hybrid selection and planting date, should be considered to avoid high temperature stress during silking and kernel development.
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