Soil Management Affects Expression of Genes Involved in Carbon and Nitrogen Metabolism in Maize

Agronomic practices affect plant growth, development, and productivity through modifications of plant physiological processes. The effect of cover crop (hairy vetch [Vicia villosa Roth subsp. villosa]), no-tillage, and N fertilizer side-dressing on plant and soil health and expression of maize (Zea mays L.) genes was measured throughout the growing season. Expression of ACS, GS2, ICDH, NiR, and PEPC genes involved in C and N metabolism was determined. No-tillage led to a greener and better hydrated maize crop at V6, greater soil moisture at V6 and silking, and greater plant height throughout the season. Cover crop resulted in higher leaf N at V6, greener crop throughout the season, and taller plants at silking and grain fill. There were signs of N deficiency in no-tillage from silking onward, which was reflected in decreased greenness at silking and reduced soil nitrate at grain fill. Expression of GS2, NiR, and PEPC was stimulated by tillage later in the season, possibly as a result of greater soil N availability or greater gene expression because fewer leaves remained on these plants. Grain yields were unaffected by tillage but increased by cover crop. It appeared that low-moisture stress in no-tillage led to greater plant vigor, but this did not translate into increased yield because of N stress. This study highlights the need to have a better understanding of global gene expression by soil management practices, which can help select and introgress specific genes for greater exploitation of the genetic potential of maize especially when grown under no-tillage.