Transgenic corn rootworm protection enhances uptake and post-flowering mineral nutrient accumulation

Although modern maize (Zea mays L.) hybrids with transgenic insect protection from corn rootworm (CRW) (Diabrotica spp.) demonstrate improved yield and insect control compared to their non-protected (refuge) counterparts, no comprehensive studies have documented the impact of transgenic insect protection on nutrient uptake and partitioning. The objective of this study was to investigate the effect of transgenic protection from CRW on the timing and quantity of uptake for key nutrients such as N, P, K, S, and Zn. Results from two similar experiments across 5 site-years were analyzed and summarized. In the first experiment, transgenic hybrids averaged greater grain yield (10%; 0.9 Mg ha-1), total biomass (7%; 1.2 Mg ha-1), and grain nutrient accumulation of N (8%), P (12%), K (9%), S (9%), and Zn (12%) compared to non-protected hybrids (P £ 0.05). In the second experiment, the yield response associated with transgenic insect protection varied among hybrids. Those hybrids which exhibited a yield response compared to their non-protected counterparts resulted in greater post-flowering acquisition of N (31%), P (24%), and K (38%) (P £ 0.05). The results indicate that in favorable environments, transgenic CRW protected hybrids not only produce more total biomass and yield, but also maintain greater rates of nutrient acquisition during grain-filling.