Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fluid Journal 1996-1998
Fall 1996 higher order roots in the fertilized layers appear in greater numbers. These observations that increased N in specific zones of the soil can alter root system growth and morphology suggest that N fertilizer management could impact root system size, which in turn could alter plant tolerance to rootworm larval feeding damage. Three aspects of N fertilizer application that could potentially impact root system size are: 1) N fertilizer rate, 2) date of application, and 3) N placement. Recent research has shown that increasing N fertilizer rate (0, 70, and 140 lbs/A applied before planting) increased the root system size (dry weight) and reduced lodging in rootworm damaged plants. Another study of split bands of UAN (applied half over the row at planting, half at cultivation) versus broadcast applications at planting found that root systems were larger (increased pull resistance) at the time of maximum rootworm damage under split banded N than under broadcast N. Lodging was reduced by split-applied banded N at low levels of infestation damage. However, the reduced lodging seen in the fertilizer treatments from both of these experiments was not accompanied by reductions in yield loss in rootworm larval damaged plants. Taken together, these results suggest that managed N application, coupled with the use of area-wide rootworm adult population management protocols and large-rooted corn hybrids, would be a step toward integrated pest management systems for limiting plant lodging and yield loss caused by pest infestation. ________________________________ Dr. Riedell is research plant physiologist at the USDA Agricultural Research Service, Northern Grain Insects Research Laboratory, Brookings, SD. ! Figure 3. Relationship between root system size and vertical root pull resistance in corn plants. Figure 4. Results of linear regression analysis of the effect of root pull resistance on plant lodging (top) and grain yield (bottom). Lodging (%) 80 60 40 20 0 110.2 220.5 330.7 441.0 Root Pull Resistance (lbs/plant) 79.5 76.3 73.1 70.0 66.8 Yield (bu/A)
Fluid Journal 1993-1995
Fluid Journal 1999-2001