Genotype By Seeding Rate Interaction in Wheat.

Genotype by seeding rate interaction can play a critical role in understanding wheat yield potential. Genotype differential ability in tillering can affect individual plant response to the use of above- and below-ground resources. This study pursues as objective to quantify wheat yield response to seeding rates with contrasting genotype strategies (differential tillering ability). Two experimental fields were planted at Ashland Bottoms and Topeka (Kansas, US) with different water regime and tillage systems (Ashland- dryland and till and Topeka- irrigated and no-till). The study consisted in two varieties (low and high tillering) and four different seeding rates (40, 80, 120 and 160 lbs/ac). Ground-truthing measurements consisted in: stand counts, canopy coverage (estimated via imagery collection), determination of gaps (missing plants), leaf area index (LAI), light interception, and imagery collection via small-unmanned aerial vehicle systems (sUAVS). Multi-spectral imagery data [infrared (IR), near infrared (NIR), red, blue and green was collected and a spectral band characterization was implemented to differentiate plants from soil. In the first year of data collection, average wheat grain yield was greater at Ashland (80 bu ac^-1) relative to Topeka (50 bu ac^-1). For the latter site, neither interaction nor single effects for genotype and seeding were documented for the yield factor. At Ashland site, only significant yield differences (p<0.001) were observed for the seeding rate factor, with yields presenting a positive response as the seeding rate improved until a plateau level, when seeding rate reached 120 lb ac^-1.