Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Purcell, Larry C.

Committee Member

Roberts, Trenton L.

Second Committee Member

Karcher, Douglas E.

Third Committee Member

Kelley, Jason P.

Keywords

Corn; Dark Green Color Index; Leaf nitrogen; Nitrogen; Pretassel; Remote Sensing

Abstract

There are a lack of tools to assess midseason nitrogen (N) status in corn (Zea mays L.) production systems and identify the need for additional N fertilization. This study was conducted to determine the ability of leaf N concentration (LN) and the Dark Green Color Index (DGCI) at the 10th collared leaf stage (V10), the 12th collared leaf stage (V12), and tasseling (VT) to predict if midseason N is required to maximize corn grain yield. From 2017 to 2019, eight field studies with 11 N treatments ranging from 0 to 258 kg N ha-1 were conducted on silt loam soils in Arkansas. Leaf samples and digital images were collected at V10, V12, and VT growth stages. Relative grain yield (RGY) was predicted as a function of LN between V10 and VT which was described by a linear-plateau regression (R2 = 0.82, P-value < 0.0001). Model predictions indicated that RGY increased linearly up to a LN concentration of 30.4 g N kg-1 and there was no additional increase when LN was greater than 30.4 g kg-1. Measurements of DGCI from the high N treatment (258 kg N ha-1) were included in the regression analysis as a reference DGCI (RDGCI) to account for differences in environmental lighting when aerial images were captured. A multiple regression equation described the relationship between LN, DGCI, and RDGCI (Pvalue

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