| Autor: |
Nelson, John Randall, Heiniger, Ronnie, Hendrickson, Larry, Deere, John |
| Zdroj: |
Proceedings of the Beltwide Cotton Conferences; 2005, p1983-1994, 12p, 2 Charts, 7 Graphs |
| Abstrakt: |
Variability in cotton plant height or internode length within a field makes it difficult to determine the proper rate and placement of growth regulators and defoliants. Remote sensing has the potential to indirectly measure plant characteristics and, coupled with site-specific applications of growth regulators or defoliants, could improve cotton yield and net economic return. The objectives of this study were to determine 1) the relationships between canopy reflectance as captured in digital, aerial near infrared or color photographs and the plant characteristics of height, height to node ratio (HNR) and internode length, and 2) the economic gain from using remote sensing to guide the site-specific application of mepiquat chloride. To address objective 1, four fields with soil properties typical of those found in the coastal plain of the southeastern US were monitored weekly from 14 d prior to first bloom to cutout by measuring plant height, HNR and internode length. Infrared and color aerial photographs were taken at first bloom and again 25 to 30 d later. Correlations between digital counts for each of the three spectral bands captured by these images or indices calculated from these bands and measured plant height, HNR and internode length were determined and linear regression models were fit to those relationships with the strongest correlations across the four fields. Regression models based on the normalized difference vegetative index calculated using near infrared reflectance captured between 51 and 82% of the variability in plant height and HNR. However, internode length was more difficult to determine with regression models only accounting for < 1 to 17% of the variability in this parameter. Uniform and site-specific applications applied to replicated strip plots in two fields near Plymouth and Lewiston, NC showed that site-specific applications of mepiquat chloride guided by remote sensing coupled with field scouting improved growth control, lint yield and economic return by as much as $66 acre-1. Partial budgets based on measured yield indicated that net return will be greater in conditions where potential cotton growth and yield are high (> 2 bales acre-1). [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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