Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Reddy, K. Raja

Committee Member

Macoon, Bisoondat

Committee Member

Baldwin, Brian S.

Committee Member

Lang, David J.

Committee Member

Reddy, Krishna N.

Date of Degree

12-15-2007

Document Type

Graduate Thesis - Open Access

Major

Agronomy

Degree Name

Master of Science

College

College of Agriculture and Life Sciences

Department

Department of Plant and Soil Sciences

Abstract

Influence of nitrogen (N) deficiency on castor cv. ‘Hale’ growth, physiology, and leaf reflectance properties were investigated. Treatments imposed were complete Hoagland’s nutrient solution (control, 100N), reduced N to 20% of the control (20N) and withheld N from the solution (0N) from 34 to 66 days after sowing (DAS) in 12-L pots grown out doors. N deficiency significantly reduced leaf area, chlorophyll and photosynthesis resulting lower total biomass. Leaf and stem growth rates were more sensitive to leaf N concentration than photosynthesis and leaf addition rates. N deficiency stress increased leaf reflectance at R555 and R715 nm and caused a red-edge shift to shorter wavelengths. Reflectance ratios of R455/R605 and R505/R605 nm was highly correlated with leaf N on weight (r2 = 0.93) and area-based (r2 = 0.90) estimations, respectively. Similarly, reflectance ratio R635/R505 was highly correlated with chlorophylls (r2 = 0.94). The N-specific wavebands and functional relationships between leaf N and growth and developmental processes would be useful for rapid and non-destructive estimation of leaf N and growth rates of castor.

URI

https://hdl.handle.net/11668/17407

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