From the Field-Agronomy Notes

— Written By jbhenry2

Tobacco Research Update: Phosphorus Deficiency of Tobacco

In this tobacco research update, we highlight the symptoms of phosphorus deficiency. These images are part of a project supported by the North Carolina Tobacco Foundation to develop a web-based diagnostic key for the identification of nutrient disorders of tobacco.

Being one of the three primary macroelements required for plant growth, phosphorus (P) deficiency symptoms develop quickly when P is in short supply.

Phosphorus deficiency in tobacco begins as a noticeable stunting when compared to a plant with a sufficient supply of P (Fig. 1).  Additionally, a P deficient tobacco plant may be more likely to develop a darker green coloration of the upper foliage. Lower leaves will become chlorotic with a mottling of olive green leaf spots (Fig. 2). The initial symptoms appearing on the lower foliage may be attributed to the fact that P is mobile within plant tissues and is translocated from these older leaves to the young developing tissues under periods of low P.

Figure 1. The initial symptoms of P deficiency include the general stunting of the plant. ©2016 Forensic Floriculture

Figure 1. The initial symptoms of P deficiency include the general stunting of the plant.
©2016 Forensic Floriculture

As symptoms progress, the leaves begin to develop sunken necrotic spots over the leaf surface (Fig 3.). The lower leaves that were previously mottled in appearance are evenly chlorotic with necrotic spotting. These necrotic spots form first on the lower leaves and later on the younger foliage. With these intermediate symptoms, the upper foliage has a generally olive green appearance.

Figure 2. The olive green leaf spots seen developing here on the lower leaves are commonly associated with P deficiency. ©2016 Forensic Floriculture

Figure 2. The olive green leaf spots seen developing here on the lower leaves are commonly associated with P deficiency.
©2016 Forensic Floriculture

In advanced cases, the plant remains severely stunted, with the oldest leaves becoming entirely necrotic. The chlorosis and necrotic spotting works its way up the foliage with only the youngest leaves remaining green. This wide range of symptoms may be observed in the 360-degree image below (Fig. 4, click image to play video).

We would like to express our appreciation to the North Carolina Tobacco Foundation for supporting this project. We will be providing updates as symptoms progress over the course of the nutrient disorder induction phase of the experiment.

Figure 3. Necrotic spotting that occurs on the foliage of tobacco is a more intermediate to severe symptom of P deficiency. ©2016 Forensic Floriculture

Figure 3. Necrotic spotting that occurs on the foliage of tobacco is a more intermediate to severe symptom of P deficiency.
©2016 Forensic Floriculture

Figure 4. The 360-degree view of this symptomatic plant with a severe phosphorus deficiency may be viewed by clicking on the above picture. ©2016 Forensic Floriculture

Figure 4. The 360-degree view of this symptomatic plant with a severe phosphorus deficiency may be viewed by clicking on the above picture.
©2016 Forensic Floriculture

Key Contact: Dr. Matthew Vann, Department of Crop and Soil Science mcvann@ncsu.edu

Contributing Authors: Josh Henry, Paul Cockson, Matthew Vann, and Brian Whipker

Funding Source: North Carolina Tobacco Foundation

Project Team: Josh Henry (NC State M.S. student in Horticultural Science), Paul Cockson (NC State B.S. student in Agroecology), Ingram McCall (Research Technician in Horticultural Science), Rhonda Conlon (Extension IT at NC State), Matthew Vann (Tobacco Extension Specialist, Dept. of Crop and Soil Science), and Brian Whipker (Professor of Floriculture and Plant Nutrition in Horticultural Science).

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