Nutrient Disorders of Burley and Flue‐Cured Tobacco: Part 2—Micronutrient Disorders

Abstract

Core Ideas Recognizing micronutrient disorders is important for commercial production. Unique, previously unobserved nutrient disorder symptoms were observed. Foliar nutrient concentrations were identified for burley and flue‐cured tobacco. Symptoms and critical values were compared with published results. Nutrient disorders often manifest unique symptoms and vary in critical nutrient ranges where visual symptoms appear depending on plant species and type. Understanding and recognizing nutrient disorders for different types of tobacco is important for maintaining yield and quality. Burley and flue‐cured tobacco (Nicotiana tabacum L.) account for over 90% of all tobacco produced in the United States, and thus, were grown in this study to investigate the effects of micronutrient disorders. Tobacco plants were grown in silica sand culture, and control plants received a complete modified Hoagland's all‐nitrate solution, whereas nutrient‐deficient treatments were induced with a complete nutrient formula withholding a single nutrient. Boron toxicity was also induced by increasing the element tenfold higher than the complete nutrient formula. Plants were automatically irrigated, and the leached solution was captured for reuse. A complete replacement of nutrient solutions was done weekly. Plants were monitored daily to document and photograph symptoms as they developed. A description of nutrient disorder symptomology and critical tissue concentrations associated with symptomology are presented.

Measures of Canopy Structure from Low-Cost UAS for Monitoring Crop Nutrient Status

“…The structural metrics were much more closely related to B concentrations measured earlier in plant development. This is consistent with other observations that symptoms of B toxicity can take 33 days to become visible [39]. Visible-range spectral reflectance explained almost no variability in B concentrations.…”

“…Table 1 summarizes the metrics used. [19] mean central tendency of per pixel chlorophyll content standard deviation variability of per pixel chlorophyll content Nutrient disorders have been shown to correlate with flue-cured tobacco size and shape in multiple prior studies [39][40][41][42]. To quantify plant size and variability in canopy height, mean and standard deviation of height were computed.…”

“…It is typically applied in time for immediate plant uptake to avoid leaching beyond the root zone. N-deficient plants are characterized by stunting, chlorosis, and upward pointing leaves forming an acute angle with the stalk [39,42]. The structural metrics explained 40% of the variation in N concentrations at the first two growth stages observed (Figure 9).…”

“…K is also an important macronutrient needed for tobacco production. Symptoms of K deficiency include chlorosis that begins on lower leaves and quickly progresses up the plant and leaves with a distinctive downward cupping or umbrella-like shape [39,42]. The canopy structural metrics were able to explain variation in foliar K levels across all dates, with the relationship increasing slightly as the crop matured (Figure 9).…”

“…It is needed in very small amounts, however, and can result in reduced leaf quality if over applied [10]. Visible symptoms of B toxicity include a very slow spreading chlorosis on lower leaves, undulating leaf deformity, and curling of leaf edges upward [39]. The canopy structural metrics were able to explain moderate variation in foliar B concentrations (Figure 9).…”