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Soil versus foliar iodine fertilization as a biofortification strategy for field-grown vegetables.

Lawson PG, Daum D, Czauderna R, Meuser H, Härtling JW - Front Plant Sci (2015)

Bottom Line: Consequently, long-term effects of a one-time iodine soil fertilization could not be observed.The results indicate that a sufficient spreading of iodine applied on the edible plant parts is crucial for the efficiency of the foliar approach and leafy vegetables are the more suitable target crops.The low iodine doses needed as well as the easy and inexpensive application may favor the implementation of foliar sprays as the preferred iodine biofortification strategy in practice.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Nutrition, Faculty of Agricultural Sciences and Landscape Architecture, University of Applied Sciences of Osnabrück Osnabrück, Germany.

ABSTRACT
Iodine (I) biofortification of vegetables by means of soil and foliar applications was investigated in field experiments on a sandy loam soil. Supply of iodine to the soil in trial plots fertilized with potassium iodide (KI) and potassium iodate directly before planting (0, 1.0, 2.5, 7.5, and 15 kg I ha(-1)) increased the iodine concentration in the edible plant parts. The highest iodine accumulation levels were observed in the first growing season: In butterhead lettuce and kohlrabi the desired iodine content [50-100 μg I (100 g FM)(-1)] was obtained or exceeded at a fertilizer rate of 7.5 kg IO3 (-)-I ha(-1) without a significant yield reduction or impairment of the marketable quality. In contrast, supplying KI at the same rate resulted in a much lower iodine enrichment and clearly visible growth impairment. Soil applied iodine was phytoavailable only for a short period of time as indicated by a rapid decline of CaCl2-extractable iodine in the top soil. Consequently, long-term effects of a one-time iodine soil fertilization could not be observed. A comparison between the soil and the foliar fertilization revealed a better performance of iodine applied aerially to butterhead lettuce, which reached the desired iodine accumulation in edible plant parts at a fertilizer rate of 0.5 kg I(-)-I ha(-1). In contrast, the iodine content in the tuber of sprayed kohlrabi remained far below the targeted range. The results indicate that a sufficient spreading of iodine applied on the edible plant parts is crucial for the efficiency of the foliar approach and leafy vegetables are the more suitable target crops. The low iodine doses needed as well as the easy and inexpensive application may favor the implementation of foliar sprays as the preferred iodine biofortification strategy in practice.

No MeSH data available.


Related in: MedlinePlus

A visual comparison of butterhead lettuce soil cube transplants 8 days after planting at different iodine doses applied by means of soil drenches. (A) 0 kg I--I ha-1, (C) 7.5 kg I--I ha-1, (E) 15 kg I--I ha-1, (B) 0 kg IO3--I ha-1, (D) 7.5 kg IO3--I ha-1, (F) 15 kg IO3--I ha-1. The black arrows indicate chlorotic intercostal areas or necrotic spots.
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Figure 2: A visual comparison of butterhead lettuce soil cube transplants 8 days after planting at different iodine doses applied by means of soil drenches. (A) 0 kg I--I ha-1, (C) 7.5 kg I--I ha-1, (E) 15 kg I--I ha-1, (B) 0 kg IO3--I ha-1, (D) 7.5 kg IO3--I ha-1, (F) 15 kg IO3--I ha-1. The black arrows indicate chlorotic intercostal areas or necrotic spots.

Mentions: The influence of different iodine fertilization techniques on crop yield and marketable quality was investigated using butterhead lettuce and kohlrabi/radish as model crops. After a one-time soil fertilization of KI and KIO3, differences in biomass production were not statistically significant in any case (Table 1). However, in the first growing season, the lowest mean crop yields were noticed at the highest iodine supply level. At the same time, the crop population became more inhomogeneous compared to the control plants. Figures 1A–F illustrate for butterhead lettuce the average development of head size and variability as affected by increasing fertilizer doses. A few days after planting, butterhead lettuce transplants cultivated at 15 kg I--I ha-1 developed chlorotic leaves with yellow intercostal leaf areas (Figure 2C) turning increasingly into necrotic spots. Although showing growth inhibition, most plantlets recovered within a short period of time. An iodine supply up to 7.5 kg I ha-1 applied as KIO3 did not affect growth or the marketable quality of the investigated crops.


Soil versus foliar iodine fertilization as a biofortification strategy for field-grown vegetables.

Lawson PG, Daum D, Czauderna R, Meuser H, Härtling JW - Front Plant Sci (2015)

A visual comparison of butterhead lettuce soil cube transplants 8 days after planting at different iodine doses applied by means of soil drenches. (A) 0 kg I--I ha-1, (C) 7.5 kg I--I ha-1, (E) 15 kg I--I ha-1, (B) 0 kg IO3--I ha-1, (D) 7.5 kg IO3--I ha-1, (F) 15 kg IO3--I ha-1. The black arrows indicate chlorotic intercostal areas or necrotic spots.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4477264&req=5

Figure 2: A visual comparison of butterhead lettuce soil cube transplants 8 days after planting at different iodine doses applied by means of soil drenches. (A) 0 kg I--I ha-1, (C) 7.5 kg I--I ha-1, (E) 15 kg I--I ha-1, (B) 0 kg IO3--I ha-1, (D) 7.5 kg IO3--I ha-1, (F) 15 kg IO3--I ha-1. The black arrows indicate chlorotic intercostal areas or necrotic spots.
Mentions: The influence of different iodine fertilization techniques on crop yield and marketable quality was investigated using butterhead lettuce and kohlrabi/radish as model crops. After a one-time soil fertilization of KI and KIO3, differences in biomass production were not statistically significant in any case (Table 1). However, in the first growing season, the lowest mean crop yields were noticed at the highest iodine supply level. At the same time, the crop population became more inhomogeneous compared to the control plants. Figures 1A–F illustrate for butterhead lettuce the average development of head size and variability as affected by increasing fertilizer doses. A few days after planting, butterhead lettuce transplants cultivated at 15 kg I--I ha-1 developed chlorotic leaves with yellow intercostal leaf areas (Figure 2C) turning increasingly into necrotic spots. Although showing growth inhibition, most plantlets recovered within a short period of time. An iodine supply up to 7.5 kg I ha-1 applied as KIO3 did not affect growth or the marketable quality of the investigated crops.

Bottom Line: Consequently, long-term effects of a one-time iodine soil fertilization could not be observed.The results indicate that a sufficient spreading of iodine applied on the edible plant parts is crucial for the efficiency of the foliar approach and leafy vegetables are the more suitable target crops.The low iodine doses needed as well as the easy and inexpensive application may favor the implementation of foliar sprays as the preferred iodine biofortification strategy in practice.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Nutrition, Faculty of Agricultural Sciences and Landscape Architecture, University of Applied Sciences of Osnabrück Osnabrück, Germany.

ABSTRACT
Iodine (I) biofortification of vegetables by means of soil and foliar applications was investigated in field experiments on a sandy loam soil. Supply of iodine to the soil in trial plots fertilized with potassium iodide (KI) and potassium iodate directly before planting (0, 1.0, 2.5, 7.5, and 15 kg I ha(-1)) increased the iodine concentration in the edible plant parts. The highest iodine accumulation levels were observed in the first growing season: In butterhead lettuce and kohlrabi the desired iodine content [50-100 μg I (100 g FM)(-1)] was obtained or exceeded at a fertilizer rate of 7.5 kg IO3 (-)-I ha(-1) without a significant yield reduction or impairment of the marketable quality. In contrast, supplying KI at the same rate resulted in a much lower iodine enrichment and clearly visible growth impairment. Soil applied iodine was phytoavailable only for a short period of time as indicated by a rapid decline of CaCl2-extractable iodine in the top soil. Consequently, long-term effects of a one-time iodine soil fertilization could not be observed. A comparison between the soil and the foliar fertilization revealed a better performance of iodine applied aerially to butterhead lettuce, which reached the desired iodine accumulation in edible plant parts at a fertilizer rate of 0.5 kg I(-)-I ha(-1). In contrast, the iodine content in the tuber of sprayed kohlrabi remained far below the targeted range. The results indicate that a sufficient spreading of iodine applied on the edible plant parts is crucial for the efficiency of the foliar approach and leafy vegetables are the more suitable target crops. The low iodine doses needed as well as the easy and inexpensive application may favor the implementation of foliar sprays as the preferred iodine biofortification strategy in practice.

No MeSH data available.


Related in: MedlinePlus