Micronutrients – This Missing Piece of the Crop Puzzle

Soil analysis ✓ pH Levels ✓ Fertilizer ✓ Seed treatments ✓Crop protection ✓ Are we missing something? While it’s always good to have the basics covered, there could be another piece of the puzzle that producers are completely overlooking. Micronutrients are a small but crucial puzzle piece if farmers want to really improve crop quality and yield. By addressing micronutrient deficiencies, we could optimize existing agricultural land to be more productive and address food security for an ever-growing population without needing more agricultural land. 

In this article, we will look at the micronutrient known as molybdenum and the effects it can have on crop yield and quality. 

What is Molybdenum? 

Molybdenum is considered a micro, but vital, nutrient in plants. This trace element is used to produce irreplaceable hormones or co-enzymes (Moco) that assist plants with nitrogen fixation and nitrate reduction. Plants can only assimilate nitrogen in two forms – NO3– and NH4+. Nitrite (NO2–) in its natural occurring form cannot be absorbed by plants and must therefore be reduced to NO3– en NH4+ through molybdenum derived enzymes. In legumes, it has been found to be especially beneficial in increasing the number and size of nodules while also improving the nitrate and nitrogen enzyme activity1. The nitrate is converted to nitrogen which is an essential building block in amino acids, proteins and chlorophyll.

Signs that your crops have a molybdenum deficiency

Molybdenum deficiency was first noted in hydroponically grown tomatoes2. The scientists found that the tomatoes that received no molybdenum developed signs of mottling lesions on the leaves and an altered leaf morphology also known as ‘whiptail’. The only trace element that could eliminate these symptoms was molybdenum. 

Because it is such a small piece of the puzzle but needed for the nitrate to nitrogen conversion, molybdenum deficiency is often mistakenly diagnosed as nitrogen deficiency. This misidentification could cause the overuse of nitrogen fertiliser which will be a waste of valuable resources and possibly lead to oxygen depletion and even acidification of the soil that further impairs molybdenum absorption. 

If your crops show the following signs despite sufficient nitrogen, then you should consult an agrichemical consultant:

  • Poor growth. 
  • Yellowing of leaves (lack of chlorophyll). 
  • Plant deformation. 
  • Underdeveloped buds and flowers. 
  • Restricted fruit setting. 

Manvert Molybdenum Mix Fruitsetter 

The Manvert Fruitsetter is rich in nitrogen and phosphate with the addition of molybdenum and amino acids. This fertilizer and biostimulant can be used on crops that are sensitive to molybdenum shortages such as alfalfa, cabbage, brussels sprouts, cauliflower, melon, watermelon, baby marrow, cucumber, spinach, lettuce, roses and tobacco. Though studies have found that tomatoes, wheat, maize and citrus fruits can also benefit from an application of molybdenum3. Specifically, legumes (soy, beans, peas, chickpeas and lentils) can benefit from an application of molybdenum. 

Studies in Australia have shown increases in grain yield of up to 60% following the application of molybdate4. While a study in Egypt found that adding molybdenum to mandarin trees, in the form of a foliar spray, increased fruit yield by 37%5. 

What causes low levels of Molybdenum? 

Plants that require higher levels of molybdenum may deplete soils of this trace element and lead to lower levels of availability. Though often the cause for molybdenum deficiency is acidic soils that decreases its absorption and availability, which is contrary to most other micronutrients that require more acidic soil.

To learn more about molybdenum deficiency and how it can be corrected, or about Manvert’s Fruitsetter and its application please contact DNA Plant Science today. DNA Plant Science is the proud distributor of the Manvert range in South Africa. 

Resources

  1. https://www.tandfonline.com/doi/full/10.1080/00380768.2015.1030690 
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC437771/?page=1 
  3. https://www.imoa.info/download_files/sustainability/IMOA_Micronutrient.pdf 
  4. Analysis of the response by wheat to the application of molybdenum in relation to nitrogen status’, Lipsett J, Simpson JR, Australian Journalof Experimental Agriculture and Animal Husbandry, 1973
  5. Ezz, TM and Kobbia, AM, ‘Effect of molybdenum nutrition on growth, nitrate reductase activity, yield and fruit quality of Balady mandarin treesunder low and high nitrogen levels’, Alexandria Journal of Agricultural Research

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