Micronutrients and sugar beet yield

Micronutrients, particularly boron, copper, manganese and zinc all have essential roles in sugar beet and a deficiency of any one will result in reduced yield or quality.

Boron deficiency will decrease sugar-beet yield and quality

Boron is a micronutrient and is essential for growth and development. During root expansion and growth, rapid cell division occurs which demands large amounts of boron. It is in highest demand during periods of rapid cell division and expansion since boron plays a key role in cell wall development. Boron is only transported in the xylem and thus deficiency appears in the youngest leaves.

The typical sign of Boron deficiency is the so called “heart rot” and “dry rot”. The growing point becomes blackened and dies. The roots get dark brown spots and dead tissue spreads to the tap root. Boron deficiency in the root can decrease yield dramatically and the quality will deteriorate in storage.

Boron is best applied before symptoms appear as applications will not cure the damage caused. Deficiency is most often associated with sandy soils having a high pH and under dry weather conditions, but it does occur on other soil types. Soil boron is easily leached so needs to be applied close to the period of growth or as a foliar treatment. Soil and foliar analysis are a useful tool to help manage boron applications.

Copper deficiency reduces sugar yield

Copper is an essential nutrient functioning as a catalyst in the two key processes of photosynthesis and respiration. It is also a constituent of several enzymes involved in carbohydrate and protein metabolism. The removal of copper with the sugar beet crop is 45 mg/ha. Ensuring the plant has the correct level of copper in the plant increases the root and sugar yield. This level is 0.23- 0.46 mg/kg fresh matter.

Copper is immobile in the soil, with only small amounts being available in the year of application. Thus, in annual crops, on copper deficient soils, it is important to use copper every season. Copper can be applied either as a mineral fertiliser or foliar product.

Deficiency symptoms are found on the youngest leaves due to the low mobility of copper in the crop.

Manganese deficiency is common in sugar beet

Manganese is involved with chlorophyll synthesis, photosynthesis, oxygen evolution and the activation of enzymes, e.g. fat forming enzymes. As a structural constituent of ribosomes, it also plays a key role in protein synthesis, helping improve nitrogen utilization in the plant. The removal of manganese with the sugar beet crop is approximately 350 g/ha. The normal level of manganese is 0.92 – 1.85 mg / kg fresh matter.

Sugar beets are sensitive to manganese deficiency and applying manganese to sugar beet often results in higher yields, especially when grown on soil conditions where manganese deficiency is a problem. Manganese deficiency is typical on sandy soils with low cation exchange capacity, soils with high pH such as calcareous soils, organic soils and drought prone soils. Manganese deficiency is often seen at the 2-3 leaf stage.

Zinc deficiency will reduce yield and quality

Zinc is a catalyst in many of the enzyme systems used for protein synthesis and carbohydrate metabolism. It is involved in the chloroplast development and is responsible for the metabolism of auxins (plant growth regulators) and thus is important for regulating key growth processes.

The removal of zinc with a 50t/ha sugar beet crop is 350 g / ha. The normal level of zinc in the fresh matter is 0.05 – 2.30 mg/ kg fresh matter.