Nitrogen, magnesium and sulphur are of particular importance in maintaining a green leaf canopy. Chlorophyll is a nitrogen and magnesium rich protein that gives the plant its green colour and is central to efficient photosynthesis. Sulphur is an important component of all proteins and is always required together with nitrogen for protein synthesis.
The relationship between leaf chlorophyll content and nitrogen is well proven with more chlorophyll as leaf percentage of nitrogen increases.
Maintaining the level of nitrogen in the leaf through to GS 65 gives optimum yield.
Magnesium is the central component of chlorophyll linked to four nitrogen molecules. The magnesium level is also therefore important in maintaining the green leaf canopy.
As well as the canopy greenness, it is also important to ensure that the structure and architecture is maintained further improving the efficiency of the crop to capture light and convert it to yield.
Potassium plays a very important role in maintaining cell turgidity and strength as well as nutrient movement around the plant.
Inadequate supplies of potassium can lead to premature wilting and a lodged canopy. Straw deficient in potassium is more brittle increasing the risk of lodging that dramatically reduces both yield and quality. The demand for potassium is higher than any other nutrient with the majority taken up in the spring. Between the beginning of tillering and end of tillering wheat will take up on average approximately 7.7 kg K20 / day. Applications should be targeted to meet this demand.