Chlorophyll is a nitrogen and magnesium rich protein that gives the plant its green colour and is central to efficient photosynthesis.
The relationship between leaf chlorophyll content and nitrogen is well proven positive.
Tools like N-Tester, that measure the chlorophyll content of leaves, make the use of this relationship to estimate the N nutrition status of crops.
As magnesium is the central atom of chlorophyll, it affects the formation of chlorophyll and the amount in the crop. Magnesium also activates enzymes and acts alongside potassium and calcium as a regulator of the osmotic potential (salt-water balance) of the plant. The salt-water balance in turn affects the movement of water and nutrients around the plant and the plant structure (wilting).
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. Potassium levels control the opening and closing of stomata, regulating water loss from the leaf surface preventing the plant from wilting in dry periods.
Potassium is needed to increase the frost resistance of overwintering plants and is one of the most common enzyme activators. It participates in the activity of more than 60 enzymes. Adequate potassium supplies will extend the grain filling period leading to improvements in grain weight. The demand for potassium is higher than any other nutrient with the majority taken up during vegetative growth. Applications should be targeted to meet this demand.