How to increase wheat grain size
Wheat grain size is strongly influenced by plant nutrition particularly during the important grain filling period. Nitrogen, phosphate, potassium, magnesium and zinc are particularly important.
Wheat grain size is determined by the plants genetics i.e. variety, and the length of the grain filling period. As soon as pollination has occurred the embryo and endosperm begin to develop with the plant redirecting photosynthates and also previously stored starch and protein (in leaves and stems) to these developing grains. The longer this period of grain fill is, the larger wheat grain size is likely to be.
Nitrogen has a large effect on grain size and weight
Nitrogen management will have the most impact on final wheat grain size and weight. Applications made early will ensure a canopy that is large, containing high levels of stem carbohydrate that is translocated to the developing grain during maturation.
This is particularly important in drought areas where 60% of the grain yield could come from this store. It is important to monitor plant nitrogen levels ensuring the canopy does not senesce early and curtail the grain filling period.
Phosphate improves grain size
Phosphate has a major role in the supply of energy for plant processes. Redistribution of stored carbohydrate requires energy making phosphate nutrition important in achieving good wheat grain size.
Both solid fertiliser phosphate and foliar phosphate can be used to improve final grain size.
Potassium extends grain filling period
Potassium aids movement of nutrients around the plant as it regulates the transpiration flows as the wheat plant redistributes minerals to the ear potassium levels need to be maintained.
Potassium will also help avoid early senescence often brought on by drought during grain fill. Potassium deficient plants are poor at regulating transpiration through the leaf leading to heat stress and wilting. Adequate potassium supplies will extend the grain filling period leading to improvements in wheat grain weight.
Manganese and zinc influence grain size and weight
Both manganese and zinc with their roles in nitrogen metabolism by the plant will improve wheat grain weight.
Other factors influencing wheat grain size
Besides nutrient management, the grain size can be influenced by water management (irrigation to avoid drought stress), as well as disease management – use fungicides and nutrients to maintain green leaf area and reduce disease incidence improving plant health.
Recommended Yara fertilisers for wheat
Related articles
How to maintain wheat green leaf canopy
The key to achieving high wheat yields, having established the correct canopy structure, is to maintain the green area right through to the final grain filling period, capturing as much of the incident light as possible and converting it to yield.
How to increase wheat leaf and tiller numbers
The number of leaves determines the size of the crop canopy and its photosynthetic potential. The number of shoots and how many of these survive through to harvest also determines the number of ears at harvest and so the potential yield.
How to increase wheat grain numbers
The grain number is itself a function of the number of fertile shoots per unit area and the number of grains per ear. The grower therefore needs to consider how nutrition can have an impact on the grain numbers per ear.
