An estimate of the upper limit of yield in wheat was made using radiation and light interception characteristics in a non-restrictive environment. It was estimated that a maximum yield of 17 tonnes per hectare could be the upper limit. It was concluded that today there is a limitation in achieving even the required dry matter and reduced nitrogen. In addition, the competition between the number of spikelets and the number of tillers before ear emergence and the number of grains per spike and the grain weight after ear emergence are major developmental constraints. Elimination of these constraints requires greater assimilation by shoots.
In conditions where water is a limiting factor, the yield potential should be assessed on the basis of available water. Since the grain development correlates strongly with the available water, the plant structure and population have to be adjusted in a manner as
Various models for obtaining a 10 tonnes ha-1 yield have been suggested and several constraints have been identified which need attention.
