4. Concluding remarks
A key factor to increase wheat yield potential is an extended
duration of grain filling resulting in increased HI. This can only be
possible if both capacities of the ‘sink’ and the ‘source’ are
increased. The ‘source’ capacity can be increased if the plant would
be able to maintain healthy green area index until the end of grain
filling (‘stay-green’). In water-limited environments such as SL,
improvement in drought tolerance which delays leaf senescence
will be essential. The ‘sink’ capacity can be increased if the number
of fertile florets at anthesis and, as a result, the number of grains at
maturity increased. The floret survival rate in most wheat cultivars
varies between 25% and 40%; so, in principal, there is a large potential
for improvement (Gonzalez et al., 2011). Ferrante et al.
(2013) studied the dynamics of floret development and its consequence
on grain number and final yield in several semi-dwarf
durum wheat cultivars in response to nitrogen (N) treatments
and water availability. The study confirmed that increasing N
availability resulted in an increased number of grains through
increasing both the number of fertile florets and the percentage of
them setting grains. Itwas shown that the fate of floret primordia in
the intermediate positions of the spikelet (F3eF5) was related to
the increase in assimilate supply during spike growth affected by N
fertilization.