Agriculture Reference
In-Depth Information
at the early fi lling stage and reached the maximum fi lling rate
late; and asynchronous; superior spikelets started fi lling and
reached the maximum fi lling rate much earlier than the inferior
ones. The order of grain fi lling percentage in the three types
of grain fi lling patterns was: fast synchronous > asynchronous
> slow synchronous. Changes in zeatin and zeatin riboside
contents in the superior and inferior spikelets were associated
with the grain fi lling patterns. Grain fi lling percentage was
signifi cantly correlated with zeatin + zeatin riboside contents
in the grains and roots at the early and middle grain fi lling
stages. IAA and GA contents in the grains and roots were
not signifi cantly correlated with grain fi lling percentage. It is
suggested that cytokinins in the grains and roots during the
early phase of grain development play an important role in
regulating grain fi lling pattern and consequently infl uence
grain fi lling percentage.
Brassinosteriods (BRs) are phytohormones mediating
multiple biological processes, such as development and stress
response. They have been used in crops to produce high yield.
In rice, the ideal plant architecture for high yield includes
effective tillers, as well as height and leaf angle, which is
modulated by BRs.
It had also been shown that endogenous hormones are
essential regulators for grain fi lling in cereals and regulate grain
weight via infl uencing grain fi lling process and activities of key
enzymes (Yang et al. 2004). It has been noted that a post anthesis
wet and moderate drying holds great promise to improve grain
fi lling of inferior spikelet through elevating cytokinin in levels
in the rice plant (Zhang et al. 2010).
Major biological processes such as cereal grain fi lling are
believed to require a close coordination of gene expression among
many important pathways. However, direct experimental
evidence for this hypothesis has been lacking due to absence
