Chemistry Reference
In-Depth Information
Kernel weight and chemical quality
A general model for kernel weight determination in maize is shown in Figure 7. Although
kernel weight differed among hybrids it did not show a clear trend with the year of hybrid
release [60].
Figure 7.
General model for kernel weight determination in maize.
Biomass accumulation in kernels begins shortly after fertilisation and it can be represented
by a sigmoidal pattern in which a lag and a linear growth phase can be distinguished [58;
59]. Of the two components that determine final kernel weight (i.e. the kernel growth rate
during the linear phase or effective grain filling period and the effective grain filling
duration; Figure 7), kernel growth rate was the main component contributing to explain
differences in kernel weight among hybrids released in different decades up to 1993 [60].
Kernel growth rate is strongly correlated with number of endospermatic cells and starch
granules, which in turn determine the potential kernel size [61-63]. This contention suggests
underlying differences among hybrids in potential kernel weight.
Duration of the grain filling period, and in turn kernel weight, is affected by the ratio
between assimilate availability (source) and the potential capacity of the ear to use the
available assimilates (i.e. ear demand, sink) during the grain filling period (Figure 7; 29; 65;
67-71). Since under optimal growing conditions, hybrids differ in kernel number per plant
but also in kernel growth rate or potential kernel weight [60]; the ear demand (i.e. sink) was
better described by both, the number of kernels per ear and their potential kernel weight
(i.e., ear demand = KNP x kernel growth rate) rather than by KNP alone as in previous
