Grain sorghum is the principal food crop in Botswana. It
is often grown in low fertility, coarse-textured soils. It is
a common practice within some ethnic groups in Botswana to
remove the primary panicle with the expectation that this will
increase the grain yield by promoting tillers.
A factorial experiment was conducted in the greenhouse to
investigate the effect of panicle removal at anthesis and N on
growth and yield of grain sorghum. Two N rates (25 or 100
kg/ha), three cultivars (Segaolane, Northrup King 2660, and
Korwane), two main panicle treatments (present or removed),
and five replications were used. Panicle removal increased
the number of tillers and kernel weight but decreased yield
(by reducing kernel number) in Segaolane and NK 2660. The
kernel weight in Korwane did not respond to panicle
treatments, but grain yield was reduced by panicle removal.
In all cultivars, photosynthesis was reduced when the main
panicle was removed. Korwane invested more assimilates in vegetative material (harvest index = 0.15), while Segaolane
and NK 2660 partitioned more photosynthates into grain yield
(harvest index = 0.5). Nitrogen application increased total
dry matter, tillers, grain yield, and number of kernels in
each variety except that Korwane was not responsive in kernel
number. Nitrogen fertilization decreased kernel weight in two
of the varieties but not Korwane. Kernel weight of Korwane
was not affected by any of the treatments in this test.
In summary, panicle removal appeared not to be a positive
management practice for increasing grain yield of any of the
varieties studied. On the other hand, N fertilization was
beneficial to yield.
next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.
![[VT]](http://scholar.lib.vt.edu/images/ETD-db/restricted.gif)
