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had more than 2.5 inches of rain since Tuesday, so our field has
good surface moisture. It is recovering from last Saturday nightís
plants in the marked area are starting to recover from the hail
damage. Iíve noticed in this row and other areas of the field
that plants that werenít developed as well were damaged more by
the hail than plants that had at least two trifoliolate leaves.
Letís look at a couple plants in the row.
first plant had its first trifoliolate leaf and growing point
destroyed by the hail. So, there arenít going to be any new
leaves above the second trifoliolate that we can see here. This
plant is going to survive, but where are any new leaves going to
come from? If you look in the axil of the nearest unifoliolate
leaf you can see ( in the shadow) a new leaf starting to grow.
Thatís where the new leaves are going to come from.
second plant is recovering nicely. It didnít have the growing
point knocked off so it will continue to develop trifoliolate
leaves from the main stem. The third trifoliolate leaf has
unfolded. On the right side, you can see a new leaf growing in the
axil of the first trifoliolate (thereís only a bare stem or
petiole remaining). That will become a branch and the plant will
appear tree-like with different branches or forks. Youíll see
what I mean later.
donít know if this is the same plant we looked at earlier in the
week, but it is a good example of how a hail-damaged soybean plant
recovers. Leaves are starting to grow in the unifoliolate leavesí
axils. This plant is going to make it, but it will develop slower.
look at some soybean roots. This is a good root system. These
roots are well-branched and growing downward. Thereís no
evidence of soil compaction, which would restrict the downward
growth of the roots. There are some round structures attached to
the roots. Do you see them? These are called nodules and they
contain bacteria. Donít worry these are good bacteria! They are
beneficial to the plant because they utilize atmospheric nitrogen
and convert the nitrogen to a form that the plant can use. The
soybean plant provides nutrients to the bacteria.
look closer at these nodules. The nodule on the left has been
sliced open and you can see a pinkish color. This is an indication
that this nodule is actively "fixing" nitrogen for the
plant. If you think about this arrangement between the plant and
bacteria, itís a good deal for both. In simplified terms, the
bacteria have free "room and board" and the plant gets
free nitrogen. This saves on fertilizer costs for farmers as well.
Soybean is not the only legume crop that has this interesting
relationship with bacteria. Other legume crops, such as alfalfa,
red clover, and peanuts also benefit.