DISCUSSIONS
The results which implied the significant
difference between studied cultivars to mechanical
damage show the character of mechanical damage is one
of the traits related to cultivar. In fact this character is
related to seed coat characteristics that the more integrated
seed coat and more lignin content, is more resistant to
mechanical damage and if the seed coat be more thin and
fragile, the susceptibility to mechanical damage will
increase. Also the cultivar with larger seed size has more
probability of mechanical damage. The results of many
researchers studies particularly Verasilpa and colleagues
(2001), Kryzanowski and colleagues (1995) also confirm
this subject. On the other hand the extent of mechanical
damage directly relate to seed moisture content. In fact
there is an optimum level of moisture which causes the
minimum mechanical damage. At moistures higher and
lower than optimum level the extent of damage as seed
crushing and bruising or breakage and cracks will be
more. It can be concluded that on optimum moisture the
soybean seed physical properties such as seed size,
porosity and density are in the best condition for reducing
mechanical damage. The results of Kashaninejad and
colleagues (2007), Sosnowski and Kuzenyar (19910),
Khazaie et al., (2009) studies also verify it.