GREEN SEED COAT COLOUR RETENTION IN LENTIL - University ...

2005). Diquat (9,10-dihydro-8a,10a-diazoniaphenanthrene) is a desiccant
commonly used in lentil production. It is used to quickly dry the green tissues of
the crop to enhance rapid drying of the seed to moisture levels suitable for combine
harvesting and safe storage. In western Canada it is most often used on pulse crops
like field pea, lentil, and chickpea. It is also used on other crops like potato
(Solanum tuberosum L.) that are grown to a limited extent in western Canada.
Diquat and glufosinate ammonium (ammonium (2RS)-2-amino-4-
(methylphosphinato)butyric acid) are the only two registered desiccants for lentils in
western Canada. For efficacy reasons and concerns about herbicide rotation, diquat
is more commonly used.
Due to the high cost of diquat, other herbicides like glyphosate (N-
(phosphonomethyl)glycine) are often used for desiccation even though plant dry
down is much slower with glyphosate. Yenish and Young (2000) reported that
glyphosate applied at the proper preharvest timing in spring wheat (Triticum
aestivum) can work well to provide a dry uniform crop at harvest. A significant
issue with the use of glyphosate as a preharvest treatment is the potential loss of
vigour if the seed is used for planting the following year. Baur et al. (1977)
indicated that the seed may have poor germination and seedling vigour because
glyphosate is translocated to the developing seed thereby killing the embryo. In
their study if glyphosate was applied too early yield was reduced mainly through a
loss in kernel weight. Slower dry down occurs with glyphosate because it is a
systemic herbicide and diquat is a contact herbicide. The main reason that diquat is
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