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

the seed produces bleached seeds with reduced germination and emergence
compared to unbleached seeds. Cheng et al. (2004) found that chlorophyllase, a
chlorophyll degrading enzyme, activity was approximately the same in green pea
genotypes that bleach versus genotypes that were more resistant to bleaching. Their
conclusion was that proteins attached to chlorophyll differ which allowed for
bleaching differences that were not explained by chlorophyllase activity, but little is
known of this process. Chlorophyll-degrading peroxidase played a much smaller
role in bleaching than chlorophyllase and its concentration was correlated to
pigment loss but the biochemical pathway of pigment loss was unknown.
Nitrogen level in the soil appears to play a small part in the bleaching
resistance of green peas. Browning and George (1981) found that plants that
received high levels of applied nitrogen were more susceptible to bleaching than
plants grown in a soil with low nitrogen concentration. In practice however this
probably has little effect on bleaching because the high nitrogen treatments in the
study had much more nitrogen available than would typically be found in soils in
western Canada.
The hardness of the seed coat also affects the amount of bleaching that
occurs in green pea. Riehle and Muehlbauer (1975) discovered that when their
laboratory bleaching technique was used, seeds that did not imbibe water quickly
(hard seeds) did not bleach as much as genotypes that imbibed water quickly. They
observed high correlation between seed hardness and bleaching resistance in
laboratory and field trials. This suggested that the seed coat’s physical attributes
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