The Seed Coat as a Control of Imbibitional Chilling Injury
- Raymond E. Tully,
- Mary E. Musgrave and
- A. Carl Leopold1
The imbibition of pea (Pisum sativum L.) seeds proceeds slowly in cold water, with little effect on subsequent vigor; soybean [Glycine max (L.) Merr.] seeds imbibe cold water rapidly, and suffer significant vigor loss. When the imbibitional rate of peas was increased by nicking the seed coats, the peas became susceptible to chilling injury. Conversely, when the rate of soybean imbibitionwas slowed with a solution of polyethylene glycol (PEG 6000), their susceptibility to imbibitional chilling was considerably lessened. Sensitivity to imbibitional chilling is thus a consequence of the rate of cold water uptake.
Cellular damage to cold-imbibed peas and soybeans was assessed as inability to reduce triphenyl tetrazolium chloride (TTC). Peas showed only a low level of damage when imbibed with intact seed coats at 2 C, but increased damage when imbibed with nicked seed coats. Soybeans, however, showed considerable cellular damage when imbibed intact, and no further damage when imbibed with nicked seed coats. Pea seed coats thus offer considerable protection against rapid imbibition and chilling damage, whereas the soybean seed coat offers little.
Soybeans with black-pigmented seed coats imbibed water more slowly than nonpigmented soybeans. Blackpigmented soybeans also showed less vigor loss following imbibition at 0 C, and exhibited no cellular damage as determined with TTC stain. Vigor of blackpigmented seeds after 23 C imbibition was less than that of nonpigmented, however, due to a slower rate of radicle penetration of the tougher black seed coats.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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