FACTORS AFFECTING THE GERMINATION AND ESTABLISHMENT OF MONOGERM SUGAR BEET
2.3.4 Effects of inhibitors on germination
Many substances have been isolated from the seed coats of sugar beet which are potentially inhibitory to germination, most of them are organic acids. Snyder, Sebeson & Fairley (1965) considered Oxalate to be the major inhibitor but did note some complex interactions with others. It was concluded that effects were specifically inhibitory rather than osmotic. Sebeson, Mitchell & Snyder (1969) studied the effects of inhibitors on Alpha-amylase activity on starch solutions (hydrolysis of starch is an essential process before germination commences). The inhibitory effects of Caffeic, Ferulic, Gallic, P-hydroxy, Benzoic and Vanillic acids, which are known to exist in beet seeds, were examined using Alpha-amylase and excised embryos. Gallic acid was found to be most inhibitory and, in general, the degree of inhibition increased with concentration in both experiments, but the effects were less pronounced on the embryos, indicating that some form of de-toxification must occur in the seed. Battle & Whittington (1971) showed that the maternal genotype influenced the early field behaviour of the progeny through control of the level of inhibitors in the seed. In earlier experiments, Battle & Whittington (1969b) showed that the inhibitors were situated in the perianth and pericarp, and also that the various other acids, including Abscisic, were involved. It was postulated that the free phenolic acids were in equilibrium with acetone insoluble esters involved in lignin bio-synthesis. Immature clusters would have a relatively higher proportion of P-coumaric acid associated with an earlier stage in lignin biosynthetic pathway.
Inhibitors may also act as 02 acceptors and affect germination in this way (Heydecker, Chetram & Heydecker 1971).
FACTORS AFFECTING THE GERMINATION AND ESTABLISHMENT OF MONOGERM SUGAR BEET
[Introduction & Contents] [Chapter One] [Chapter Two] [Chapter Three] [Chapter Four] [Chapter Five] [Chapter Six] [Chapter Seven]
[2.3] [2.3.1] [2.3.2] [2.3.3] [2.3.4] [2.3.5]
