Effects of genotype and environment on the sprouting propensity and other grain characters of wheat (Triticum aestivum L.): a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University

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Sprouting damage nay occur when wet weather initiates germination processes in unharvested grain, with subsequent deterioration in breadmaking quality. It is a potential hazard to wheat growing regions throughout the world, e.g. Europe (Olered, 1967; Belderok, 1968), Australia (Moss, et al., 1972) and New Zealand (Sanders, 1974; McEwan, 1976a). Seed dormancy is usually accepted as being related in some way to resistance to sprouting damage (e.g. Belderok, 1968a); that is, dormancy may be associated with lack of catabolic processes in the endosperm (Ching, 1972; Leshem, 1973; Villiers, 1972). Several enzymes initiated during the germination process are involved in the degradation of the starch and protein of the endosperm. These enzymes include alpha-amylase, which break the branch chain amylopectin starch molecules to dextrins and amylases, and beta-amylase which degrade these smaller compounds to low molecular weight dextrins and maltose (Kent-Jones and Amos, 1967; Pyler, 1969). Beta-amylase is present in the sound grain but its activity is restricted, as there are relatively few exo-groups at which this enzyme is capable of hydrolysing (Kent-Jones and Amos, 1967; Pyler, 1969). Alpha-amylase appears a major factor in starch dextrinisation, and levels of this enzyme relate to the degree of sprout damage (Johansson, 1976; Olered, 1967; Moss et al., 1972). Other enzymes may also be involved in early germination, such as proteolytic enzymes (Gordon, 1975; Kruger, 1976). In sprout damaged wheat, the increased level of starch dextrinisation results in an inferior loaf (Olered, 1967; Pyler, 1967; Moss et al., 1972). The loaf is reduced in volume, has a grey and sticky crumb, and a dark crust colour (Olered, 1967; Kent-Jones and Amos, 1968; Pyler, 1969; McDermott, 1971). Sprout damaged grain may also have a lighter bushel or test weight (Ghaderi and Everson, 1971; Fouler and de la Roche, 1975), and lowered milling yield (Belderok, 1968; McEwan, 1959). [From Introduction]
Wheat Genetics, Wheat