EFFECTS OF WETTING TREATMENT PERIOD AND M OISTURE-CONTENT ON WATER-UPTAKE BY WHEAT-GRAIN DURING GERMINATION AND ALPHA-AMYLASE ACTIVITY

To vary the moisture content in wheat grain fi-om 20 to 45%, various q uantities of water were instilled in non-dormant grains in two varieti es and one pedigree (Chihokukomugi, Horoshirikomugi and Kitakei-1354), After incubation for 24 and 72 hr, the incidence of germination and a lpha-amylase activity were evaluated. 1) Germination and activation of alpha-amylase were not observed in grains having a moisture content u nder 25%. 2) Grains with moisture content from 25 to 30% showed relati vely high activity in the absence of germination. 3) In grains with a moisture content over 30%, the relationship between alpha-amylase acti vity and germination was affected by wetting periods. At 72 hr of wett ing, almost all grains showed high alpha-amylase activity with germina tion. 4) Whereas at 24 br of wetting, some grains with a moisture cont ent over 30% exhibited relatively low activity in spite of apparent ge rmination. Thus in 2) and 4), correspondence between germination and a ctivation of alpha-amylase was not observed. With respect to 4), grain s absorbed water rapidly after wetting and immediately showed signs of germination, while alpha-amylase was activated slowly because de-novo synthesis needed a considerable period. Concerning 2), a difference b etween the moisture content which activated alpha-amylase and that whi ch induced germination was a probable cause. Finally alpha-amylase act ivity in Kitakei-1354 was lower than the other two varieties, which wa s possibly influenced by varietal differences in water uptake rate.