Alpha-amylase and protease activities and water relations in germinating sorghum (Sorghum bicolormoench) seeds as affected by animal-waste composts

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Abstract
Effect of animal-waste composts on α-amylase and protease activities of sorghum (Sorghum bicolor Moench) seeds was investigated under laboratory conditions using several cattle, chicken and hog-waste composts. The sorghum seeds were imbibed in 1, 4, and 8% (w/v) water extracts of the composts for 4 h. Alpha-amylase activity of the non-imbibed seeds increased by 46% during the 4-h imbibition in water. The increase of the amylase activity of the seeds imbibed in the majority of the germination-inhibitor composts, however, remained at a level between 50 and 66% of the increase observed in the water control. The amylase activity of the imbibed seeds showed a linear correlation with amount of water absorbed by the seeds (r = 0.82**) and also with the rate of subsequent seed germination (r = 0.85**). The protease activity was not affected by the addition of animal-waste composts. Starch degradation and the sugar and amino acid contents of the compost-imbibed seeds were in good agreement with the respective enzyme activities.