Seasonal variations in drought resistance of exposed rhizomes of quack grass
1942
Dexter, S.T.
Quack grass rhizomes were dug at intervals throughout three growing seasons and were subjected to various degrees of desiccation in a "drought machine". Subsequent recovery between moist blotters in a seed germination was used as a measure of survival. A very marked seasonal fluctuation in drought resistance and sprouting ability was found. Carbohydrate and total nitrogen determinations were made. There was found to be a close positive correlation between total nitrogen content and sprouting ability before and after exposure to drought. Rhizomes dried until the content of water remaining is 40% of the total weight may be killed in July, but only slightly injured in November. In the very early spring or late fall, rhizomes dried to a content of 30% water may survive to a considerable extent, and in November and December, rhizomes dried to less than 20% water sometimes survived. When killing is to be accomplished largely through drying out, as in the case of the use of the field cultivator, it is suggested that the field be harrowed very thoroughly in the early part of the season.
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