Orientation of Wheat Seedling Organs in Relation to Gravity

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Abstract
Orientation erect to gravity was compared with that produced on a horizontal clinostat. Comparative tests were also made with barley, rye and oat seedlings.. The coleoptile and roots devlop characteristic curvatures when geotropic responses are eliminated during growth. The symmetry of root system in wheat was found to depend on epinasty in the early lateral roots, a force not previously known in roots. They grow in a plane at angles of about 57.5[degree] with the ideal primary root under the influence of gravity but this angle is about 47.5[degree] larger if the lateral roots develop on a clinostat. Root epinasty is also an active factor in the seminal roots of barley and rye but not of oats. It appears to be based on auxin imbalance, similar to that described by Lyon in branches and petioles.