On the formative effect of hormone herbicides (2, 4-D, MCPA) in fibre flax plant

Abstract

1. From the results of the field experiments with two pinds of herbicides (2, 4-D and MCPA) applied to the flax (variety Saginaw 2) crops carried for four years, we arrived to a conclusion that the growing process of flax should be divided into following four stages (Fig. 2) with regard to the formative effect to these herbicides. (a) Stem malformation stage (b) Branch malformation stage (c) Stem twisting stage (d) Branch twisting and sterility stage. Each stage of (a) and (c) has larger practical importance than the rest. The formative effect was larget in 2, 4-D than in MCPA and the latter was very small in the stage (a). 2. Industrial significance of such stem malformation was studied anatomically, with the results: i) Various malformations were found out at one point of some flax stem in the stage (a). The structure severely demaged is shown in Fig. 4 and such damaged portions will be a weak point in the process of harvesting and scutching. ii) The degrees of twisting and curving of stem were classified as shown in Fig. 3 and anatomical views of these stems were shown in Fig. 5. When the degree of curveture exceeds 3 (4, 5, 6 in Fig. 5), the deformation of fibre cells becomes severer and also forms a weak point. The distribution of damaged tissue in the abnormal stems is shown in Fig. 6 with the dotted area. 3. For the sake of avoiding malformation, it should be better to use MCPA than 2, 4-D, and apply it as early as possible to restrict curving at the base of stem, and thus the damage of the flax crop may be podsibly reduced withont much loss of the weed controlling effect of the chemical.