split pea stems curvature test
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1. If growing stems of pea seedlings are split and immersed in a solution containing auxin, the two halves will curve inward (fig. 5). This pea test curvature is proportional to the logarithm of the auxin concentration (fig. 6). The curvature is due to differential growth. 2. The epidermis side of the halved stems grows faster than the wounded inside (fig. 1). This difference in growth in turn is caused by the fact that auxin is unable to enter the stem through the wounded surface. If auxin is forced into the halved stems by infiltration with auxin solutions, the inside will grow just as much as the unwounded epidermis side (table 6). 3. The pea test can be successfully used for quantitative auxin determinations, the technique of which is described. 4. The pea test curvature is dependent upon the pH of the auxin solutions (fig. 6). At greater acidities greater curvatures are obtained. As in the Avena coleoptile, the sensitivity of the pea stems to auxin has a daily and seasonal variation. A wide variety of pea races was found to be suitable material for the pea test. Of the fifty-five varieties investigated only two did not give any curvature at all. The rate of curvature was shown to be independent of the auxin concentration, but the higher the concentration the longer the period of time during which the curvature proceeds.
1. If growing stems of pea seedlings are split and immersed in a solution containing auxin, the two halves will curve inward (fig. 5). This pea test curvature is proportional to the logarithm of the auxin concentration (fig. 6). The curvature is due to differential growth. 2. The epidermis side of the halved stems grows faster than the wounded inside (fig. 1). This difference in growth in turn is caused by the fact that auxin is unable to enter the stem through the wounded surface. If auxin is forced into the halved stems by infiltration with auxin solutions, the inside will grow just as much as the unwounded epidermis side (table 6). 3. The pea test can be successfully used for quantitative auxin determinations, the technique of which is described. 4. The pea test curvature is dependent upon the pH of the auxin solutions (fig. 6). At greater acidities greater curvatures are obtained. As in the Avena coleoptile, the sensitivity of the pea stems to auxin has a daily and seasonal variation. A wide variety of pea races was found to be suitable material for the pea test. Of the fifty-five varieties investigated only two did not give any curvature at all. The rate of curvature was shown to be independent of the auxin concentration, but the higher the concentration t