Der bayerische Forsterverein

Ohne Zusammenfassung     

Ripening of Tomatoes

Experiments were carried out with aldrin, dieldrin, isodrin, endrin and DDT to ascertain whether, employed as insecticides, these compounds had any effect on cell division in onion root-tips. The doses used were equal to, or greatly in excess of, the recommended rates of application. By germinating onion seeds in direct contact with the insecticide under investigation, it has been shown that none of the compounds had any effects on germination or growth rate. High doses of aldrin, dieldrin or isodrin had a slight toxic effect on the resting cell, which, with aldrin, was also caused by the recrystallized compound. Aldrin and dieldrin had no effect on the dividing cell. Isodrin and endrin caused slight stickiness between chromatids in anaphase, which was insufficient to prevent the completion of division in the cell, and DDT caused a delay in the early stages of prophase and a shortening of chromosomes in metaphase.

Pot experiments, with high doses of each compound, showed that germination and growth rate were unaffected by any of the compounds. Resting cells were not affected and dividing cells were affected only by slight stickiness in anaphase, except with DDT, which also caused a slight delay in metaphase.

Attention has been drawn to the advantages of these compounds over gamma-BHC, chlordane and toxaphene as insecticides, from the point of view of causing less damage to the plant.     

Studies of Fruit Development in Relation to Plant Hormones: IV. Acidic Auxins and Growth Inhibitors in Leaves and Fruits of the Apple

Apple leaves and fruits are shown to contain three acidic growth-promoting and two acidic growth-inhibiting substances which appear to be different from any chemically known auxins or growth-inhibitors. By means of the technique of paper chromatography the distribution of these substances in fruits and seeds at different stages of development has been investigated. On the basis of the results so far obtained the possible significance of certain of these substances in fruit development is discussed.