Abstract
In order to investigate the formative effects of 2.4-D on the rice plant, the subject being of specila importance among our agronomical research items, the author carried out experiments with a paddy rice variety, Norin No. 1. As the results 2.4-D when sprayed to the soil either during the nursery stage of growth or whithin the definite period after transplanting the seedlings, was found to induce many characteristic effects on the plant, the principal aspects being as follows: 1. Roll leaf. As shown Figure 1. the leaves on the plants affected were deformed into cylindrical shapes, and in such leaves, as shown in Table 1, the number of the middle-sized vascular bundles was slightly smaller than that in normal plants and that of the inferior ones was remarkably reduced to about 1/3 of the normal value. 2. Abnormal cell-division in the culm-base tissues. Remarkable fanwise tillering of shoots was observed on the plants sprayed with 2.4-D under unfavaravble conditions, the phenomenon being supposed to be partly due to the abnormal cell division in the culm base tissues as shown in Figure 10. 3. Stumpy root. The stumpy roots on the plants affected as shown in Figure 12 were distinguished from the mormal roots by the difference in the thickness of epidermis as well as by indistinctness of the confines between coetex and central cylinder.
