Several grasses were sown in this district and the field experiments for cutting was done in 1949. According to these results the most productive grass is Sudan grass, and the next is Pearl millet. Crasses are supposed to be suitable in autumn sowing than in spring, on account of vigor of weeds in spring. Consider to the resistance to heat, drought, and cold of the plants, Pearl millet, and Sudan grass are most resistant to dry and heat, and Red clover, and Alfalfa also are reasonable by deep root system. Redtop, Meadow foxtail, and Italian rye grass have less resistance to cold or less winterhardened than Canary grass, and Tall meadow fescue. And the latter two keep green in winter. From the results above mentioned Sudan grass and Pearl millet are seen to be suitable for cutting in this district, and the others may be hopeful by means of fitting irrigation in summer, or taking care of the growth in spring and autumn.

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(1) In 1949, at rice nursery, in order to know the effects of 2.4-D on rice plants growing as well as weeds, the following tests were made. A) Two or three weeks before the sowing of rice seeds, 2.4-D which were disolved each 0.25g, 0.5g, and 1.0g in water of 1.5 liter per 1.8m² (1 tsubo) were sprayed. To save from the toxity of 2.4-D, at the time of sowing, the rice seeds were treated with anti-2.4-D (the mixture of active carbon and active clay). The method is as follow. a) The rice seeds were covered with powder of anti-2.4-D. b) On the nursery bed, 2% suspension solution of anti-2.4-D were sprayed and 30g were used per are. c) No treatment. Morever, each section ((a), (b) and (C)) divided into two parts, the one covering the seeds with sand and the other with ash of boked chaffs. B) On Jun. 11th and 23th, 2.4-D of 20-200g were sprayed per 10 ares. (2) At half-drained nursery (flooded only furrows), the treatment of soil with 2.4-D of 0.5-1.0g per tsubo was benificial to control of the weeds, on the other hand, many abnormal and dead seedlings were appeared. Only in the plots which was applied 2.4-D of 0.25g with anti-2.4-D the normal seedling was found. (3) At flooded nursery all seedlings were normal when seeds covered with ash after pretreatment of 2.4-D. But on the occasion of 1.0g covered with sand abnormal seedlings appeared, while no abnormality was found by the use of anti-2.4-D and the weeds reduced to 1/2∼1/(10) compared with the untreated section. (4) The reduction of the toxic action of 2.4-D (neutralize action) was more efficiently when seed covered with anti-2.4-D powder than it sprayed on the soil. (5) The rice seedling which were slightly injured at nursery bed recovered their activity afterwards, and after transplanting they had grown up as well as the untreated seedlings. At flooded nursery, rice yield of the plots which were treated by 2.4-D, in some cases, were somewhat great compared with untreated section. (6) At the plots in which were applied 2.4-D of 20-50g on Jun.11th and 25th, the control effect of weeds was not remarkable but the injury of seedling was not great, and yield of rice were increased when sprayed 20 grams. On the other hand, at the plots in which were used 2.4-D of 100-200g, the weeds were fairly killed, but the growth of seedlings were prevented and have little yield.

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(1) In 1946, in order to recognize the result of previous report again the experiment were carried out at the paddy field where the rice plants were transplanted on July 2nd and only one time weeding was done with hand weeding machine before the spray. (2) Na-2.4-D which was made in U.S.A. and two chemicals which were made in Japan, were used for this test. (3) On July. 28th or Aug. 8th 2.4-D of 40-60g which were disolved in water of 75 litres were sprayed per 10 ares after drained. The area of every test plots are 1/5 are and some treatment had repeated in four plots, and as a cotrast 4 times band weeding plot and no-weeding plot were set up. And the effect of weeding on the paddy field and on the yield of rice were investigated. (4) On July 28th when 2.4-D of 40-60g were sprayed per 10 ares the weeds were all killed except graminous such as Echinochlola Crus-galli BEAV. and Leptichla chinensise NEGS. within 10 days, and this effect for weeding are equal to that of 4 times by hand. This is a proof of the remarkable weeding effect of 2.4-D. (5) On the other hand, in case of spraying of 2.4-D of 40g on July 28th. there is no damage in growth of rice plants, and from this on treated plot there were the same yield of rice as compared with the plot which were weeded 4 times by hand, although, formers were little inferior to the latter in plot to the number of tiller and the weight of stalks. This fact was all alike the result of the last year. (6) In the plots which were sprayed 2.4-D of 60g, slight injury was appeared in growth of rice plants and weights of grains of each rice plants is dainger of decrease. Therefore, the use of 40g is suitable. (7) The yield of rice, at the plot in which 2.4-D of 40g was used on Aug. 8th, decreased and this was because that as the weeds grew closely before the spraying, the growth of rice plants were checked. (8) From above mentioned result, it can conclude that, at rice paddy fields, application of 2.4-D of 40g per 10 ares can practically use.

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(1) Effects of I. P. C., a chemical herbicider of graminous weeds, have been tested since the spring in 1949. (2) Although the tests were ended in failure frequently at summer season. In October when seedling of onion, spinach and graminious weeds grew up about 3∼7 cm in height, water solution ot 0.67% I.P.C. at the rate of 15∼22.5 liter per are (100∼200g of I.P.C. was used per are) were sprayed over the field. It was proved that this water solution was so effective a selective weed killer that raminous weed were all killed ter solution was so effective a selective weed killer that raminous weed were all killed within 2∼3 days without damage to seedlings of onion and spinach, and no weeds grew there after. (3) However, oil solution of 4% I.P.C. at the rate of 0.75∼1.5 liters per are (30∼60 g of I.P.C. was not only weeds but also the crop all together, therefore oil solution of of I. P. C. was not recognized to act selectively. (4) It is noted also that the effect of I.P.C. is not remarkable for the grown up graminous plants. (5) On November 18th, immediately after the seeds of pea, broad beans, rape, wheat and barley were sown, 100∼150 g of I.P.C. water emulsion and 30∼60 g of I.P.C. oil solution per are were sprayed over the field. (6) In this series of experiments, it was found that in plot where more than 60 g of I.P.C. was used, no weed was seen for 40 days and after 135 days, the quantity of weeds was only 1/5∼1/(50) as compared with that of the untreated plot. There was no damage on the germination and the growth of pea, broad bean and rape, while barley and wheat grew very sparsely. (7) It was concluded from the results that I.P.C. was a effective weeder acting selectively on the Graminious plants only. It was also noted that pretreatment of soil with I.P.C. was most effective and its application to young weeds also gave considerably good results.

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It was confirmed that the checking of seed development or the mote-formation in cotton occurs with numerous forms at various stages or perhaps at any stage in development beginning from the day of flowering and even prior to flowering. So far as this investigation is concerned, the following factors have been observed. The materials studied were each one variety of upland and Chinese cotton. 1. The ovule itself was defective and failed to receive pollen-tube. In this case are involved the ovule in which the embryosac is thoroughly lacked and replaced by nucellus (Fig.2) and also ovule in which the embryosac is located but the egg cell, synergids and polar nuclei therein are either misplaced and hot organized (Fig.5), while in other ovule they are shrunken (Fig.4). Each instance should be undoubtedly induced prior to the day of flowering. 2. The ovule was normally formed, but the pollen-tube although reaching to ovule failed in completing the fertilization. Two stages could be identified in this case, namely, failure of pollen-tube to enter into embryosac (Fig.6) and failure of male gametes which entered into embryosac to fuse with the female gametophyte (Fig.7). All of them were observed in bolls or 4∼7 days after anthesis. The male gametes as well as female gametophyte remained unharmed without degeneration in every case. The failure of ovule to receive pollen-tube due to defective pollination, insufficient supply of pollen grains and so forth was not disregarded herein, but within the extent of this experiment no applicable cases were found. The abortive seeds of this kind might be expected to occur with the much frequency as suggested by previous investigators. 3. The fertilization was normally functioned but the successive development of ovule was arrested to grow into normal seed (Fig.8∼11). The occurrence of motes induced for the above No.1 and No.2 reasons appears to be relatively very few, but to be the source responsible for formation of typical small-motes. Meantime, the majority of motes produced in cotton boll appear to depend upon No.3 case in general. Different stages of development forming a graduated series were involved in this case, but for the most parts they appear to arrest at the comparatively very early stage and to result in developing into tiny structure of small-motes. The mote-formation due to the bollsucking insect injury was out of consideration, since here was lacked in insects of this kind. In addition, some observations were made on the variation of mote occurrence with position in locks. The procedure in obtaining the position data employed was similar to PEARSON'S idea classifying the locks as to size, but differed in classifying the ovules in two groups further according to placental ridges with which the ovules are found to attach in line. More consistent tendency was obtained in that the mote production for tip positions was smaller than that for the basal ones in upland cotton as compared with that of previous reporters, while the situation was slightly the reverse in oriental variety (Table 2). The false motes were excluded from counting the mote numbers. They were frequently found in upland variety, but no presence was recognized in oriental one.

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Inducing bud- and boll-shedding in Asiatic cotton plants by shading (dark) treatment and drought treatment for 2 or 3 days, we studied how the bud- and boll-shedding depended upon the stage of their fruiting processes, and also we examined the relations between the development of abscission layer and the concurrent damage to floral organs. Under both conditions of treatments young squares seldom shed, and the rates of shedding begin to increase after the starting of microsporogenesis. Under the light deficient conditioo, the peak of shedding rate takes place from the beginning of macrosporogenesis to the end of nuclear divisions in embryo sac, accompanying chiefly with the damages of the megaspore mother cell or of the female gamatephyte. The rate of shedding decreases in old squares, a few days before flowering, but almost of them shed after flowering, accompanied with the damages of the egg cell or of the developing embryo. Under water deficient condition, the peak of shedding takes place during before and after megasporogenesis, accompanying chiefly with dissolution of the cells surrounding the megaspore mother cell. Comparing the effects of these two conditions, we could find a tendency that squares were very sensitive to drought condition while bolls were rather sensitive to light deficient condition. Concerning the boll shedding, it seems probable that the damages of the egg or young embryo are the main cause which induces stimulus to abscission. The rare shedding with the increasing age of the bolls seems to be due to the development of the embryo and endosperm, and also to the strengthening of the mechanical tissues of the pedicel. Evidence is presented which indicates that under shedding condition the absciss layer begins to develop a little later after the occurrence of damage of the megaspore mother cell or of the female gamatephyte, while under drought condition the development of the absciss layer is so rapidly induced, that it seems probable that loss of water from the pedicel tissue might directly serve as a stimulus to abscission.

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The author investigated the influence of pruning on the vegetative growth of Japanese peppermint (Mentha arvensis, L., var. piperascens, MAE.) by pot-culture, and obtained the following results ; 1) The growth of plant-height is temporarily delayed. 2) The third leaf is promoted to develop and as a result the total number of leaves are increased. 3) The time of flowering trends to become more uniform, while is delayed slightly. 4) The irregularity of correlations is seen between the height of plant at the time of treatment and the respective height measured several times there after. 5) The irregularity of correlation is seen between the weight of the subterranean part and weight of the terrestrial part. 6) The dry-weight of leaves and stems are increased. 7) The content of essential oil is increased. 8) The content of menthol in the essential oil is increased.

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1) Study on the rotation has not yet been cleared scientifically, so that the rotation of farmers has been only depended upon their experience. To establish the theory of rotation, the 1st thing to do is to clear the characters of each crop and to find the rational combination of the former and succeeding crops. Viewing of this point, this experiment was planned and practised. 2) Each crop differs in the requirement of the amounts of manures and its constituents. Each crop also have different tolerance for the continuous cropping. These facts enable to manifest the character of each crop on the demand for manures. 3) The favourable hardness of soil for each crop may seem to exist, but the investigation should be practised more scientifically. 4) The root development and the root system of each crop were studied. The roots develops more widely and deeper as considered. Viewing of the character of roots, it seems to be important to investigate the rational soil treatment and the soil condition influenced by the roots of each crop. 5) The shape of crop vegetation influences remarkably on the cleanness of the fields. For instance, soybean eradicates the weeds and makes clean the fields. Each crop has different character of these points. 6) Viewing of these character, the rational rotation (specially, the former and the succeeding cropping) in this district may be that of the table 2. (This experiments are now going on.)

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