Using the several rice varieties which were produced at the same place and in the same year, the authors have carried out some diagnostic studies concerning the chemical characteristics of polished rice to improve the cooked rice. They have obtained the following results; (1) As far as the sample varieties produced at Furukawa in 1972 are concerned, KOSHIHIKARI contained extraordinary high amount of free amino acids such as glutamic acid, aspartic acid and alanine etc., and other tested varieties followed in the order of SASANISHIKI, TOYONISHIKI, REIMEI and HONENWASE. (2) Glucose, sucrose and maltose were the major three sugars contained in polished rice, but a new sugar, maltotriose, was introduced by trypsin treatment. Much glucose was produced in polished rice by maltase treatment. Trypsin and maltase did not interfere each other even though they were mixed and applied to the polished rice. (3) When trypsin was applied overnight to the polished rice at room temperature, much amount of free amino acids, such ad glutamic acid, aspartic acid, alanine, valine and leucine were released, comparing with the control. The trypsin-treated cooked rice seemed to be apparently improved in the taste, softening the one year-old rice, according to the results of repeated sensory test. (4) The plasticity, one of the physical properties of cooked rice, of both trypsin-treated and the control were compared, using the Parallel Plate Plastometer. The trypsin-treated plot clearly indicated the larger plasticity than the control, and the results of sensory tests mentioned above were proved. The authors hope to develop further the taste-improving technique concerning the safty culture, higher yield, good quality and better taste.

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In order to clarify the morphological and physiological causality responsible for the sterility in sunflower, the authors carried out histological observations on the male sterile plants as comparing with fertile ones. Fertile and male sterile inflorescences of sunflower (Helianthus annuus L.) 'P 21 ms' which inherit male sterility genetically, were used for this study. For histological observations, paraffin sections were cut to a thickness 15 μm and stained with the modifications of triple stain of Himes'es et al.. On observation with the behavior of tapetum during microsporogenesis, the sunflower studied in this experiment belong to the plasmodial type. After the microspore stage, distinguishable differences in the anther were observed. The tapetal cell wall of the fertile anther breaks down, and the tapetal protoplasm extruds into the anther loculus to envelop the microspores. On the contrary, tapetal cell wall of the sterile anther exists in situ and the tapetal cell increase in size. In addition, at both sites and shapes of tapetal nuclei at the microspore stage, a clear difference between the two types of fertilities could be distinguishable. As a result it is concluded that the abnormality of the tapetal cell lysis is closely related with male sterility. And it is also presumed that the sites or shapes of the nuclei were related with male sterilty. For the histochemical reactions, no conspicuous difference between the types of fertilities could be observed.

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Investigations have been carried out to determine the effect of size of seed, variety and crop year on the oil content and fatty acid composition of soybean seeds of 13 varieties grown at the same location in the 2 crop years. The variety, as compared with the size of seed, was more influential on the oil content and the fatty acid composition. When the size of seed decreased, however, the oil and oleic acid contents decreased and the linolenic acid content increased. This finding was more conspicuous in indeterminate type varieties than in determinate type varieties. When comparing the crop year and the variety, the oil content and oleic and linolenic acid contents were influenced by the crop year, and linoleic acid content by the variety. On the correlation between the oil and fatty acid contents, the oil content was positively correlated with the palmitic and oleic acid contents, and negatively with the linolenic acid content. On the correlation between the fatty acid pairs, the negative correlations were shown between the linoleic acid content and the palmitic, oleic or linolenic acid content, and the linolenic and olec acid contents, and the positive correlations were shown between the stealic acid content and the palmitic or linolenic acid content.

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Effects of tannic acid on GA₃-induced growth were studied using 'Ginbozu', a normal and 'Tan-ginbozu', a dwarf rice cultivars. Tannic acid inhibited the GA₃-induced growth of the second leaf sheath of 'Tan-ginbozu' though it did not inhibit their endogenous growth. It also showed no effect on the endogenous growth of the second leaf sheath in 'Ginbozu' with the range of the concentrations from 1 to 1000 ppm. Moreover, tannic acid treatment at panicle initiation stage reduced the GA₃-induced increase of the plant height and internode length in 'Tan-ginbozu'. Their endogenous growth, however, was not affected with tannic acid in 'Ginbozu' as well as in 'Tan-ginbozu'. From the results obtained, it may be suggested that tannic acid may compete with GA₃ in the process of absorption and translocation of exogenous GA₃ or conjugation of GA₃ into the site of action in plant tissues.

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The author tested the influence of the frequency of mowing on the growth of orchardgrass and Ladino clover grown in mixtures in the same sward. For that purpose, both species were grown in pure and mixed sward, and three cutting plots were set up in two swards respectively, i.e., Plot A: the plot cut at 6 times a year (in late April, late May, late June, late July-early August, late August-early Sept., and Oct.); Plot B: the plot cut at 4 times a year (mowings in late June and late July.early Aug. were saved as compared with the case of plot A) ; and Plot C: the plot cut at 3 times a year (in early May, late July and late Sept.). In mixed sward, Ladino clover has become extinct in case where the two species covering the mixed sward were cut less frequently, while orchardgrass had a tendency to become extinct in case where they were cut more frequently. Namely, the yearly changes of yield of the two species corresponded to the yearly changes of population of the two. All the stolons of Ladino clover died out by early May in the first year in case of plot C, and by mid-June in the second year in case of plot B. While the stolons of clover per unit length of string (the number of stolons was shown by the frequency of stolons crossing the unit length of string setting in the sward at random) in plot A began to increase after June in the first year and reached the maximum in June in the second year. After that it showed no appreciably great changes. The number of hills of orchardgrass per unit area decreased temporarily for the first year, but after that it showed little or no changes in case of plot B and C, while the number of hills of orchardgrass per unit area in case of plot A showed a marked decrease in sumrner (June and July) and showed a tendency to decrease year after year. In pure sward, it was not observed the extinction of clover in case of plot B and C, and a tendency of the extinction of orchardgrass in case of plot A. Namely, the number of stolons of clover per unit length of string has been increased in all plots, but the increasing rates were higher in case of plot B and C than that in case of plot A. The number of hills of orchardgrass per unit area decreased temporarily for the first year, but after that it showed little or no changes in case of plot B and C as with in that case in mixed sward. While the number of hills of orchardgrass per unit area in case of plot A showed slowly decrease every summer, but has highly maintained comparing with plot B and C. The data for the mixed and pure sward showed that the extinction of clover or orchardgrass in mixed sward can be ascribed to the competition between the two species led by the mowing rather than to direct influence exerted by the mowing itself.

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The author tested the influence of the mutual shading on the growth of orchardgrass and Ladino clover grown in mixtures in the same sward. For that purpose, both species were grown in pure and mixed sward, and three cutting plots were set up in two swards respectively: three cutting plots in mixed sward were provided a range from extream grass dominance to extream clover dominance. Yield and plant density were measured in pure and mixed sward. And botanical composition, leaf area index and light intensity were measured at 10 cm vertical intervals in each plots of mixed sward at each harvests. The following results were obtained. 1) Long cutting interval gave increased plant height of orchardgrass at any seasons. Under conditions of increased plant height of orchardgrass and consequent low light intensity at the clover canopy, the growth of clover not only become slow but eventually was strongly negative, leading to a marked reduction in both the stolon number and the yield of clover. 2) Short cutting interval gave increased plant height of clover relatively during summer and autumn. Under conditions of increased plant height of clover and consequent low light intensity at orchardgrass surface, the growth of grass not only become slow but evtentually was strongly negative, leading to a marked reduction in both the hill number and the yield of orchardgrass.

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Transpiration and photosynthesis in the upper and lower surfaces of fully expanded intact tobacco leaves (var. Bright Yellow) were examined in reference to the beavior and density of stomata under controlled, turning light environment. In addition, the stomatal responses in both surfaces to varying intensity were investigated. A method of measuring continuously the transpiration rates from the upper and lower surfaces of intact leaf was described. The results were as follows ; 1. The stomatal opening in the upper and lower surfaces by the alternation of light and dark were markedly different. On the upper surface, the stomata opened a little. Both the opening and closing responses of stomata to light were more sensitive on the lower side than on the upper one. 2. The time course changes of transpiration from both surfaces following the onset or close of illumination were nearly similar to those shown by the stomtatal responses. CO₂ exchange, however, increased or decreased more rapidly as compared with the transpirational process. 3. It was observed that larger parts of transpiration and CO₂ exchange were conducted on the lower surface, and that the rate of transpiration as well as that of CO₂ exchange in both surfaces didn't corresponed to the difference of stomatal densities. Therefore, it may be quite all right to consider that their rates in both surfaces were remarkably affected by the stomatal aperture. From the observation on the relation of transpiration to stomatal aperture, it was elucidated in the lower side that transpiration rapidly rised in the range of 2.5-3.5 μ of stomatal aperture. 4. A large difference between the upper and lower leaf surfaces was recognized in the stomatal response to varying light intensity. The active stomatal opening followed by the increased light intensity was observed in the lower side. In the upper side, on the other hand, the stomatal aperture didn't increase under the condition of light intensity more than 10, 000 lx.

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Morning glory was found to be an indicator plant suitable for detecting photochemical oxidants. Typical symptom was small flecks of chlorosis only on the upper surface of the leaves. If the damage was more severe, it became to necrosis. Twelve cultivarieties of morning glory were exposed to the natural photochemical oxidants at Konosu or artificially produced ozone to determine the diffrence of susceptibility among the cultivarieties. Two varieties, Heavenly Blue and Pearly Gate, belonging to Ipomoea tricolor Lam.. were the most susceptible. Among the species of Pharbitis nil Choisy, varieties Scarlet O'hara and Rose Queen were also sensitive. On the other hand, dwarf varieties both Carol Red and Carol Blue, and Uzu type variety Murasaki-jishi were tolerant. Four to five matured leaves between the 10th leaf to the 14th (leaf position was counted from the top of the plant) wete more sensitive than expanding, just expanded young leaves and overmatured leaves during the period from the 15th to 70th leaf stage. Morning glory grown at a normal fertilizer level was more sensitive to photochemical oxidants than that at a lower nutrient level. The plant was less sensitive when water supply was partially withheld than supplied sufficiently.

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The study was carried out to make clear the seasonal change of the type of proliferations differentiated in the spikelets of a mutant induced by X-ray irradiation. Results obtained were as follows: 1. Morphological changes seen in the spikelets of the mutant: (1) The number of vascular bundles had increased both in empty glumes and lemma than usual, and additional differentiation of glumes was too recognized through all seasons. (2) The degenerating tendency of stamens appeared presenting a striking contrast to the increase of glumes mentioned above. (3) Most of spikelet-type (S-type) proliferation occurred from July to October and leafyshoot-type (L-type) one occurred from January to March, showing a striking difference in the type of proliferations by seasons. (4) Especially on December that is the intermediate period when the type of proliferations transformed from the S-type into the L-type, pistilate organs increased remarkablly in a spikelet and the pistil-type (P-type) proliferation appeared. 2. Spikelets obtained from normal strain had also various morphological abnormalities, suffering from the influence of low temperature. 3. Refering to the seasonal change of day length through a year, the S-type proliferation occurred on the decreasing period of day length, the L-type one on the increasing period of it, and appearance of the P-type proliferation coincided with the transition period of day lengh from shortening to lengthening one. From the facts above mentioned, we might be able to draw following schemes on the influence of temperature and day length upon the type of proliferations : a. Moderate (or high) temperature + day length inclining to short day → the S-type proliferation b. Low temperature + short day → the P-type proliferation c. Low temperature + day length inclining to long day → the L-type proliferation Since the stage enhanced the differentiation of pistilate organs most remarkablly was followed by that of vegetative proliferation, it was considered that both the P-type proliferation and the L-type one were seemed to be a series of phenomena having a common physiological back ground, and the change of the type of proliferations might be induced by the enhancement of endogenous auxin level. On the significance of the development of proliferations in the spikelets, some discussions were undertaken from the point of the mode of propagations in rice plant.

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The present study was undertaken to investigate the effect of 3-hydroxy-5-methyl isoxazole (HMI) on the reduction of overhead flooding damage and herbicide injury to rice seedlings. HMI was applied to the soil immediately after sowing of rice seeds in the seedling beds. Seedlings transplanted from these beds showed greater rooting ability and increased physiological activity in their roots. It was observed that the pre-treatment of rice seedlings with HMI promoted the shoot elongation, compared with untreated seedlings, under overhead flooding condition. A drastic reduction in overhead flooding damage was observed when rice seedlings were pre-treated with HMI. The pre-treament of rice seedlings with HMI also reduced the Phytotoxic action of five of seven herbicides applied three days after transplanting. The five herbicides whose phytotoxic action was reduced were simetryne, MCC·MCP, NIP (nitrofen), CNP and DCPA (propanil). The reduced submergence damage and herbicidal injury observed in rice seedlings may be due to increased seedling vigor induced by HMI. The improved physiological condition in these rice seedlings may increase their resistance to submergence treatment and some injurious herbicides.

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Interspecific competition between plant species has long been interesting subjects among agriculturalists who have studied mixed culture of crops, range management, weed control and so on. But it is very difficult to explain the whole results about plant growth in mixed stands competing each other because of their complexity. Recently, however, it becomes able to analyze the dynamics of ecosystem by model simulation with electric computer owing to introduce the method of systems engineering into ecological research. This report deals with model simulation of plant gtowth in mixed stands competing each other in relation to light environment. In constructing a dynamic model of interspecific competition it was thought to be useful to apply the theory of system dynamics developed by J. W. Forrester, because it was simple and easy to understand. The direct object of the model construction in this study was limited to simulate the interspecific competition by simple factors and mathematics as possible, since it was easy to propose an alternative model after partly succes of a preliminary model. The model constructed has the following basic structures and functions. 1. Model plants grow in simple process, such as photosynthesis by leaves, respiration of plant organs and translocation of photosynthates (Fig. 1). Interspecific competition is assumed to play an important role only in relation to light environment of the canopy. 2. It is supposed that the competing force of the plants is realized by the following three subsystems; a. Decision of vertical distribution of leaf area in the canopy. b. Calculation of layers mean of radiation fluxes in the canopy. c. Calculation of gross photosynthesis in layers of the canopy. 3. Leaf area in each canopy layer is decided by top dry weight, plant height, canopy height, LAI and distribution pattern of leaf area density. 4. Radiation fluxes at the bottom of each layer are obtained by RAD(i)=RAD(i-1)EXP[-KC·LA(i)C-KW·LA(i)W], and layers mean of the flux densities are approximated by I(i)=[RAD(i-1)+RAD(i)]/2, where, RAD(0), RAD(i), solar flux density (constant value), and radiation flux density in the i-th layer, respectively; LA(i)C, LA(i)W, leaf area of crop and weed in the i-th layer; and KC, KW, extinction coefficient of crop and weed. 5. Photosynthetic rates in the i-th layer of crop is, then, approximated by PHS(i)C=[KC·BC·I(i)·LA(i)C]/[1+AC·I(i)·KC], where, AC, BC, parameters of light-photosynthesis curves. 6. Plants respire dark respiration which is proportional to its dry matter in day and night and light respiration which is proportional to the gross photosynthesis of the plant in daylight (12 hrs.). 7. It is assumed that the model plants have the flows of photosynthates from leaves to each organs after temporary store (one day). The following results were obtained by 100 day simulation of the interspecific competition model, supposing that crop was tipland rice and weed was crabgrass (Digitaria adsendens): 1. Comparison of simulated values obtained with parameters in Table 1 and initial values in Table 2 to observed values in field experiments reported earlier shows good agreement between both plant growth curves except only in the later growth stages of weed (Fig. (6). 2. The alternative values of the parameters, such as specific leaf area, respiration normals and growth normals (allocation ratio) of each organ, clearly show the dependence of growth curves of both plant on these parameters. It is evaluated that specific leaf area and growth normals have stronger effect than respiration normals (Figs. 7, 8 and 9). 3. Weeding experiments with the model simulations agree well to the field experiments obtained earlier, supposing a clean culture, weeding at early and middle growth stages of crop and no weeding with the use of the alternative values of initial dry matter of both model plants (Fig. 10).

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The whiteness values for hulled rice and milled rice were measured by the whiteness meter in relation to the rice quality. The values measured by the whiteness meter are propotionated to the values of light reflected by rice grains. The values for hulled rice were influenced by color of bran layer and opacity of starch-cell layer. As compared with normal grain, rusty grain and green grain showed low values according to the degree of deepness of color. White-belly grain, milky-white grain and the other grains which have chalky parts in their endosperm showed high values in proportion to the grade of opacity. Among normal grains, the values were rather low for the grains of good quality as they were more translucent than the grains of bad quality. The values for milled rice were affected by the degree of milling and the grade lof opacity of endosperm. They became higher with progress of milling. Among fully milled grains, the grains of bad quality showed higher value than the grains of good quality for the formers had somewhat opaque endosperm.

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