Purple nutsedege (Cyperus rotundus L.) is one of the most troublesome perennial weeds in the southern part of Japan. It is reported that yellow nutsedge (Cyperus esculentus L.) is about as formidable as purple nutsedge in U.S.A., and the same plant in Egypt has very nourishing tubers. In this study the growth of yellow nutsedge obtained from Egypt and purple nutsedge in our country were compared, and following results were obtained.
1. The plant height was 25-30cm in purple nutsedge and 70-100cm in yellow nutsedge. The shape of leaf blade and sheath was almost same in two species. Every shoots of purple nutsedge grew scatteringly, on the contrary, those of yellow nutsedge grew fasciculately.
2. In purple nutsedge, the tuber located at the junction of the rhizome and leaf. In yellow nutsedge, on the other hand, the tuber located in the tip of rhizome, and the portion of the junction of rhizome and leaf did not grow upon tuber.
3. From above results, it seemed that the yellow nutsedge obtained from Egypt was fairly domesticated plants.

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Growth and reproduction of Pinellia ternata Breit. was surveyed from standpoints of emergence of tuber, leaf types related to tuber age, depth and extent of tuber dispersal, enlargement of tuber and formation of bulblet, vegetative reproduction of cut section of tuber, and so on.

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Nutsedge, Cyperus rotundus L., is one of the most serious perennial weeds in upland fields of Japan, and EPTC (ethyl N, N-dipropylthiocarbamate) has been found to be effective to the control of this weed.
This experiment is undertaken to obtain some informations about effects of EPTC on nutsedge tuber germination.
The results obtained are as follows:
(1) EPTC remarkably inhibited the germination without killing the tubers and induced, so called, dormant state.
(2) The dormancy induced by EPTC was broken when the tubers were immersed into gibberellin (GA₃) solution.
(3) No obvious changes were observed in contents of carbohydrates and also in O₂-consumption during the germination stages.
It appears, therefore, that a mode of action of EPTC is the inhibition of GA₃ synthesis.

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Studies were carried out to obtain the effective herbicides for the control of Cyperus serotinus Rottb. in the early growing period of rice plants.
37 herbicides were tested, and it was recognized that dichlobenil (DBN), mixture of DBN and Allyl-MCPA (or MCPA and MCPP), mixture of DBN, MCPB and PCP, mixture of chlorothiamid (DCBN-3) and 2-methyl-4-chlorophenoxyacetohydrazide, SAP (O, O-diisopropyl-2 (benzenesulfamidoethyl) dithiophosphate), mixture of SAP and prometryne, mixture of SAP and MCPP, and HE-314 were very effective.
The optimum application time and dosage of these herbicides are discussed.

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In the previous report the author pointed out that the number of roots on both nodes, coleoptile and the first leaf, in barnyardgrass (Echinochloa crusgalli) was clearly less than those of rice plants.
Present report is an anatomical survey on the leaf blade and leaf sheath in barnyardgrass seedlings. Some distinguishing traits even in these aerial parts were observed. Obtained results were as follows:

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Over a period of two years, 1965 and 1966, the degree and pattern of the damage to riceplants due to the competition with barnyardgrass at the nine stands of 0, 2, 5, 10, 20, 40, 80, 160, and 320per spuare meter were studied under two fertilizer levels and on three rice densities. The results are summarized as follows:
1. Ths height of rice plants, when coexisting with a higher number of barnyardgrass stands, tended to increase during the middle stages of the growing season. The number of tillers of rice plants was reduced seriously owing to coexistence with barnyardgrass. However, the tillering until around late July was not so detrimentally affected, but that after early August was so seriously done, and the number of tillers with panicles was reduced by about 50per cent at the harvest time.
2. An injurious effect on the heading of rice plants was scarcely found. However, when rice plants grew together with barnyardgrass at the highest number of stands, they delayed one or two days in the heading time. In addition, stunting of the heading was found in some of the rice plants in 1965.
3. The yield of rice plants was reduced more seriously as the stands of barnyardgrass increased, being in a curved negative regression against the Logarithm of the number of barnyardgrass stands. The percentage of reduction varied considerably according to fertilizer levels and rice densities, so that it was impossible to express the relation of the rice yield to the number of barnyardgrass stands by only one emperical formula. But its relation to the barnyardgrass weight was expressed by the following formula: logY=a-bX (Y, X, and a, b are barnyardgrass wt, index of rice yield, and constants, respectively.), irrespective of fertilizer and rice density condition.
4. The components contributing to the reduction of rice yield were the number of panicles, the weight of grains, the number spikelets per a panicle, and the fertilization percentage of the spikelets in the order of decreasing importance.
5. In a mixed population of rice-barnyardgrass, the reduction of incident light, the change of the productive structure of rice population, the decreasing of LAI and dry weight of leaves, and the lowering of nitrogen content of upper leaves were found, A difference between rice and barnyardgrass in their absorbing pattern for the nitrogen element was observed, so that it was proposed that the competition for nitorgen uptake between both plants should be more serious during the first half of the growing season.

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This experiment was carried out for the purpose of finding out the activity of some contact herbicide mixture and their effect on mulberry-tree from 1964 to 1965. Atratone, sodium cyanate, propanil (DCPA) and a mixture of the last two were examined.
A mixture of sodium cyanate and propanil was superior to the others and propanil was inferior. Atratone and propanil slightly injured one-year-old mulberry-tree, but the mixture of sodium cyanate and propanil did not. Sodium cyanate accelerated growth of top and root of mulberry plant.

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1) Inhibitory activity on the seminal root elongation of rice and barnyardgrass seeds by CIPC (isopropyl N-(3-chlorophenyl) carbamate) was seventy times stronger than that of MCC.
2) MCC showed the greatest herbicidal activity within the group of methyl N-(mono or di- substituted phenyl) carbamates. Although CIPC and MCC possess the excellent herbicidal properties; the compounds which exchanged their chlorine-substituted phenyl rings each other, isopropyl N-(3, 4-dichlorophenyl) carbamate and methyl N-(3-chlorophenyl) carbamate had very low phytotoxicity in both the soil and foliage application.
3) The rice plants before the 1st leaf stage were not so influenced by MCC absorbed through only the roots under soil culture, but were most susceptible from the 2nd to 3rd leaf stage. This tendency was the same as in the case of foliage application.
4) The effects on the rice plants of MCC were increased by adding of a little amount of carbaryl (NAC, 1-naphthyl N-methylcarbamate) under solution culture, but this synergistic action was less than that of propanil (DCPA). The synergism was not found at the germinating stage.

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When MCC was incorporated into the root zone and shoot zone of the soil sown rice plants and barnyardgrass, the following observations were obtained.
(1) It was discovered that in both the root zones and the shoot zones swep was more toxic to barnyardgrass than rice plants. In rice plants the toxicity was almost the same in both zones, but in the case of barnyardgrass, the toxicity of swep was much stronger in the shoot zone than it was in the root zone.
(2) On the selectivity of swep it was shown that in both rice plants and barnyardgrass the selectivity was not too high when the treatment was made in the root zone. However, there obtained a high degree of selectivity when the treatment was made in the shoot zone. In the case of the shoot zone, the selectivity was much higher when the treatment was made in the upper layer of the shoot zone than in the lower layer of it.

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TDW (CABAC)-63, 39 and 43 are selective soil treatment herbicides which have been developed in Japan. The chemical name of TDW is benzyl N, N-dialkyl dithiocarbamate and each alkyl radicals are methyl, ethyl, and isopropyl in TDW-63, TDW-39, and TDW-43 respectively.
These herbicides had no inhibitory activity on germination of weed seeds. In growth inhibition tests, they showed stronger activities on the part of shoots than roots of Gramineceous plants such as rice plants and barnyardgrass. On the other hand, stronger inhibitory activities were observed in the part of roots of broad leaf plants such as Japanese radish than shoots of them. Relationships between the herbicidesabsorption part and the growth inhibitory activity in just germinated plants showed the same tendency in rice plants and barnyardgrass. In the treated shoots and leaves, the injury was most severe, and the shoots and leaves in the treatment of roots was the second.
Soil treatments above seeds were more effective than the treatement just under the seeds. In the soil treatment, the following orders of effects were observed.
Cypraceae>Graminae>Broadleaf weeds Selective properties were observed among gramineceous familiy. The dosage which has herbicidal effects on fingergrass and barnyardgrass did not show any phytotoxicity on rice plants.

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The concentrations of 50 percent inhibition of growing roots (LC₅₀) in the 3rd leaf stage of rice plants were about 100ppm in the three benzyldithiocarbamates, TDW-63, 39 and 43, respectively, while 3ppm in nitrofen (NIP, TOK). The minimum inhibitory concentrations (MIC) were 25ppm in the formers and 0.8ppm in the latter. In the usual dosage of application, it was found that the three benzyldithiocarbamates were safer for 11 times than nitrofen.
At the dosages of practical herbicidal activity, TDW-63, 39, and 43 had no phytotoxicities on rice plants transplanted just after the soil incorporation of these herbicides. Soil treatment of these benzyldithiocarbamates after transplantation of rice seedlings showed no phytotoxicity even in the shallow planting, where pentachlrophenol gave phytotoxicity. In the soil treatment after transplanting, water depth showed no effect on the phytotoxicity on rice plants. In the case of soil application in direct sowing or transplanting culture, no interaction was observed with insecticides and fungicides such as organo-phosphorus group, carbamate group, pentachlorophenyl derivatives, and antibiotics.

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The adequate spray time of CMMP for the control of weeds on the field and the mixing effect of CMMP with other chemicals and susceptibility of CMMP for tomato plants under various cultural conditions in greenhouse, were investigated.
(1) The most adequate spray of CMMP was 2 leaves stage for panic grass and 1 to 2 leaves stage for some kinds of galingale.
(2) The effect of soil treatment continued for 20 to 30 days. And it was confirmed by analysis that CMMP in moist soil was decomposed 90% for 20 days after spraying.
(3) The mixing effect CMMP with EPN, MEP, PAP, DDVP, malathion, carbaryl and diquat were synergistic on herbicidal activity of weeds. And combinations such as CMMP with EPN, PAP, malathion, and diquat presented no injury on tomato plants of 8 to 9 leaves stage.
(4) CMMP action for tomato plants cultivated under deficiency of nitrogen and phosphorous slightly increased, but deficiency of potassium, magnesium and excessive quantity plots were almost the same as the standard plot.

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Among the several pyridazine derivatives, 3-phenoxy pyridazine and 3-(2-methyl phenoxy) pyridazine were almost the same in their herbicidal activity in condition of upland field, but the latter showed as twice activity to barnyardgrass (Echinochloa crusgalli (L.) Beauv.) and slender spikerush (Eleocharis acienlaris (L.) R. & S.) in condition of paddy field as the former.
Residual activity of 3-(2-methyl phenoxy) pyridazine was long although its mobility in soil varied considerably depending on soil type and decreasing rate of depth of irrigation water in condition of paddy field. Generally its herbicidal activity was stronger in pre-emergency treatment than in postemergency treatment, and decreased as growth stage of the weeds to be treated proceed.
Gramineous and cyperaceous grasses were especially susceptible to 3-(2-methyl phenoxy) pyridazine, which was also effective to some of broad-leaved weeds. Gramineous crops were very susceptible whereas leguminoseous and solanaceous crops were tolerant. Tomato (Lycopersicum esculentum Mill.) was especially tolerant.

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Studies on the effective time to incorporate trifluralin emulsion with soil were carried out in peanut field, and studies on the mode of action in soil were carried out by pot experiment.
The soil incorporations at 0-15, 30-60, and 90-120 minuites after spraying of trifluralin emulsion were very effectively, but in the soil incorporation at 24 hours after spraying it was 50% controled.
The soil incorporating layers in the pot experiment were made at the surface, 1, 2, 3, 5 and 7cm depth in soil.
In each treatments in soil, trifluralin was diffused up and downward from the treatment layers and the activity of trifluralin ranged from the surface to 7cm depth in soil. But, in the treatment at the surface of soil, the downward diffusion was small comparatively.

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Injury by simazine and prometryne in upland rice on volcanic ash soil was studied. So-called A-layer and B-layer of volcanic ash soil were used and compared with alluvial soil. And the effects of adding the organic manure and clean sand to the soil were also investigated. Upland rice and chinese cabbage were grown in the Wagner's pots and/or petri dishes for bio-assays in greenhouse. The results obtained were as follows:
The injury of plants by the herbicides on the B-layer was more severe than that on the alluvial soil, while less on the A-layer, presumuably, this is due to the content of organic matter and clay of these soils.
When the organic manure was added to the B-layer of volcanic ash soil, however, weight ratio of treated plants to non-treated ones did not increased, even at an experiment, decreased; suggesting that the increased organic matter and clay was unequal to the naturally accumulated one.
Soil-absorption of prometryne was also examined with petri dishes. Absorption of prometryne was less in the soils on which this herbicide was highly phytotoxic.
Leaching extent of prometryne through soils were studied with bio-assay method. Tendency of the extent was very related to that of injury. Presumuably, the difference of plant injury by prometryne or another s-triazine herbicides on various soils bases upon the difference of the leaching extent in soils which is due not to free drainage value but absorbing capacity of soil, especially when much rain falls at early stage of plants.

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In order to develop a sensitive and simple bioassay method for evaluating the phytotoxicity of NIP in soil, tests were conducted to determine the relative sensitivity of rice plant (Oryza sativa L.), wheat (Triticum aestivum L.), barnyard millet (Panicum crus-galli L. var. frumentaceum Hook. f.), radish (Raphanus sativus L.), Chinese cabbage (Brassica pekinensis Rupr.), cucumber (Cucumis sativus L.), and buckwheat (Fagopyrum esculentum Moench) to NIP in laboratory, and buckwheat was found to be the most sensitive of all the plant species tested.
Newly developed bioassay method of NIP in soil was based on the measurement of primary root length of buckwheat seedlings in Petri dishes in a nearly vertical position after 36 hours. Petri dishes are filled with treated or untreated soil and buckwheat seedlings are grown across the soil surface and in contact with their lids in the light.
Using this method, it was found that the concentration of NIP in soil required to give 50% reduction of the primary root growth of buckwheat was 10ppm (by weight), and the range of concentration detected by the method was 2-10ppm.

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The effects of propanil on water metabolism and photosynthesis of intact rice plants and barnyardgrass were examined to investigate the primary action of the herbicide. The moisture content in leaves of both propanil-sprayed rice plants and barnyardgrass was higher than that of the checks soon after the foliar application. In barnyardgrass, the moisture dropped sharply when visible symptoms appeared, wheras in rice plants it restored to the level of the check, and no visible evidence of damage was observed throughout the experiments. Both water uptake and transpiration of these two species were severely reduced immediately after the treatment. These reductions in rice plants were recovered to a level of 70per cent of the check one hour after the spraying, and their water uptake and transpiration reached to almost the same level as the untreated plants one day after the treatment. On the other hand, barnyardgrass did not show any recovery.
Photosynthesis of either rice plants or barnyardgrass was inhibited completely whithin half an hour after the spraying of propanil. The inhibition in rice plants was recovered, but the recovery delayed as compared with those of water uptake and transpiration. The barnyardgrass died without any recovery of photosynthesis.
From these results it may be concluded that, as the primary action of propanil, the drastic action which appeared as the inhibition of water metabolism should be mentioned in addition to the inhibition of photosynthesis.

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In the previous paper, we have reported that the effect of a high temperature on the phytotoxicity of herbicides was the greatest in prometryne out of 7 root-applied herbicides tested. Then, this study has been carried out in attempt to consider the factor of variation on the phytotoxicity of prometryne as influenced by temperature and to learn the degree of its variation of 9 s-triazine herbicides.
The phytotoxic action of prometryne was influenced more by a high temperature than by a soil one. The downwards movement of prometryne into the soil was not increased by raising the temperature.
Furthermore, in order to learn the relation of air humidity and temperature on the phytotoxicity of prometryne, the effect of prometryne on the transpiration rate of rice seedlings, and the relationship between the period and duration of high temperature treatment and the phytotoxicity of prometryne, a several number of experiments have been conducted, using rice seedlings grown in sand and solution cultures with prometryne.
As a result, it could be presented that the relation of a high temperature to the phytotoxicity of prometryne on rice seedlings should be considered in relation to the following three factors: 1) change in the pattern of prometryne uptake, which is mainly depending on transpiring stream, probably characterized by rapid absorption of prometryne soon after treatment, 2) increase in the physicochemical reaction of prometryne against plans cells under a high temperature, and 3) change in the physiological and biochemical states of rice seedlings (see Fig. 3).
Increasing in the phytotoxic action of s-triazine herbicides by a high temperature was clearly different according to the kind of substitutes in a triazine ring, Namely, it was greater in order of -OCH₃, -SCH₃, and -Cl in the 2 position of a triazine ring (R₅ in Fig. 2), and tended to be greater in isopropyl than ethyl in the 4 and 6 positions (R₂, R₄ in Fig. 2).

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The present investigation was undertaken in order to evaluate both dormancy-breaking and lethal effects of 21 halogenoalkylcarboxylic acid esters on the barnyardgrass dormant seeds, and also the inhibitory effect of those on the germination of the scarified seeds.
All compounds revealed the lethal effect on the dormant seeds and scarified seeds. Some of the compounds broke the dormancy of the seeds and resulting germination occurred.
The both activities, however, were affected not only by temperatures and concentrations of the compounds, but also by physiological conditions of seeds.

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