Alopecurus Aequalis Research Articles

Studies on the flora and vegetation of the Golestan National Park*, NE Iran. II. A new Poa and some new and noteworthy grass records for Iran

Poa golestanensis H. Scholz & Akhani spec. nov. is described from the Golestan National Park, NE Iran. The following species are added to the grass flora of Iran from that area: Alopecurus aequalis Sobol., Cleistogenes serotina (L.) Keng, Heteropogon contortus (L.) P. Beauv. ex Roem. et Schult., Hordelymus europaeus (L.) Harz. The occurrence in Iran of Poa compressa L., P. densa Troitsky, and Bothriochloa bladhii (Retz.) S.T. Blake which were not mentioned in Rechinger's Flora Iranica but were reported in later papers is confirmed. The maps of distribution in the Park are provided for the treated species.

Selectivity of Cyhalofop-butyl in Poaceae Species.

Responses to foliar-applied cyhalof op-butyl of the seedlings of 29 Poaceae species at about 3- to 4-leaf stage were examined. Species belonging to subfamilies of Panicoideae, except for Imperata cylindrica, and Eragrostoideae were all susceptible, being completely controlled at 100g ha-1. Most of these species are important summer weeds in crops. Alopecurus aequalis (Pooideae) and Agrostis alba (Pooideae) were also susceptible. Six of 10 other Pooideae species and the two Oryzoideae species tested, as well as I. cylindrica, in which all treated plants survived at 300g ha-1, were shown to have tolerance to cyhalofop-butyl. The other four Pooideae species were less susceptible and incompletely controlled at 100g ha-1. Oryza sativa displayed the highest tolerance; plants treated at 300g ha-1 did not show any significant differences from untreated plants. The typical visual symptom common through all plants of affected species was withering of the emerging leaves. The critical response that led to plant death, however, appeared to be the suspension of new growth. Plant survival after this phase seemed to depend on whether new development was restored before unaffected leaves lost their activity, by resumption of healthy leaf emergence mainly by formation of tillers or rhizomatous shoots.

Effect of Winter Weeds on Growth and Yield of Direct-Seeded Rice in No-tillage Dry Paddy Field.

The effects of winter weeds on the growth and yield of direct-seeded rice (Oryza sativa L. cv. Akebono) were evaluated in a no-tillage dry paddy field where Alopecurus aequalis Sobol. var. amurensis (Komar.) Ohwi was uniformly dominant, in Kurashiki, Okayama, Japan, in 1994 and 1995. Winter weeds significantly inhibited the growth and spikelet production of rice plants as compared to those in the control plots, which were established by herbicide application. The reduction in the spikelet number finally resulted in a 12.6 to 15.6% yield reduction, although the percentage of ripened grains of rice increased somewhat because of the inhibition of the spikelet number by winter weeds. Rice yields in the weedy and control plots increased in different ways according to the increase in straw weight. The number of spikelets on the rice plants in the control plots increased as straw weight increased. In contrast, the percentage of ripened grain on the rice plants in weedy plots increased as straw weight increased. A higher rate of fertilizer greatly recovered the growth and yield of rice in weedy plots. This result suggests that the basal dressing of fertilizer at a higher volume would reduce the frequency of herbicide application for winter weeds.

Effects of Ploughing of Fallow Paddy Fields on the Population Density of the Green Rice Leafhopper, Nephotettix cincticeps(UHLER)(Hemiptera:Cicadellidae)

The green rice leafhopper, Nephotettix cincticeps, is an important vector of rice dwarf virus disease in southwestern Japan. The nymphs and adults of the overwintering generation as well as the first generation inhabit Alopecurus aequalis (SOBOL) in fallow paddy fields. The effects of ploughing fallow paddy fields on the population density of the first generation were investigated and compared to an unploughed field in Okayama, western Japan. Three treatments were used: ploughing once before the emergence of overwintering adults, ploughing once at the peak oviposition period of overwintering females, and ploughing at the times of both emergence and oviposition peaks. The density of eggs, immature stages and adults was significantly lower in the last two fields, although the density of all stages of the leafhopper between the two fields was not significantly different. Therefore, ploughing once at peak oviposition of the females is the most effective strategy to reduce density of the first generation.

Survival characteristics of buried seeds 10 years after the eruption of the Usu volcano in northen Japan

In the crater basin of the Usu volcano, where the vegetation has almost completely been destroyed by 1977–1978 eruptions, a study was conducted in 1987 to determine the survival characteristics of buried seed populations. A total of 17 618 seeds were extracted from six 25-L former topsoil blocks by a flotation test. Data showed that even after 10 years burial by 65–140 cm volcanic deposists, 16.6% of the seeds, representing 25 species, were viable. There were few predators in the former topsoil below the thick volcanic deposits. Seed volume of most species was less than 2.0 mm3 and smaller seeds had a greater rate of survival than larger seeds. Seed survival rates of Poa annua, Rumex obtusifolius, Alopecurus aequalis var. amurensis, and Viola grypoceras were positively correlated with the thickness of volcanic deposits, suggesting that the most important factor for seed survival is stable soil temperature with little diurnal fluctuations. Absence of light may be an important variable in seed survival, but this factor did not sufficiently explain survival under the thick volcanic deposits. Key words: buried seed, burial depth, seed size, seed survival, soil temperature, volcano Usu.

水田裏作雑草カズノコグサとスズメノテッポウの幼植物の簡易識別法と除草剤に対する反応の差異

水田裏作雑草カズノコグサとスズメノテッポウの幼植物の簡易識別法と除草剤に対する反応の差異

Cytological studies on some Kashmir grasses. VI. Cytomorphological polymorphism in Alopecurus aequalis Sobol.

Detailed cytology of two populations of Alopecurus aequalis has been worked out. While the count of 2n=14 observed in Tangmarg population confirms the earlier reports, the 2n=28 in the Ganderbal population is a new record. In the present paper morphological and cytological details of the two cytotypes are described.

The impact of copper pollution on water foxtail ( Alopecurus aequalis sobol.) populations and winter weed communities in rice fields

Water foxtail ( Alopecurus aequalis Sobol.) is a winter-annual grass dominant in rice fields in Japan. The seeds were collected from copper-polluted (30–300 ppm) and non-polluted control fields in Ohta (Gunma-ken) and Tsuru (Yamanashi-ken), and were sown in pots with varying levels of copper (0–400 ppm) in the soil. Percent survival on copper-containing (toxic) soils depended mainly on the ability to recover from frost heaving of the roots affected by copper. It varied from 30 to 90% among strains and showed a strong correlation with soil copper content at the collection site. Percent heading of plants on toxic soil also appeared to be an indicator of copper tolerance. Copper-tolerant strains accumulated more copper and manganese in their roots than non-tolerant ones, although the copper content of the tops showed no such relation. When the strains were mix-planted with milk vetch ( Astragalus sinicus L.), their resistance to the latter species showed a negative correlation with copper tolerance indicating a trade-off relation between tolerance and competitive ability. A counterbalance of trade-off to the selection for tolerance may account for the correlation found between tolerance and soil copper content. The percentage of water foxtail plants to total plants emerging from buried seeds was correlated with soil copper content at the sampling site. The dominance of water foxtail in polluted fields was also recognized from a direct observation of the fields. The tendency of species diversity and equitability in the community to decline with increasing copper level in the soil was observed with plants from buried seeds as well as in the fields.

Vegetation changes in shallow marsh wetlands under improving moisture regime

Changes in species composition and plant cover were studied in relation to moisture regime over a 10-year period in 71 shallow marsh wetlands in the grassland and parkland regions of Saskatchewan. Decreases in density of the shallow marsh emergents Polygonum coccineum, Carex atherodes, Scolochloa festucacea, and Eleocliaris palustris occurred with greater-than-normal water depth at the start of the growing season but 2 or more years of continuous flooding were required to eliminate emergent cover completely and convert the wetland to open water. Repeated autumn reflooding also resulted in complete elimination of emergent species. Changes in species composition occurred when basins were grazed and as vegetation reestablished after cultivation but no changes followed mowing or burning. Alopecurus aequalis, Beckmannia syzigachne, Glyceria grandis, and G. pulchella are designated as "disturbance" species on the basis of their response to soil-exposing events. Presence of small amounts of deep marsh emergents in shallow marsh wetlands is not considered a reliable indicator of wetter moisture regime. Species composition of rooted submergents in a wetland can be used as an indicator of its moisture regime. Shallow marsh wetlands in basins of 1 ac (0.41 ha) or less experienced little year-long flooding and converted to open water only under atypical conditions. Larger wetlands required basin depths in excess of 36 in. (96.4 cm) to have any amount of year-long flooding and to convert to open water. These basin size and depth criteria have applications in habitat evaluation by waterfowl managers.

Bacterial halo-blight of oats in Japan

A disease of oats hitherto unrecorded in Japan was found in Okayama Prefecture at 1952. The same disease was found later in Chiba Prefecture. The disease is characterized by diffuse halo-like discoloration around elliptic or streaky leaf lesions.A bacterium was isolated, and on the base of its morphology, cultural characteristics, and inoculation tests, it was identified as Pseudomonas coronafaciens (Elliot) Stevens, which is known to cause the halo-blight of oat in U.S.A.Characteristics of this bacterium was found to be as follows:Rod-shapes, 0.4∼0.6×1.5∼2.5 microns; capsulate; motile with one to three polar flagella; no spore. Gram negative. Aerobic. Beef peptone agar colonies, round to irregular, white, circular, flat, smooth or with slightly raised margins, smooth to slightly contoured. Beef bouillon moderately clouded with flocculent white pellicle. Gelatin liquefied slowly. Milk not coagulated and not peptonized. Litmus milk no reduction. Nitrate slight reduction. Ammonia produced, but no hydrogen sulphide nor indol. Uschinsky's, Fermi's and Fraenkel's solutions, good growth; not with Cohn's solution. Acid but no gas from sucrose, glucose, xylose, galactose, fructose, arabinose, mannitol, glycerol; no acid nor gas from maltose, rhamnose, lactose, dextrin, ethyl alcohol, inulin, inosite, soluble starch. Starch hydrolysis moderate. Optimum temperature 22.5°C, maximum 33°C, minimum 4°C.Host: (spray inoculation) Avena sativa L.(Multiple needle inoculation) Avena sativa L., Hordeum distichum L. emend Lamark, H. vulgare L., H. vulgare var. nudum Hook., Secale cereale L., Triticum sativum Lam., Agropyron tsukusiense var. trasiens (Hach.) Ohwi, Alopecurus aequalis Sobol., Andropogon scoparius Michx., Beckmannia syzigachne (Steud.) Fernald, Bromus catarticus Vahl., B. inermis Leyss., Dactylis glomerata L., Lolium italicum Braum, Lycopersicum esculentum Mill., Oryza sativa L., O. sativa var. terrestris Makino, Panicum miliaceum L., Phleum pratense L., Poa annua L., Polypogon fugax Steud.

Some Fundamental Studies on the Weed Control by Herbicide CAT in Barley and Wheat Cultivations

It was made an attempt to know the safe and effective method of utilizing herbicide CAT in barley and wheat cultivations. 1.) The pot tests were carried out to investigate the circumstances of movement of t he chemical under various conditions combining several kinds of soil and amounts of rainfall, where the seedlings of rape and wheat were used as test plants. It was made clear that the chemical moved into the soil 3 cm depth from the surface, under the condition which had 20 mm rainfall on Nagano loam with a little water capacity and humus content. Some matters that demand special attention for use of the chemical were pointed out from this fact. 2) Differences were found on the germination phases in Alopecurus aequalis var. amurensis between the plants grown on plowed and non-plowed paddy fields. On the plowed paddy fields, plants can emerge easily from the deep parts under the ground. As it causes the growing of numerous number of weeds on the plowed paddy fields, othet suitable means togethet with the chemical should be adopted to weed control in such case. 3) The interrelation between the growing stages of wheat or Alopecurus aequalis var. amurensis and the chemical injuries was investigated. The chemical injury is raised in an early stage when the plants have not attained the leaf number of 2.5. Therefore, the attention should be paid for the growing stage when the chemical is used.

Comparison in Ecological Characteristics of Noxious Weeds in Winter Cropping

The noxious weeds in winter cropping on drained paddy fields in Japan are Alopecurus aequalis, Beckmannia erucaeformis, Agropyrum semicostatum, Poa annua, Stellaria uliginosa, S. media, Sagina japonica, Cardamine flexuosa, Galium Aparine and Lapsna apogonoides, and their ecological characteristics, such as dormancy, germination, emergence and longevity of seeds in the soil, are as follows. 1. Freshly harvested ripened seeds of these weeds are more or less dormant (Fig. 1), and the dormancy of them is overcome by autumn in soil outdoors (Fig. 2). Low-temperature treatment (5°C, moist) is effective to overcome the dormancy for 4 species belonging to Gramineae (Fig. 3). The dormancy of most species is overcome by placing the seeds at high temperature (30°C) in moist condition (high-temperature treatment) in normal air or in absence of oxygen for some periods (Fig. 4). 2. Though optimum temperature for germination vary more or less according to kinds, it is generally from 10°or 15°to 20°C. The germination of all kinds of seeds except Alopecurus aequalis is favored by light (Fig. 5). Some seeds do not germinate and others germinate to a lesser degree under the continuous dark condition. No germination occurs in absence of oxygen, and oxygen requirement for germination is not same for each weed (Fig. 6). 3. The maximum elongation length of plumule in a dark germinator varies according to kinds and is correlated with seed size in general. Depth of emergence is generally shallow, but differs with weed kinds (Tab. 1). It is caused by differences of weeds in light requirement for germination and in penetrating power of plumule through the soil layers as well as in the maximum elongation length of plumule in the dark condition. 4. Longevity of seeds in the soil of paddy fields (upland fields condition from autumn to spring) or upland fields is generally short, but it varies from one to two years according to the kind of weeds and moisture content of soil. The longevity of seeds is closely related to the germinating ability within soils. 5. The above-mentioned facts show that these weeds vary in main ecological characteristics in detail each other, though they are adapted to the environmental conditions of winter cropping on drained paddy fields.

Ecological Studies on Alopecurus aequalis Sobol., a Noxious Weed in Winter Cropping. : 9. On the secondary dormancy of the seed.

The seeds which have awaked from the primary dormancy are then exposed to the secondary dormancy under certain conditions. The following facts were found concerning the secondary dormancy. 1. The seeds which have been kept within submerged soil outdoors become to show poor percentage germination since November, and hardly germinate in a germinator at 20°C in February of the next year, that is to say the secondary dromancy is induced. The secondary dormancy is overcome by August and induced again in November. And this process is repeated till the seeds lose their viability (Fig. 1). 2. With progress of the secondary dormancy under submerged soil, maximum and optimum temperature for germination become lower together with poor percentage germination (Fig. 2). 3. The secondary dormancy is induced experimentally by placing the seeds showing the environmental dormancy under absence of oxygen at low temperature 5°C, and to a certain extent at 20°C, but not induced at 30°C (Fig. 3, 4). 4. The secondary dormancy is overcome by low-temperature treatment (Fig. 5), high-temperature treatment in normal air or in absence of oxygen (Fig. 6), alternating-temperature treatment (Tab. 1) and pricking seeds coats (Fig. 7), as observed with the primary dormancy. And the low-temperature treatment and alternating-temperature treatment are effective similary to overcome the second secondary dormancy (Fig. 8). 5. Accordingly, it was well established that the seeds in the soil, if no germination occurs because of unfavorable condition for germination (such as in lower layer of the soil in poor-drained fields), are forced to go into the secondary dormancy under the condition of oxygen absence at low temperature in winter, and the dormancy is overcome under the condition of oxygen absence at higher temperature in summer. The mechanism of overcoming the secondary dormancy was seemed to be similar to the primary dormancy.

Ecological Studies on Alopecurus aequalis Sobol., a Noxious Weed in Winter Cropping : 7. 8. On the primary dormancy of the seed

As a fundamental investigation of controlling Alopecurus aequalis, a noxious weed in wheat and barley cultivation on drained paddy fields, the primary dormancy of the seed was studied. The results are as follows: 1. The glumes have no part in the dormancy, and the seed coat does not inhibit the seed itself from absorbing water. 2. The period of dormancy varies according to the moisture content of the seed during its storage. In case of high moisture content of seeds, such as a wet storage at 20°C (with about 55% moisture content of seeds) or a dry storage in a paper bag at room temperature (about 15% moirture), the dormancy lasts about 4 months after harvest, while it lasts longer when seeds are stored in a desiccator at room temperature (6%) 3. Low-temperture treatment is effective to overcome the dormancy in wet condition at temperature ranging from 1°C to 5°C (Fig. 1). Drying the seeds or placing them in a moist condition at 30°C for one day or more after the treatment lowers the effect of overcoming the dormancy. A low-temperature treatment in absenoe of oxygen is less effective (Fig. 2). 4. Placing the seeds at temperatures higher than the germination temperture (high-temperature tretment) is also effective to overcome the dormancy unless the seeds lose their vitality. This treatment is most effective in moist conditions at 30°C (Fig. 3), and effective in the same manner for the seeds buried in the soil. The treatment in absence of oxygen is much more effective (Fig. 4). 5. 5°C/20°C alternating-temperature treatment accelerates the effect of low-temperature treatment (Fig. 5A). 10°C/12°C alternating-temperature treatment is also effective to overcome the dormancy (Fig. 5B). 6. The dormant seeds germinate slowly if the seed coats are pricked with a pin (Fig. 6). The pricked seeds can not germinate if the pricked openings are covered with paraffin (Fig. 7). 7. As the results of these findings, it was clarified that high temperature in the absence of oxygen under submerged soil in summer is important for overcoming the dormancy of the seeds in paddy fields.