MOVEMENT OF 2,6-DICHLOROBENZONITRILE IN SOILS AND IN PLANTS IN RELATION TO ITS PHYSICAL PROPERTIES

Summary. The movement of the herbicide H133 (2,6-dichlorobenzonitrile) in soils and in plants is shown to be governed mainly by its relatively high volatility, its low solubility in water and its strong adsorption on lignin, on humic matter and on lipid material. Some evidence for a transformation of H133 in plants is presented.
Les déplacemcnts du 2,6-dichlorobenzonitrile dans les sols et dans les plantes et leurs relations avec les proriétés physiques     

THE MOVEMENT OF PARAQUAT IN PLANTS

Summary. A qualitative study of the movement of the herbicide paraquat from droplets applied to leaves of tomato plants, using ¹⁴C-methyl-labelled and ¹⁴C-ring-labelled paraquat dichloride and di(methylsulphate), has shown that it moves in the xylem with the transpiration stream. The chemical is as well transported from young leaves as from mature ones, and will move through a steam-ringed petiole. The enhancement of the amount of paraquat transported from the treated leaves which occurs when treated plants are kept in darkness for a period following treatment and then exposed to light, is probably due to the greater movement into the xylem through undamaged tissue which can occur in the dark. Once the chemical has been absorbed into treated leaves, light-induced damage is required for significant movement through the rest of the plant to take place, but the damage then inhibits further entry of paraquat into the xylem. The movement of paraquat in broad bean and maize is essentially similar, though the enhancement of movement by a period of darkness after application is much less marked.
La migration du paraquat dans les plantes     

THE MOVEMENT OF LABELLED 2,4-D IN YOUNG BARLEY PLANTS

Summary. After the 4- or 5-leaf stage in young barley plants, there is a decrease in the translocation of 2,4-D from the leaves to the root system. It is shown that there is no relation between this phenomenon and ear initiation, which occurs at this stage of development. Movement of 2,4-D out of leaves of the tiller in the axils of the 1st and 2nd leaves was also shown to be very small. There is some evidence for a'block'in the movement of 2,4-D in established grass plants.
La migration du 2,4-D marqué dans l'orge     

RESIDUAL ACTIVITY OF PARAQUAT IN SOILS I. FACTORS AFFECTING PERSISTENCE

Summary. Phytotoxic residues were recorded on soil surfaces sprayed with paraquat (1,1'-dimethyl-4,4'-bipyridylium-2 A ) at 1 and 2 Ib/ac a.i. Phytotoxicity was greater on organic than on mineral soils though on both the residues persisted unchanged for at least 14 days and were greater with the higher dose.
Germination of Brassica napus L. was only slightly affected and most seedlings did not show phytotoxic symptoms until after cotyledon expansion. The cotyledons of Trifolium repens L. showed symptoms on emergence from the testa. By contrast, grains of Lolium perenne L. either failed to germinate on paraquat-treated soils or showed reduced germination.
Seedlings of T. repens were susceptible; both root and shoot systems were affected as they grew through layers of soil previously treated with paraquat. Ground limestone appeared to reduce the phytotoxicity of paraquat under some circumstances. Phytotoxic residues were not reduced by surface irrigation but disappeared if the soil surface was disturbed mechanically.     

THE PERSISTENCE AND PENETRATION OF LARGE DOSES OF SIMAZINE IN UNCROPPED SOIL

Summary. The residues remaining in the soil from repeated annual application of simazine at 2–8, 5–6, and 22–4 kg/ha to uncropped plots on a loam soil were measured by chemical or bioassay methods at various intervals after treatment.
The total simazine residue present 12 months after the last of three treatments with 2–8 kg/ha and 8 months after the last of five treatments with 5–6 kg/ha was less than 10% of the annual dose. This rapid decomposition is considered consistent with the soil and climatic conditions. In contrast a much larger residue (a mean value of 1·7 kg/ha) was found on plots sampled 21/2 years after the last of two annual applications of simazine at 22·4 kg/ha and the reduction in the amount of residue during the next 12 months was only of the order of 25%.
In all treatments the highest concentration of simazine was found in the surface layers of the soil but measurable residues were detected to 60 cm depth, 31/2 years after the last 22·4 kg/ha application.
There was considerable variation in the total residues recovered between replicate plots and between different positions on the same plots in all treatments regardless of the depth of the sample. The possible causes of this variation are discussed.
Persistance et pénétration de fortes doses de simazine dans un sol non cultivé     

噻嗪酮在水和水稻植株中的残留动态及转运

采用反相高效液相色谱法研究了噻嗪酮在水和水稻植株中的残留动态。该法的平均回收率为72.70％—91.46％,水和水稻植株中的最低检出浓度分别为0.002mg/ks和0.005mg/kg。研究结果表明:水稻茎部能不断从水中获取噻嗪酮并使之浓缩,噻嗪酮在水稻植株中存在一定的内渗和内吸传导,其中由下向上传导率较高。作者还讨论了噻嗪酮在水和水稻植株中的残留动态及转运与其对稻飞虱具高效、长效防治作用的关系。     

THE RELATIONSHIP BETWEEN THE HERBICIDAL EFFECT OF 2,6-DICHLOROBENZONITRILE AND ITS PERSISTENCE IN THE SOIL

Summary. A series of experiments with 2,6-dichlorobenzonitrile is described. It is demonstrated that 2,6-DBN is highly phytotoxic when applied as a soil drench or preemergence spray in the greenhouse, but measurement of crop and weed responses in the field, accompanied by quantitative assessment of the chemical residues in the soil, indicates that the persistence of 2,6-DBN following surface application is short under both tropical and temperate (winter) conditions. It is, however, extended from a few days to several weeks if the chemical is incorporated into the soil immediately after application. Under tropical conditions the effect of 4 lb/ac applied to the surface is roughly equated to 2 lb/ac immediately watered-in, 1.5 lb/ac immediately raked-in, or 1 lb/ac both watered- and raked-in, and a delay of 4 hours between application and incorporation is shown to reduce the effectiveness of the chemical by about half. The lack of persistence of 2,6-DBN when applied to the soil surface, and the modifying influence of soil incorporation and watering is attributed to its high vapour pressure (5 × I0⁻⁴ mm Hg at 20° C) and its relatively low solubility in water (20 ppm at 25° C).
Le rapporl entre l'activité herbicide du 2,6-dichlorobenzonitrile et sa persistance dans le sol     

PHOTOLYSIS OF FLUORODIFEN

Summary. A dry film or p. -nitrophenyl-α,α,α:-trifluoro-2-nitro-2-tolyl ether (fluorodifen) decomposed rapidly under ultraviolet (2537 run) irradiation in the laboratory. Photolysis under growth chamber lights was slower. One major photolysis product (probably a polymer of fluorodifen) and several minor products were detected.
Photolyse du flurodifene
Résumé. Un film sec de p -nitrophényl-α,α,α-trifluoro-2-nitro- p -tolyl äther (fluorodifènc) a été rapidement décomposé sous une irradiation dans l'ultra-violet (253,7 nm) au laboratoire. La photolyse sous l'éclairage des chambres elimatisées fut plus lente. Un produit important de la photolyse (probablement un polyméie du fluorodiféne) et plusieurs produits secondaires ont été détectés.
Photolyse von Fluorodifen
Zusammenfassung. Ein trockener Film von p -Nitrophenyl-α,α,α-trifiuor-2-nitro- p -tolyläther (Fluorodifen) zersetzte sich im Laboratorium schnell bei Bestrahlung mit ultraviolettem Licht (253,7 nm). Unter Klimakammerlampen war die Photolyse lang-samer. Es konnten ein Hauptprodukt der Photolyse (wahrscheinlich ein Polymer von Fluorodifen) sowie mehrere Nebenprodukte festgestellt werden.     

THE MOVEMENT AND METABOLISM OF PYRAZON IN TOLERANT AND SUSCEPTIBLE SPECIES*

Summary. Pyrazon (5-amino-4-chIoro-2-phenyl-3(2H)-pyridazinonc) labelled with tritium in the phenyl ring, was applied to both the root and shoot of seedlings of red beet (Beta vulgaris L., cultivar Detroit Dark Red I, German millet (Setatra italica J.), and tomato (Lycopersicon esculentum Mill., cultivar Heinz 1350). Of these species, red best is tolerant, millet is moderately tolerant, and tomato is susceptible to pyrazon. When the roots were exposed to 1–325 ppm ³H-pyrazon in the nutrient solution, the greatest root absorption and transiocation to the shoot was observed in tomato and the least in red beet, while millet was intermediate. Applications to the first true leaf indicated that pyrazon was absorbed by the foliage of all three but that it was not transported basipetally. The absorption and translocation studies indicated that pyrazon mi transported primarily in the xylem. A radioactive metabolite of ³H-pyrazon was detected in the shoots of red beet, but there was no evidence for its presence in the shoots of the other two species. Since this metabolite is radioactive, its structure must contain at least some altered form of the phenyl ring which contained the tritium in the parent molecule. This differentiates it from 5-amino-4-chloro-pyridazinone, the previously proposed degradation product of pyrazon, since this compound lacks the phenyl ring. On the bash of these results, it is hypothesized that pyrazon will be phytotoxic if a suffic inn mm entration of the unaltered chemical reaches the site of herbicidal action in the shoot. Migration et métabolisme de la pyrazone dans les espéces rislstantes et sensibles     

柴达木盆地农田土壤盐渍化特征及其防治对策研究

本文首先分析了柴达木盆地农田土壤盐渍化类型和分级;其次结合卫片探讨了农田盐化程度及分布状态;最后,主要围绕降低农田盐化土壤地下水位、改良土壤物理化学性状和减少蒸发强度三个方面提出了盐渍化土壤的改良措施,主要包括：水利工程改良、农业改良、生物改良、化学改良。     

新疆两大沙漠风沙土土壤理化特性对比分析

本文对塔克拉玛干沙漠和古尔班通古特沙漠的风沙土土壤理化特性进行了对比分析，结果表明：两大沙漠风沙土土壤肥力无明显差异，土壤有机质很低；塔克拉玛干沙漠风沙土在全盐、ＣａＣＯ３含量上高于古尔班通古特沙漠；塔克拉玛干沙漠风沙土分选好，颗粒组成以细沙为主，而古尔班通古特沙漠风沙土分选较差；两大沙漠风沙土在２４种化学元素含量上多数存在明显差异。     

OCCURRENCE AND PERSISTENCE OF PICLORAM IN GRASSLAND WATER SOURCES

Summary. At 2 weeks following application, concentrations of picloram in surface runoff water collected adjacent to a South Texas grassland treated with 1·1 kg/ha ranged from 0·055 to 0·184 ppm as detected by gas chromatography. Picloram in surface runoff water diminished with time and amount of rainfall as a decay function. Picloram was not detectable in a flowing stream 0·8 km below a 32-ha area treated with 1·1 kg/ha. Residual picloram was not detected in domestic water wells at any time up to 2 years following treatment of adjacent areas with 1·1 kg/ha.
Dissipation of picloram from treated livestock-watering ponds was concentration-dependent, with the final losses resulting largely from dilution. Initial loss rates in the ponds ranged from 14 to 18%/day but decreased to less than 1%/day at 100 days following treatment. After 100 days, when the concentrations were less than 0·005 ppm, the primary changes in picloram content appeared to be due to dilution from rainfall or to concentration by runoff from adjacent treated areas.     

EFFECT OF TEMPERATURE ON THE ACTIVITY AND PERSISTENCE OF AMITROLE AND 2,4-D

Summary. One leaf of each of several tomato plants 5–6 weeks old maintained at 55, 70 or 85° F was dipped in 0.05 M amitrole or 0.005 M 2,4-D solution. The treated leaf was removed 1 week later. Scions taken from untreated plants were grafted to the treated plants at intervals up to 4 months after treatment.
Amitrole-treated plants maintained at 55° F were killed within 1 month but those at 70 and 85° F recovered.
Plants treated with 2,4-D showed typical symptoms when maintained at 70 and 85° F but no symptoms at 55° F. Scions grafted on plants maintained at 55, 70 and 85° F for 60 days after 2,4-D treatments exhibited typical symptoms. Grafts made more than 60 days following the 2,4-D application did not exhibit symptoms except a slight malformation on the plants held at 55° F.
New growth on the scions grafted up to 103 days after amitrole treatment on plants which had been maintained at 70 and 85° F exhibited typical amitrole symptoms (i.e. white foliage) but scions grafted after this lime did not. New shoots developing from buds on the treated plants also produced green growth 115 days after treatment but produced white foliage prior to that time.
Effet de la température sur l'activi'ité et la persistance de l'aminotriazole et du 2,4-D     

THE PERSISTENCE OF SIMAZINE APPLIED ANNUALLY IN THE PROLONGED ABSENCE OF SOIL CULTIVATION

Summary. Successive bioassays during 1966 and 1967 showed that simazine degradation reached 80% in 11 and 22i weeks, respectively, in soil from the 0–2 in. horizon of a gooseberry experiment to which simazine had been applied annually in the absence of soil cultivation from 1960. Where an annual farmyard-manure mulch was also applied, the same loss of residual activity was reached in 10 and 20 weeks. This mulch initially reduced the simazine level rapidly compared to that of unmulched soil, but the subsequent rates of degradation were similar. The rate of simazine degradation depended more on environmental conditions each year than on soil type. The results indicate that an annual simazine degradation in excess of 80% can be expected in Loughgall soils in conditions of non-tillage. Even if simazine applications continued indefinitely at an annual dose of 20 Ib/ac–the current dose in the gooseberry experiment–a large residue accumulation could not occur with or without a mulch.
Persistance de la simazine appliquée annuellement en l'absence prolongée de façons culturales     

毛乌素沙地沙生植物的水分关系及生态适应性

本文研究了毛乌素沙区的常见植物:沙米、沙竹、虫实、籽蒿、油蒿、杨柴、牛心朴子、柠条、臭柏、黑格兰、巴锡藜、本氏针茅、糙隐子草、赖草、冷蒿、黄蒿、狭叶柴胡、达乌里胡枝子、细叶远志、沙柳、旱柳、新疆杨、樟子松等的蒸腾作用特点和水势状况,并对各种植物的生态适应性做了比较。     

STUDY ON THE INTRODUCTION OF LAWN PLANTS AND THE TECHNOLOGY OF PLANTING THEM IN NINGXIA''''S ARID AREA

<正> Ningxia lies inland in China. Its annual rainfall is from 130 mm to 380 mm. It lies inthe arid and semiarid areas of the midtemperate zone. Dry climate, sand blown by thewind, common salinization and scattered plants are the main climatic characteristics. So itis very important for the afforestation, environmental protection and management of cities     

TRANSLOCATION AND PERSISTENCE OF 2,4-D IN POPULUS TREMULA L.

Summary. Treatment of aspen ( Populus tremula L.) with 2,4-dichlorophenoxyacetic acid (2,4-D), using a leaf spray, basal bark spray or a stem injection method of application, resulted in some reduction of stump regrowth although downward translocation of 2,4-D was slight. Persistence of 2,4-D in dead leaf tissue and in woody tissue near the injection sites was observed. This persistence could in certain circumstances be noted 6 years after treatment.
Migration et persistance du 2,4-D chez Populus tremula L.     

绿洲吨粮田土肥因素的分析

分析论证绿洲吨粮田土肥因素,结果表明培肥提高地力任务之艰巨。同时,为了良田常在,永续利用,必须改变单一种植业结构,农、林、牧相结合,科学地轮作施肥管理,方可实现生态良性循环的持续农业。     

呼和浩特市郊区土壤与蔬菜中苯并(a)芘(B_(a)P)的污染现状研究及其防治对策

呼市蔬菜区长期受工业“三废”排放的影响,农业生态系统已经受到一定程度的污染。本文通过对呼市蔬菜区土壤和蔬菜中B(a)P污染物的分析和研究,结果表明土壤中B(a)P的含量范围在5.5—63.13PPb之间,蔬菜中B(a)P含量范围在0.25—5.00PPb内,不同的蔬菜对B(a)P的吸收能力不同,土壤有一半受到B(a)P污染影响;对蔬菜的综合评价认为,除个别地方外,蔬菜大部分没有受到B(a)P污染。其污染源主要是大气污染所致,并提出了防治B(a)P污染的对策。