UPTAKE, TRANSLOCATION AND METABOLISM OF SIMAZINE IN NORWAY SPRUCE (PICEA ABIES)

Summary. Uptake, distribution and fate simazine (2-chioro-4,6-biserthylamino- s -triazine) in 4-year-old seedlings of Norway spruce ( Picea abies ) are discussed. Simazine was found to be readily absorbed and distributed in the spruce seedlings. A positive relationship between the amount of simazine absorbed and the growth intensities of the plants indicates an active mechanism of uptake. A fixation of simazine in roots and sterm was observed.
Simazine was degraded by roots and stem to hydroxysimazine and two other unknown metabolites. No simazine and only metabolites could be traced in the needles, indicating a very rapid rate of metabolism in the root system. The glucose derivative of benzoxazinone was extracted from all parts of the spruce seedlings and is probably responsible for the hydrolysis of simazine.
The results indicate a very slow degradation of the metabolites to CO₂ as one of the final products.     

EFFECT OF 2,4-D AND PICLORAM ON TRANSLOCATION OF 14C-ASSIMILATES IN VITIS VINIEERA L.

Summary. High concentrations of 2,4-D and picloram interfered with the downward movement of ¹⁴c-assimilates infield-grown vines. The interference in translocation was appreciably greater with picloram than it was with 2,4-D, Although basipetal translocation was retarded, translocation within the treated shoots continued from the vegetative part to the clusters. Translocation of 2,4-D appeared to follow the same route as ¹⁴c-assimilatcs for the most part. Formative effects were absent on untreated grape shoots although the adjacent shoots treated with 2,4-D or picloram on the same cordons were killed; however, formative effects were evident on some of the stump sprouts which developed after the vines were harvested. The malformed leaves on the stump sprouts were twelve or more nodes from the base of the shoots, while ¹⁴c was in the more basal leaves.
Thompson Seedless (Sultanina) rootings treated with 20 000 ppm 2,4-D or picloram transported less ¹⁴C to the roots than did the controls. Treatment with either herbicide resulted in a marked increase in the labelling of the stems.
Effet du 2,4-D et du pichlorame sur la migration de métabolites marqués au ¹⁴C dans Vitis vinifera L.     

PRELIMINARY STUDIES ON THE TRANSLOCATION OF 14C-LABELLED HERBICIDES IN BRACKEN (PTERIDIUM AQUILINUM)

Summary. The translocation of ¹⁴C-labelled herbieides in field bracken has been sludied in some preliminary experiments by means of autoradiography. A detailed account is given of the methods employed. It is shown that when 2,4-D is applied to fronds at different stages of development movement of the tracer into the rhizome is considerably greater from parts of the frond which are still immature. Trasnslocation within the frond is predominantly basipetal at all stages of development; within the rhizome the direction of movement appears to be determined primarily by the nature of the vascular connections with the treated pinna.
In a comparison between the translocation of 2,4-D, 4-CPA and dalapon no difference was apparent after 24 hours, but when the treatment period was extended to 96 hours there was evidence that 4-CPA bad been translocated in a considerably greater amount than either of the other two herbicides.
Rechrches iréliminaires sur la migration des herbieides marqués am ¹⁴ C dans la fougrère algle (Pteridium aquilinum)     

AN ASSEMBLY FOR THE CONTINUOUS RECORDING OF CO2 EXCHANGE AND TRANSPIRATION OF WHOLE PLANTS

Summary. Photosynthesis, respiration and transpiration of whole platns are continuously recorded with the assembly described. An infra-red gas analyser is used for photosynthesis and respiration measurements, while for transpiration data psychrometers are employed, Air and leaf temperatures as well as light intensity are recorded. The assimilation chamber is constructed in such a way that whole platns of various plant species can be investigated under constant conditions of CO₂ content of the air and air humidity. Some experiments with simazine and monuron are described.
Un appareil pour enregistrer continuellement l'échange de CO₂ et la transpiration des plantes entiéres     

STUDIES ON THE TRANSLOCATION IN AGROPYRON REPENS OF 14C-LABELLED 2,2-DICHLOROPROPIONIC ACID

Summary. Previous findings suggested that the translocation in Agropyron repens of 2,2-dichloropropionic acid (dalapon) may be considerably affected by the transpiration rate. This relationship has been studied further in the present investigation using ¹⁴C-labelled material and autoradiography.
It was found that when dalapon was applied to the leaves and the treated plants were placed in darkness a reduction in the transpiration rate of ca. 90% was associated with a marked increase in the amount of dalapon translocation into the roots and tillers. The evidence provided by the autoradiographs was confirmed by a quantitative assay of the ¹⁴C present in the roots. It was also found, however, that translocation was not appreciably affected either by a 50% reduction in the light intensity or when the transpiration rate was reduced by placing the plaints under conditions of high humidity in the light or by the application of white petroleum jelly to the leaves. An alternative hypothesis, namely that the effect of darkness on the movement of the herbicide might be due to changes induced in the normal pattern of assimilate translocation was also investigated but was not supported by the results obtained. Further experimentss, in which various parts of the treated shoot were placed in the dark, suggested that the effect of darkness on the translocation of dalapon is exerted primarily on the treated leaf itself.
Etudes sur to migration dans Agropyron repens de l'acide 2,2-dichloropropionique marqué avec ¹⁴C     

AN AUTORADIOGRAPHIC STUDY OF THE MOVEMENT OF 14C-LABELLED ASSIMILATES IN THE DEVELOPING WHEAT PLANT

Summary. ¹⁴CO₂ together with autoradiographic techniques was used to stuy the movement of labelled carbon within wheat plants at different stages in their development. Movement of ¹⁴C about the plain was found to be extensive in the early stages, gradually bccoming more localized until at a stage after ear emergence there was little transference of labelled carbon between tillers within a 24-hour period.
In the early stages of development ¹⁴C from leaves on the main shoot was transported throughout the plant but accumulated in greatest amounts in the meristematic regions. Assimilates produced by the leaves of newly formed tillers were distributed mainly to the meristematic regions of those tillers although labelled carbon was moved in into the rest of the plant. In the later stages of development of each tiller the labelled assimilate was restricted to the tiller itself and to any very young tillers associated with it. After car emergence the pattern of distribution of the labelled carbon from the youngest and second youngest leaves was found to differ. Movement was predominantly towards the ear from the flag leaf and towards the root system from the leaf below the flag.
It was noticed that mature leaves accumulated some labelled material and the possibility that this occurred via the transpiration stream following migration from phloem to xylem, as is the case with some of the case with some of the translocated herbicides, was investigated, but no indication of xylem transference was obtained.
The possible application of these studies to investigations into the relationship between the movement natural assimilates and of translocated herbicides is discussed.     

Cutting weeds with a CO2 laser

Stems of Chenopodium album . and Sinapis arvensis . and leaves of Lolium perenne . were cut with a CO₂ laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO₂ laser than C. album . When stems were cut below the meristems, 0.9 and 2.3 J mm⁻¹ of CO₂ laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne .     

THE EFFECT OF CHLORMEQUAT SEED-PARENT TREATMENT ON THE RESISTANCE OF WHEAT SEEDLINGS TO TERBUTRYNE AND SIMAZINE

Summary. The effects of pre-sowing treatments with terbutryne (4-ethylamino-2- niethylthio-6-t-butylamino-1,3,5-triazine) and with simazine (2-chloro-4,6-bisethyl-amino-1,3,5-triazine) on seedling mortality of wheat grown from regular seed and from seed containing about 40 ppm chlormequat (2-chloroethyl trimethylammonium chloride), due to a late chlormequat treatment of the seed-parent, were tested in two pot experiments. In another pot experiment the effects of pre-sowing and post-emergence treatments of terbutryne on dry matter accumulation and moisture content in SPT (= Seed-Parent Treated) and regular wheat seedlings were examined.
No significant differences in simazine resistance between regular and SPT seed were found. However, there was a marked and significant increase in terbutryne resistance of SPT over regular seeds, which was expressed by a longer period to 50% seedling mortality as well as by a lower daily increase in mortality. Growth retardation, caused by pre- sowing as well as by post-emergence terbutryne treatments, was appreciably less in the SPT seedlings than in the regular ones. The higher terbutryne resistance of the SPT seedlings may be attributable to their higher moisture content induced by the chlormequat.
Effet du traitement des pieds meres avec le chlorméquat sur la résistance des plantules de blé a la terbutryne et à la simazine     

碳标记甲霜灵在黄瓜植株体内的吸收、分布、传导以及种衣剂缓释作用的研究

 本文以¹⁴C-甲霜灵作为示踪剂,运用放射自显影及放射性强度测定技术,研究了甲霜灵在黄瓜植株体内的吸收、分布、传导以及种衣剂的缓释作用机理,结果表明:¹⁴C-甲霜灵在黄瓜体内的传导是迅速的,随药剂作用时间的延长,放射性物质在叶部的积累增加,在根、茎、子叶中却降低;种衣剂中的关键助剂——成膜剂,能将种衣剂中的有效成分固着在种子表面,具有使药剂缓释和延长持效期,提高药剂利用率的作用。     

TRANSLOCATION OF 14C-ASSIMILATES AND 3-AMINO-1,2,4-TRIAZOLE AND ITS METABOLITES IN AGROPYRON REPENS

Summary. Translocation of 3-amino-1,2,4-triazole-5-¹⁴C (¹⁴C-aminotriazole) was compared to that of ¹⁴C-assimilates in couch grass ( Agropyron repens (L.) Beauv.) at three different growth stages.
Assimilates of ¹⁴CO₂ were translocated from the treated shoot to other shoots and rhizomes at the 2–3-leaf and 3–4-leaf stages of development. Much less labelled material was translocated into untreated shoots at the 5-leaf stage. More ¹⁴C-assimilates were translocated to the roots than to untreated shoots at all developmental stages. The translocation patterns of ¹⁴C-aminotriazole and ¹⁴C-assimilates were similar.
Two metabolites, A and B, were formed from ¹⁴C-aminotriazole, which chromatographed identically to previously described metabolites in Cirsium arvense (L.) Scop. A was further metabolized into B. Labelled aminotriazole and its two metabolites were translocated throughout the plants. Metabolite A was phytotoxic when concentrated and re-applied to couch grass, but its properties were not those of Unknown II from Cirsium arvense. They were the same as those of Unknown III. Whether or not metabolite A and Unknown III are identical was not established.
Migration des substances assimilables marquées au ¹⁴ C, du 3 amino-1,2,4-triazole et de ses métabolites chez Agropyron repens     

碳标记甲霜灵在黄瓜植株体内的吸收、分布、传导以及种衣剂缓释作用的研究

本文以~14C-甲霜灵作为示踪剂,运用放射自显影及放射性强度测定技术,研究了甲霜灵在黄瓜植株体内的吸收、分布、传导以及种衣剂的缓释作用机理,结果表明:~14C-甲霜灵在黄瓜体内的传导是迅速的,随药剂作用时间的延长,放射性物质在叶部的积累增加,在根、茎、子叶中却降低;种衣剂中的关键助剂——成膜剂,能将种衣剂中的有效成分固着在种子表面,具有使药剂缓释和延长持效期,提高药剂利用率的作用。     

The relationship between CO2 assimilation and the metabolism of bentazone in wheat plants

The assimilation of CO₂ by wheat plants after treatment with various amounts of bentazone was investigated. Maximum inhibition of assimilation always occurred at the same time after treatment irrespective of the amount of bentazone applied. The reduction in CO₂ assimilation rate was correlated with the uptake of active ingredient in the leaf tissue. Assimilation increased again, when the concentration of bentazone inside the leaf dropped as the results of metabolism to hydroxybentazones. The toxicity of 6- and 8-hydroxybentazone to sensitive mustard plants was lower than that of the parent compound. It is suggested that hydroxylation is a step in the detoxification of bentazone.     

The effect of elevated CO2 levels on the symptom expression of Colletotrichum gloeosporioides on avocado fruits

Exposure of freshly harvested avocado fruits to different concentrations of CO₂ (11, 16 and 30%) for different lengths of time (4, 17 and 26 h) affected the decay development caused by Colletotrichum gloeosporioides. The delay in symptom development depended on the treatment given, the temperature regime of the fruit and time after harvest for treatment application. The most appropriate treatment was the application of 30% CO₂ for 24 h at a temperature of 20-25 C on the day of harvest. Treatment for shorter time periods, at lower temperatures or 50 h after harvest, resulted in a reduced response and, in some cases, enhanced symptom expression. Concentrations of 11 or 16% CO₂ were less effective than 30% CO₂ as the fruits became more mature. It is concluded that treatment of avocado fruits with high levels of CO: for a short period has the potential to provide an alternative means of controlling anthracnose.     

锐劲特与马拉硫磷混用对麦穗鱼的影响研究

锐劲特fipronil(化学名(±)-5-氨基-1-(2,6-二氯-α,α,α-三氟-ρ-甲苯基-)-4-三氟甲基-亚硫酰基吡唑-3-碳化腈),是一广谱的新型杀虫剂,其作用靶标是γ-氨基丁酸调节的神经轴突氯离子通道。进入我国市场后能有效防治蔬菜、水稻害虫[1～3],具有较好的推广潜力。有关该农药对家蚕、鱼、天敌的毒性已有研究[1～5]。但该药与其他农药的相互作用,尚未见报道。本文研究了该农药与马拉硫磷混合使用时,对麦穗鱼的影响。1　材料与方法1.1　实验用鱼麦穗鱼(Pseudorasboraparva),体重0.39-1.09g,体长4.1-5.8cm,购自杭州花鸟市场,试验前在实验室驯养一…     

食物对真水狼蛛发育和繁殖的影响

研究4种食物对真水狼蛛发育和繁殖的影响。结果表明：单喂果蝇时,幼蛛世代存活率最低;喂混合食物时幼蛛历期最短;单喂果蝇时,历期最长。幼蛛腹部体色与所喂食物颜色相近。喂混合食物的幼蛛,其背甲宽度和体重均大于其他3种食物。雌蛛所产卵袋数和产卵总量均以喂混合食物时为最高。多种食物混合喂养,有利于真水狼蛛的个体发育和繁殖。     

施肥对麦田杂草发生、生长及危害的影响

应用微区试验研究了在种植小麦的情况下,不同施肥水平对杂草及其防除效果的影响。结果表明,在缺磷土壤上单施氮肥,杂草发生和生长受到抑制;增施磷肥,氮肥效应得到充分发挥,杂草发生和生长迅猛提高。杂草根系发达,对钾肥不敏感。有机肥养分完全,显著促进杂草发生和生长。在不施肥(对照)及适合杂草和小麦生长的平衡施肥处理区(NP和NPK),麦田杂草的危害(小麦减产百分率)最为严重。杂草危害程度和施除草剂的增产效果均与小麦长势呈极显著负相关(相关系数分别是-0.5121、-0.5418,n=27)。肥料对甲磺隆钠盐杂草防效的影响与施药时间有关。在小麦苗前至苗后早期施药,防效高,且不受施肥影响;施药过迟,杂草长大,防效下降。研究结果还表明,杂草发生和生长在受施肥影响的同时,也受小麦长势和长相的影响。