Growth characteristics of spring barley and selected weeds. I. Effect of irradiance in growth chambers

A study in growth chambers with three irradiance levels was carried out over a four-week period on individual seedlings of spring barley (Hordeum vulgare L.) and five weed species (Brassica rapa L. ssp. oleifera (DC.) Metzger, Chenopodium album L., Galeopsis tetrahit L., Stellaria media (L.) Vill., and Viola arvensis Murray). Increased irradiance resulted in larger dry weight, net photosynthetic rate, relative growth rate (RGR), net assimilation rate (NAR), and lower leaf area ratio (LAR). The number of leaves per plant, plant length, leaf area, and shoot/root ratio were unaffected by irradiance levels, During the experimental period the net photosynthetic rate increased, while NAR remained the same, and RGR, LAR, and shoot/ root ratio decreased. On the basis of leaf area and dry weight, especially at the high irradiance level during the last part of the experimental period, barley, B. rapa, and C. tetrahit had the largest values, followed by C. album and S. media with medium values, and V. arvensis with the smallest values. As for leaf area and dry weight, S. media took more advantage of the low than the high irradiance level compared with C. album. Species differences are discussed with regard to competitive ability.     

烟嘧磺隆·莠去津防除春玉米田杂草的效果

防除春玉米田一年生2～3叶期稗草、灰菜、反枝苋,用52％烟嘧磺隆·莠去津WP100—125g／667m。进行茎叶喷雾处理,药后30d对杂草鲜重防效为96．0％～97．8％,好于4％玉农乐SC100g／667m^2和莠去津SC200g／667m^2,可达到一次用药同时防除玉米田单双子叶杂草的目的。     

Hap1型棉蚜在5种春季杂草上的生长发育情况

棉蚜Aphis gossypii Glover是重要的棉花Gossypium hirsutum和葫芦科蔬菜害虫,严重影响寄主植物的生长发育、产量和品质。棉蚜在冬季寄主上产卵越冬,早春孵化后进行寄主转移扩散。阿拉伯婆婆纳Veronica persica、猪殃殃Galium spurium、飞蓬Erigeron canadensis等是早春时期的优势杂草,可能是棉蚜向棉花转移过程中的中间寄主。本试验选用Hap1型棉蚜,记录其取食棉花以及阿拉伯婆婆纳、猪殃殃、飞蓬、荠菜Capsella bursa-pastoris、飞廉Carduus nutans等5种早春优势杂草时的生长发育、产仔量等数据,并通过计算、对比各组的生命表参数,从而得出Hap1型棉蚜在此5种春季杂草上的适合度。试验表明,Hap1型棉蚜在不同寄主上的若虫发育历期及各龄若虫的发育时间存在明显差异。相较于取食棉花叶片的Hap1型棉蚜,取食杂草的棉蚜总生殖前期缩短0.2～0.9 d,每雌生殖力最多减少50%。Hap1型棉蚜取食5种杂草及棉花的生命表参数显示,Hap1型棉蚜最适寄主为棉花,寿命比取食杂草高0.4～0.9倍。Hap1型棉蚜...     

双氯磺草胺在东北地区春大豆田的应用效果

为明确双氯磺草胺土壤封闭与茎叶处理对东北地区春大豆田阔叶杂草的防除效果和对作物的安全性。采用随机区组设计, 连续2年开展田间试验。结果表明:25.2~76.5 g/hm2有效成分剂量下84%双氯磺草胺水分散粒剂用于大豆田进行土壤封闭处理, 施药后60 d, 对东北地区常见阔叶杂草藜、本氏蓼、苍耳、苘麻、水棘针的株防效和鲜重防效都在90.0%以上, 对龙葵的株防效和鲜重防效都在87.0%以上。对阔叶杂草的总株防效为93.3%~99.0%, 总鲜重防效为94.7%~99.4%。25.2~63.0 g/hm2有效成分剂量下84%双氯磺草胺水分散粒剂茎叶喷雾处理, 施药后30 d, 对本氏蓼、苍耳、苘麻的株防效和鲜重防效都在93.0%以上, 对水棘针的株防效和鲜重防效都高于82.0%, 对藜、龙葵的株防效为59.8%~85.5%, 鲜重防效为62.5%~90.9%。对阔叶杂草总的株防效为80.1%~93.2%, 总的鲜重防效为82.2%~95.9%, 施药后初期, 大豆叶片有受害症状, 后期新生叶片正常。双氯磺草胺土壤封闭和茎叶喷雾施药方式都能有效控制东北地区春大豆田的阔叶杂草, 但依据大豆产量分析, 84%双氯磺草胺水分散粒剂有效剂量25.2~76.5 g/hm2 4个土壤封闭处理区大豆产量与人工除草相比差异不显著。本试验为大豆田苗后除草剂选择提供了新思路, 茎叶喷雾施药方式适宜的剂量为84%双氯磺草胺水分散粒剂 31.5~37.8 g/hm2;土壤封闭施药方式具有更好的除草效果, 适宜的施药剂量为84%双氯磺草胺水分散粒剂25.2~50.4 g/hm2。     

Potential contribution of selected canopy traits to the tolerance of foliar disease by spring barley

A model of canopy photosynthesis and above-ground growth rate was used to investigate the potential impact of several canopy traits on tolerance of foliar disease by barley. Disease tolerance was defined as the reduction in predicted crop dry-matter growth rate per unit of visible disease symptoms. The traits were canopy area (leaf area index, LAI ), light extinction coefficient ( k ) and the ratio of virtual to visible lesion size ( β ). The effects of altering the area of the healthy flag leaf and its light-saturated rate of photosynthesis (P_max) in response to disease elsewhere on the plant were also investigated. The model was parameterized for spring barley and run with a solar radiation and temperature regime typical of north-east Scotland. Predicted reductions in growth rate per unit increase in disease were greatest at high disease severity and when disease was distributed relatively uniformly through the canopy. Tolerance was increased by increasing LAI to >3 and k to >0·3, but the beneficial effects depended on the severity and, to a lesser extent, the distribution of disease. Tolerance was reduced by increasing β . A sensitivity analysis performed at a single disease severity and distribution showed that tolerance was most sensitive to variations in β and compensatory adjustments in area and P_max of the flag leaf, and least sensitive to whole canopy LAI and k . Future research should quantify the genetic variation in these traits within barley germplasm to evaluate the scope for improving the disease tolerance of spring barley.     

炔草酸·唑啉草酯乳油春季防除冬小麦田禾本科杂草的效果

50g／L炔革酸·唑啉草酯乳油对冬小麦田禾本科杂草硬草和茼草有良好的防效,春季使用的适宜剂量为45—60g／hm^2,防效优于精嗯唑禾草灵和炔草酸（麦极）,并且对小麦安全。     

Selective control of graminaceous weeds in spring wheat

Infestation of wheat fields in Israel by graminaceous weeds is increasing due to effective control of broad-leaf weeds and lack of crop rotation. The main graminaceous weeds are wild oat (Avena sterilis L.) and wild canarygrass (Phalaris paradoxa L. andPh. brachystachys L.). In eight experiments carried out in wheat fields during 1975–1977, wild oat was effectively controlled by post-emergence applications of barban, isoproturon and difenzoquat, while wild canarygrass was controlled by post-emergence applications of barban, isoproturon and metha-benzthiazuron.     

阔世玛春后防除麦田杂草的效果及对小麦的安全性

2007年3月5日～3月10日用3.6%阔世玛WG 25 g/667m2+伴宝80 ml/667m2防治麦田杂草有良好的效果,药后40 d对禾本科杂草株防效达90.8%～94.9%,鲜重防效达92.4%～96.9%,对阔叶类杂草的株防效为69.8%～75.0%,鲜重防效为75.6%～78.6%,对小麦生长安全,小麦增产24.4%～29.9%.     

Dicotyledonous weeds of spring cereal crops in north-east Scotland

A survey of dicotyledonous weeds of spring cereals was conducted prior to herbicide application in 1985 in six districts of north-east Scotland, which involved a total of 113 fields. Results were similar to those from an earlier survey in 1973. The main species remained the same but in four of the six districts, total weed densities were lower. Stellaria media was the most common species except in Upper Banffshire and Morayshire where Galeopsis spp. and Polygonum aviculare, respectively, were predominant. The main changes apparent were a decline of Spergula arvensis and Polygonum persicaria, and an increase in Matricaria perforata and Viola arvensis in several districts.     

Effect of fungicide treatment on yield of winter wheat and spring barley cultivars

Analyses of the results of 21 winter wheat and 32 spring barley trials showed that cultivars differed significantly in their yield response to a standard fungicide treatment. Responses were also strongly influenced by differences between sites and between years. Regression analyses showed that responses were significantly related to reductions in foliar disease, particularly that of mildew, although the proportion of variance accounted for was small. Measurements made on seven winter wheat trials indicated that the percentage of leaf area remaining green after anthesis was increased by the fungicide treatment to a greater extent than could be attributed to reduction in foliar disease alone. In one of these trials, yield response was more closely correlated with the increase in leaf area remaining green than with reduction in foliar disease.     

Effect of crop density on competition by wheat and barley with Agrostemma githago and other weeds

The effect of Agrostemma githago L. and other naturally occurring weeds on biomass production and grain yield was studied in winter wheat and winter barley. Naturally occurring weeds had only a negligible effect on barley, but reduced wheat grain yield by 10% at a quarter of normal crop density. The interaction between the cereals and A. githago was studied in additive series employing different crop densities. Growth of this weed species was strongly dependent on crop density, which was more important for controlling weed growth than it was for obtaining a normal grain yield. Wheat and especially barley had a better competitive ability than A. githago. Wheat and A. githago utilized resources for growth better when grown in mixture than when grown in pure stands as the relative yield totals were significantly larger than unity.     

The growth of Arrhenatherum elatius var bulbosum (Willd.) Spenn. in spring barley, as influenced by cultivation

Populations of Arrhenatherum elatius var bulbosum were established either from seed or vegetatively and studied under four cultivation regimes. Treatments were carried out in the autumn and winter and the experiment was sown with barley in the following spring. Winter mouldboard ploughing gave the greatest reduction of tillers and bulbs of established plants, but was less effective when preceded by rotary cultivation in the early autumn. Tine cultivations increased the numbers of tillers and bulbs, but the largest increase in growth was recorded on plots that were not cultivated. The germination of seeds was not affected by early autumn cultivations. Mouldboard ploughing, tine cultivation and paraquat at 060 kg a. i. /ha each gave complete control of seedlings in winter. A simple test on the morphology of plants grown from seed agreed with earlier conclusions that the bulbous form is not a distinct variety. It is suggested, nonetheless, that the bulbous form should be named seperately as in practice it alone succeeds as an arable weed.     

北部高寒区大豆田恶性杂草生长特点及化学防控技术

北部高寒区是大豆主产区,因长残留除草剂的禁用,用于大豆田防除杂草的除草剂品种减少.防控大豆田恶性杂草,需了解大豆田恶性杂草发生的原因、恶性杂草的种类及生物学特性,方能有效地控制杂草危害.     

Effects of selective cutting and timing of herbicide application on growth and development of Cirsium arvense in spring barley

Recently, a new implement for controlling weeds in cereals (CombCut) has been developed. It cuts weeds in growing cereals without damaging them by using the physical differences (in height, stem thickness, straw stiffness and branching pattern) between crops and weeds. To evaluate and compare the effects of selective cutting with different timings of herbicide application on Cirsium arvense in spring barley, a randomised block experiment was conducted in Sweden in 2015–2017, in a field with a naturally occurring C. arvense population. Treatments consisted of control (C), herbicide application at 4–5‐leaf stage of C. arvense (H1), herbicide application at 8–10‐leaf stage (H2) and selective cutting at 10‐leaf stage (S). The treatments were performed in 2015 and repeated in 2016 in the same plots, and a final evaluation was performed in 2017. Compared to the control, S, H1 and H2 were equally efficient in reducing above‐ground biomass production of C. arvense and increasing spring barley grain yield per unit area. The number of C. arvense shoots per area was, however, higher in S compared to H1 and H2. No differences in control effects on shoot number were observed between H1 and H2. Our study indicates that (i) selective cutting (S) reduces C. arvense equally efficient as herbicide application and (ii) early herbicide spraying is as efficient as spraying later in the season.     

紫花苜蓿田春季阔叶杂草除草剂筛选及安全性评价

为明确适用于紫花苜蓿田防除春季阔叶杂草的除草剂,本研究通过室内和田间试验筛选了对紫花苜蓿安全且对春季阔叶杂草防效好的除草剂。室内试验表明,供试的11种除草剂中仅有唑草酮、吡草醚、乙羧氟草醚等3种除草剂对紫花苜蓿具有较好的安全性。通过田间试验发现,40%唑草酮WG 30～66 g/hm²(有效成分用量,下同)和10%乙羧氟草醚ME 75～90 g/hm²处理对春季阔叶杂草具有较好的防治效果,株防效为83.68%～97.32%,鲜重防效为73.18%～95.62%,且对紫花苜蓿有较好的安全性,增产12%以上。综上所述,在紫花苜蓿返青期进行唑草酮和乙羧氟草醚处理可用于紫花苜蓿田春季阔叶杂草防除,具有较好的应用前景。     

Leaf blotch severity on spring barley infected by isolates of Rhynchosporium secalis under different temperature and humidity regimes

The infection efficiency and severity of leaf blotch on spring barley inoculated with three pathotypes of Rhynchosporium secalis from central Norway were studied under different temperature and humidity regimes. Seedlings of the cultivar Arve were subjected to two constant temperatures, 13° or 18°C. Dry periods of 8 h or longer before or after a wet period of 4 h, carried out in the first 48 h postinoculation, reduced disease severity assessed 16 days after inoculation. The effect of dry periods of up to 24 h was nullified when plants were subjected to high humidity for 48 h after the dry treatment. The disease developed most rapidly when the wet period was 48 h and the temperature 18°C. At or near the optimum temperature for R. secalis (18°C), leaf wetness duration as short as 2 h resulted in considerable disease. Isolates reacted differently to temperature. The most aggressive isolate caused severe disease irrespective of temperature (56–70% of the leaf area infected); however, disease severity caused by the least aggressive isolate was significantly higher at the optimum temperature compared with a lower temperature (13°C). This information can facilitate evaluation of weather data in relation to predicting leaf blotch for advisory purposes.