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1.
Field trials were conducted at Samaru in the northern Guinea and at Bakuta and Kadawa in the Sudan Savanna ecological zones of Nigeria to identify suitable herbicides for weed control in irrigated onion. The herbicides tested were chlorthal-dimethyl, fluorodifen and oxadiazon. In the trials each herbicide treatment was compared with an identical treatment which received supplementary hand-weeding. The results of these experiments show that oxadiazon at 1·0–2·0 kg a.i./ha, with or without supplementary hoe-weeding at 6 weeks after transplanting, combined effective weed control with high bulb yields in irrigated dry season onions. While fluorodifen at 1·5 kg a.i./ha followed by supplementary hoe-weeding may be effective at sites with low weed infestation, a higher rate (3·0 kg/ha) may be desirable at sites with a higher broad-leaved weed infestation. Chlorthaldimethyl at 10·0 kg a.i./ha effectively controlled weeds at all the sites and gave high onion yields at sites with 6–12% clay; the selectivity was, however, lower at Bakura with very light soil. Uncontrolled weed growth caused 49–86% reduction in the bulb yields compared with the best herbicide treatments.  相似文献   

2.
Field experiments were conducted in the wet seasons of 2005 and 2006 to evaluate the effect of pre-emergence application of herbicides on cowpea. A mixture of metolachlor and prometryn at 1.25+0.08 kg a.i./ha was consistent in better growth and seed yield. However, application of mixtures of metolachlor and terbutryn at 0.99+0.50 kg a.i./ha and ametryn and terbutryn at 1.60+1.00 kg a.i./ha gave lower vigour score of the crop, higher crop injury, smaller canopy spread and lower seed yield. It can be concluded that the metolachlor and prometryn mixture gave good selective weed control and can be used instead of hand weeding in cowpea in northern Nigeria.  相似文献   

3.
Avoidable losses and economic injury levels (EILs) were computed for the sorghum head bug, Calocoris angustatus Leth., on three cultivars during three rainy seasons (1985–1987) at ICRISAT. Grain yield in plots protected with 2–5 insecticide sprays (carbaryl at 500 g a.i./ha) between the half-anthesis and the dough stage was significantly higher than in untreated plots, with cost-benefit ratios > 1. Plots that were not protected at half-anthesis and/or complete-anthesis, and at milk and dough stages, suffered a significant loss in yield. Bug damage spoiled the grain quality in terms of germination, 1000-grain mass, grain hardness and percentage floaters. Three to four sprays between complete-anthesis and the dough stage prevented a significant reduction in grain quality. Head bug density at half-anthesis, complete-anthesis, milk and dough stages was significantly and negatively associated with grain yield. Bug density at different stages explained 43–94% of the variance in yield. Direct effects of bug numbers at the milk stage and the indirect effects of head bug density at other stages through the milk stage contributed towards maximum reduction in yield. Maximum avoidable losses were recorded in cultivar ICSV 1 (88·6%), followed by CSH 1 (69·9%), and CSH 5 (53·9% in 1986 and 55·0% in 1987). Loss in grain yield/ha due to one insect/panicle at half-anthesis and that based on natural increase, were 548 and 232 kg in CSH 5 during 1986 and 1987, respectively, 251 kg in ICSV 1, and 77 kg in CSH 1. EILs based on a cost-benefit ratio of 1:1 ranged from 1·3–1·4 insects/panicle for CSH 1, 0·4 for ICSV 1, and 0·4–0·6 and 0·2–0·4 for CSH 5 during 1986 and 1987, respectively. Simple cost estimates for insecticide sprays and the resultant saving in grain yield are a useful tool for decision-making in pest management.  相似文献   

4.
Three field experiments were conducted at the research fields of Plant Protection Research Institute, Iran, at different locations in 2004–2005 to study the efficacy of different broadleaved herbicides to control weeds in wheat. Treatments were the full-season hand weeded and weed-infested controls, and post-emergence applications of florasulam plus flumetsulam at 8.75, 10.50, and 12.25 g a.i./ha, 2,4-D plus carfentrazone-ethyl at 210, 245, 280, and 490 g a.i./ha, bromoxynil plus MCPA at 75, 100, and 150 g a.i./ha, 2,4-D at 560, 720, and 1120 g a.i./ha, tribenuron methyl, and 2,4-D plus MCPA. Herbicides were applied at wheat tillering stage. Naturally occurring broadleaved weed populations were used in experiments. Results indicated that bromoxynil plus MCPA at 150 g a.i./ha, 2,4-D plus MCPA, and 2,4-D plus carfentrazone-ethyl at 490 g a.i./ha were the best options to control weeds. Bromoxynil plus MCPA at 150 g a.i./ha and 2,4-D plus MCPA also resulted in the highest wheat yield. Overall, it could be concluded that rotational application of bromoxynil plus MCPA at 150 g a.i./ha, 2,4-D plus MCPA, and 2,4-D plus carfentrazone-ethyl at 490 g a.i./ha would be the best option to achieve satisfactory weed control, high grain yield and prevention of evolution of herbicide-resistant weeds.  相似文献   

5.
Field and laboratory experiments were conducted in the early and late rainy seasons in Thailand to evaluate the effect of pre-emergence application of herbicides and determine the herbicide residues on vegetable soybean (Glycine max L. Merrill cv. No. 75) production. No visible crop injury was observed after application of alachlor 469 g a.i./ha, clomazone 1080 g a.i./ha, metribuzin 525 g a.i./ha, pendimethalin 1031.25 g a.i./ha, tank-mixed clomazone 960 g a.i./ha + pendimethalin 928 g a.i./ha, or tank-mixed metribuzin 350 g a.i./ha + pendimethalin 928 g a.i./ha. However, acetochlor 1875 g a.i./ha, isoxaflutole 75 g a.i./ha, and oxadiazon 1000 g a.i./ha caused visible crop injury. Plant bioassay of herbicide residues in the soil after harvest showed no phytotoxic effect on baby corn (Zea mays Linn. cv. Suwan 3), cucumber (Cucumis sativus L. cv. Pijit 1), pak choi (Brassica chinensis Jusl. cv. Chinensis), and soybean (G. max L. Merrill cv. CM 60). Gas Chromatography-Mass Spectrometry (GC–MS) analysis showed no significant herbicide residues on crop yield (or MRLs < 0.01 ppm) for all herbicides used in this study. The application of metribuzin at 525 g a.i./ha was sufficient to provide satisfactory full-season control of several weed species and gave the highest crop yield. In addition, pendimethalin at 1031.25 g a.i./ha, and tank-mixed metribuzin at 350 g a.i./ha + pendimethalin at 928 g a.i./ha can provide a similar level of weed control as an alternative to reduce herbicide dosage thereby increasing food and environmental safety in vegetable soybean production.  相似文献   

6.
The effect of weed control treatments for long season control of weeds in maize under zero and minimum tillage was evaluated at Samara in northern Nigeria. Among the weed control treatments evaluated, soil ridging plus application of either 2,4-D or atrazine at 1.5 kg a.i/ha performed well as they effectively controlled weeds and resulted in better growth and a grain yield that was comparable to the hand weed control. Maize production under minimum tillage was better than under zero tillage.  相似文献   

7.
An economic analysis on the use of herbicide to control weeds in garlic production in 2002/2003 and 2003/2004 dry seasons indicated a considerable reduction in the cost of weed control and labour demand with the application of herbicide. Although the hoe weeding and the herbicide gave comparable bulb yield in 2002/2003 dry season, the net return per hectare was higher with herbicide application in both seasons. Similarly, the value of labour saved through herbicides use was positive throughout and increased significantly in 2003/2004 dry season.  相似文献   

8.
《Crop Protection》1987,6(5):283-288
Field trials were conducted in the Nigerian savanna to evaluate the performance of various herbicide mixtures for weed control in chilli pepper (Capsicum frutescens L. var. Serrano chilli) during the wet seasons of 1982 to 1984 and in the 1982/83 dry season. Linuron at 0·5 kg or 0·75 kg a.i./ha in mixture with either alachlor at 1·5 kg, metolachlor at 1·5 kg, oxadiazon at 1·5 kg, or diphenamid at 3·0 kg, as well as metolachlor plus metobromuron at 1·0 + 1·0 kg and 1·5 + 1·5 kg a.i./ha all followed by supplementary hoe-weeding at 6 weeks after transplanting combined effective weed control with high chilli pepper fruit yields comparable to the hoe-weeded control in all the trials. Unchecked weed growth throughout the crop life cycle resulted in an 86–90% reduction in potential chilli pepper fruit yields.  相似文献   

9.
EPTC was tested in glasshouse and field experiments for its potential as a herbicide to control Bromus species in winter cereals. Bromus hordeaceus, Bromus commutatus, Bromus pectinatus and Bromus sterilis were all selectively controlled in barley by EPTC. Winter wheat was found to be susceptible but winter barley tolerated doses up to 2·0 kg a.i./ha. The barley cultivar Sonja was more resistant than both Athene and Maris Otter. In the first field trial, 1·0 kg a.i./ha EPTC reduced B. sterilis plant numbers by 75% giving a barley yield increase of 2·84 t/ha. In the following year 2·0 kg a.i./ha reduced B. sterilis numbers by 54% and increased yield by 1·75 t/ha.  相似文献   

10.
以矮秆耐密型玉米辽单565为试材,研究不同种植密度和栽培形式对其光合性能、农艺性状及产量的影响。结果表明,叶面积指数随着种植密度的增加总体上呈增加趋势,当种植密度超过6.75万株/hm2时,宽窄行处理叶面积指数较高。除清种处理外,光合速率随着种植密度的增加总体上呈单峰曲线变化,当种植密度超过6.00万株/hm2时,二比空和宽窄行栽培形式光合速率较高。与穗位叶和穗下叶叶向值相比,穗上叶的叶向值较高。随着种植密度的增加,穗位高逐渐增加,穗长和百粒重逐渐下降。与其他栽培形式相比,大垄双行栽培形式在不同种植密度下茎粗和穗长变化较小,且茎粗表现较好。不同生态区域测产结果表明,栽培形式间和种植密度间均存在极显著差异,栽培形式与种植密度互作极显著,在缩距增密、大垄双行和宽窄行栽培形式基础上,种植密度超过6.00万株/hm2时,辽单565易获高产。  相似文献   

11.
The sowing method of spring‐type canola (Brassica napus L. var. oleifera) for forage has a major influence on its productivity and agronomic management. A field experiment was conducted in Matamoros, Coahuila, Mexico, during two growing seasons (2008–2009 and 2009–2010) to determine dry matter (DM), crude protein (CP) and net energy for lactation (NEL) yields, as well as canola forage chemical composition as a function of six sowing methods. The treatments assessed were broadcast sowing and five different row spacings: 0·19, 0·38, 0·57, 0·76 and 0·95 m (double row, 0·20 m apart). In the first year, with a mean growing season temperature of 17·2°C, sowing methods did not affect DM yield, but CP and NEL content and yield were higher in 0·19‐m row spacing. The mean temperature in the second year (13·5°C) was slightly lower than the long‐term mean (14·8°C) in the region, resulting in the highest DM (8840 kg ha?1), CP (2486 kg ha?1) and NEL yields (51 103 MJ ha?1) with 0·19‐m row spacing. In row‐sowing methods with over 0·19‐m row spacing, DM, CP and NEL yields decreased by 19·3–39·7, 20·4–42·1 and 21·2–42·7% respectively. Results indicate that sowing methods significantly affected canola forage productivity.  相似文献   

12.
In order to investigate the effect of trifluralin, pronamide, haloxyfop-p methyl, propaquizafop and isoxaben on weed control and oilseed rape yield, a two year field experiment was conducted at Darab, Iran, during 2004–2005 and 2005–2006 growing seasons. Herbicides reduced weed biomass compared with the weedy check. In 2004–2005, at 16 WAP (weeks after planting), application of trifluralin plus propaquizafop plus isoxaben at 1200 + 200 + 250 g a.i./ha and trifluralin plus haloxyfop-p methyl plus isoxaben at 1200 + 100 + 500 g a.i./ha provided best control (80%) of wild mustard (Sinapis arvensis L.), compared to other treatments. At 8 and 16 WAP, wild mustard control decreased to 47 and 42%, respectively, when trifluralin was applied alone at 1400 g a.i./ha. In 2005–2006 at 16 WAP, maximum reduction in wild mustard biomass (82%) was achieved with trifluralin plus propaquizafop plus isoxaben at 1200 + 200 + 250 g a.i./ha. In both years, all herbicide treatments controlled fumitory (Fumaria officinalis L.) 64–96%. In 2004–2005, at 16 WAP, wild oat (Avena fatua L.) biomass reduction by trifluralin plus propaquizafop plus isoxaben at 1200 + 200 + 250 g a.i./ha was 95%. In 2005–2006, at 8 and 16 WAP, minimum biomass reduction of wild oat (37–53%) was observed with trifluralin at 1200 and 1400 g a.i./ha. In both years, at 8 and 16 WAP, the most effective herbicide treatments were trifluralin plus propaquizafop plus isoxaben and trifluralin plus haloxyfop-p methyl plus isoxaben regardless of the dose applied and provided maximum reduction in total weed biomass (77–89%) compared to other treatments. Results of both years showed that all herbicide treatments increased oilseed rape grain yield as compared with the weedy check but percentage of oil was not affected by various herbicide treatments. Maximum grain yield was obtained with trifluralin plus haloxyfop-p methyl plus isoxaben at 1200 + 100 + 500 g a.i./ha.  相似文献   

13.
An experiment was conducted in inland northern New South Wales (NSW) to assess the response of tropical perennial grasses Chloris gayana (Rhodes grass) cv. Katambora and Digitaria eriantha (digit grass) cv. Premier and annual forage sorghum (Sorghum bicolor ssp. bicolor × S. bicolor ssp. drummondii hybrid) cv. Sweet Jumbo fertilized with five rates of nitrogen (N; 0, 50, 100, 150 and 300 kg N ha?1) and defoliated every 2 or 6 weeks over two growing seasons. Tropical perennial grasses were highly responsive to N fertilizer, while there was no significant response by forage sorghum. Herbage production of Rhodes grass increased linearly whereas digit grass had a high response at 50–100 kg N ha?1. Nitrogen‐use efficiency was highest during the growing season when rainfall was higher. During this season, digit grass had the highest N efficiency (148 kg DM kg?1 N applied) at 50 kg N ha?1, and Rhodes grass (66 kg DM kg?1 N applied) at 100 kg N ha?1. Plant frequency of both perennial species increased and then stabilized at high levels (>84%, cell size 0·1 by 0·1 m) during the two growing seasons. Plant frequency of Rhodes grass declined over the winter period, but recovered within 6 weeks of commencement of the growing season. Soil nitrate levels indicated that unused nitrate moved down the soil profile during wet winters. Implications of leaching below the rooting zone are discussed.  相似文献   

14.
Yield constraints of rainfed lowland rice in Central Java, Indonesia   总被引：1，自引：0，他引：1  
The low and unstable yields of rainfed lowland rice in Central Java can be attributed to drought, nutrient stress, pest infestation or a combination of these factors. Field experiments were conducted in six crop seasons from 1997 to 2000 at Jakenan Experiment Station to quantify the yield loss due to these factors. Experimental treatments—two water supply levels (well-watered, rainfed) in the main plots and five fertilizer levels (0-22-90, 120-0-90, 120-22-0, 120-22-90, 144-27-108 kg NPK ha−1) in the subplots—were laid out in a split-plot design with four replications. Crop, soil, and water parameters were recorded and pest infestations were assessed.

In all seasons, rice yield was significantly influenced by fertilizer treatments. Average yield reduction due to N omission was 42%, to K omission 33–36%, and to P omission 3–4%. Water by nutrient interactions did not affect rice yield and biomass production. In two of the three dry seasons, an average of 20% of the panicles were damaged by pests and estimated yield loss from pests was 56–59% in well-watered and well-fertilized treatments. In one out of six seasons, yields under rainfed conditions were 20–23% lower than under well-watered conditions. Drought, N and K deficiencies, and pest infestation are the major determinants for high yields in rainfed environments in Jakenan. Supplying adequate nutrient and good pest control are at least as important as drought management for increasing crop productivity of rainfed rice-growing areas in Central Java. The relative importance of drought, nutrient and pest management may vary in other rainfed areas. Yield constraints analysis should be systematically carried out to identify appropriate management strategies.  相似文献   


15.
不同氮量和密度对吉单96冠层特性及产量的影响   总被引：1，自引：1，他引：0  
在大田条件下设置纯氮用量0、150、225、300和375 kg/hm~2共5个氮肥量级和6万、7万、8万、9万和10万株/hm~2共5个密度梯度,研究不同氮肥量级条件和不同密度梯度下吉单96的冠层生理及结构指标、产量及产量构成指标。结果表明,冠层叶绿素含量的敏感时期为大喇叭口期和抽雄期,其中,大喇叭口期叶片叶绿素含量受氮肥影响最大,抽雄期叶片叶绿素含量受密度影响最大。225～300 kg/hm~2施氮量且分配60%的追肥可以保持冠层叶绿素在较高水平;叶面积指数受密度调控更显著,7.7万～8.0万株/hm~2为试验最适密度,可维持最大叶面积指数在5.5左右。在中高肥力条件下,采用7.7万～8.0万株/hm~2的种植密度和225～300 kg/hm~2的施氮量,可维持冠层结构和功能,协调穗粒数和百粒重同步增长,产量可达到12 780.9 kg/hm~2。  相似文献   

16.
In the Netherlands complete elimination of the stem nematode Ditylenchus dipsaci (Kühn, Filipjev) in tulip by destruction of infested lots and sterilization of infested soil is the aim of the Plant Protection Service. Elimination of stem nematode in narcissus bulbs is achieved by hot-water treatment, but this treatment is not appropriate for tulip bulbs because these are damaged at temperatures of 43 · 5°C and higher. As the effects of the systemic nematicides aldicarb and oxamyl looked promising, these were investigated further. Aldicarb, 6 kg a.i./ha, was applied once in the autumn and once in spring. Oxamyl, 2 · 88 kg a.i./ha, was applied three times in spring. The efficacy of these nematicides was shown not only by a reduction in the numbers of infested bulbs but also by a reduction in nematode numbers in the bulbs, shown here in the frequency distribution of infested bulbs over nematode numbers. However in some bulbs, probably those which had the highest number of nematodes before planting, a few stem nematodes could still be detected, having survived high dosages of nematicides. Therefore, complete elimination of stem nematodes from infected bulbs with very high nematode numbers is probably impossible. It is expected, however, that repeated treatment will increase the percentage of nematode-free bulbs and will lead to almost healthy tulip-bulb stocks.  相似文献   

17.
Six insecticides (terbufos, chlorpyrifos, ethoprophos, phoxim, bendiocarb and lindane) were tested against sugar-cane wireworm Agrypnus variabilis (Candèze) in maize. The first five insecticides were applied at 0·25, 0·5 and 0·75 kg a.i./ha (2·27, 4·55 and 6·82 g a.i./100 metres of row) while lindane was applied at the registered rate of 0·29 kg a.i./ha (2·64 g a.i./100 metres of row). In addition, bendiocarb was applied as a seed treatment at the rates of 4000 and 6000 ppm. The insecticides were applied at planting as insecticide/fertilizer mixtures in 18 cm wide bands, 2–3 cm below the soil surface and 3–5 cm above the seed. The minimum effective rates were terbufos 0·25 kg a.i./ha, lindane 0·25 kg a.i./ha and chlorpyrifos and ethoprophos both at 0·5 kg a.i./ha. These treatments gave at least 5 weeks' residual control. The bendiocarb seed treatments were phytotoxic. No residues were detected in the cobs or grain at the minimum effective rates of the terbufos, chlorpyrifos or ethoprophos treatments. The positive linear relationship between plant population and yield showed that for every 1% loss in plant stand below the optimum range of 60 000–65 000 plants/ha, there is a 0·72-0·74% loss in grain yield respectively. Control measures would be economically justified with only a 2·3% reduction in plant stand (assuming $20/ha for cost of control and $150/tonne for maize).  相似文献   

18.
Herbicides applied to combat weeds and increase crop yields may also have undesired effects on beneficial soil microorganisms. Field studies were conducted in 2005 and 2006 in Zaria, Nigeria, to evaluate the response of weeds and soil microorganisms to imazaquin applied at 0.05, 0.10, 0.20 and 0.40 kg a.i./ha and pendimethalin applied at 1.0, 2.0, 4.0, and 8.0 kg a.i./ha in cowpea and soybean. Hoe-weeded and unweeded (no herbicide) plots were controls. Both herbicides significantly reduced weed biomass in both crops, when compared to the unweeded control, which had the highest weed biomass at all sampling dates. Treatments with 0.40 kg a.i./ha of imazaquin, 2.0 and 4.0 kg a.i./ha of pendimethalin, and the hoe-weeded control, had the highest cowpea grain yield. The unweeded control had the lowest grain yield which was comparable to that in all other herbicide treatments. All treatments except 4.0 and 8.0 kg a.i./ha of pendimethalin had higher soybean grain yield than the unweeded control. Soybean yield was lowest in the unweeded control, and treatments that received 4.0 and 8.0 kg a.i./ha of pendimethalin. All rates of imazaquin gave similar soybean grain yields that were 29–41% higher than that from pendimethalin. The hoe-weeded control had the highest yield, which was 79% more than that in the unweeded control. Higher rates of imazaquin and pendimethalin reduced nodulation, nitrogen fixation, and vesicular arbuscular mycorrhizal (VAM) fungi colonisation in both crops. VAM fungi species diversity and species richness in cowpea rhizosphere soil and species diversity in soybean rhizosphere soil were reduced relative to the controls due to application of both herbicides with the rates of 0.10, 0.20, and 0.40 kg a.i./ha of imazaquin and 8.0 kg a.i./ha of pendimethalin being significantly effective.  相似文献   

19.
There is limited information on the effect of s-metolachlor application timing on cabbage tolerance in Ontario. A total of five field trials (1999–2004) were established near Ridgetown Ontario, Canada to evaluate tolerance of cabbage to s-metolachlor applied pre-transplant incorporated, pre-transplant and post-transplant at 800, 1600 and 2400 g a.i./ha. s-Metolachlor applied pre-transplant incorporated, pre-transplant and post-transplant at 800, 1600 and 2400 g a.i./ha did not have any effect on visual injury, marketable head production, marketable head weight and yield of cabbage. There was also no difference among s-metolachlor application timings (pre-transplant incorporated, pre-transplant and post-transplant) in respect to cabbage tolerance. Based on these results s-metolachlor applied pre-transplant incorporated, pre-transplant and post-transplant at 800, 1600 and 2400 g a.i./ha has an acceptable level of crop safety in cabbage.  相似文献   

20.
The effect of nitrogen (N) fertilization on the dry‐matter (DM) yield and nutritional value of sorghum (Sorghum sp., cv. Jumbo) and black oat (Avena strigosa cv., IPR 61) was investigated in the context of forage and livestock production in southern Brazil. Sorghum was cultivated with 0, 37·5, 75, 150, 225, 300 and 375 kg N ha?1 during the summer crop seasons of 2010/11 and 2011/12. Black oat received 0, 40, 80, 120, 160, 200 and 240 kg N ha?1 in the winter of 2011. According to the adjusted polynomial regression, sorghum DM yield increased in response to N up to 288 (12·9 t ha?1) and 264 kg ha?1 (5·6 t ha?1) in 2010/11 and 2011/12 respectively. Crude protein (CP) content of sorghum was highest at 349 and 328 kg N ha?1, but in vitro dry‐matter digestibility (IVDMD) was highest at 212–207 kg N ha?1 in 2010/11 and 2011/12 respectively. Sorghum neutral detergent fibre (NDF) and acid detergent fibre (ADF) were not affected by N fertilization. In black oat, the maximum DM yield (6·0 t ha?1) was obtained with 187 kg N ha?1; the IVDMD, NDF and ADF were not affected by N fertilization, but the CP content increased up to 220 kg N ha?1. It is concluded that these forage species can improve the year‐to‐year amount and quality of forage produced but high rates of N fertilizer are required to achieve high yields. Fertilizer N rates of 210–280 kg N ha?1 in sorghum and 180 kg N ha?1 in black oat in the crop rotation provide the greatest responses in DM yield consistent with good nutritional quality for livestock production.  相似文献   

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