Application Of Imazethapyr Research Articles

Influence of a thiamethoxam seed treatment on acetolactate synthase–inhibiting herbicide–induced injury to inbred and hybrid imidazolinone-resistant rice

AbstractThe increased use of insecticide seed treatments in rice has raised many questions about the potential benefits of these products. In 2014 and 2015, a field experiment was conducted near Stuttgart and Lonoke, AR, to evaluate whether an insecticide seed treatment could possibly lessen injury from acetolactate synthase (ALS)–inhibiting herbicides in imidazolinone-resistant (IR) rice. Two IR cultivars were tested (a hybrid, ‘CLXL745’, and an inbred, ‘CL152’), with and without an insecticide seed treatment (thiamethoxam). Four different herbicide combinations were evaluated: a nontreated control, two applications of bispyribac-sodium (hereafter bispyribac), two applications of imazethapyr, and two applications of imazethapyr plus bispyribac. The first herbicide application was to two- to three-leaf rice, and the second immediately prior to flooding (one- to two-tiller). At both 2 and 4 wk after final treatment (WAFT), the sequential applications of imazethapyr or bispyribac plus imazethapyr were more injurious to CLXL745 than CL152. This increased injury led to decreased groundcover 3 WAFT. Rice treated with thiamethoxam was less injured than nontreated rice and had improved groundcover and greater canopy heights. Even with up to 32% injury, the rice plants recovered by the end of the growing season, and yields within a cultivar were similar with and without a thiamethoxam seed treatment across all herbicide treatments. Based on these results, thiamethoxam can partially protect rice from injury caused by ALS-inhibiting herbicides as well as increase groundcover and canopy height; that is, the injury to rice never negatively affected yield.

Effect of planting methods and weed management practices on yield of green gram {Vigna radiata (L.) R. Wilczek}, weed dynamics vis a vis phytotoxicity in green gram

An experiment was carried out to find out suitable method of planting and weed management in green gram grown during the kharif season of 2014 and 2015. The density of E. colona and C. rotundus was significantly reduced in raised bed planting method. Significant reduction in total dry weight of weeds was obtained in raised bed planting method as compared to conventional and zero till planting method. Maximum weed control efficiency was found in raised bed planting method. Significantly more number of seeds pod-1 were observed in raised bed planting method as compared to conventional and zero till planting method. Seed yield and straw yield were found maximum in raised bed planting method during both years of study and were statistically at par in conventional and zero till planting method. Harvest index was not influenced by planting methods. Phytotoxicity on crop due to different herbicides was similar under different planting methods. Among different weed management treatments, HW at 15 and 30 DAS was found most effective in reducing density and dry weight of weeds during crop growing period except at 15 DAS (where weeding was done after taking observation). Maximum weed control efficiency was observed in HW (15 and 30 DAS). Weedy check treatment resulted in minimum while weed free treatment resulted in maximum number of seeds pod-1. Among the treatments having herbicide application, post emergence application of Imazethapyr @ 100 g ha-1 resulted in maximum seed and stover yield.

Impact of imazethapyr and its ready-mix combination with imazamoxto control weeds in blackgram

The bio-efficiency of imazethapyr and its combination with imazamox or pendimethalin in comparison to hand weeding against weeds, their effect on growth, yield and phytotoxicity on black gram and residual effect on succeeding mustard crop were studied during 2014–15 and 2015–16. Hand weeding twice resulted in the highest overall weed control efficiency followed by pre-emergence application of imazethapyr + imazamox 80 g/ha, preemergence imazethapyr + imazamox 70 g/ha and pre-emergence imazethapyr + pendimethalin 1000 g/ha. Hand weeding twice and pre-emergence imazethapyr + pendimethalin 1000 g/ha were comparable to pre-emergence imazethapyr + imazamox 70 g/ha for seed yield. With every increase of one weed per square metre, the blackgram seed yield was reduced by 2.1 kg/ha. Similarly with every g/m2 increase in weed weight, the blackgram yield was subjected to fall by 5.1 kg/ha. The economic threshold levels i.e. No/m2 and g/m2 with the weed management practices studied varied between 8.3–42.0/m2 and 3.5–17.6 g/m2. Weed persistence index (WPI) was lowest and crop resistance index (CRI) was highest in the hand weeding twice treatment. Post-emergence application of imazethapyr 70 and 80 g/ha and imazethapyr + imazamox 70 and 80 g/ha caused mild toxicity during 2014 and had therefore lower crop resistance index. Efficiency index was the highest under hand weeding followed by preemergence application of imazethapyr + imazamox 80 g/ha, pre-emergence imazethapyr + pendimethalin 1000 g/ha and pre-emergence imazethapyr 80 g/ha. Weed index indicated 55.4% reduction in yield of blackgram due to weeds. Preemergence imazethapyr 80 g/ha, imazethapyr + imazamox 80 g/ha, imazethapyr 70 g/ha and imazethapyr + pendimethalin 1000 g/ha had higher overall impact index than hand weeding due to lower cost. Residual effect/phytotoxicity was not observed on succeeding crop of mustard during 2014 and 2015 as well.

Leaching of Imidazolinones in Irrigation Systems in Rice Cultivation: Sprinkling and Flooding

ABSTRACT: Herbicides of the imidazolinone group have been used in irrigated rice and presented a long persistence in the soil, especially in floodplain areas with a low drainage, and could cause environmental contamination. This study aims to evaluate the leaching and residual of herbicides belonging to the imidazolinone group in sprinkler and flood irrigation systems. The experiment was carried out under greenhouse conditions, with the application of the herbicides imazethapyr, imazethapyr + imazapic, and imazapyr + imazapic in soil irrigated by flooding and sprinkling. Subsequently, the soil was collected from the layers of 0-5, 5-10, 10-15, 15-20, and 20-25 cm and packed in 500 mL capacity plastic pots in order to sow tomato as a bioindicator plant of the presence of the herbicides belonging to the imidazolinones. Phytotoxicity, length, and shoot dry matter mass of tomato plants were evaluated at 10 and 20 days after emergence. The herbicides of the imidazolinone chemical group presented a high potential for leaching and persistence with effects for more than 180 days after application. Based on the symptoms presented by the sensitive crop, the degradation of imazethapyr, imazethapyr + imazapic, and imazapyr + imazapic in the 0-15 cm layers was higher in soil with sprinkler irrigation when compared to flood irrigation. Thus, non-flooded soils present a greater capacity to degrade the herbicides belonging to the imidazolinone chemical group.

Pre-and post-emergence herbicides effect on growth, nodulation and productivity of greengram

A field experiment was conducted during Kharif season to study the efficacy of different pre-and post-emergence herbicides for weed management in greengram. Pre-emergence (PE) application of pendimethalin + imazethapyr at 0.75 kg/ha (pre-mix) effectively reduced both the density and dry matter of weeds whereas post-emergence (PoE) application of imazethapyr 10 SL at 55 g/ha significantly reduced Cyperus rotundus. All the PE and PoE herbicides significantly reduced the dry weight of weeds at 30 and 60 days after sowing (DAS) as compared to weedy check. The highest weed control efficiency was recorded in two hand weeding (90.2%), and was followed by pendimethalin + imazethapyr (pre-mix) 0.75 kg/ha applied as PE (86.8%). PoE herbicides (imazethapyr, imazamox+ imazethapyr and clodinafop-propargyl + aciflourfensodium) not only suppressed the crop growth, but also exhibited antagonistic effect on root nodulation. Significantly higher seed yields were recorded under two hand weeding and pendimethalin + imazethapyr at 0.75 kg/ha (PE). Two hand weeding also recorded the highest gross and net returns, and was followed by pendimethalin + imazethapyr (pre-mix) at 0.75 kg/ha (PE). Application of pendimethalin + imazethapyr at 0.75 kg/ha (PE) also gave the highest B: C ratio, and it was followed by two hand weeding. All the PoE herbicides fetched comparatively lower returns and B: C ratio.

Herbicidal weed management in groundnut (Arachis hypogaea)

A field experiment was conducted at Research Farm of Agriculture Research Station, S K Rajasthan Agricultural University, Bikaner during 3 consecutive kharif season of 2014, 2015 and 2016with fourteen weeds control treatments of pendimethalin 1.0 kg/ha (PPI), pendimethalin 1.0 kg/ha (PE), imazethapyr + pendimethalin 800g/ha, imazethapyr + pendamethalin 900g, imazethapyr + pendamethalin 1000g, imazethapyr 50g, imazethapyr 70g/ha,imazethapyr + imazemox 60g/ha, imazethapyr + imazemox 70g/ha, oxyfluorfen 40g/ha, fenoxaprop p-ethyl 50g/ha, propaquizafop 62g/ha, weed free and weedy check in randomized block design with three replications. Weed free was found most effective to control weeds in groundnut and recorded lowest weed count and weed dry matter of both broad leaved and grassy weeds. Among the different herbicides, application of imazethapyr + pendamethalin 800g recorded efficiently controlled weed count and weed dry matter of both broad leaved and grassy weeds as well as significantly highest yield attribute and yield in groundnut over all the other herbicidal treatments viz. dry matter accumulation (75.2g), number of pods/plant (31.2), pod (2979 kg/ha), haulm (7711 kg/ha) and biological yield (10690 kg/ha). Among the different herbicides, application of imazethapyr + pendamethalin 800g recorded higher net returns of84132/haand B:C ratio of 2.22.

Evolving Viable Weed Management Practices for Rainfed Greengram

A field experiment was conducted at Agricultural Research Station, Kovilpatti during kharif 2017 to study the effect of pre and early post emergence herbicides on weed control in rainfed greengram. In this study, PE Oxyfluorfen @ 0.10 kg ha-1 + EPOE Imazethapyr @ 50 g ha-1 on 20 DAS or PE Pendimethalin @ 0.75 kg ha-1 + EPOE Imazethapyr @ 50 g ha-1 on 20 DAS provided a broad spectrum of weed control by significantly reducing weed density and dry weight at 45 DAS and resulted in higher weed control efficiency and lower weed index. PE application of Oxyfluorfen @ 0.10 kg ha-1 + EPOE application of Imazethapyr @ 50 g ha-1 on 20 DAS or application of Pendimethalin @ 0.75 kg ha-1 + Imazethapyr @ 50 g ha-1 on 20 DAS recorded significant improvement in plant height, yield attributes like number of pods plant-1, number of seeds pod-1, test weight (g) and produced higher grain and haulm yields of rainfed greengram.

Impacts of tillage and herbicide mixture on weed interference, agronomic productivity and profitability of a maize – Wheat system in the North-western Indo-Gangetic Plains

Weeds comprising of annual monocotyledons, dicotyledons and perennial Cyperus rotundus L. (hereafter referred to as nutsedge) are important constraints in maize-wheat production system in India. They can cause yield losses of 25–30% in maize and 10–25% in wheat. Recently, continuous use of selective herbicides has led to an increase of nutsedge and other annual weeds in maize. There is need for a broad-spectrum weed control strategy that includes control of nutsedge in maize. Herbicide mixtures, containing a nutsedge killer partner herbicide may prove to be more effective for this. Imazethapyr among herbicides available in India possesses nutsedge-killing action, but the tolerance of maize to this herbicide, which is usually recommended for application as post-emergence in soybean and groundnut, is variable. We observed dose-dependent selectivity/tolerance of maize to imazethapyr when applied as post-emergence in a previous trial. Imazethapyr’s pre-emergence application may prove more useful in offering selectivity to maize, but is hardly studied. In addition, its residual/carry-over effect may lead to weed control in following wheat crops grown in sequence with maize, economizing production costs of the maize-wheat system. Therefore, this experiment was designed to evaluate the efficacy of imazethapyr against weeds including nutsedge, and its selectivity in maize crops when applied as pre-emergence in tank-mixture with pendimethalin; to compare these tank-mixtures effects with that of the sequential applications of pendimethalin (pre-emergence) and imazethapyr (post-emergence) in maize; and to evaluate their residual actions combined with tillage and crop residue in wheat under a maize- wheat system. The application of pre-emergence tank-mixture of pendimethalin 0.75 kg a.i. ha−1 + imazethapyr 0.050 kg a.i. ha−1 caused significant reductions in densities of broad-leaved (30%), nutsedge (45.2%), grassy (79.7%) and total weeds (49.1%) compared with un-weeded control (UWC) in maize. It reduced total weed dry weight by 58.3% and gave 56.1% higher maize yields than UWC. Among the tillage treatments adopted in the wheat crop, zero tillage (ZT) + residue (R) resulted in 14.0% greater reductions in weed dry weight and 6.9% higher wheat yields than conventional tillage (CT). It increased maize-wheat system productivity by 5.4% and 7%, respectively over CT and ZT without residue. The application of a tank-mixture of pendimethalin + imazethapyr gave 2.9% lower system productivity, but 8.2% higher net returns than the weed-free control, reducing the weed seed bank by 65% at 0–15 cm soil layer in two years. The application of this tank-mixture (in maize), followed by ZT + residue (in wheat) was more remunerative and could lead to better weed control with 25% and 50% lower doses of pendimethalin and imazethapyr, respectively, and 50% reduction in application cost. This practice can be adopted in maize-wheat system under irrigated conditions in the North-western Indo-Gangetic Plains of India, and in similar agro-ecologies of the tropics and sub-tropics. This result can also be applicable to cropping systems like maize – mustard, maize – barley/oat, subject to further evaluation and refinement under field conditions.

Tank-mix insecticide and herbicide application effects on weeds, insect-pest menace and soybean productivity in Semi-Arid Northern Plains of India

The effects of herbicides, alone application or in combination with insecticides, on performance of soybean [Glycine max (L.) Merrill] were examined at ICAR- Indian Agricultural Research Institute, New Delhi during rainy seasons of 2013 and 2014. Alone application of imazethapyr 10 SL @ 1.0 l/ha or in combination with indoxacarb 14.5 SC @ 300 ml/ha and rynaxypyr 20 SC @ 100 ml/ha lowered monocot and dicot weed count, reduced weed dry matter and increased weed control efficiency in comparison with other herbicide and insecticide applications, individual or in combinations. These results suggested that the imazethapyr can effectively control different categories of weeds, especially of monocots in soybean field. However, seed yield, net returns and B: C ratios were higher in the quizalofop ethyl 5 EC (1.0 l/ha) applied plots followed by combined application of rynaxypyr 20 SC (100 ml/ha) + quizalofop ethyl 5 EC (1.0 l/ha)).

Weed management effect on weeds, crop, nutrients uptake and soil physico-chemical properties in blackgram

Field experiment was conducted during Kharif season 2015–16 at N.D. University of Agriculture and Technology, Kumarganj, Faizabad, (UP) to asses the weed management effect on weeds, crop, nutrients uptake and soil properties in black gram. The result of the investigation revealed that application of imazethapyr + imazamox 80 g/ha PE was found superior in controlling weeds, increasing blackgram yield and nutrient uptake and recorded maximum benefit: cost ratio. Next best treatments were pendimethalin 1000 g/ha and metribuzin 200 g/ha PE.

Pre-and post-emergence herbicides for weed control in blackgram

Application of imazethapyr at all the rates of application (60, 75, 100 and 150 g/ha) significantly reduced the weed density and biomass as compared to quizalofop-ethyl followed by pendimethalin, alachlor and hand hoeing. Hand weeding superseded over all the treatments with the highest weed control efficiency of 96.5% followed by imazethapyr at 150 g/ha (71.9%), 100 g/ha (70.2%) and quizalofop-ethyl (70.3%). The post-emergence application of imazethapyr at 60, 75, 100 and 150 g/ha recorded significantly higher seed yield than pre emergence application of pendimethalin and alachlor and post emergence grass weed killer quizalofop-ethyl. The net monetary returns was maximum with hand weeding twice followed by imazethapyr at 150 g, 100 g and 75 g/ha. However, the benefit: cast ratio was the highest under imazethapyr at 75 g/ha followed by 100 g/ha

Effect of Propaquizafop and Imazethapyr Mixture on Weed Dynamics, Growth, Yield and Economics of Soybean [Glycine max (L.) Merill

The results of field experiments conducted during Kharif seasons of 2013 and 2014 to adjudge the efficacy of propaquizafop and imazethapyr mixture (tank mixed) to combat weeds and impact the growth and yield of soybean are reported. The treatments consisted of four doses of propaquizafop + imazethapyr mixture (47 + 70, 50 + 75, 53 + 80 and 56 + 85g ha−1), sole application of propaquizafop (75 g ha−1) and imazethapyr (100 g ha−1) as early post-emergence and pendimethalin (1000 g ha−1) as pre-emergence, hand weeding(HW) twice at 20 and 40 d after sowing(DAS)and weedy check. The dry matter accumulation for all the recorded weed flora was found the lowest in combined application of herbicides rather than their sole application, being higher under propaquizafop + imazethapyr mixture applied at 53 + 80 g ha−1 or higher rate (56 + 85 g ha−1). Higher values of growth parameters (plant height, branches plant−1, nodules plant−1), yield attributes (pods plant−1, seeds pod−1, seed index), yield and B: C ratio were recorded under propaquizafop + imazethapyr mixture applied at 56 + 85 g ha−1 followed by 53 + 80 g ha−1 which were comparable to hand weeding twice at 20 and 40 DAS.

Weed management in chickpea under irrigated conditions

In a study on chickpea at Uttar Pradesh, two hand weeding done in weedy check and weed free plot results indicated that weed control treatments significantly reduced the density of weeds. Maximum weed control efficiency (100%) was recorded with weed free plot. Among herbicides, maximum WCE (95.0%) was recorded in pre-emergence of pendimethalin1000 g/ha followed by combined PoE application of imazethapyr 75 g + quizalofop-ethyl 60 g/ha at 35 DAS and lowest WCE was recorded in weedy check. Among herbicides, the lowest number of plants (20.7/m2), plant height (33.4 cm) and number of pods/plant (22.4) at harvest stage of chickpea were recorded in PE application of pendimethalin 750 g/ha followed by combined PoE application of quizalofopethyl 60 g + oxyfluorfen 200 g/ha at 30 DAS. Maximum net monetary returns ` 53588/ha was recorded with pre-emergence application of pendimethalin 1000 g and PoE application of clodinafop 60 g/ha at 35 DAS.

Weed management in groundnut under rice-fallow

A field experiment was conducted at Agricultural Research Station, Utukur, Kadapa, Andhra Pradesh, India during Rabi seasons of 2016 and 2017 to test the efficacy of herbicides in rice-fallow groundnut. It is common that previous rice volunteer plants will come in the succeeding crops after rice. Keeping all this in view, the experiment was conducted with six weed control treatments arranged in a randomized block design (RBD) with four replications. Preemergence application of pendimethalin 1.5 kg/ha followed by post-emergence application of imazethapyr 75 g/ha at 18–20 DAS recorded lower density of both broad-leaved and grassy-weeds. Weed free throughout the crop period recorded higher pod yield (4.24 t/ha), which was at par with hand weeding twice at 20 and 40 DAS (4.19t/ha) and pendimethalin 1.5 kg/ha as pre-emergence followed by imazethapyr 75 g/ha as post-emergence at 18–20 DAS (3.91 t/ha). Higher benefit: cost ratio (2.20) was recorded with pre-emergence application of pendimethalin 1.5 kg/ha followed by post-emergence application of imazethapyr 75 g/ha at 18–20 DAS.

Weed Management in Rice under Sprinkler and Flood Irrigation Systems

ABSTRACT: This study aimed to assess the efficiency and selectivity of herbicides in rice submitted to sprinkler and flood irrigation systems. The experimental design was a randomized block design arranged in a 2 × 9 factorial scheme. Factor A consisted of irrigation systems (sprinkler and flood) and Factor B consisted of herbicide treatments (T1 - control; T2 - imazethapyr + imazapic, 75 + 25 g a.i. ha-1; T3 - imazethapyr + imazapic, 150 + 50 g a.i. ha-1; T4 - imazapic + imazapyr, 73.5 + 24.5 g a.i. ha-1; T5 - imazapic + imazapyr, 147 + 49 g a.i. ha-1; T6 - imazethapyr, 106 g a.i. ha-1; T7 - imazethapyr, 212 g a.i. ha-1; T8 - sequential application of imazethapyr + imazapic, 75 + 25 g a.i. ha-1; and T9 - sequential application of imazapic + imazapyr, 73.5 + 24.5 g a.i. ha-1). The application of imazethapyr and formulated mixtures of imazethapyr + imazapic and imazapyr + imazapic provided a control higher than 97% in flood and sprinkler irrigation systems. Herbicide selectivity is not altered in the sprinkler irrigation system when compared to the flood irrigation system.

Characterization of an acetohydroxy acid synthase mutant conferring tolerance to imidazolinone herbicides in rice (Oryza sativa).

The acetohydroxy acid synthase S627N mutation confers herbicide tolerance in rice, and the rice variety containing this mutation produces good yields. This variety is commercially viable at Shanghai and Jiangsu regions in China. Weedy rice is a type of rice that produces lower yields and poorer quality grains than cultivated rice. It plagues commercial rice fields in many countries. One strategy to control its proliferation is to develop rice varieties that are tolerant to specific herbicides. Acetohydroxy acid synthase (AHAS) mutations have been found to confer herbicide tolerance to rice. Here, we identified a single mutation (S627N) in AHAS from an indica rice variety that conferred tolerance against imidazolinone herbicides, including imazethapyr and imazamox. A japonica rice variety (JD164) was developed to obtain herbicide tolerance by introducing the mutated indica ahas gene. Imidazolinone application was sufficient to efficiently control weedy rice in the JD164 field. Although the imazethapyr treatment caused dwarfing in the JD164 plants, it did not significantly reduce yields. To determine whether the decrease of the ahas mRNA expression caused the dwarfism of JD164 after imazethapyr application, we detected the ahas mRNA level in plants. The abundance of the ahas mRNA in JD164 increased after imidazolinone application, thus excluding the mRNA expression level as a possible cause of dwarfism. Activity assays showed that the mutated AHAS was tolerant to imidazolinone but the catalytic efficiency of the mutated AHAS decreased in its presence. Moreover, the activity of the mutated AHAS decreased more in the presence of imazethapyr than in the presence of imazamox. We observed no difference in the AHAS secondary structures, but homology modeling suggested that the S627N mutation enabled the substrate to access the active site channel in AHAS, resulting in imidazolinone tolerance. Our work combined herbicides with a rice variety to control weedy rice and showed the mechanism of herbicide tolerance in this rice variety.

Imazethapyr plus Propanil Mixtures in Imidazolinone-Resistant Rice

AbstractA study was conducted in three locations in Louisiana to evaluate interactions of imazethapyr at 0 and 70 g ai ha−1mixed with propanil at 0, 1,120, 2,240, 3,360, and 4,480 g ha−1for the control of red rice, barnyardgrass, and hemp sesbania. According to Blouin’s modified Colby’s, a synergistic response occurred for red rice treated with imazethapyr mixed with propanil at 4,480 g ha−1for all evaluations. Observed control was 93% to 95% compared with expected control of 81% to 87%. An antagonistic response occurred for barnyardgrass control with imazethapyr mixed with propanil at 1,120 g ha−1at 35 and 49 d after treatment (DAT), with control of 75% and 64%, respectively, compared with expected control of 89% and 78%. However, a neutral response occurred for barnyardgrass control when treated with all other imazethapyr plus propanil combinations. An antagonistic interaction occurred for hemp sesbania when treated with imazethapyr plus propanil at 3,360 and 4,480 g ha−1at 21 DAT with an observed control of 89% compared with an expected control of 96%; however, a neutral response occurred at all other evaluation dates. An increase in rice yield was observed with an imazethapyr plus propanil at 4,480 g ha−1mixture compared with a single application of imazethapyr or propanil at any rate evaluated.

Imazethapyr persistence in sandy loam detected using white mustard bioassay

ABSTRACTField experiments were conducted during two years at Srem region to investigate the influence of meteorological conditions, time and rate of application on soil persistence of imazethapyr in sandy loam type of soil. Imazethapyr was applied PRE- and POST-EM and in both cases in three application rates: 80, 120 and 160 g a.i./ha. Soil samples were collected from the day of herbicide application in predetermined intervals up to one year after application and residual concentrations were determined with a white mustard root bioassay. Imazetapyr persistence was significantly influenced by meteorological conditions with average half-life being 6 days longer in season with lower precipitation level. Time of application induced slower imazethapyr dissipation resulting in higher average t1/2 (seven and nine days in first and second year of examination, respectively). Application rates had no consistent effect on imazethapyr persistence. Imazethapyr residue level one year after application caused no visible injuries on white mustard shoots, while root growth reduction ranged from 4.6 to 27.7%. Obtained residue levels were further compared with known data on crop sensitivity in order to assess possibility of crop injuries one year after imazethapyr application.

Weed flora dynamics and growth response of green gram (Vigna radiata (L.) R. Wilczek) under varied agri-horti system and weed management practices

Horizontal expansion of pulse production can be achieved by introduction of short duration pulse crop like, green gram (Vigna radiata (L.) R. Wilczek) under agri-horti system. Response of green gram under different agri-horti system and weed management practices is lacking. Therefore, an agronomic trial was conducted during monsoon season of 2011 at Agricultural Research Farm, Rajeev Gandhi South Campus, Banaras Hindu University, Barkachha, Mirzapur, Uttar Pradesh, in split plot design, consisting of three agri-horti systems [guava, custard apple and open field] in main plots and six weed management practices [pendimethalin 1000 g/ha (PE), imazethapyr 125 and 200 g/ha (PoE), 1-HW (20 DAS), 2-HW (15 and 30 DAS) and weedy check] were assigned to sub plots and replicated thrice. Green gram variety ‘Samrat’ was sown as per standard agronomic package of practices on August 5, 2011 in open field as well as within the alleys of, 5-year old, guava and custard apple agri-horti system. Agri-horti systems, did not significantly (P<0.05) affect the growth, yield attributes, yield and nutrient content in green gram. The weed management practices significantly affected the CGR, RGR and yield of green gram. Application of imazethapyr 200 g/ha recorded 79.08% reduction in weed biomass and 11.38% lower seed yield as compared to weedy check and 2-HW (15 and 30 DAS), respectively. 2-hand weeding effectively reduced weed biomass (88.07%) and showed highest yield (888.79 kg/ha), and CGR (13.61 g/day) followed by imazethapyr 200g/ha yield (787.66 kg/ha) and CGR (13.14 g/day).

Effect of weed management and fertility levels on productivity of clusterbean [Cyamopsis tetragonoloba (L.)Taub

A field experiment was conducted during Kharif seasons of 2014 and 2015 at Udaipur (Rajasthan) to find out the effect of weed management on productivity of clusterbean under varying fertility levels. The results revealed that among various weed management practices, two hand weeding 20 and 40 DAS recorded significantly lower weed dry matter, higher weed control efficiency, higher values of yield attributes, seed, haulm and biological yield during both the years over rest of the treatments except sequential application of pendimethalin fb imazethapyr which was statistically at par. Further, application of Imazethapyr fb hand weeding and pendimethalin fb hand weeding also gave comaparable results with pendimethalin fb imazethapyr in terms of weed control efficiency and yields. Among the fertility levels application 20 Kg N + 40 Kg P2O5 ha-1 significantly increased pods plant-1 (24.04), seeds pod-1, (7.12), test weight ( 25.33 g), seed ( 1035 kg ha-1), haulm (2161 kg ha-1) and biological (3196 kg ha-1 ) yield and harvest index ( 31.98 %) of clusterbean over 10 Kg N + 20 Kg P2O5 ha-1 however, it was found statistically at par with fertility level 30 Kg N + 60 Kg P2O5 ha-1. Therefore, clusterbean should be fertilized with 20 Kg N + 40 Kg P2O5 ha-1 and weeds must be controlled with pendimethalin (PE) fb imazethapyr 0.1 kg ha-1 20 DAS .