Echinochloa Colona Research Articles

Weed growth, nutrient removal and yield of direct-seeded rice as influenced by establishment methods and chemical-cum-mechanical weed management practices

Direct seeding of rice (Oryza sativa L.) has since long been viewed as a potential alternative to unsustainable water-intensive transplanted rice (TPR) world-over, but heavy infestation of a variety of weed species limits the large-scale adoption of direct-seeded rice (DSR) cultivation. Hence, a 2-year field investigation was carried-out in a spilt-plot design, at Banaras Hindu University, Varanasi, during rainy seasons of 2016 and 2017 to assess the influence of various crop establishment methods (CEMs) and weed management options (WMs) on diverse weed-flora, nutrient removal by weeds, weed-control efficiency (WCE) and yield of DSR (cv. Rajendra Kasturi). The results revealed that zero-till DSR + residue + Sesbania brown manure (ZTDSR + R + SBM) was most effective in containing crop-weed competition, lowered density of Echinochloa colona (L.) Link, Echinochloa crusgalli (L.) Beauv., Cynodon dactylon (L.) Pers., Eclipta alba (L.) Hassak., Caesulia axillaris Roxb., Cyperus rotundus L., Cyperus iria L., Fimbristylis miliacea (L.) Vahl. by 63.4% and enhanced grain yield by 22.8%. Further, applying pendimethalin at 1000 g ai ha−1 as PRE. and later post-emergence (POST) spray of chlorimuron + metsulfuron at 4 g ai ha−1 each 20 days after sowing (DAS) supplemented with 1 hand-weeding (HW) 45 DAS was found to be a better weed management option as this treatment recorded the lowest density and nutrient depletion by above mentioned weeds and higher WCE, thereby improving rice yield by 3–19.5% over other studied WMs. Also, the combination of this weed management option with ZTDSR + R + SBM suppressed weeds to a greater extent, restricting weeds to deplete nutrients (N, P and K) from the soil and finally fetched the highest DSR yield.

Phenology, growth, and seed production of junglerice (Echinochloa colona) in response to its emergence time and populations

AbstractJunglerice [Echinochloa colona (L.) Link.] is the most important grass weed species in Australian summer cropping systems. Although it is mainly a spring- and summer-emerging weed species, field observations suggest that E. colona is expanding its seasonality. A common garden experiment was conducted at the University of Queensland farm to examine the effect of planting dates on phenology, growth, and fecundity of eight populations of E. colona. All populations were planted every second month from September to July in 2019 to 2020 and 2020 to 2021. Echinochloa colona took the shortest time (4 to 6 d) to emerge when planted in November or January. However, the November population took the longest number of growing degree days to exhibit panicle emergence. In both years, populations differed in height and leaf, tiller, panicle, and seed production in response to planting times. Plants produced significantly greater biomass for the November planting (123 to 147 g plant−1) followed by the January planting and then the September planting. The March planting produced the lowest biomass. In the first year, the lowest number of seeds (3,500 seeds plant−1) was produced by the March planting; however, in the second year, similar numbers of seeds were produced by the March and July plantings. In the first year, seed production (51,000 seeds plant−1) was greatest for the November planting; however, some populations also produced a similar number of seeds for the January planting. In the second year, significantly greater seed production (111,000 seeds plant−1) was observed for the January planting compared with other planting dates. The aboveground biomass and seed production of E. colona were positively correlated. This study reveals variations among E. colona populations and suggests that although greater emphasis must be placed on controlling spring- and summer-emerging plants, management practices need to be extended throughout the year to control E. colona in southeastern Australia.

Evaluation of the food of red-billed quelea (Quelea. quelea) during off-cropping season in Gyawana ecosystem Adamawa State

The evaluation of the food items of red-billed quelea during off-cropping season in Gyawana ecosystem was carried out, to ascertain the wild food of Quelea quelea foraged on during off- cropping season. Red-billed quelea (Q, quelea) devastation of crops continues to be a problem that militates against food security in Adamawa State and other arid regions of Nigeria. The bird appears to have alternative food sources which ensure its survival and breeding during off- cropping seasons. The crop contents of Q, quelea were analysed. Nine (9) different food items were identified including seeds of different grasses, insect remains and Grits from the crops of one hundred and fifty (150) Q, quelea sampled for this study. Echinochloa colonum has the highest frequency and magnitude of occurrence in the food items foraged on by the Q, quelea with a mean value of 40.20±0.72, followed by Digitaria ciliaris (35.33±1.03), Digitaria iburua (29.96±1.12), Setaria pallidofusca (29.33±0.41), Roetboellia exaltata (21.67±0.25), Brachiaria mutica (1.71±0.16) and the least seed consumed is Cenchrus biflorus with a mean of 1.15±0.02. Grits was consumed in small quantity (0.15±0.36) by both sexes, while insects remained was observed only in female’s crop of the Quelea birds. Analysis of variance was used to compare the mean number of various seeds consumed by the Q, quelea during the period of the study. The result shows no significant difference in the food items consumed by Red-billed Quelea during off-cropping season at P >0.05. Based on the findings of this research work, the researchers therefore, recommend that further study should be carryout on the food items of Q, quelea during cropping season and also biological control of this Quelea birds (Q, quelea).

Colorimetric loop-mediated isothermal amplification assay for detection and ecological monitoring of Sarocladium oryzae, an important seed-borne pathogen of rice.

Accurate and timely disease detection plays a critical role in achieving sustainable crop protection. Globally, rice has been a staple crop for centuries plagued by the diseases that greatly hamper its productivity. Sheath rot, an emerging disease of rice caused by the seed-borne pathogen Sarocladium oryzae, has reportedly caused heavy losses to agricultural produce in recent years. Our study has led to the development and validation of a LAMP assay for early detection of S. oryzae, the causal agent of sheath rot from the live-infected tissues, seeds, weeds, and environmental samples. The assay could detect as low as 1.6 fg/μl of the pathogen in 15 min. The assay was implemented to bio-surveil the presence of this pathogen by testing it on three weed species (Echinochloa colona, Echinochloa crus-galli, and Cyperus teneriffae) growing around the rice fields. The results showed the presence of the pathogen in two of the weed species viz. E. colona and E. crus-galli. The assay was used to test 13 different rice varieties for the presence of S. oryzae in seeds. In total, three of the varieties did not show the presence of S. oryzae in their seeds while the rest were found to harbor the pathogen. The developed assay can effectively be used to detect and screen the presence of S. oryzae in live samples including seeds and field soil.

The Influence of Different Row Spacing and Weed Control Intervals on Weed Infestation and Yield-Related Traits of American (Gossypium hirsutum L.) and Desi (Gossypium arboreum) Cotton

Narrow row spacing has attracted significant attention due to its beneficial impacts on weed management in cotton. This study compared the effects of normal and ultra-narrow row spacing on critical periods of weed control in American (Gossypium hirsutum L.) and ‘Desi’ (Gossypium arboreum) cotton. Two different row spacings (i.e., recommended (75 cm) and ultra-narrow (30 cm)) and three weed control intervals (i.e., weed control at 30, 60 and 90 days after sowing (DAS)) were included in the study. Weedy-check and weed-free treatments were included in the experiment as controls for comparison. ‘Desi’ cotton grown under ultra-narrow spacing recorded the lowest weed density and individual density of Trianthema portulacastarum L., Cyperus rotundus L., Cynodon dactylon L., Echinochloa colona (L.) Link and Digera muricata (L.) Mart. Moreover, ‘Desi’ cotton sown under ultra-narrow spacing with weed-free and weed control at 30 DAS resulted in the highest leaf area index (LAI), leaf area duration (LAD), net assimilation late (NAR), root elongation rate (RER) and root growth rate (RGR) at all sampling dates. Likewise, ‘desi’ cotton sown under recommended row spacing and weed-free conditions produced the highest number of sympodial and monopodial branches, number of flowers and bolls per plant, whereas the highest seed cotton yield of ‘Desi’ cotton was noted under ultra-narrow spacing and weed-free conditions. It is concluded that sowing both cotton types in ultra-narrow row spacing and controlling weeds at 30 DAS will result in lower weed infestation and higher seed cotton yield.

Tillage and crop establishment effects on weeds and productivity of a rice-wheat-mungbean rotation

Weeds are one of the key threats in sustaining the productivity of the rice-wheat cropping system in the Indo-Gangetic Plains. The development of sound integrated weed management technologies requires knowledge of mechanisms that influence weed flora composition and weed seedbank dynamics. A long-term study was initiated in 2015 at Patna, Bihar, India to evaluate the effect of seven tillage and crop establishment methods on weed density, weed seedbank composition, and crop productivity in rice-wheat-mungbean rotation. All the treatments included zero-till mungbean after wheat. Tillage and crop establishment methods had differential effects on weed and weed seedbank composition. In rice, zero-till direct-seeded rice recorded 62% lower emergence of Cyperus iria, 82–90% of Echinochloa colona, and 81–83% of total weeds compared to tilled systems, but the system of rice and wheat intensification favoured E. colona. In wheat, the system of wheat intensification favoured the Phalaris minor and Solanum nigrum. Zero-till rice and wheat reduced the seedbank of Trianthema portulacastrum by 95%, and total weed seedbank by 62% compared to the system of rice and wheat intensification. Nearly, 72% of C. iria seeds, 62% of grasses, and 64% of broad-leaved weeds were in 0–15 cm soil layer. Zero-till direct-seeded rice produced a 13% lower rice grain yield than conventional puddled transplanted rice. Compared to the system of wheat intensification, zero-till wheat under triple zero-till systems produced an 11.5% higher grain yield. Managing weed seedbank is a long-term endeavour. The present study revealed that tillage and crop establishment methods influence weed density and diversity. Under zero-till rice-wheat system, rice yield decreases marginally, but the system productivity maintains due to improvement in succeeding wheat yield. This system is also helpful in reducing the weed flora density and soil weed seedbank. Regular monitoring and management of emerging pests such as armyworm (Mythimna separata) are, however, required. The study suggests that the adoption of triple zero-tillage can be a viable option for reducing the weed density and weed seedbank concurrently increasing the system productivity of the rice-wheat-mungbean cropping system in eastern Indo-Gangetic Plains.

BIOASSAY OF ALLELOPATHIC POTENTIAL OF BERMUDAGRASS AND SORGHUM ON GERMINATION AND RELATED TRAITS OF WEEDS ASSOCIATED WITH RICE

With growing concern towards human health and ecological concerns related to prolonged use of herbicides, research is undergoing globally for alternate weed managing methods. Allelopathy is one of the very efficient methods for management of weeds. Experiment was conducted during 2016 & repeated in 2017 under laboratory conditions in Kharif (summer) season using completely randomized design for allelopathic potential assessment of bermudagrass (Cynodon dactylon L.) and sorghum (Sorghum bicolor L.) with 03 replicates. The treatments under study comprised: control (check), bermudagrass & sorghum root & shoot powders @ 15 and 30 g kg-1 soil as well as water extracts @ 15 and 30 ml kg-1 soil. It is obvious from the present data that allelopathic plants powders & water extracts caused significant adverse effects on tested weeds i.e. Sawari (Echinochloa colonum L.), Saon (Echinochloaa crusgalli L.) and Kabah (Cyperus rotundus L.). Bermuda grass and sorghum water extracts exhibited strong allelopathic efficacy on germination, roots & shoots length, as well as fresh & dry biological weight of weeds included under study. It is further argued that greater inhibitory effects on weeds were caused by extracts prepared from bermudagrass and sorghum in comparison with their powders. Hence, it is evident from the results that bermudagrass & sorghum materials possess phytotoxic potential which can suppress growth of target plant. This allelopathic herbage could be utilized by soil incorporation or extract for weed management in rice as environment friendly strategy.

The Effect Of Combination Of Technology Of Planting And Control Of Weeds On The Dominant Value Of Weeds And Rice Productivity

The problem currently arises in lowland rice cultivation is the presence of nuisance plants, namely weeds which can reduce crop yields by up to 90%. Therefore, it is necessary to find a way out by testing several weed control technologies that farmers can use. The objectives of the study were (1) to determine the effect of technology for planting methods, namely Tabela in arrays, evenly spaced tables, and evenly distributed tables, on the growth and production of lowland rice, (2) To determine the effect of weed control technology using herbicides with active ingredients metsulfuron-methyl and 2,4 -D on the growth and production of lowland rice and (3) To determine the effect of the Combination of planting technology and weed control technology on the growth and production of lowland rice. The experiment was carried out using a Randomized Block Design (RAK) as the environmental design. The treatment design was a split-plot design: Main Plot, Planting Method Technology (T): T1 = Array Tables, T2 = Distance Tables, T3 = Tables Spread Evenly. Sub-plots, Weed Control Technology (G): G1 = Herbicide with active ingredient mtsulfuron methyl, G2 = Herbicide with active ingredient 2,4-D, G3 = Combination of mtsulfuron methyl and 2,4-D. Thus there were nine treatments, each treatment was repeated three times, so there were 27 experimental units. One experimental plot measuring 4 x 6 m. The placement of all treatments in the experimental plot was done randomly. The dominant weed species observed were Paspalum disticum, Fibristylis litoralis, Marsilea crenata, Cyperus iria and Echinochloa colonum. The dominant weed species in all treatment combinations observed at 21 DAP were Paspalum distichum, Echinochloa crusgalli, Marsilea crenata, Lersia hexandra and Fimbristylis litoralis. There was no difference in rice production in all treatment combinations. The difference in production only occurred in the average planting method, where the highest production occurred in the T1 treatment.

Screening of Herbicides for Rice Seedling Safety and Echinochloa colona Management under Australian Conditions

Different herbicides are currently required for sustainable weed management in aerobic rice. Three pot experiments were conducted using different herbicides to evaluate rice safety and for the control of Echinochloa colona, a major weed of aerobic rice. Among the pre-emergence (PRE) herbicides, it was found that pendimethalin (594 g ai ha−1) and flumioxazin (60 g ai ha−1) were relatively safe herbicides for rice and provided 100% control of E. colona. All other PRE herbicides, such as atrazine, cinmethylin, clomazone, dimethenamid-P, isoxaflutole, metribuzin, prosulfocarb + S-metolachlor, pyroxasulfone, trifluralin, and S-metolachlor reduced the biomass of rice compared with the non-treated control. Dose-response studies revealed that flumioxazin and pendimethalin even at low doses (30 g ai ha−1 for flumioxazin and 294 g ai ha−1 for pendimethalin) provided excellent control (>95%) of E. colona. Post-emergence (POST) application of paraquat (360 g ai ha−1) at the time of rice emergence caused toxicity in the crop, but also provided excellent control of E. colona. When applied just after crop emergence (11 days after sowing), Pendimethalin was found to be safe for rice (2% mortality) and reduced the biomass of E. colona by 88% compared with the non-treated control. It is quite possible that the rice variety Reiziq used in this study may have a tolerance to flumioxazin, which needs further investigation involving more rice varieties. This study suggests that flumioxazin can be used as an alternative to pendimethalin for the sustainable management of E. colona in aerobic rice.

Structural analysis and engineering of aldo-keto reductase from glyphosate-resistant Echinochloa colona

Glyphosate is a dominant organophosphate herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) of the shikimate pathway. Glyphosate is extensively applied since manufactured, which has led to the emergence of various glyphosate-resistant crops and weeds. However, the molecular mechanism of many glyphosate-resistance machineries remains unclear. Recently, the upregulated expression of two homologous aldo-keto reductases (AKRs), designated as AKR4C16 and AKR4C17, were found to contribute to the glyphosate resistance in Echinochloa colona. This represents the first naturally evolved glyphosate-degrading machinery reported in plants. Here, we report the three-dimensional structure of these two AKR enzymes in complex with cofactor by performing X-ray crystallography. Furthermore, the binding-mode of glyphosate were elucidated in a ternary complex of AKR4C17. Based on the structural information and the previous study, we proposed a possible mechanism of action of AKR-mediated glyphosate degradation. In addition, a variant F291D of AKR4C17 that was constructed based on structure-based engineering showed a 70% increase in glyphosate degradation. In conclusion, these results demonstrate the structural features and glyphosate-binding mode of AKR4C17, which increases our understanding of the enzymatic mechanism of glyphosate bio-degradation and provides an important basis for the designation of AKR-based glyphosate-resistance for further applications.

Interference of junglerice (Echinochloa colona) in mung bean

AbstractJunglerice [Echinochloa colona (L.) Link] is increasing its prevalence in eastern Australia by adapting to Australia’s changing climatic conditions and conservation agricultural systems and by evolving resistance to glyphosate. Information is limited on the growth and seed production dynamics of E. colona when it interferes with mung bean [Vigna radiata (L). R. Wilczek], a major potential export crop for eastern Australia. This field study examined the interference of E. colona in mung bean for two summer seasons (2020 and 2021) at Gatton, QLD. Different infestation levels (0, 2, 4, 8, 16, and 32 plants m−2) of E. colona were assessed for their potential to cause yield reductions in mung bean. Seed yield of mung bean was highest in the weed-free plots (2,767 kg ha−1) and declined by 20%, 27%, 34%, and 43% at weed infestation levels of 4, 8, 16, and 32 plants m−2, respectively. Echinochloa colona biomass in mung bean varied from 11 to 137 g m−2 as weed density increased from 2 to 32 plants m−2. Based on a three-parameter hyperbolic rectangular decay model, crop yield loss was 52% and 57%, respectively, when weed density and weed biomass approached maximum. Echinochloa colona at the highest density (32 plants m−2) produced a maximum of 15,140 seeds m−2, and this seed production was reduced by 50% at a weed density of 10 plants m−2. Echinochloa colona plants retained 63% to 68% seeds at mung bean maturity, indicating a great opportunity for harvest weed seed control. This study suggests that a high infestation of E. colona in mung bean fields could cause a substantial yield loss and increase the weed seedbank.

Bio-efficacy of Bentazon against Weeds in Direct Seeded Rice under Kymore Plateau and Satpura Hill Zone

The experiment was conducted at Research Farm of Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh, India to study the “Bio-efficacy of Bentazon against Weeds in Direct Seeded Rice under Kymore Plateau and Satpura Hill zone” during kharif season of 2016 under edaphic and climatic conditions of Jabalpur (M.P.). The dominant weeds associated with direct seeded rice in the experimental field comprised of monocot like Echinochloa colona and Dinebra retroflexa, sedges like Cyperus iria and dicot weeds including Mullogo pentaphylla and Alternanthera philoxeroides. Experiment consisted of total ten treatments comprising of seven doses of Bentazon 600, 800, 1000, 1200, 1600, 1800 and 2000 g/ha, 2,4-D 380 g/ha as post-emergence, hand weeding twice at 20 and 40 DAS including weedy check, the experiment was laid out in randomized block design (RBD) with 03 replications. The post-emergence application of Bentazon at 1600 g/ha was found economically best suitable for effective control of dicot weeds in direct seeded rice.

Response of Rice (Oryza sativa L.) to Weed Management Methods in the Lower Gangetic Plain Zone

Background: In India, rice covers largest area under cultivation. Among the biotic stresses weeds pose serious threat to rice if not controlled in its critical crop-weed competition period, reducing yield by 50%, in case of transplanted rice. The experiment was carried out to evaluate effectiveness of different herbicides and its combination with mechanical weed control methods in checking weed population in transplanted rice so as to maintain sustained production. Methods: The experiment was carried out in lower Gangetic plain zone during kharif season of 2018. It was laid out in randomized block design with seven treatments replicated thrice. The treatments were pretilachlor 50% EC@ 1500 ml ha-1 (0-4 DAT), butachlor 50% EC @ 4000 ml ha-1 (0-4 DAT), bispyribac Na 10% SC @ 200 ml ha-1 (Post-emergence), Sesbania intercrop @ 25 kg ha-1 up to 30 DAT followed by mechanical incorporation followed by 1 hand weeding @ 50 DAT, pretilachlor 50% EC @ 1500 ml ha-1 (0-4 DAT) followed by bispyribac Na 10% SC @ 2000 ml ha-1 (25 DAT), two hand weedings at 25 DAT and 50 DAT and untreated control. Result: Cyperus rotundus, Cyperus difformis, Alternanthera philoxeroides, Ludwigia octovalvis, Echinochloa colona, Fimbristyslis sp. were the dominating weed species as per experimental findings. Among all treatments two hand weedings at 25 DAT and 50 DAT significantly reduced the total weed density (no.m-2) while total weed biomass (g m-2) as was found to be lowest in treatment of pretilachlor 50% EC @ 1500 ml ha-1 (0-4 DAT) followed by bispyribac Na 10% SC @ 2000 ml ha-1 (25 DAT). Highest growth characteristics in rice was observed in treatment of two hand weedings at 25 DAT and 50 DAT. Pre- emergence and post-emergence application of pretilachlor and bispyribac sodium, respectively, was successful in achieving highest yield attributes, yield (4.12 t ha-1) and economic return (Rs. 47438 ha-1).

Assessment of critical period for weeding and yield loss in direct seeded rice (Oryza sativa)

A field experiment was conducted at research farm of Regional Rainfed Lowland Rice Research Station, ICARNational Rice Research Institute, Gerua, Assam during two consecutive boro seasons of 2014–15 and 2015–16 to assess yield losses in direct seeded rice (DSR) under weeding times. There were two DSR establishment techniques (dry and sprouted seeding) in main plots and four weeding times (15, 30, 45 and 60 DAS) in sub plots. It was found that Scirpus juncoides, Echinochloa colona, Cyperus difformis, Cyperus iria, Monochoria vaginalis and Ludwigia octovalvis were the dominant weed species in shallow lowlands. DSR establishment techniques had non-significant effect on weed characteristics as well as growth, yield attributes and productivity of rice. Weed density of individual weed group and dry matter were significantly influenced by weeding times. Weeding at 15 DAS resulted in significantly low weed density and biomass as compared to weeding at 45 and 60 DAS. Growth and yield attributes, viz. plant height, panicles/m2, filled grains/panicle and fertility percentage were significantly higher and subsequently resulted in higher grain and straw yield under early weeding at 15 DAS. The highest grain yield losses due to weeds were calculated with weeding at 60 DAS (20.4%) followed by 45 DAS (15.8%) in DSR. Thus, early weeding in DSR plays an important role to obtain higher productivity of rice and minimise yield loss due to weeds.

High Resistance to Quinclorac in Multiple-Resistant Echinochloa colona Associated with Elevated Stress Tolerance Gene Expression and Enriched Xenobiotic Detoxification Pathway.

Echinochloa colona and other species in this genus are a threat to global rice production and food security. Quinclorac, an auxin mimic, is a common herbicide for grass weed control in rice, and Echinochloa spp. have evolved resistance to it. The complete mode of quinclorac action and subsequent evolution of resistance is not fully understood. We analyzed the de novo transcriptome of multiple-herbicide-resistant (ECO-R) and herbicide-susceptible genotypes in response to quinclorac. Several biological processes were constitutively upregulated in ECO-R, including carbon metabolism, photosynthesis, and ureide metabolism, indicating improved metabolic efficiency. The transcriptional change in ECO-R following quinclorac treatment indicates an efficient response, with upregulation of trehalose biosynthesis, which is also known for abiotic stress mitigation. Detoxification-related genes were induced in ECO-R, mainly the UDP-glycosyltransferase (UGT) family, most likely enhancing quinclorac metabolism. The transcriptome data also revealed that many antioxidant defense elements were uniquely elevated in ECO-R to protect against the auxin-mediated oxidative stress. We propose that upon quinclorac treatment, ECO-R detoxifies quinclorac utilizing UGT genes, which modify quinclorac using the sufficient supply of UDP-glucose from the elevated trehalose pathway. Thus, we present the first report of upregulation of trehalose synthesis and its association with the herbicide detoxification pathway as an adaptive mechanism to herbicide stress in Echinochloa, resulting in high resistance.

Outburst of pest populations in rice-based cropping systems under conservation agricultural practices in the middle Indo-Gangetic Plains of South Asia

Conservation agriculture (CA), which encompasses minimum soil disturbance, residue retention either through crop residue, or cover crops and crop diversification-based crop management practices can modify the status of pest dynamics and activities under the changing climatic scenarios. CA has been advocated extensively to optimize the use of available resources, maintain the environmental quality, enhance crop productivity, and reduce the climate change impacts. Information related to the impacts of long-term CA-production systems under rice-based cropping systems on pest status is lacking, particularly in middle Indo-Gangetic Plains (MIGP). Under CA, puddling is completely avoided, and rice is directly sown or transplanted to maintain better soil health. Different sets of experimentations including farmers practice, partial CA and full CA (CA) as treatments in rice-based cropping systems, were established from 2009, 2015 and 2016 to understand the long-term impacts of CA on pest dynamics. In this study, direct and indirect effects of tillage (zero, reduced and conventional tillage), residue retention and cropping sequences on abundance and damage by pests were investigated. After 4–5 years of experimentation, populations of oriental armyworm [Mythinma (Leucania) (Pseudaletia) separata (Wlk.)] in wheat, mealybug [Brevennia rehi (Lindinger)] and bandicoot rat [Bandicota bengalensis (Gray)] in rice were found to increase abnormally in CA-based production systems. Conventionally tilled plots had a significant negative effect while residue load in zero-tilled plots had a significant positive effect on larval population build-up of M. separata. Zero tillage had a higher infestation of mealybug (52–91% infested hills) that used grassy weeds (Echinochloa colona, Echinochloa crusgalli, Cynodon dactylon, Leptochloa chinensis and Panicum repense) as alternate hosts. Cropping sequences and no disturbance of soil and grassy weeds had higher live burrow counts (4.2 and 13.7 burrows as compared to 1.47 and 7.53 burrows per 62.5 m2 during 2019–2020 and 2020–2021, respectively) and damaged tillers (3.4%) in CA-based practices. Based on the present study, pest management strategies in CA need to be revisited with respect to tillage, residue retention on soil surface, grassy weeds in field and cropping sequences to deliver the full benefits of CA in MIGP to achieve the sustainable development goals under the climate change scenarios.

Maize weed control and yield using different applications of tembotrione

Present study employed different methods of tembotrione applications for weed management in maize and investigated if integration of a herbicide in intra-row and hand weeding in inter-row could provide similar level of weed control to blanket application of a herbicide. The field study was conducted in 2018 and 2019 on loamy sand soil at Ludhiana and on a clay loam soil in 2018 at Langroya, in India. At Ludhiana, Cyperus rotundus L., Dactyloctenium aegyptium (L.) Willd., Acrachne racemosa Ohwi and Trianthema portulacastrum L. and, at Langroya, C. rotundus, D. aegyptium, Echinochloa colonum L. and T. portulacastrum were major weeds. Integrated use of tembotrione at 36.7 g ha−1 alone or its tank mixture with atrazine 208 g ha−1 as band application (intra-row) with manual weeding (inter-row) provided similar level of weed control and maize grain yield to blanket application of tembotrione 110 g ha−1 alone or its tank mixture with atrazine 625 g ha−1. The study concluded that integration of herbicide application on crop rows and hand weeding in inter rows could be adopted in maize.

Genetic diversity and population structure analysis to study the evolution of herbicide resistance in Echinochloa colona ecotypes in Australia

Genetic diversity and population structure analysis to study the evolution of herbicide resistance in Echinochloa colona ecotypes in Australia

Phytotoxicity in aqueous methanolic extracts of rice against junglerice and total activities of identified phytotoxic compounds

AbstractThis study examined phytotoxic activities of several Vietnam localised OM rice (Oryza sativa L. OM) cultivars on junglerice (Echinochloa colona (L.) Link), an invasive weed threatening rice production, and identified allelochemicals and their activities for OM 4498, the most allelopathic cultivar. The aqueous MeOH extracts of all rice cultivars inhibited root and shoot growth of junglerice at a concentration as low as 0.01 g ml−1. Inhibitory effects were greatest in OM 380, OM 2395 and OM 4498, with the average effective doses (EDs) of extracts required for 90% inhibition (ED90) on junglerice as low as 0.981, 0.632 and 0.702 g ml−1, respectively. The phytotoxic substances salicylic acid, vanillic acid, p‐coumaric acid, 2,4‐dimethoxybenzoic acid, benzoic acid, p‐hydrobenzoic acid, trans‐cinnamic acid and coumarin were identified in OM 4498 at concentrations ranging from 0.066 to 11.412 mg in 100 g fresh weight of rice tissue. Two of these substances, 2,4‐dimethoxybenzoic acid and coumarin, have never previously been identified in rice. Compared to other compounds, p‐coumaric acid may have the greatest weed‐suppressant potential on junglerice, with the average ED50 being 0.28 mM. The total activities of salicylic acid, vanillic acid, p‐coumaric acid, trans‐cinnamic acid and 2,4‐dimethoxybenzoic acid in an OM 4498 rice plant on junglerice seedlings were 59.60, 0.78, 3.47, 2.52 and 0.61 mM/mM, respectively. The results clearly suggest that OM 4498 rice extract is an excellent source for allelochemicals against junglerice, and this rice cultivar should be considered in rice production areas invaded by junglerice.

A Phytosociological Survey on weed Flora and Diversity in Rice Fields of Chidambaram Block, T.N., India

A phytosociological survey was carried out to assess the varied weed flora and diversity in rice fields of Chidambaram block, Tamil Nadu, India. Chidambaram lies in low land habitat and the climate is subtropical. An average annual rainfall varies between 1200 to 1500 mm. The study has been done during 2020, Navarai season to determine the weed flora, species composition, density, frequency and important value index (IVI). To project the types of weed sps that are mainly affected the low land rice ecosystems. A total of 4 sedges, 3 grasses, 8 broad leaved weeds and 1 aquatic weed were detected. Sedges are most prominent weed flora found in the rice fields of Chidambaram block. The findings indicated that Cyperus difformis, Echinochloa colonum are the most abundant weeds in rice field followed by Cyperus rotundus, Echinochloa crusgalli, Leptonchloa chinensis, Eclipta alba and Sphenoclea zelyancia.