79 research outputs found
The role of arbuscular mycorrhizal fungi in plant invasion trajectory
No full textBackground: Invasive plant species pose a global threat because they alter ecosystem functioning and biodiversity. The majority of plants form mutualistic mycorrhizal associations with mycorrhizal fungi, which contribute to the nutrient and water supply as well as diversity, competitive ability, and ecosystem productivity. In addition, the role of mycorrhizal interactions in plant invasiveness and the susceptibility or resistance of a habitat to invasion is increasingly recognized. However, the mechanisms by which mycorrhizae contribute to invasion remain unresolved. Scope: Here, we provide an overview of the empirical evidence and discuss the prospects for mycorrhizaemediated plant invasion. Overall, mycorrhizal fungi appear to have impacts on plant invasion that depend on the similarities between the mycorrhizal associations of the alien and native plants. We introduce plant mycorrhizal niche space (PMNS) as a plant’s ability to exploit and shape the mycorrhizal fungi pool of a habitat based on its dependency on mycorrhizal fungi, traits and priority effects. Conclusions: Collectively, the available evidence supports the idea that PMNS is independent of place of origin (invasive status). Understanding the drivers of the PMNS of both native and alien plant species may help to predict the potential invasiveness of plants and the invasibility of a habitat, to elucidate the role of the mycorrhizal fungal community in plant invasion and the impact of plant invasion on the structure of the mycorrhizal fungal community in new habitats (i.e., neighbour effect) and to improve restoration planning. In this regard, we highlight a number of knowledge gaps and discuss future research directions.</p
Weed Diversity Under Different Water Regimes in Irrigated Direct-Seeded Rice Cultivation
No full textThis study comprised two sets of experiment. The field trials were conducted at MARDI Bertam Rice Research Station in Seberang Perai, Penang, while the experiments on weed seed viability were done in a glass house and the Weed Biology Laboratory at Universiti Putra Malaysia. This study began in February 2004 and ended in June 2006. All field trials and weed seed viability studies were done in Off Season 2004 and Main Season 2004/2005. The objectives of the study were: a) to investigate the population and status of dominant weeds and their effect on rice yield under different water regime treatments in field condition; b) to determine the total weed seed reserve, species composition of the entire weed seed bank in the soils and their viability after being treated under different water regime treatments in the rice field.
Five water regime treatments were used namely; T1 = continuous flooded condition until maturity, T2 = early flooding until 55 DAS (day after sowing) followed by saturated condition until maturity, T3 = early flooding until 30 DAS followed by saturated condition until maturity, T4 = continuous saturated condition until maturity, T5 = continuous field capacity condition throughout the experiment period.
Results from field trials indicated that in unweeded plots (no weed control treatment involved), T1 and T2 showed the lowest number of weed m-2 and weed biomass m-2 compared to the other water regime treatments. Plots treated with T1 and T2 significantly suppressed weed population to approximately 18 – 58% and reduced weed biomass to 14 – 57% as compared to the highest in T5 at all sampling dates (30, 60 and 90 DAS) in both Off Season 2004 and Main Season 2004/2005. For weed composition across the water regime treatments, 11 weed species were recorded in Off Season 2004 and 10 weed species in Main Season 2004/2005. Broadleaved weeds mostly Monochoria vaginalis and Limnocharis flava were the most dominant weeds in most of the water regime treatments. The SDR values of broadleaved weeds were 48.7% (T2) > 46.4% (T1) > 44.2% (T3) > 40.7% (T5) > 35.8% (T4) in Off Season 2004. In Main Season 2004/2005, the SDR values for broadleaved weeds increased to 79.5% (T2) > 68.2% (T1) > 62.4% (T3) > 62.2% (T4) > 50.57% (T5). Sedges mainly Fimbristylis miliacea and Cyperus iria were dominant in Off Season 2004 with SDR value more than 34% in all water regime treatments, but decreased to less than 23% in Main Season 2004/2005. For grasses, mostly Echinochloa crus-galli, Echinochloa colona and Leptochloa chinensis, SDR value more than 20% were recorded in T4 and T5 in Off Season 2004 while in Main Season 2004/2005, SDR value between 21 – 34% were observed in T1, T3 and T5.Meanwhile rice plants treated with T1 significantly produced the highest rice grain yield, followed by T2 and T3, while T4 and T5 were the lowest in weeded plots in both planting seasons. However, rice yield in unweeded plots were not significantly different in all water regime treatments. The rice productions in weeded plots were in the range of 22 – 60% higher in Off Season 2004 and 56 – 78% higher in Main Season 2004/2005 than in unweeded plots. Weed control treatment evidently showed stronger influence than water regime treatments. The percentages of reduction in weeded plots from the highest rice yield in T1 to lowest in T5 were 40% in Off Season 2004 and 44.4% in Main Season 2004/2005. Meanwhile the reduction of rice yield in unweeded plots compared to weeded plots was much higher, which recorded the highest of 59.1% (in T1) in Off Season 2004 and 78.3% (in T4) in Main Season 2004/2005.
The effect of different water regime treatments on viability of weed seeds in rice field was evaluated. Total weed seed reserves in soils taken from Off Season 2004 rice plots were dominated by broadleaved weeds (90625 seeds m-2) mainly Hedyotis corymbosa, Monochoria vaginalis and Ludwigia hyssopifolia, followed by sedges (34257 seeds m-2), mostly F. miliacea and Cyperus iria, while grasses (20647 seeds m-2), predominantly Leptochloa chinensis recorded the lowest number in all water regime treatments. In soils taken from Main Season 2004/2005 rice plots, sedges (53041 seeds m-2) mainly Fimbristylis miliacea along with broadleaved weeds (54624 seeds m-2), predominantly Monochoria vaginalis and Ceratopteris pteridoides dominated in most of the water regime treatments, while grasses, mainly Leptochloa chinensis and Panicum repens again recorded the lowest number (24935 seeds m-2). 10 weed species, which were not observed in the field trials, were recorded from the same soil in the weed seed bank experiment.Differences in water regime treatments did not significantly reduce the viability of weeds seeds in the soil in Off Season 2004. However, a small reduction in seed viability (approximately 8%) was observed in Main Season 2004/2005. As for the similarity between weed seed bank composition and aboveground weed flora composition, a moderate value (62.07 - 73.33%) was observed in Off Season 2004, while in Main season 2004/2005, the value was slightly lower (51.65 – 64.29%)
Parthenium hysterophorus Weed Fecundity and Seed Survival at Different Soil pH and Burial Conditions
No full textParthenium hysterophorus L. is regarded as one of the most invasive weed species. This study evaluated the effect of soil pH on P. hyterophorus weed growth and fecundity, as well as the effect of burial depths on P. hyterophorus seed survival and emergence. The first study evaluated five soil pH levels (acidic, sub-acidic, neutral, sub-basic, and basic) in a randomised complete block design. Seed germinability and subsequent seedling growth (height, leaf area, biomass, and seed number/plant) were evaluated. This study showed that P. hysterophorus seeds have a similar germination capacity under varying soil pH conditions. However, acidic soil indicated accelerated growth (25% higher biomass with 15.2% more leaf area) and fecundity (13.4% faster to enter the flowering stage at 74 days after sowing). In the second study, two factors were tested; burial depths (0.5, 5, 10, and 20 cm) being nested into seven burial durations (0, 2, 4, 6, 8, 10, and 12 months). Seed viability (final germination percentage and germination rate index), electrical conductance, and emergence percentage were assessed with the burial conditions. The results showed that only seed buried at 0.5 cm depth indicated emergence (81.3% of cumulative emergence). Forty per cent of the seeds remained viable after exhumation at 0.5–5 cm depth, while only 19–27% survived as the burial depth increased beyond 10 cm depth within 12 months. The seed remained viable for more than 12 months as a seed bank, despite faster deterioration at increasing soil depth
Occurrence and management of resistant weed species in FGV plantation in Malaysia : a review
No full textOil palm, currently the world’s main vegetable oil crop, is characterized by a large productivity and a long life span (25 years). Weeds are the unwanted plants that grow aggressively, restrict sunlight and compete with desirable plants for nutrients. Weeds population is mainly a mixture of grasses, sedges, broad-leaved weeds plants and fernsin oil palm plantation management. Asystasia gangetica (creeping broad leaf weed), Clidermia hirta (upright woody weed) and Dicranopteris linearis (fern) are amongst noxious weeds under the “must be eradicated”list because of their high tendency to aggressively absorb nutrients and water. In Malaysia alone, since 2004, the use of herbicides has been 67.49% of the total pesticides used. The application of herbicides (e.g. glyphosate, glufosinate, metsulfuron-methyland the recently banned paraquat) in plantations is a common practice even though farmers understand that they are harmful to both applicators and crops if not carefully used. Understanding the mode of herbicidal action is also very useful when diagnosing symptoms of herbicide injuries and to reduce the risk of resistance development in weed populations. Resistance frequently occurs with herbicides that come with very great efficacy to specific weed species, be it acute kill or chronic/slow effect. Herbicide resistance phenomenon in weeds is very depending on the type of herbicides being used (mode of action and selectivity), the period they have been used for, spray dose of the herbicides, the residual effect of the herbicides, the biology and genetic of the weed species being targeted, and existence of other crop management practices that farmers employ.Therefore, weed resistance in Malaysian oil palm plantation is crucial and must be hadle with care to avoid unnecessary effect from herbicide resistance
Introduction to Robotics Agriculture in Pest Control: A Review
No full textAgriculture is one of the latest industries that uses robotic technologies. Cultivation of crops with high yield and quality can be enhanced when technological sustenance is involved. Pests are nuisance and cannot be completely eliminated, but with effective control and management. damages caused by pests could be minimized below economic threshold. Automation in agriculture is stable and accurate and is mainly incorporated in mechanized farming system. However its numerous application in different agricultural practices is not well noticed. Hence this paper attempts to provide profound awareness on robotic technology in agriculture. Robots could have a specific or multiple functions and, most commonly, they are made up of five basic components; sensors, effectors, actuators, controller and arms. Use of automation in weeding, weed mapping, micro spraying, seeding, irrigation and harvesting are progressions which promote sustainable agriculture and food security. In future, solar robots with battery inverter may be invented
Correction: Ser-653-Asn substitution in the acetohydroxyacid synthase gene confers resistance in weedy rice to imidazolinone herbicides in Malaysia.
No full text[This corrects the article DOI: 10.1371/journal.pone.0227397.]
Corn growth, yield and weed composition as influenced by different nitrogen rates and plant densities
No full textSufficient nitrogen application is the main factor in plant growth and yield development processes. Therefore, a field research was conducted during 2020 at Field 15, Faculty of Agriculture, Universiti Putra Malaysia in Serdang, Selangor, to quantify the effect of four nitrogen rates N1 (120 kg N/ha), N2 (140 kg N/ha), N3 (160 kg N/ha) and N4 (180 kg N/ha) and two planting densities D1 (75 x 20 cm) and D2 (65 x 20 cm) on growth and yield attributes of corn variety (GWG 888) and weed composition. The results showed that both factors (nitrogen rates and planting densities) significantly influenced corn growth, yield and weed composition. It was observed that N3 (160 kg N/ha) produced the maximum plant height, number of leaves, cob number, cob length and dry mater yield. The maximum number of the weed species and weed population were obtained with 180 kg N/ha. Higher plant density (65 x 20 cm) decreased plant height and leaf; however, it significantly enhanced dry matter yield. The findings suggested that the use of 160 kg N/ha was appropriate nitrogen rate at 75 x 20 cm, which improved corn growth and yield
Integrated weed management programs at oil palm plantation -A Survey
No full textWeed control is always regarded as one of the essential operations in the oil palm plantation management. It is the second most costly operation after fertilising. Hence, it is vital to manage noxious weeds’ growth in oil palm plantation areas effectively. Integrated weed management (IWM) refers to a system of sustainable weed management. This system is comprehensive through various control strategies that are undeniably capable of reducing the weeds’ impact to reach economically acceptable levels. The most widely practiced IWM method by plantation companies has been mainly spraying herbicide and cultural practices; many companies are solely depending on the chemical approach for weed control. Our survey indicated that IWM methods always produced lower management costs than non-IWM in FGV Lepar Utara. This indicates that the implementation of IWM could save
on weed control cost up to RM34.00/ha/year. Besides, the cultural practices like mulching (in immature palm) and EFB
applications would reduce weeding cost-efficiently. In addition, the arrangement of fronds, circle raking would reduce weeding cost. Thus, the combination of chemical control and cultural practices was preferred. As a conclusion, it would be appropriate to argue that through IWM implementation, among others, weed populations will be reduced to manageable levels, in addition to the environmental impact that can be reduced significantly instead of adopting an individual weed management practice and reducing the occurrence of herbicide resistance in weed species
The impact of carbon dioxide (co2) enrichment on rice (Oryza sativa l.) production: a review
No full textRice (Oryza sativa L.) is one of the world's most important crops and the primary source of calories for more than three
billion people worldwide, especially in Asia. Currently, atmospheric carbon dioxide (CO2) concentration is 416 µmol mol-1 and increasing rapidly due to industrialization, which is the main cause of global warming. Current climate change and rising CO2 concentration in the atmosphere have varying global impacts on crop performance. As CO2 is one of the limiting factors in photosynthesis, adding this gas can increase carboxylation activity, hence increasing productivity and yield. Elevated CO2 (eCO2) significantly impacted C3 crops' productivity by increasing photosynthesis, biomass, and grain yield. Plants cultivated under eCO2 conditions demonstrated better development and photosynthesis, lower transpiration, improved water efficiency, decreased inorganic nutrition concentration, increased plant hormone, and compact stomatal density than the plants grown under ambient CO2 (aCO2) conditions. This review discusses the effects of eCO2 on rice plant photosynthesis and growth. The review also describes that eCO2 increased yield components of rice plants. Finally, the current review emphasizes the grain quality of rice that was negatively affected by eCO2. The review paper aims to describe rice production under CO2
increases under climate changes in the future. The synthesis of all this information is helpful to the researchers, advisors of rice farmers, and policymakers to provide a favourable plan by using eCO2 to increase rice plant growth and yield and maintain grain quality through enriching free-air CO2 enrichment (FACE) system for the rice plant to produce enough, and high-quality food for the increasing population of the world
Ser-653-Asn substitution in the acetohydroxyacid synthase gene confers resistance in weedy rice to imidazolinone herbicides in Malaysia
No full textThe continuous and sole dependence on imidazolinone (IMI) herbicides for weedy rice control has led to the evolution of herbicide resistance in weedy rice populations across various countries growing IMI herbicide-resistant rice (IMI-rice), including Malaysia. A comprehensive study was conducted to elucidate occurrence, level, and mechanisms endowing resistance to IMI herbicides in putative resistant (R) weedy rice populations collected from three local Malaysian IMI-rice fields. Seed bioassay and whole-plant dose-response experiments were conducted using commercial IMI herbicides. Based on the resistance index (RI) quantification in both experiments, the cross-resistance pattern of R and susceptible (S) weedy rice populations and control rice varieties (IMI-rice variety MR220CL2 and non-IMI-rice variety MR219) to imazapic and imazapyr was determined. A molecular investigation was carried out by comparing the acetohydroxyacid synthase (AHAS) gene sequences of the R and S populations and the MR220CL2 and MR219 varieties. The AHAS gene sequences of R weedy rice were identical to those of MR220CL2, exhibiting a Ser-653-Asn substitution, which was absent in MR219 and S plants. In vitro assays were conducted using analytical grade IMI herbicides of imazapic (99.3%) and imazapyr (99.6%) at seven different concentrations. The results demonstrated that the AHAS enzyme extracted from the R populations and MR220CL2 was less sensitive to IMI herbicides than that from S and MR219, further supporting that IMI herbicide resistance was conferred by target-site mutation. In conclusion, IMI resistance in the selected populations of Malaysian weedy rice could be attributed to a Ser-653-Asn mutation that reduced the sensitivity of the target site to IMI herbicides. To our knowledge, this study is the first to show the resistance mechanism in weedy rice from Malaysian rice fields
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