Reduced Weed Growth Research Articles

Comparative analysis of weed management techniques in taro (Colocasia esculenta (L.) Schott)

Weed management poses a significant challenge in taro cultivation since it’s a long-duration crop grown during the monsoon season. The warm, humid conditions of its extended growing period promote rapid weed germination and growth, complicating weed management efforts. To address this issue, a study was conducted at the Bangladesh Agricultural Research Institute, Jashore, in 2021 and 2022 to evaluate sustainable weed management strategies for taro. The experiment, designed as a randomized complete block (RCB) with three replications, tested seven weed control methods: T1= straw mulching (SM), T2= pre-emergence herbicide+SM, T3= poly mulching (PM), T4= pre-emergence herbicide+PM, T5= intercropping+two hand-weeding, T6= pre-emergence herbicide, and T7= four hand-weeding, alongside T8= weed-free and T9= weedy control treatments. Results indicated that all mulching treatments achieved 70% to 80% weed control efficiency, significantly reducing weed growth up to 120 days after emergence (DAE). The intercropping+hand-weeding treatment provided 75% to 80% weed control up to 90 DAE. Among the mulches, straw mulching resulted in the tallest and widest plant base girths, leading to the highest yield and benefit-cost ratio, followed by other mulch and intercropping+hand-weeding treatments. Pre-emergence herbicide treatments were ineffective due to their short duration of action. Additionally, combining mulching (SM & PM) with pre-emergence herbicide offered no advantage over mulching alone. These findings highlight straw mulch as the most effective weed management strategy for taro, eliminating the need for herbicides. Where mulch is unavailable, intercropping combined with hand weeding can be a viable alternative for effective weed control.

Impact of organic and mineral mulch on species richness and weed biomass in newly established wildflower meadows

Creating wildflower meadows through sowing often results in weed emergence during the first year, with irrigation further encouraging annual weed germination. Mulching helps to reduce weeds, alter nutrient levels, and retain soil moisture. This study aimed to investigate the effects of organic (compost) and inorganic (sand) mulch on the number of germinated wildflower species and weed biomass over a two-year period without irrigation. A late autumn (European continental climate) sowing was performed using three wildflower mixtures. Sand and compost, each applied 75 mm thick, were used as mulching materials, with one plot left unmulched as a control. Weed biomass was measured, and species richness and abundance were assessed in the second year. Statistical analysis showed that mulch significantly influenced both species richness and weed biomass. Sand mulch proved particularly effective for establishing wildflower meadows, reducing weed growth. Initially, compost showed good results, but its effects diminished over time, leading to more weeds and reduced species richness. These findings are useful for establishing flowering meadows on soils with a high weed seedbank.

Pioneering Innovations in Biological Weed Control: A Comprehensive Review

The biological method of weed control is an effective option. Before implementing bio-agents, there is a need for a better understanding of the mechanisms involved in interactions by multiple agents against weeds. This covers knowledge of how plants integrate and prioritize their responses to multiple attackers. Across the globe, terrestrial ecosystems are known to be characterized by a huge diversity of species and a corresponding diversity of interactions between these species. These include species of different trophic levels of habitats on the same food chain. Plants undoubtedly play significant role as intermediaries in interactions between the insect and microbial populations with which they are involved. Plant interactions brought forth by one species can have cascading impacts on other species, influencing their abundances and the composition of communities. Several research efforts are underway to develop highly effective biological control agents to reliably control a problematic broad spectrum of weeds. Sustainable and ecosystem-compatible weed management for controlling weeds by biological means, such as insects, bio-agents, myco-herbicides and harmful Rhizobacteria. Their interaction with cultural practices and allelochemicals are some biological components of sustainable agriculture. Hence, biological agents enhance efficiency and restrict the detrimental effect of weeds compared to weeds being left alone. The challenge is to identify appropriate microbe/bioagents, which reduce weed growth. Logically, biological weed management is the only way to control weeds in eco-friendly weed management.

Ultraviolet Shielding Performance of Coconut Coir as a Filler in Low-Density Polyethylene (LDPE) Plastic Mulch

Plastic mulch is a layer of material applied to the soil surface to maintain moisture retention in the soil by preventing evaporation, reduce weed growth by blocking sunlight from reaching underlying weeds, and optimize fertilizer use by minimizing nutrient loss to the environment. However, the degradation of low-density polyethylene (LDPE), a thermoplastic commonly used for mulching, into microplastics due to exposure to UV radiation. This research explored the potential of coconut coir, a natural fiber with a high lignin content ranging from 30 to 46%, as a UV protective agent. The objective was to develop biodegradable plastic-based mulch composites that have better resistance to UV exposure by incorporating coir as a filler material in LDPE-based composites. Different ratios of coconut fiber were used (10%, 20%, 30%, and 40%), and Maleic anhydride grafted polyethylene (PE-g-MAH) was used as a binder at 2% of total weight mixed with LDPE in a rheomixer (80 rpm, 120°C for 10 min). The resulting plastic mulch bio-composites were evaluated for thermal, mechanical, UV resistance, and biodegradability properties. The results showed that the higher addition of coconut coir resulted in a decrease in the thermal and mechanical characteristics of the composite. However, the addition of higher coconut coir in the composite at 40% can provide an increase in the composite's resistance to ultraviolet light exposure, and the properties are easily degraded by the environment (biodegradable).

Soil C:N impacts on soil biological health and consequences on weed control in soybean and corn systems

Abstract Nitrogen availability has an important influence on agricultural weed growth, because many weeds in annual cropping systems are more competitive in high-nitrogen soils. A potential method to control nitrogen availability is through soil carbon amendments, which stimulate soil microbial growth and immobilize nitrogen. Additionally, carbon amendments may alter soil microbial community composition, increase soil biological functioning, and improve soil health. In a 2-yr field experiment in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.], we implemented five amendment treatments to test their ability to alter weed and crop growth through soil nitrogen availability and soil biological functioning. The treatments included: an untreated control, an unamended weed-free control, rye hay adding 3,560 kg C ha−1 and 3,350 kg C ha−1 in 2020 and 2021, respectively, sawdust adding 5,030 kg C ha−1 and 4,350 kg C ha−1 in 2020 and 2021, respectively, and a rye hay and sawdust combined treatment adding 8,590 kg C ha−1 and 7,700 kg C ha−1 in 2020 and 2021, respectively. Each treatment was replicated five times in corn and six times in soybean. Each season, we explored correlations between crop and weed biomass and weed community composition and nitrogen immobilization measured through soil respiration and nitrogen availability. We also explored changes to the soil microbial community composition and soil health as a secondary result of the carbon amendment treatments. Nitrogen availability was lowest in plots treated with the highest C:N amendment. Increasing carbon improved soil health metrics, but the microbial community composition was most affected by the rye hay treatment. Amendments with high C:N reduced weed growth in both soybean and corn plots but only selected for specific weed communities in soybean, leading to improved soybean competitiveness against weeds. In corn, crop growth and weed community composition remained consistent across amendment treatments. Targeted nitrogen immobilization may improve leguminous crop competition in some weed communities as part of an integrated weed management program.

Biological control of selected weeds of direct-seeded rice through application of allelopathic Pseudomonas strains

ABSTRACT Weeds are a major obstacle in the widespread implementation of direct seeding of rice (DSR). Traditional weed control methods have raised serious environmental and health concerns. In this study rhizobacterial strains were assessed for the growth inhibition of Leptochloa chinensis, Dactyloctenium aegyptium, and promotion of rice. For initial screening, hydrogen cyanide (HCN) and Escherichia coli (E. coli) was employed. After screening, plant growth-promoting traits were assessed, and two in vitro growth reduction and growth promotion trials were conducted on weeds and rice. Based on 16S ribosomal RNA (16S rRNA) gene sequencing, all selected rhizobacteria belonged to Pseudomonas spp. The results of the laboratory experiment showed that strains R4-1 (Pseudomonas plecoglossicida) and R16-10 (Pseudomonas fluorescens) exhibited significant ability to inhibit the growth of selected weeds, while potential to enhance the growth of rice. Further evaluation in pot trial under ambient light and temperature conditions showed that the selected strains significantly reduced weed growth and yield parameters of both weeds compared to the control. Strains R16-10 and R4-1 decreased the biomass of Leptochloa chinensis and Dactyloctenium aegyptium by 20% and 15%, respectively. The trial confirmed that strain R16-10 significantly increased DSR growth traits infested with Leptochloa chinensis and Dactyloctenium aegyptium, including grain yield (10% and 12%) and photosynthetic rate (9% and 7%). Furthermore, strain R4-1 was also effective in promoting the growth, yield, and physiological attributes of DSR. These results suggest that the strain R16-10 and R4-1 can reduce Leptochloa chinensis and Dactyloctenium aegyptium growth while promoting DSR growth.

Weed control and productivity of maize (<i>Zea mays </i>l.) interseeded with Jointvetch (<i>Aeschynomene histrix</i> Poir.) at different sowing arrangements

The use of forage legume with cereals offers a potential for increasing food and forage production. Field study was conducted during the rainy seasons of 2015 and 2016 to determine the effect of interseeding Jointvetch (Aeschynomene histrix) at different sowing arrangements on weed control, growth and yield of maize. The treatments were one hoe weeding at 3 weeks after sowing (WAS) followed by (fb) one row of Jointvetch drilled by the side of the ridge at 3 WAS, one hoe weeding at 3 WAS fb two rows of Jointvetch drilled by the sides of the ridge at 3 WAS, one hoe weeding at 3 WAS fb one row of Jointvetch drilled within the furrow at 3 WAS, one hoe weeding at 3 WAS fb two rows of Jointvetch drilled within the furrow at 3 WAS, one hoe weeding at 3 WAS fb Jointvetch broadcast within the plot at 3 WAS, two hoe weeding at 3 and 6 WAS and a weedy check arranged in a randomized complete block design (RCBD) and replicated three times. Data collected on weed dry weight, plant height, cob length, cob diameter and grain yield were subjected analysis of variance (ANOVA) at P ≤ 0.05. Weed dry weight, plant height, cob length, cob diameter and grain yield were significantly (p≤0.05) influenced by Jointvetch arrangement. The magnitude of weed suppression was lowest in the plot with Jointvetch broadcast, which also produced taller plants, longer cobs, wider cobs and highest grain yield compared to the weedy check. Grain yield in plots interseeded with Jointvetch and two hoe weeding at (3 and 6 WAS) were comparable and higher than that in the weedy check. Our findings demonstrated that one hoe weeding at 3 WAS fb Jointvetch broadcast can reduce weed growth and increase grain yield of maize.

A comprehensive life-cycle assessment of plastic mulching for maize

While plastic mulch (PM) can increase crop yield, there are negative environmental impacts associated with the production, use and disposal of PM films. There is currently a gap in the literature on the negative impacts of PM throughout its entire life cycle, with most studies focusing on the global warming potential (GWP) only. The objective of this study is to conduct a life-cycle assessment (LCA) of PM to investigate the environmental impacts of all stages of mulching. The LCA was conducted using the SimaPro with data obtained from the relevant literature and ecoinvent database. The system boundaries include the production, transportation, installation, operation, removal and disposal of PM. The results reveal that the field operation of PM has the highest impact in GWP. A sensitivity analysis was also conducted and the GWP impact was observed to be sensitive to changes in carbon dioxide and net ecosystem carbon dioxide budget. The production of PM has the highest impact in abiotic depletion, but this impact can be reduced through energy recovery. Incineration yields the least harmful impacts, but the results of the study may vary depending on the exact disposal method. The impact of PM can be mitigated through proper waste management and mitigation measures, including regulations on disposal.

Effect of plastic mulch and strip tillage on soil hydrothermal characteristics and potato cultivation in the Bogura district of Bangladesh

AbstractFuture periods with limited water resources in Bangladesh will need the use of effective water‐saving technology, such as mulching, to increase potato production in a sustainable way. This study investigated the effect of plastic mulch on soil hydrothermal status and its consequent effect on potato production over 2 years in field experiments in Bogura, Bangladesh. We cultivated potato under four treatments: two coloured (black and blue) plastic mulches, strip tillage and no mulch. The black plastic mulch raised the soil temperature by 1.2–2.4°C in the early growth stages and by 0.4–1.2°C in the later growth stages compared to the no‐mulch treatment. This mulch raised soil moisture by 5.1–15.9% and reduced weed growth by 91% compared to no mulch. The nitrogen, phosphorus and potassium contents of the soil were significantly higher under the mulching treatments compared to no mulch. When compared to the blue and no‐mulch treatments, black mulch provided 31–34% and 45–48% more tuber yield of potato, respectively, which significantly improved the economic benefits under mulching treatments. Black plastic mulch is therefore suggested as a workable adaptation approach to increase potato production under limited water resources in northern Bangladesh and elsewhere with similar agroclimatic conditions.

Enhanced-efficiency fertilizers on the growth of coffee plants under weed (Bidens Pilosa) competition stress

The interference of weeds in coffee cultivation is one of the factors contributing to losses and impairments in crop growth and productivity. Consequently, it becomes necessary to employ strategies aimed at mitigating this stress and facilitating optimal crop development through enhanced nutritional practices. This study aimed to assess the impact of various sources and modes of release of enhanced-efficiency phosphate fertilizers on the initial growth of Coffea arabica L. plants in competition with the weed Bidens pilosa in a greenhouse. The experiment was conducted at the Federal University of Vales do Jequitinhonha and Mucuri – Diamantina MG, Brazil, employing a block design in a 4 x 6 factorial arrangement with four replications. The factors corresponded to four levels of B. pilosa infestation and six phosphorus sources (Super Single, Conventional, MAP, Granulated Organomineral, Pelleted Organomineral, MAP Coated with Polymer, and a control treatment without fertilization). The findings suggest that under the experimental conditions of this research, the escalating density of weed competition from B. pilosa negatively impacts the initial growth of coffee plants. However, this effect is dependent on the source of phosphate fertilization. Fertilizers with slow-release phosphate sources are recommended for coffee plantations, as they contribute to reduced weed growth in comparison to coffee plants.

Occurrence of Pesticides in Polished Rice Samples From Tanjung Karang and Sekinchan and the Health Risk among Consumers

Introduction: One of the key staple foods in many different countries, including Malaysia, is rice (Oryzae sativa L.). Pesticides are used to reduce weed growth and safeguard crops from insect attacks in order to boost paddy output. Objective: This research quantifies the concentration of pymetrozine, chlorantraniliprole, and difenoconazole, along with any potential health risks to consumers. Methods: Samples of polished rice from three rice milling factories in Tanjung Karang and Sekinchan were extracted using the QuEChERS (Quick Easy Cheap Effective Rugged Safe) technique. The amount of pesticide residue in polished rice was then measured using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A health risk assessment was conducted utilizing the Hazard Quotient (HQ) and Lifetime Cancer Risk (LCR) to estimate the non-carcinogenic and carcinogenic health risks. Results: The mean concentration of pesticides in polished rice ranged from less than the detection limit (difenoconazole) to 1.122 µg/kg (pymetrozine). No rice samples above the Maximum Residue Limit (MRL) specified in the Food Act 1983 as implemented by Malaysia’s Food Regulations 1985. Pymetrozine, chlorantraniliprole, and difenoconazole in rice had respective MRLs of 50 µg/kg, 2000 µg/kg, and 100 µg/kg. For all age groups, no significant non-carcinogenic health risk was associated with consuming polished rice from the study area, where the HQ and Hazard Index (HI) were less than one. When LCR values were less than 10-6, carcinogenic health risks of consuming polished rice from the study area were at a clearly acceptable risk level. Conclusion: As no sample exceeded the MRL, the findings indicated that all rice samples collected from Tanjung Karang and Sekinchan were safe for consumption.

Impact of different establishment methods for summer-sown cover crops in Southwestern Germany on their weed suppression properties

Early establishment of cover crops (CCs) is essential for attaining successful weed suppression in the autumn-to-spring period. Due to reduced precipitation and extended periods of drought in the summer within temperate zones, the establishment of CCs poses challenges. Three methods of cover crop (CC) establishment were tested: 1) preharvest sowing 10 days before harvest of cash crop (PreHa); 2) no-till sowing directly after harvest of cash crop (NoTi) and 3) sowing with reduced tillage 10 days after harvest of cash crop (ReTi). The five CC species black oat (Avena strigosa Schreb.); common buckwheat (Fagopyrum esculentum Moench), phacelia (Phacelia tanacetifolia Benth.), fodder radish (Raphanus sativus var. oleiformis L.) and common vetch (Vicia sativa L.), along with a mixture comprising 20% of all five species, were included as second factor in a three-year field experiment (2020–2022) conducted in South West Germany. One treatment per establishment method was maintained without CCs as a control. Measurements of CC, volunteer cereal and weed density, soil coverage, and dry matter were carried out throughout the autumn-to-late autumn timeframe. On average across all years and CCs, the PreHa and NoTi establishment demonstrated the highest CC dry matter contents of 99 g m−2 and 119 g m−2, respectively, despite lower CC densities. This had a particularly notable impact on weed density in the ReTi variant, which, over the three-year average across all CC treatments, was 5 times higher than in NoTi and PreHa but exhibited a 18–27% smaller volunteer cereal density by comparison, thereby influencing the respective volunteer cereal and weed coverages. Meanwhile, weed and volunteer cereal dry matters were consistent across all establishment methods. The CC mixture exhibited enhanced resilience to fluctuating weather conditions, leading to an overall superior performance across the three-year experimental period and showing highest measured CC dry matters up to 272 g m−2 in 2022. However, the observed effects in the treatments varied considerably depending on the CC species, sowing date, and weather conditions. In summary, this study demonstrates that early CC sowing, whether directly after the cash crop harvest or 10 days before the cash crop is harvested, has a positive impact on CC biomass formation, especially leading to a reduced weed emergence. Additionally, under variable weather conditions, a diverse CC mixture can exhibit a more stable overall performance compared to CC monocultures.

A review of soil pollution from LDPE mulching films and the consequences of the substitute biodegradable plastic on soil health

The plastic film mulching system has a significant role in increasing crop grain yields by changing the microenvironment of the plant. On the other hand, plastic mulching materials pollute the land and water because they are not degraded or disposed of properly. Biodegradable plastic mulches (BPM) may be used as a substitute for conventional low-density polyethylene (LDPE) to protect soil health. In this review, the effect of micro(nano)plastics on soil health and function has been discussed in light of their distribution in soil, changes in soil biochemistry, interactions between microplastics with soil microbes and plants, and their growth patterns. The nano-plastics are now incorporated into the food chain from the soil through plants and finally harm the whole ecosystem, including humans. The use of BPM has been practiced recently, but only 1% of the world’s total plastic production is from biodegradable materials. In the second part of the review, the confusing terms "bio-based" and "biodegradable" were clarified based on their polymeric constituents. The physical parameters of different constituent materials for mulching purposes and their capability for sustainable solarization have been discussed. The effect of biodegradable mulches on soil health and other ecotoxic effects on plants, soil microorganisms, and other soil dwellers like Daphnia magna, Vibrio fischeri bacteria, green algae, slime mould, protozoa, invertebrates like earthworms, and common water fleas have been focused on in this review. In conclusion, the use of BPM for mulching purposes was reported to improve crop quality and yield and reduce weed growth in comparison to naked soil. The recent short-term studies ensured that mulches stayed unbroken throughout the growing season. But simultaneously, the biodegradable mulches affect soil health and have a substantial impact on physical parameters such as soil pH, electrical conductivity, aggregate stability, infiltration, nitrate-N, exchangeable potassium, etc. Therefore, a lot of long-term research is required for the use of BPM as a substitute for conventional LDPE as a mulching film in the agricultural field.

Living Mulch as Sustainable Tool to Improve Leaf Biomass and Phytochemical Yield of Cynara cardunculus var. altilis

Living mulch (LM) provides many beneficial agro-ecological services by reducing soil evaporation, conserving moisture, controlling soil temperature, reducing weed growth, increasing organic matter and nutrient availability, and improving microbial activities. Legumes, commonly used as living mulches, can affect the yield and quality of main crops. We hypothesized that Egyptian clover co-cultivated with Cynara cardunculus var. altilis (cultivated cardoon) can positively affect both leaf biomass and phytochemical yield. The study was performed on two growing seasons of field experiments to evaluate the potential variation in biomass and phytochemical yields of cardoon leaves. In addition, the leaves were collected at 90, 120, and 150 days after transplanting to evaluate the possible effect of the harvest time. LM improved the fresh and air-dried leaves biomass yields, total phenolic, and dry matter content, while it had no effect on the content of crude fibre, total sugars, L-ascorbic acid, total chlorophylls, and antioxidant activity. Except for luteolin-7-O-glucoside content, no negative effect of LM was observed on the polyphenol profile. Behind the cultivation system, the parameters were also affected by both the harvest time and growing season. According to our data, the proposed intercropping of cultivated cardoon with LM could represent an innovative cultivation system to increase both leaf biomass and the health-promoting compounds of cultivated cardoon leaves by sustainable soil management.

Increasing Array of Herbicides for Post-emergence Weed Control and Seed Yield in Maize (Zea mays Linn)

Study was conducted at the Institute of Agricultural research and Training (IAR&T) Ilora (Derived savanna agro-ecology) substation in the rainy seasons of 2014 and 2015, to appraise herbicides for post-emergence weed control and increase array of herbicides for weed control in maize. Weed samples were taken from a three-year fallow field before land preparation. Herbicides under evaluation were assigned to 3 x 3 plots at different rates. These were arranged in randomized complete block design (RCBD) with three replicates. The results showed that initial weed flora richness were 22% and 78% grass and broad-leaved weeds respectively. These were found in five (5) plant families. All the weeds sampled were annuals. Narrow annual weed spectrum, described continuous cropping activities in the location. Herbicides improved plant height by 36 to 50% compared to weed infested maize plants. Though phyto-toxicity was evident at three and twenty-one days after treatment (DAT), ranging from 1/10 to 3.79/10 and 2/5 and 3.67/10 correspondingly when visually rated (0 – 10 scale). Notwithstanding, herbicides gave impressive weed control rate (WCR) at 21 DAT (6.7/10 - 8.7/10), with evidence of superior weed control efficiency (WCE >80%) at harvest across herbicide treated plots relative to weedy control plots. 2,4-D DMA (0.86 kg ai/ha), Fluroxypyr methyl (0.40 ai kg/ha), 2,4-D + Dicamba (0.68 + 0.24 kg ai/ha) and 2,4-D DMA (2.58 kg ai/ha) had <30% relative yield loss (RYL%) with comparable seed yield compared to the highest recorded in weed-free plot (13.29 t/ha). Plant height at 8 WAS (weeks after sowing) had significant inverse relationship with weediness at 5 WAS and weed dry weight at harvest (- 0.62). Consequently, early weed control is essential for maize performance. On the other hand, plant height enhanced weed control efficiency at harvest (0.62). Tall plants have tendency to reduce relative yield loss (RYL %) as they were inversely related 1 (- 0.42). Comparable WCE% (83 -99%) in herbicide treated plots reduced weed growth by about 88%. Hence, lower rate of herbicides with <30% phyto-toxicity level should be considered to increase array of herbicides for post-emergence weed control, sustainable maize production and environmental friendliness.

Chemical leaching from polyethylene mulching films to soil in strawberry farming

Mulching is a widely practiced agricultural technique able to boost crop productivity and to reduce weed growth and water evaporation. One of the most common materials used for mulching is polyethylene. Polyethylene films are known to contain phthalates, plasticizers recognized as endocrine disruptors, thus able to endanger the hormonal system. Only few data exist on the possible transfer of plasticizers from polyethylene mulching films to agricultural soil, especially in Europe, or on the potential implications for the environment and human health. In this study, we analyzed the occurrence of plasticizers such as phthalates and acetyl tributyl citrate from polyethylene mulching films and soil samples collected from strawberry fields where polyethylene films have been used. The samples were analyzed with a gas chromatograph-mass spectrometer and the results indicated that the soil exposed to polyethylene mulches contained a significantly higher concentration, compared to the control soil, of some of the most common plasticizers, including dibuthyl phthalate, benzylbutyl phthalate and acetyl tributyl citrate. These outcomes highlight the need to carry out further research to understand the potential risks that mulching practices can cause for the environment and human health.

Complementary peptides represent a credible alternative to agrochemicals by activating translation of targeted proteins

The current agriculture main challenge is to maintain food production while facing multiple threats such as increasing world population, temperature increase, lack of agrochemicals due to health issues and uprising of weeds resistant to herbicides. Developing novel, alternative, and safe methods is hence of paramount importance. Here, we show that complementary peptides (cPEPs) from any gene can be designed to target specifically plant coding genes. External application of synthetic peptides increases the abundance of the targeted protein, leading to related phenotypes. Moreover, we provide evidence that cPEPs can be powerful tools in agronomy to improve plant traits, such as growth, resistance to pathogen or heat stress, without the needs of genetic approaches. Finally, by combining their activity they can also be used to reduce weed growth.

Effect of Substrate Stratification Without Fine Pine Bark Particles on Growth of Common Nursery Weed Species and Container-grown Ornamental Species

Substrate stratification is a new research area in which multiple substrates, or the same substrate with differing physical properties, are layered within a container to accomplish a production goal, such as decreasing water use, nutrient leaching, or potentially reducing weed growth. Previous research using stratification with pine (Pinus sp.) bark screened to ≤1/2 or 3/4 inch reduced the growth of bittercress (Cardamine flexuosa) by 80% to 97%, whereas liverwort (Marchantia polymorpha) coverage was reduced by 95% to 99%. The objective of this study was to evaluate substrate stratification with pine bark screened to remove all fine particles as the top strata of the substrate and determine its effect on common nursery weeds and ornamental plants. Stratified treatments consisted of pine bark screened to either 1/8 to 1/4 inch, 1/4 to 1/2 inch, or 3/8 to 3/4 inch, applied at depths of either 1 or 2 inches on top of a standard ≤1/2-inch pine bark substrate. An industry-standard treatment was also included in which the substrate was not stratified but consisted of only ≤1/2-inch pine bark throughout the container. A controlled-release fertilizer was incorporated at the bottom strata in all stratified treatments (no fertilizer in the top 1 or 2 inches of the container media), whereas the industry standard treatment had fertilizer incorporated throughout. Compared with the nonstratified industry standard, substrate stratification decreased spotted spurge (Euphorbia maculata) counts by 30% to 84% and bittercress counts by 57% to 94% after seeding containers. The shoot dry weight of spotted spurge was reduced by 14% to 55%, and bittercress shoot dry weight was reduced by 71% to 93% in stratified treatments. Liverwort coverage was reduced by nearly 100% in all the stratified substrate treatments. Compared with the industry standard substrate, stratified treatments reduced shoot dry weight of ligustrum (Ligustrum japonicum) by up to 20%, but no differences were observed in growth index, nor were any growth differences observed in blue plumbago (Plumbago auriculata).

Agri-Biodegradable Mulch Films Derived from Lignin in Empty Fruit Bunches

Mulch films increase soil temperature, maintain soil moisture, improve water and fertilizer absorption, and reduce weed growth. This work studied a mulching film made using polyvinyl alcohol (PVA) and lignin extracted from empty fruit bunches (EFBs). The mulch films were investigated for opaqueness, biodegradation, water-solubility, absorption, and mechanical properties. Life cycle assessment (LCA) and cost estimate analysis were conducted. The composite mulch film-PVA solution was blended with 6% EFB lignin in dimethyl sulfoxide (DMSO) solution using five different amounts (0, 20, 40, 60, or 80 wt% lignin). The results showed that increasing the amount of lignin increased the film’s water solubility, moisture content, and biodegradability. At the same time, water absorption tended to decrease. Consequently, the light transmittance of the film was reduced, which had a positive effect on preventing soil weed growth. Tests of the mechanical properties showed that 60% lignin in the PVA film had the highest tensile strength (16.293 MPa). According to the LCA studies and cost estimation, the lignin-mixed PVA film had the lowest impact and was cheaper than the commercial mulching film. The results suggested that it is possible to blend polyvinyl alcohol polymer with lignin to improve biodegradability up to 25.47% by soil burial and 32% by water solubility.

Influence of Weed Control Techniques on Weeds, Yield, and Economics of Dry Direct-seeded-Drip-irrigated Rice under Philippine Conditions

The use of herbicides in combination with hand weeding has been shown to be effective against a variety of weeds in irrigated and rainfed wet direct-seeded rice in the Philippines. In the case of dry direct-seeded-drip-irrigated rice; however, these aspects are not known. A study was conducted to determine the influence of two weed control techniques on weeds, yield, and economics of dry direct-seeded-drip-irrigated rice under Philippine conditions. Four treatments – [T1] unweeded; [T2] application of pre-emergence herbicide using pretilachlor, followed by two times hand weeding; [T3] application of post-emergence herbicide using bispyribac-sodium, followed by two times hand weeding; and [T4] weed-free using the sequential application of pre- and post- emergence herbicides followed by six times hand weeding – were tested and arranged in RCBD with three repetitions. T1 has the highest weed density and biomass with lower grain yield (901.8 kg ha–1) but no net income. T2 and T3 had lower weed biomass than T1 but could not be compared with T4, where no weed density and biomass were recorded at 15, 30, and 45 DAS (days after seeding) in both dry and wet seasons. Grain yields at T2 (3,794.4 kg ha–1) were not significantly different from T3 (4,341.3 kg ha–1) except when compared with T4 (5,7245 kg ha–1). Net income in T2 was higher by PHP 20,575.1 over T1 and T3 by PHP 9,831.4 over T2. T4 had the highest grain yield among all treatments and achieved an advantage of PHP 45,272.1, 24,697.0, and 14,865.7 over T1, T2, and T3, respectively, in terms of net income. Herbicide application followed by hand weeding reduced weed growth and improved rice yield and net income. The combination of pre- and post-emergence herbicides followed by six times hand weeding was much more effective at suppressing weeds and achieving higher grain yield and net income.