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Weeds are one of the major limiting factors for wheat production. So, a study was conducted to integrate allelopathic bacteria with a reduced dose of chemical herbicide for sustainable wheat production in wild oat infestation. Cyanide-producing Pseudomonas strains were applied in 4 combinations with and without 2 chemical herbicides (Axial and Atlantis) at the 25% and 50% recommended doses under axenic conditions. Results showed that the C4 bacterial combination (combination of B11×T19×T24×T75 bacterial strains) significantly reduced the growth and development of wild oat under 50% Axial while increasing wheat growth. Subsequently, C4 combination and Axial herbicide were selected for field evaluation, where they reduced the weed density (82.1%), soil plant analysis development (SPAD) value (26.0%), grain yield (88.2%) under 75% Axial, relative wild oat density (70.9%), photosynthetic rate (26.6%), and transpiration rate (25.6%) under 50% Axial in wild oat. While the C4 combination improved SPAD value (26.9%), shoot length (10.1%), tillering (33.3%), biological yield (32.7%), straw yield (24.4%), grain yield (46.8%), transpiration rate (9.6%), and stomatal conductance (14.7%) in wheat under 75% Axial. The increase in growth and yield of wheat was found to be similar to C4 under 50% and 75% Axial. Thus, it is concluded that allelopathic bacteria could be used with 50% Axial for sustainable wheat production under wild oat. [ABSTRACT FROM AUTHOR]

The allelophaty expressed by soil cover crops over weed varies according to species, quality and quantity of material produced. The purpose of this study was to evaluate the potential of cover crops and in the management of weeds and their effects on soybean yield. The experiment was laid in tri-factorial randomized block design with four replication. Factor A was cover crops (oats, forage chicory, quinoa and fallow), factor B was application of paraquat 400 g i.a ha−1, glyphosate 1200 g i.a ha−1 and mowing and factor C was one and two applications of post-emergent herbicide (glyphosate). For cover crops, the percentage of soil cover was evaluated at 53 DAE (days after emergence) of soybean. Weed species and their densities at 53 DAE of soybean were identified. At the end of the experiment, soybean yield was evaluated. The data were analyzed by the F test and comparison between means by the Tukey test (P ≤ 0.05). Oats are the best option for weed inhibition and early soybean development. Quinoa and forage chicory were slow to cover the soil, but weed inhibition occurred. There were no large variations in post-emergence herbicide applications, which made possible to reduce an application without compromising the expected result. [ABSTRACT FROM AUTHOR]

To solve the problems of the damage of weed in paddy field on crop yield and quality, the impact of chemical herbicides on the ecological environment, and the soil pollution caused by plastic film mulching, the field-positioning test was carried out in 2015 to 2017. Taking Daohuaxiang 2 as the test material, three treatments (plant fiber-based degradable film, plastic film, and CK) were setup to investigate the effects of plant fiber-based degradable film on the weed inhibition, warming effect under mulching cultivation, rice yield, rice quality, and economic benefit. The results showed that compared with CK, the plant fiber-based degradable film and plastic film reduced the weed by 85.5% to 87.7% and 78.7% to 81.7%, respectively. Plant fiber-based degradable film mulching cultivation can increase the soil temperature of soil layer 0 to 0.1 m depth. In 2015 to 2017, rice yield with plant fiber-based degradable film increased by 8.71%, 7.53%, and 9.02%, respectively. Plant fiber-based degradable film can significantly reduce the hardness, increase its adhesion, and improve the eating quality of rice. Different films mulching had a certain impact on crop economic benefit. During the developmental stage of the panicle, the plant fiber-based degradable film began to crack, and by the blossom fruit period, the degradation rate reached the grade of 3 or 4. Therefore, the use of plant fiber-based degradable film instead of plastic film can reduce the amount of weed under the membrane and create a more suitable soil temperature, which was conducive to rice yield and quality. [ABSTRACT FROM AUTHOR]

In this study, we investigated the allelopathic effect of Secalecereale cultivars on different weeds that grow in the cultivated fields of Perilla frutescens. Two S. cereale cultivars, Paldong and Singhi, were used to test the allelopathic effect on in vitro grown Digitaria ciliaris, Chenopodium album, Amaranthuslividus, Portulaca oleracea, Pinellia ternata and Commelina communis. The results indicated that S. cereale extracts affect callus growth of weeds in terms of fresh weight and percentage of growth inhibition. The inhibitory effects of both S. cereale cultivars combined with grass cover extracts were higher than using grass weeds alone. Concentrations of all identified phenolic compounds were significantly higher in the leaves extracts of Paldong compared to Singhi. Particularly, syringic acid in leaves extract of the Paldong cultivar were 12.87-fold higher than in the Singhi cultivar. The other predominant phenolic compounds such as salicylic acid, p-coumaric acid, vanillic acid, and p-hydroxybenzoic acids were 3.30, 4.63, 3.11, and 1.28 times higher, respectively, in the leaves extracts of Paldong compared to Singhi. Principal component analysis (PCA) results indicated that the composition of phenolic compounds was significantly related to cultivar types and plant parts used. In addition, biomass increase caused increased weed inhibitory capacity of S. cereale both in tillage and no-tillage regimes. These results suggest that the biomass of cover crops negatively influenced weed density. [ABSTRACT FROM AUTHOR]

In this study, we investigated the allelopathic effect of Secale cereale cultivars on different weeds that grow in the cultivated fields of Perilla frutescens. Two S. cereale cultivars, Paldong and Singhi, were used to test the allelopathic effect on in vitro grown Digitaria ciliaris, Chenopodium album, Amaranthus lividus, Portulaca oleracea, Pinellia ternata and Commelina communis. The results indicated that S. cereale extracts affect callus growth of weeds in terms of fresh weight and percentage of growth inhibition. The inhibitory effects of both S. cereale cultivars combined with grass cover extracts were higher than using grass weeds alone. Concentrations of all identified phenolic compounds were significantly higher in the leaves extracts of Paldong compared to Singhi. Particularly, syringic acid in leaves extract of the Paldong cultivar were 12.87-fold higher than in the Singhi cultivar. The other predominant phenolic compounds such as salicylic acid, p-coumaric acid, vanillic acid, and p-hydroxybenzoic acids were 3.30, 4.63, 3.11, and 1.28 times higher, respectively, in the leaves extracts of Paldong compared to Singhi. Principal component analysis (PCA) results indicated that the composition of phenolic compounds was significantly related to cultivar types and plant parts used. In addition, biomass increase caused increased weed inhibitory capacity of S. cereale both in tillage and no-tillage regimes. These results suggest that the biomass of cover crops negatively influenced weed density.

[Display omitted] • An anti-freezing and self-healable hydrogel (COCu-K) mulch film is fabricated for weed control. • The structure and gelation time of COCu-K can be moderated by the addition of KCl. • Dehydrated COCu-K fragments spread on soil self-heal in situ into an intact gel film by watering. • COCu-K gel promotes pepper seedlings' growth and inhibites germination of weed seeds. • COCu-K hydrogel mulch has suitable biodegradability and good biosafety. Hydrogel is widely used in agriculture as water retention agent and fertilizer delivery vehicle due to its highly porous and hydrated structure. Hydrogel loses water gradually and becomes fragile, which greatly hinders its potential application as mulching film for weed control as the weeds can penetrate the weakened hydrogel film easily. Here, we report a self-healable and biodegradable hydrogel (COCu-K) mulching film composed of chitosan derivatives, copper-doped carbon dots (Cu-CDs) and KCl for weed inhibition. The dehydrated COCu-K hydrogel fragments spread on top of soil self-heal in-situ into an integrate hydrogel film by simple watering, preventing the germination and growth of weeds. SEM reveals the well-dispersed multi-hierarchical structure on the surface of COCu-K hydrogel. The effects of dosages of KCl and Cu-CDs on the hydrogel structure and consequent performances of hydrogel mulching film including self-healing, anti-freezing, weeds inhibition have been explored. The pot experiments illustrated a weed seeds inhibition ratio of 90% and strengthened growth of pepper seedlings induced by the best practice hydrogel COCu 0.08 -K 2.5. Meanwhile, the COCu 0.08 -K 2.5 hydrogel shows an outstanding degradability with a degradation rate of 63.61±3.26% within eight weeks, and soil containing degraded COCu 0.08 -K 2.5 hydrogel presents no phytotoxicity. This study provides a facile and viable strategy to design and utilize hydrogel mulching for weed control. [ABSTRACT FROM AUTHOR]

Na literatura mundial, observa-se predominância das folhas como meio preferencial de estudos de compostos químicos promissores, embora informações sobre outras frações da planta também sejam encontradas. Essa tendência se deve ao fato de que a maioria dos estudos mostra as folhas com atividade potencialmente alelopática de intensidade superior à das demais frações. Nesta revisão, procurou-se compilar e analisar as informações disponíveis sobre a importância das sementes como fonte alternativa de compostos químicos com atividade alelopática. São discutidas as variações na produção e na alocação de aleloquímicos em função do estádio ontogenético das sementes presentes no banco de sementes. É discutido também o papel dos aleloquímicos produzidos por sementes na repelência de insetos, na inibição do desenvolvimento de patógenos nas sementes, na inibição do desenvolvimento inicial de plantas daninhas e como sinalizador positivo para a simbiose com microrganismos do solo. Apresenta-se ainda a atividade alelopática de diversas substâncias isoladas de sementes, destacando-se os alcaloides, flavonoides, benzoxazinoides e resinas glicosídicas. Os estudos de aleloquímicos produzidos por sementes podem contribuir expressivamente para o melhor entendimento do papel ecológico que essas substâncias desempenham na ecologia química dos agro e ecossistemas.In the literature, leaves predominate as preferred source of studies of promising allelopathic compounds, but information on other plant fractions are also found. This trend is due to the fact that most studies show that leaves have higher allelopathic potential than other plant fractions. In this review, we compiled and analyzed the information available on the importance of seeds as an alternative source of chemical compounds with allelopathic activity. We discussed the variations in production and allocation of allelochemicals at different ontogenetic stages of the seeds in the seed bank. The role played by the allelochemicals produced by the seeds on insect repellency, inhibition of the development of pathogens in seeds, initial development of competing plants and as positive signaling for the symbiosis with soil microbes were also studied. The allelopathic activity of several compounds isolated from the seeds was presented, especially alkaloids, flavonoids, resins, and benzoxazinoid glucosides. Studies of allelochemicals produced by the seeds can contribute significantly to a better understanding of the ecological role they play in the chemical ecology of agro-ecosystems and ecosystems.

Since 2015, chemical weed control on public pavements in Flanders has been banned. This necessitates alternative weed control strategies. In this study, growth chamber experiments evaluated the weed suppressive ability of different joint filling materials under various water regimes. The tested materials comprised five unbound standard fillers (white quartz sand, sea sand, limestone 0/2 mm, limestone 2/6.3 mm and porphyry 2/6.3 mm) and two innovative materials (Dansand® and Eco Fugensand®). Their weed suppressiveness was tested in pure and organically polluted states. Germination and biomass accumulation of two weed species that are abundantly found on public pavements ( Lolium perenne and Taraxacum officinale) were investigated. Germination and biomass accumulation were lowest in both innovative materials, irrespective of organic contamination level, plant species and water regime. Weed growth in the standard materials was affected by plant species and water regime. Monthly biomass accumulation increased with increasing monthly water supply and number of irrigation days. Furthermore, the materials best capable of reducing weed growth, under all water regimes, even when organically polluted, were the innovative materials and sea sand. The results of this study show that the implemented water regime can influence weed suppressiveness (absolute as well as relative) of a joint filler. Hence, to fully assess weed suppressive ability, commercially launched joint fillers should be tested under diverging water regimes. [ABSTRACT FROM AUTHOR]

The recent phase-out of herbicide use on public pavements in Flanders has triggered the development of alternative strategies for weed prevention and control. In this study, growth chamber experiments investigated the ability of various water permeable joint filling materials for pavements to prevent weed growth. Joint fillers included in the tests comprised five innovative (iron slag sand, polymeric bound sand and three sodium silicate enriched fillers) and eight standard joint fillers (four fine materials, for example, sea sand, white sand, sandstone and fine limestone, and four coarse materials based on porphyry and limestone). Their ability to suppress weeds was investigated by examining seedling emergence and biomass production of seven test species in pure or organically polluted (5%, 10%, 20%, 40% and 80% compost by volume) filler substrate. Selected test species were dominant, hard-to-control weeds found on pavements. Seedling emergence and weed biomass were lowest in iron slag sand, polymeric bound sand and most sodium silicate enriched fillers, irrespective of pollution level or test species. Within standard joint fillers, pure white sand, sandstone and the coarse materials also reduced biomass, but their inhibitory effect dropped quickly once organically polluted, in contrast to fine limestone and sea sand for which weed suppression lasted longer (up to 40% compost by volume). Weed suppression of joint fillers was species specific. Our results show that there is potential for preventing weed growth using fillers that prevent the growth of a wide spectrum of plant species over a long period. [ABSTRACT FROM AUTHOR]

Abstract: A major constraint on vegetation succession on abandoned land is dominance by early successional species. Our aim was to inhibit weeds and alter the initial vegetation succession by the introduction of legume species (Medicago sativa, Melilotus suaveolens, and Astragalus adsurgens) into abandoned fields on the Loess Plateau, China. Results from our study showed that the addition of legume species strongly affected the dominance pattern of the abandoned-field vegetation. The number of naturally colonizing species was inhibited by the introduction of legume species in the first two growing seasons. The strongest effect on weed inhibition appeared by sowing Melilotus suaveolens. Vegetation cover and above-ground biomass increased after introduction of legume species and the number of naturally colonizing plant species showed a positive correlation with above-ground biomass. Later successional species like Stipa breviflora and Astragalus polycladus appeared three years following the introduction of Melilotus suaveolens, indicating that the course of old-field succession may be accelerated by introducing legume species such as Melilotus suaveolens, at least temporarily. [Copyright &y& Elsevier]