Cultural Practices and Mechanical Weed Control for the Management of a Low-Diversity Weed Community in Spinach

Low-diversity weed communities are dominated by few species that are highly competitive to crops. The management of such weed communities should rely upon sustainable cultural and non-chemical practices, especially in crops such as spinach (Spinacia oleracea L.), where very few herbicides are available. A two-year field trial (2020 and 2021) was conducted to evaluate different fertilization practices (broadcast and banded), intra-row spacings (15 cm, 11 cm, 7 cm), and mechanical weed control treatments (untreated, one treatment, two treatments) for the management of a low-diversity weed community in spinach. Weed competition severely affected spinach commercial biomass (R2 = 0.845). Compared to broadcast fertilization, banded fertilization reduced weed biomass and improved spinach yield and nitrogen use efficiency. Narrow intra-row spacing (7-cm) reduced weed biomass by 28 and 45% compared to intra-row spacings of 11-cm and 15-cm, respectively. Two mechanical weed control treatments resulted in 49% lower weed biomass compared to a single treatment. Commercial biomass increased with decreasing intra-row spacing (R2 = 0.881) and increasing the number of mechanical treatments (R2 = 0.911). More cultural and non-chemical practices should be evaluated for weed management in spinach, especially at sites infested with low-diversity weed communities.

Relative importance of region, seasonality and weed management practices effects on the functional structure of weed communities in French vineyards

Winegrowers have diversified their weed management practices over the last two decades changing the structure and the composition of weed communities. Complementary to taxonomic studies, trait-based approaches are promising ways for a better understanding of weed communities responses to environmental and agronomic filters. In the present study, the impacts of climate, soil characteristics, seasons and weed management practices (chemical weeding, tillage and mowing) were assessed on weed communities from 46 plots in three French wine-growing regions (Champagne, Languedoc and Rhone valley). These agro-environmental gradients structuring weed communities according to their combinations of traits were highlighted using multivariate analysis (RLQ). The impacts of these filters on Community Weighted Means (CWM) and Community Weighted Variance (CWV) of weed communities were analysed using mixed and null modelling. Our results showed that spatio-temporal and weed management practices variables explained from 13% to 48% of the total variance of CWM (specific leaf area, maximum height, seed mass, flowering onset and duration and lateral spread). Region, seasonality and management practices explained 53%, 28% and 19% of CWM marginal variance, respectively. Weed management impacted CWM and CWV through two main gradients: (i) a soil disturbance gradient with high mechanical disturbance of soil in tilled plots and low mechanical disturbance in chemically weeded plots and (ii) a vegetation cover gradient with high vegetation abundance in mowed plots compared to more bare soils in tilled and chemically weeded plots. In Languedoc, chemical weeding filtered weed communities with ruderal strategy trait values (low seed mass, small-stature) while mowed communities were more competitive (higher seed mass, higher stature and lower SLA). In Languedoc and Champagne, tillage favoured communities with high seed mass that increases the viability of buried seeds and high lateral spread values associated to the ability to resprout after tillage. This study demonstrated that trait-based approaches can be successfully applied to perennial cropping systems such as vineyards, in order to understand community assembly to better guide weed management practices.

COMPARATIVE EVALUATION OF DIVERSITY AND HOMOGENEITY OF WEED COMMUNITIES OF WHEAT CROP IN TEHSIL RAZAR DISTRICT SWABI, PAKISTAN

The present study explains comparative evaluation of diversity and degree of homogeneity of weed communities of wheat crop using different indices. This study was conducted in tehsil Razar District Swabi Khyber Pakhtunkhwa, Pakistan during February-April 2016. A total of 200 quadrats having size (1x1 m2) were placed in 20 randomly selected wheat fields in the study area. Analytical quantitative characters like density, frequency and cover were calculated for each weed species. Twenty weed communities were established in 20 selected sites. Comparative evaluation of diversity revealed that Menhinick index ranged from 0.61 to 1.72, Margalef richness ranged from 2.82 to 6.3, Simpson diversity index ranged from 0.78 to 0.94, Shannon-Wiener diversity index varied from 2.13 to 3.24, Pielou evenness index varied from 0.67 to 0.97 while Pichi-Sermolli maturity index ranged from 39.6 to 67.7. Based on Raunkiaer’s law of frequency, out of 20 weed communities, 13 communities were found heterogeneous while 7 were homogeneous. Maximum number of weed species were distributed in frequency class A, B and E.

Weed communities with alien plant species on the south-east area of the Orenburg Region

The presence of agrocoenotic factors constantly acting on segmental (weed-field) communities leads to a high level of community invasion - a potential opportunity to accept new species. In many cases, it is through synanthropic communities that invasions of alien species occur in the Urals, which cause significant damage to both agriculture and the entire economy of the region as a whole. The aim of investigation is to survey and identify the coenotic diversity of communities involving alien species in the steppe zone of the southeastern part of the Orenburg Region. The paper provides data on weed communities with the participation of Acroptilon repens , the Sisymbrium volgense and Artemisia sieversiana . Communities were identified in spring wheat crops in the southeast of the Orenburg Region (Dombarovsky and Svetlinsky administrative districts). Communities develop on dark chestnut soils in arid conditions of the steppe zone. As a result of a synaxonomic analysis, communities were classified into three new variants of the association Lactucetum tataricae Rudakov in Mirkin et al. 1985 previously described in the Republic of Bashkortostan. Perennial weed species prevail in the agrobiological spectrum of the coenoflora nucleus of the studied segetal communities, the share of which is 70%. The most active of them are root-sprung perennials, which are found with high constancy and often dominate: Acroptilon repens , Fallopia convolvulus , Cirsium arvense , Convolvulus arvensis , Lactuca tatarica , Euphorbia virgata . Using the indirect ordination method (DCA), the features of ecological differentiation of communities are demonstrated. The studied phytocoenoses are associated with the driest habitats with poor soils.

A Review of Research Directions and Research Methods of Farmland Weeds

Farmland weeds are an important part of farmland ecosystems. Research on farmland weeds is one of the major research fields in agricultural ecology. It is of great significance for achieving high yield, high quality and high efficiency in agriculture. In recent years, research on farmland weeds has focused on investigation of weed communities, research on weed seed banks, and research on weed control. These three research directions complement each other. Among them, the investigation work of weed communities and the research of weed seed banks are helpful for us to grasp the occurrence of farmland weeds more accurately and provide references for the control of farmland weeds. This article summarizes the research directions of farmland weeds in recent years (weed community investigation, weed seed bank, weed control) and the research methods used, provide reference value for the follow-up research work of farmland weeds, and provide theoretical support for promoting the development of rural ecological industry and building beautiful villages.

The Effect of Different Soil Tillage Systems and Crop Residues on the Composition of Weed Communities

The composition of weed communities in agricultural crops is dependent on soil properties and the applied agronomic practices. The current study determined the effect of different tillage systems and crop residue on the soil weed community composition. The research programme encompassed 2013–2015 in a long-term field experiment located in the Experimental Station of Vytautas Magnus University in Lithuania. The soil type in the experimental field was qualified as Endocalcaric Stagnosol (Aric, Drainic, Ruptic, Amphisiltic). Weeds were categorised into communities according to soil pH, nitrogen and moisture indicators. The results of investigations were grouped using cluster analysis. Agricultural crops were dominated by different weed species depending on the soil pH and moisture. Weed species were relatively more frequent indicating nitrogen-rich and very nitrogen-rich soils. In the reduced tillage and no-tillage systems, an increase in the abundance of weed species indicating moderate acidity and low acidity, moderately wet and wet, nitrogen-rich and very nitrogen-rich soils was observed. The application of plant residues decreased the weed species abundance. In the reduced tillage and no-tillage systems, the quantitative distribution of weed was often uneven. By evaluating the association of weed communities with groups of different tillage systems with or without plant residues, their control can be optimised.