Results of the study of the weed-field flora of Primorsky Territory in 2016-2020

The results of the study of the weed component of soybean, early grain crops and maize agrocenoses in Primorsky Territory are presented. In total, 111 species of weeds belonging to 35 families were found during the period from 2016 to 2020. Compared with the results of crop surveys conducted in 2006-2015, the total number of species detected has increased by 23. The largest number of species belongs to the families Asteraceae (24), Poaceae (15), Polygonaceae (11), Fabaceae (9), Brassicaceae (8), Caryophyllaceae (7) and Lamiaceae (5). The remaining 26 families were represented by 1-3 species each. For the first time weeds-representatives of the families Scrophulariaceae, Violaceae, Lythraceae, Onagraceae, Asclepiadaceae and Boraginaceae have been discovered. The floristic composition of soybean agrocenoses was the highest with 108 weed species from 31 families. In cereal and maize crops, weed diversity was less significant, with 75 species in 22 families and 72 species in 25 families, respectively. Weed vegetation in all the above crops is represented by 62 species of 19 families. The main weed species that grew on 97-99% of the surveyed territory with a sufficiently high average density of standing (21-61pcs/m2) were Asian copperleaf, cockspur grass and common ragweed. Also, more than half of the surveyed crops of soybeans, cereals and corn were hairy cupgrass, perennial sow thistle, common couch-grass, common lamb’s quarters, wormwood species, field horsetail, yellow thistle, dayflower and yellow foxtail. Practical measures to protect against weeds on the Primorsky Territory should be primarily aimed at controlling these species.

The Effect of Weed Management on Seed Banks in Paddy Rice Fields

Weeds are one of the problems in rice plants, so the presence of weeds in rice fields must be controlled. Different ways of managing weeds on agricultural land can affect the seed bank of weeds in the soil. This study aims to determine differences in weed seed banks due to differences in weed management, especially the use of herbicides in lowland rice. The study was conducted at the Agricultural Training and Development Research Center, Faculty of Agriculture, Padjadjaran University, Bandung Regency, Indonesia from May–July 2020. The study used a paddy field plot consisting of intensive, less intensive use of herbicides and non-herbicide use. This research was conducted with survey and descriptive methods to see the type and composition of weeds at a certain depth and to see differences in seed banks. Observations were made including analysis of weed vegetation, community coefficients, weed diversity, weed dominance and differences in seed bank from depth. The results showed that there were 7 weed species found, namely Rorippa palustris, Monochoria vaginalis, Leptochloa chinensis, Echinochloa crus-galli, Eclipta prostate, Lindernia procumbens, and Marchantia polymorpha. Weed management with herbicides is proven to reduce weed populations that grow.

Landscape Is the Main Driver of Weed Assemblages in Field Margins but Is Outperformed by Crop Competition in Field Cores

Weeds are considered a major pest for crops, and as such have been intensively managed by farmers. However, weeds, by providing resources, also support farmland biodiversity. The challenge for sustainable weed management is therefore to maintain weed diversity without compromising crop production. Meeting this challenge requires determining the processes that shape weed assemblages, and how agricultural practices and landscape arrangement affect them. In this study, we assess the effects of crop competition on weeds, nitrogen input, weed control and landscape on both weed diversity and abundance in the margins and centres of 115 oilseed rape fields in Western France. We show that weed assemblages in field cores were mainly shaped by crop height, a proxy of crop competition. By contrast, weed assemblages in field margins increased with the number of meadows in the landscape, revealing the role of spatial dispersal. Using structural equation modelling, we further show that in the field core, weed assemblages were also indirectly shaped by landscape through spatial dispersal from the field margin. Overall, our study gives empirical support for crop competition as a way to reduce the intensity of chemical weeding, and for meadows as a way to enhance biodiversity in the landscape.

Weeding Frequencies Decreased Rice–Weed Competition and Increased Rice N Uptake in Organic Paddy Field

Different weeding frequencies (WFs)―0WF, 2WF, 4WF, 6WF, and 8WF―were adopted in an organic rice field to investigate their influence on weed types, rice and weed biomass, rice tiller and weed number, N concentration, and N uptake. The study field was located in Tsuruoka, Yamagata, Japan. Rice (cv. Sasanishiki) was planted from May to September 2019, and all weeding events were carried out until 49 days after transplantation (DAT) using a rotary weeder. Rice and weed samples were collected at 60, 88, and 110 DAT. Echinochloa crus-galli (E. crus-galli), Schoenoplectus juncoides, and Monochoria vaginalis (Burm. f.) were the most commonly found weeds. High weed diversity was observed at both 6WF and 8WF, E. crus-galli was the dominant weed at 0WF. Compared to 0WF, 2WF displayed a significantly decreased weed biomass. However, at 8WF, the weed biomass was reduced by 79.0%, the rice biomass was increased by 277%, and the rice tiller number was almost three times higher than that at 0WF and 110 DAT. Compared to 0WF, a significantly increased rice N uptake was observed at 4WF, and rice N uptakes achieved at 6WF and 8WF were two and four times higher than those at 0WF, respectively. Higher weeding frequencies provide notable benefits in suppressing weeds and supporting rice growth, especially in N uptake competition with weeds.

PERBANDINGAN VEGETASI GULMA PADA PERKEBUNAN KELAPA SAWIT (Elaeis guineensis Jacq.) MENGHASILKAN DAN BELUM MENGHASILKAN DI LAHAN GAMBUT

Weed vegetation analysis is important to do in order to know the composition and structure of the vegetation to determine the appropriate weed control measures. This study aims to compare the composition and structure of weeds on peatland immature oil palm plantations and mature palm. This research was conducted from October to December 2020. Vegetation analysis was carried out using a survei method with purposive sampling technique. The parameters observed were density, frequency, dominance, important value index (INP), summed dominance ratio (SDR) and species diversity index (H'). The results showed that the composition of weeds on immature oil palm plantations was found 12 species with number of individual 847, while on mature palm found 9 species with number of individuals 980. The dominant weed structure on immature oil palm plantations is Lempuyangan with SDR values 29,9 % and mature palm is Bandotan with SDR value 23,4%. Weed diversity index on immature oil palm plantations and mature palm is categorized as high with a value of 1.50 for immature oil palm plantations and 1.65 for mature palm.

Technology Levels in Cassava Cultivation Alter Phytosociology of Weeds

This study aimed to assess the phytosociology of weeds as a function of different crop management technology levels in cassava production. Field experiments were conducted in Santa Maria (29°41′03″ S; 53°48′25″ W) and Itaqui (lat. 29°07′31″ S; long. 56°33′11″ W), Rio Grande do Sul, Brazil. Treatments consisted of three technology levels: low (postemergence weeding without basal dressing); medium (weeding performed at 7 and 40 days after planting and fertilization with 6.25, 25, and 25 kg⋅ha−1 of N, P, and K, respectively); and high (postemergence application of s-metolachlor; 1250 kg⋅ha−1 of lime and 12.5, 50, and 50 kg⋅ha−1 of N, P, and K, respectively). Weed frequency, density, relative abundance, and importance values were calculated for each location. Then, locations were compared using a dissimilarity matrix. Weed density and diversity decreased linearly as technology levels increased. The predominant weed species found in Itaqui and Santa Maria belong to the Poaceae family. Itaqui presented highest weed diversity among the locations. The genus Cyperus had the highest importance value index in Santa Maria. The use of S-metolachlor at the high technology level provided a lower frequency and lower diversity of weed species than did levels without chemical control in Itaqui and Santa Maria.

Varying tillage promotes weed diversity, while a perennial alfalfa–grass mixture promotes weed control in an organic tillage system experiment in Germany

In organic farming the control of perennial weed species, in particular Cirsium arvense, can be a major concern for farmers, especially if there is no regulation through perennial forage production. To test whether the stubble cleaner (SC), an enhanced skim plow (PL), is as effective in the control of C. arvense and other weeds as conventional ploughing and perennial forage production, an organic field experiment was established. Three different tillage/crop rotation systems were compared: an SC system and a PL system, both in a cereal-based crop rotation and an additional PL system in a crop rotation that included a perennial alfalfa–grass mixture (PLALF). In the SC system, tillage was carried out solely with the SC, while in the PL and PLALF systems, ploughing was alternated with chiseling. In the fifth year, each main plot was divided into subplots, and seven different cover crop treatments were integrated into each of the three systems. The effects of the three systems and the cover crop treatments on weed cover and density, weed biomass, and weed diversity in the sixth and seventh year of the experiment are the subjects of this paper. The choice of cover crop species was of minor importance for weed control. The PLALF system was generally more effective in controlling C. arvense than the PL and SC systems. No significant differences between the PL and SC systems regarding the control of C. arvense could be identified in four of five assessments. The SC system had significantly higher total weed density than the PLALF and PL systems in both years. However, the differences in weed emergence between the PL and SC systems diminished until the assessment of weed cover and biomass in the main crops, when no significant differences between these two systems (2012) or no differences at all (2013) could be identified. Species richness was not significantly influenced by the tillage/crop rotation system in both years. Evenness and Shannon–Wiener index were significantly higher in the PLALF and PL systems than in the SC system on most assessment dates in 2012. In 2013 there was no clear trend regarding evenness and Shannon-Wiener index probably due to a hoeing operation.. In conclusion, for weed control, the choice of crop rotation was more important than the choice of tillage method, while for the diversity of the weed community, the choice of tillage method was more important than the crop rotation.

IDENTIFICATION OF ORGANIC MULCH EFFECTS ON WEED DIVERSITY AND SHALLOT (Allium ascalonicum L.) PRODUCTIVITY

Shallot cultivation in North Kalimantan has not been implemented properly. This is because the soil in North Kalimantan is acid so the yield of shallot is low. One effort to increase soil pH using organic mulch. Organic mulch has the function of maintaining soil moisture and inhibiting the growth of weeds so that shallot cultivation can grow well. This study aims to determine the effects of organic mulch on weed diversity and yield of shallot. The study was conducted using Randomized Block Design with the treatment without mulch (P0), Imperata cylindrica mulch (P1), Cyperus rotundus mulch (P2), Eleusine indica mulch (P3) and Cynodon Dactylon mulch (P4). The results showed that the parameters of shallot using Cyperus rotundus mulch and Eleusine indica mulch increased the number of tubers is 11.57%. In this study, species of weeds had the highest a on each treatment were species Elusine indica on without mulch (21.93%), Cyperus rotundus mulch (54.26%), and Eleusine indica mulch (28.79%). Then, species Borreria latifolia on Imperata cylindrica mulch (28.79%), and species Cynodon dactylon on Cynodon dactylon mulch (47.21%).