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No-tillage altered weed species dynamics in a long-term (36-year) grain sorghum experiment in southeast Texas

این تحقیق جهت مقایسه تنوع زیستی علف‌های‌هرز بوم‌نظام‌های برنج (Oryza sativa L) شهرستان‌های بابل و بابلسر انجام گردید. نمونه‌ها از شش مزرعه دو نظام مدیریتی (ارگانیک و پرنهاده)، در سال زراعی 91-1390، جمع‌آوری شد. داده‌ها (شامل تعداد گونه‌های علف‌هرز و فراوانی هر یک) از نُه کوادرات (یک×یک متر) هر مزرعه، طی چهار مرحله (پنجه‌زنی، ساقه‌روی، پرشدن دانه و پس از برداشت) به‌دست آمد. مقایسه میانگین شاخص-های تنوع زیستی دو نظام مدیریتی، نشان داد که علی‌رغم افزایش مقادیر شاخص‌های تنوع در نظام ارگانیک، اختلاف معنی‌داری بین دو نظام قابل مشاهده نبود. مقایسه مراحل مختلف نمونه‌برداری بر اساس میانگین دو نظام، حاکی از کاهش تنوع و یکنواختی علف‌های‌هرز در مرحله چهارم (پس از برداشت) بود. ارزیابی شاخص‌های تنوع زیستی دو نظام پرنهاده و ارگانیک نیز حاکی از کاهش معنی‌دار شاخص‌های تنوع زیستی علف‌های‌هرز در مرحله چهارم نسبت به مراحل قبلی بود. این نتیجه می‌تواند به‌علت تخریب ایجاد شده در بوم‌نظام‌های برنج، ناشی از برداشت محصول و فراهم شدن زمینه برای ظهور گونه‌های مختلف علف‌هرز باشد. علی‌رغم اینکه در این شرایط انتظار افزایش تنوع می‌رود، اما به‌واسطه وجود تنش خشکی در مرحله برداشت، گونه‌های مقاوم به تنش ظاهر شده و مستقر گردیدند. برتری تنوع در نظام ارگانیک، به‌ویژه در مرحله چهارم را می‌توان به ظهور و استقرار علف‌های‌هرز مقاوم به شرایط تخریب و تنش مانند علف انگشتی (Digitaria spp.)، توق (Xanthium strumarium L.) و اکلیپتا (Eclipta prostrata L.) (گونه‌های شرایط غیرغرقاب) علاوه بر علف‌های‌هرز رایج (گونه‌های شرایط غرقاب) بوم‌نظام برنج مانند سوروف (Echinochloa crussgalli P. Beauv) و گونه‌های اویارسلام (Cyperus spp.) نسبت داد. نتیجه این که در مجموع، شاخص‌های تنوع زیستی (تنوع و یکنواختی) علف‌های‌هرز در نظام ارگانیک نسبت به رایج برتری داشت.

For developing ecological prevention and management techniques for invasive and dominant weed species, the screening and using of high value species with strong competitive ability (e.g., local food, native species and/or cash crops) have captured widely attention. To explore the effects of sweet potato (Ipomoea batas) cultivation on community composition and species diversity of weeds, the composition, density, importance value, species richness, diversity indices, and Pielou index were analyzed under five different cover scenarios (0%, 1–25%, 26–50%, 51–75, 76–100%). The study took place in arid cultivated fields in Jianshui County, Yunnan Province, China. A total of 25 weed species from 18 families were identified. Of these, four invasive species Ageratum conyzoides, Bidens pilosa, Eleusine indica, and Galinsoga parviflora and two native species, Digitaria sanguinalis and Portulaca oleracea had the highest population density and were most dominant. Population density and importance values of the six dominant weed species declined as sweet potato cover increased. A significant negative correlation was observed between importance values and sweet potato cover (P<0.05). Population density of two less dominant native species, Calystegia hederacea and Poa annua, increased significantly with increasing sweet potato cover. Similarly, the importance values for two additional native species Acalypha australis and Echinochloa crusgalli was positively correlated with sweet potato cover (R=0.964, R=0.891, P<0.05). Maximum values for species richness (23.5, 24.5), Simpson index (0.89, 0.85), Shannon-Wiener index (2.36, 2.35) and Pielou index (0.75, 0.73) corresponded to sweet potato cover ranges of 1–25% and 26–50% respectively. As sweet potato cover increased species richness and diversity values significantly declined. Overall, the results indicate that the cultivation of sweet po486 生 物 多 样 性 Biodiversity Science 第 22卷 tato alters the community composition and diversity of weeds limiting the occurrence of the dominant and invasive weed species. As a result, mid to low percent cover values should be considered an effective and ecologically-based weed management strategy to replace herbicide use in arid fields.

The objective of this research was to explore the influence that weed decision threshold (DT; expressed as plants m−2), weed spatial distribution patterns, and spatial resolution of sampling have on potential reduction in herbicide use under site-specific weed management. As a case study, a small plot located in a typical corn field in central Spain was used, constructing very precise distribution maps of the major weeds present. These initial maps were used to generate herbicide prescription maps for each weed species based on different DTs and sampling resolutions. The simulation of herbicide prescription maps consisted of on/off spraying decisions based on information from two different approaches for weed detection: ground-based vs. aerial sensors. In general, simulations based on ground sensors resulted in higher herbicide savings than those based on aerial sensors. The extent of herbicide reductions derived from patch spraying was directly related to the density and the spatial distribution of each weed species. Herbicide savings were potentially high (up to 66%) with relatively sparse patchy weed species (e.g., johnsongrass) but were only moderate (10 to 20%) with abundant and regularly distributed weed species (e.g., velvetleaf). However, DT has proven to be a key factor, with higher DTs resulting in reductions in herbicide use for all the weed species and all sampling procedures and resolutions. Moreover, increasing DT from 6 to 12 plants m−2resulted in additional herbicide savings of up to 50% in the simulations for johnsongrass and up to 28% savings in the simulations for common cocklebur. Nonetheless, since DT determines the accuracy of patch spraying, the consequences of using higher DTs could be leaving areas unsprayed, which could adversely affect crop yields and future weed infestations, including herbicide-resistant weeds. Considering that the relationship between DT and accuracy of herbicide application depends on weed spatial pattern, this work has demonstrated the possibility of using higher DT values in weeds with a clear patchy distribution compared with weeds distributed regularly.

The paper reviews the development of practices for the adjustment of soil management and in particular fertiliser inputs to rubber to cater for variations within an area based on planting material (clone), soil and its variations, tapping system, yield levels and other factors. The practice which was folly evolved by mid 1970's was termed "discriminatory fertiliser use" and seems to fit into the newly emerging terminologies of "precision agriculture" and or "site specific management". Keywords: Discriminatory fertiliser use, rubber, soil management, precision agriculture.

Allelopathy is an important factor which contributes in determining distribution of species and their abundance within communities. Plant-plant interference is the combined effect of allelopathy, resource competition, and many other factors. Weed infestation is a major problem limiting the growth and yield of rice. Synthetic herbicide has been used for over 50 years as the prime source of weed control. The repeated use of herbicides in rice has already led to the evolution of resistance in some weed species. The conventional synthetic herbicides are becoming less effective against the resistant weed biotypes. Due to increase in the number of herbicide-resistant weeds and environmental concerns in the use of synthetic herbicides, allelopathy has been gaining preference as one of the considerable efforts in designing alternative weed management strategies. Modern ecotoxicologists and allelopathy researchers have been trying to identify allelochemicals to use as biodegradable pesticide. Two allelochemicals have been discovered, namely hexanedioic acid dioctyl ester and di-n-octyl phthalate which can be used as biopesticide. However, still there is enough scope to conduct such research that will contribute to protect our environment as well as increase food safety. DOI: http://dx.doi.org/10.3329/agric.v11i1.15251 The Agriculturists 2013; 11(1) 112-121

IntroductionFlood recession farming, locally known as molapo farming, is an important livelihood activity for the subsistence farming community around the Okavango Delta. The study was aimed at investigating the influence of cultivation frequency on non-crop species composition. It was carried out in the peripheral settlements of Shorobe, Makalamabedi and Lake Ngami.MethodsVegetation sampling was conducted from March to April 2016 in 36 fields of varying historical cultivation frequencies. The cultivation frequencies were 5, 10 and 15 years with an uncropped control site. Sampling was done in 1-m2 quadrats placed 10 m apart along a line transect. Shannon’s diversity and equitability indices were used to compare diversity for each cultivation frequency within and across the study sites. The Kruskal–Wallis test was used to investigate significant differences in diversity between cultivation frequencies. Rank of abundance was used to determine the association of weeds with the cultivation frequencies.ResultsCultivation frequency did not influence species diversity (p > 0.05) at either Lake Ngami or Shorobe. Species evenness was significantly different (p < 0.05) between the cultivation frequencies at Shorobe, but not at either Makalamabedi or Lake Ngami. There was a significant difference (p < 0.05) in diversity indexes across the four cultivation frequencies. The 5-year frequency recorded the highest median score (Md = 1.352) while the 15-year frequency recorded the lowest median score (Md = 1.035). Corchorus tridens was the most abundant non-crop species at the 5- and 15-year frequencies. Cynodon dactylon was most abundant in the 10-year frequency while Cyperus esculentus was most abundant in uncropped fields.ConclusionsCultivation frequency influenced weed species diversity and composition in flood recession farming. Flood recession farming fields were dominated by common weed species which are also troublesome in dryland arable farming. Uncropped sites were composed of wetland species that tolerate some dry periods or seasonal flood plains.

This field experiment was carried out to evaluate the weed species distribution in the experimental plots of an intercrop of juvenile oil palm trees (Elaeis guineensis Jacq.) with maize (Zea mays Linn.), okra (Abelmoschus esculentus Moench) and pepper (Capsicum annuum var. abbreviatum). This was carried out during the cropping season between July and October 2012. The crops were intercropped with the juvenile oil palm trees of about 3-years-old. The experiment was laid out in a completely randomized block design with five (5) replicates. The treatments comprised of intercropping distances of 1 m, 2 m and 3 m each for the three (3) crops (maize, okra and pepper) and a plot for each of the three (3) arable crops without oil palm trees as control. Weed species distribution was carried out in each of the plots to determine the Simpson’s Diversity Index (D), Simpson’s Index of Diversity (1-D) and Simpson’s Reciprocal Index (1/D). Weed species’ frequency, density, relative density, relative frequency, importance value, abundance, dominance and relative dominance were also computed from data collected at 3WAP and 6WAP. The results showed that the control plot has the highest weed species distribution at 3WAP having the lowest Simpson’s Diversity Index (D) of 0.0930. Okra plot has the least weed species distribution with the highest Simpson’s Diversity Index (D) of 0.2726. At 6WAP, the pepper plot has the highest weed species distribution having the lowest Simpson’s Diversity Index (D) of 0.1741. Control plot has the least weed species distribution with highest Simpson’s Diversity Index (D) of 0.2831.

Herbicide resistance (HR) has been a major management challenge and ongoing threat in cropping regions over several decades, particularly in the time since the widespread adoption of no-tillage cropping systems. Despite extensive and severe development of resistance in Australian cropping regions, growers have been able to maintain control of new weed populations by introducing new herbicides and non-herbicide practices. These integrated weed management (IWM) practices have helped farming systems maintain productivity and adapt to changing environmental and agronomic conditions. Earlier studies found that the adoption of these alternative practices was associated with a reaction to the initial development of forms of HR on a farm. Practices include those classified as harvest weed seed control (HWSC) that kill potentially herbicide resistant weed seeds and reduce overall weed seedbank populations without increasing HR selection pressure. A largely unexplored aspect of the socioeconomics of HR management is whether the initial ‘reactive’ adoption of IWM has a ‘preventative’ effect on the further spread or proliferation of resistance development to other herbicides and in other weed species. To gain a deeper understanding of the farm-scale factors determining the presence of HR, the adoption of IWM practices, and the relationship between IWM use and HR status, we focus on whether initial reactive adoption of IWM has a preventative effect on further resistance development. Data from 602 broadacre grain growers across 13 agroecological zones of Australia were analyzed using Ordinary Least Squares and Logistic regressions to assess the extent of IWM practice adoption, while Ordered Logit models were used to capture the diversity of IWM practice use, including HWSC strategies. Notably, we found that adoption of IWM (including HWSC) was higher in the Western and Southern regions, most likely where HWSC practices can offer greater control on the most common resistant weed types, such as annual ryegrass. There was no evidence to support the argument that IWM use on farms is associated with reduced herbicide use, but there was considerable evidence to show that early forms of HR development on farms have led to the use of IWM practices, such as HWSC, that have the potential to reduce the seed set of weeds with potential new forms of resistance. The extent of HR was the only consistently highly significant variable to explain IWM use. These results have the capacity to pre-emptively identify sustainable weed management scenarios in various regional farming systems and future contexts, including where earlier ‘reactive’ adoption of resistance management practices may now be offering ‘proactive’ benefits. • Examine farm-scale factors influencing IWM and HWSC in Australian cropping systems. • First nationwide farm-level study links HR presence to proactive adoption of IWM practices. • Analysis of 602 growers' data across 13 AEZ using OLS, logistic, and ordered logit models. • HR presence, farm size, no-till years, and advisory support strongly drive IWM uptake, especially in WA & SA. • Evidence-based guidance for regional policymakers to target HR management and support IWM adoption.

Purpose This study explores the efficacy of microwaves as a method for the control of three weed species particularly widespread and problematic in the Italian farms cultivating IV range crops. These findings, based on laboratory experiments, are part of a project (MOPAS Project—Microwaves for Sustainable Agriculture) meant to realize a prototype for use in real field situations. Methods Seeds from weed species ( Trifolium repens L., Portulaca oleracea L., and Solanum nigrum L.) were subjected to microwave treatments at 480 and 900 W power levels for 10 and 30 s. The impact on seed germination and ion leakage was assessed. Histological changes induced by microwaves were also examined through microscopic analysis. Results Significant germinability decreases were observed in S. nigrum and T. repens with increasing treatment duration and intensity. P. oleracea exhibited lower sensitivity, with detrimental effects only at the highest power levels suggesting that seed size and the associated differences in water absorption may play a crucial role in determining sensitivity to microwave exposure. S. nigrum membrane stability was affected only at the highest irradiation power, while all species showed increased ion leakage across treatments. Observations revealed wilting of stems and leaves, indicating cell turgidity loss in inner tissue layers. Conclusion Microwave radiation may be a non-chemical weed control strategy, though efficacy is influenced by variability in seed traits. Further research is necessary to optimize treatment parameters and assess scalability under field conditions. This approach holds potential for reducing herbicide use and promoting sustainable agricultural practices.

In precision agriculture, precise and real-time identification of crops and weeds species is necessary to reduce herbicides, lower the cost of operation, and enhance the output. The traditional dichotomous crop-weed dichotomous classification systems do not generalize in a real-life agricultural context, especially when two or more types of crops, and different weed species are grown within the same field. The proposed study presents a powerful YOLO-based multi-class detection system that will be able to detect many types of crops and weed in changing environmental factors. The study provides a diversified, field-measured data set with different light, soil, and occlusion conditions and implements augmentation strategies at the highest level to make the models more robust. The performance of three variants of YOLO was assessed in three metrics mAP, precision, recall, and F1-score, and the speed of real-time inference. YOLOv9 was found to have a better mAP at 0.5 of 95.4, 74.6 at 0.5:0.95, and F1-score of 92.3. The model was tested in deployment on edge devices like Jetson Xavier NX and Google Coral TPU and has been validated as being able to be used in real-time on-field to manage weeds. The suggested framework has a great contribution to the multi-class detection performance, providing a scalable and viable solution to sustainable precision agriculture.

Effective weed management is always an important aspect in crop production. Of the all-possible weed control techniques including physical, chemical, mechanical, cultural and biological, use of chemical is always prioritized first to the farmers due to its’ quick response and effective weed control efficacy. However, selection of an optimized dose for each herbicide is crucial considering its’ effectivity and eco-toxicological aspect. An experiment was conducted at the research field of Agronomy Division, Gazipur during the Rabi season of 2013-2014 to find out the optimum rate of herbicide (MAGZIN 70 WG) to control weeds in brinjal field. Six treatments viz.: (i) MAGZIN 70 WG @ 750 mL ha−1 spraying at 15 DAS and 45 DAS, (ii) MAGZIN 70 WG @1000 mL ha−1 spraying at 15 DAS and 45 DAS, (iii) MAGZIN 70 WG @1250 mL ha−1spraying at 15 DAS and 45 DAS, (iv) MAGZIN 70 WG @ 1500 mL ha−1 spraying at 15 DAS and 45 DAS, (v) Two hand weedings at 30 and 60 DAS, (vi) No weeding (control) were used in the experiment. Among the weed species, Bathua (Chenopodium album), Durba (Cynodon dactylon), Anguli (Digitaria sanguinalis), Helencha (Jussiaea repens), Hatishur (Heliotropium indicum), Shama (Echinochloa crusgalli), Swetlomy (Gnaphalium japonicum), Mutha (Cyperus rotundus), Shaknote (Amaranthus viridis), Gaicha (Paspalum commersonii), Chapra (Eleusine indica), Bon Masur (Vicia sativa) were dominant in brinjal field. The results showed that the highest dry weight of weeds at 30 and 60 DAS were 12.24 gm m−2and 24.12 gm m−2, respectively found in control plot whereas the lowest with two hand weeding at 30 and 60 DAS. The maximum weed control efficiency (WCE) over control both at 30 and 60 DAS were 79.41 and 74.32%, respectively in treatment two hand weeding at 30 and 60 DAS. The highest number of fruits plant−1 (11.05), single fruit weight (86.48 g), fruit length (24.09 cm), yield (14.56 t ha−1) was found in two hand weeding and the lowest in no weeding (control). Though the WCE was highest in two hand weeding, but due to higher labor cost, the maximum benefit cost ratio (MBCR) (1.26) was highest in application of MAGZIN 70 WG@ 1500 mL ha−1 spraying at 15 and 45 DAS. As a system of mechanization of agriculture, the labor unavailability is a serious problem in Bangladesh. So, use of MAGZIN 70 WG@ 1500 mL ha−1 spraying at 15 DAS and 45 DAS may be economically viable. Bangladesh Agron. J. 2024, 27(2): 55-60

One of the most serious threats to global crop productivity and sustainable weed management in present scenario is herbicide resistance. Dependency on repeated application of herbicides with similar modes of action, simple cropping systems and reduced diversity among agronomic practices turns out to be major reason for evolution of resistant weed populations across different agroecosystems. Currently, around 260 weed species have been reported to be resistant to one or more site of action, leading to increased yield losses, production cost and environmental concerns. Resistant weed populations usually evolve through different mechanisms such as target-site resistance, which mainly occurs due to genetic mutations at the specific herbicide binding site, and non-target-site resistance, which includes different mechanisms like enhanced herbicide metabolism, reduced translocation or sequestration. To delay or avoid the development of herbicide resistance and restore sustainability we have to implement agronomic mitigation strategies which include crop diversification, cultural and mechanical interventions, use of integrated weed management practices (combination of chemical, cultural, mechanical and biological methods) and precise use and application of herbicides Globally, herbicide resistance has started to become a wide spread problem in controlling the weeds. Studies have reported that resistant weed species can easily cause around 20–70% yield losses, depending on the crop, weed species and infestation level. To delay or avoid the development of herbicide resistance and restore sustainability we have to implement agronomic mitigation strategies which include crop diversification, cultural and mechanical interventions, use of integrated weed management practices and precise use and application of herbicides. It proper and timely solution of this problem is not developed or left unchecked than it can cause uncontrolled losses to crop yield.

Intercropping with Lolium spp. instead of applying soil-active herbicides confined weeds in three years of continuous maize cropping

Effective weed management is essential for maximizing sugarcane productivity, with pre-emergence herbicides representing a fundamental strategy for controlling weed infestations. The study evaluates the efficacy of flumioxazin, alone and combined with other herbicides, for weed control in sugarcane. A greenhouse experiments assessed control of various weed species: Rottboellia cochinchinensis, Urochloa decumbens, Digitaria horizontalis, Merremia aegyptia, Merremia cissoides, and Ipomoea triloba. The completely randomized 9 × 5 factorial design with four replications with nine herbicide treatments and five sowing intervals, applied in pots containing a dystrophic Red Latosol. Evaluations included percentage control at 35 d after application (DAA) and reduction in dry mass. Results showed flumioxazin alone had variable efficacy, with high initial effectiveness but significant decline over time. In contrast, combinations such as flumioxazin + metribuzin and flumioxazin + diclosulam maintained high efficacy (>90%) throughout all periods. Flumioxazin + isoxaflutole was initially effective but diminished after 20 DAA. Combinations with herbicides of similar half-lives, like metribuzin, suggested synergistic effects, while pairings with longer half-life herbicides, like imazapic, complemented flumioxazin’s action. Mixtures of flumioxazin with other herbicides effectively reduced weed dry mass, highlighting the advantage of herbicide combinations for sustained and efficient weed management in sugarcane cultivation. This study emphasizes the importance of herbicide combinations in overcoming management challenges and selecting appropriate herbicides for diverse field conditions.