Critical Period Of Weed Interference Research Articles

The Critical Period of Weed Control Influences Sunflower (Helianthus annuus L.) Yield, Yield Components but Not Oil Content

Field studies were conducted in the northeastern part of the Republic of Croatia to determine the influence of the critical period of weed interference on sunflower (Helianthus annuus) yield, yield components, and oil content. For this purpose, different durations of competition were established, allowing weeds to infest the crop for increasing periods of time after planting or maintaining plots weed-free for increasing periods of time after planting. The beginning and the end of the critical period of weed control (CPWC), based on a 5% and 10% loss of sunflower yield, were determined by fitting the four-parameter log-logistic equations to the relative seed yield. The total weed biomass increased progressively in relation to the increase in the competition. The beginning of the CPWC period, based on a 5% acceptable yield loss, ranged from 141 to 234 growing degree days (GDD), which corresponded to the two-to-four true leaf development stage (the V2–V4 growth stages) across both sites and years. The crop had to be kept weed-free until a period when sunflower inflorescence began to open and flower (the R4–R5 growth stage) or from 1365 to 1932 GDD. The sunflower yield and yield components varied between the years and among locations. An increasing duration of weed interference negatively affected crop height, head diameter, and 1000-kernel weight, but not seed oil content.

Assessing the critical period of weed interference in groundnut Arachis hypogaea L. in Ogun State, south western Nigeria

The critical period of weed interference in groundnut was investigated in 2018 and 2019 early cropping seasons at the Federal University of Agriculture, Abeokuta, Ogun State, Nigeria. The experiment consisted of ten treatments arranged in a randomized complete block design and replicated three times. Treatments includes keeping plots weed free initially for 3, 6, 9, 12, 15 weeks after planting (WAP) and keeping plots weed infested initially for 3, 6, 9, 12, 15 WAP. Data collected on weed cover score, weed dry matter production, crop vigour score, canopy spread, pod yield and numbers were subjected to analysis of variance and treatment means were separated using least significant difference at P ≤ 0.05. The results showed that total weed dry matter production increased with weed infestation period and decreased with weed free period. Also, there was significant increase in pod yield and count when plots were kept weed free for 6 WAP and more. Our findings showed that, the highest percent weed accumulation, weed removal, pod yield loss and pod yield gain all occured between 3 and 6 WAP. Therefore, the critical period of weed interference in groundnut is between 3 and 6 WAP. Also, there was 83.4% pod yield loss in groundnut when weed was allowed to compete freely with the crop throught crop life cycle.

Minimal Necessary Weed Control Does Not Increase Weed-Mediated Biological Pest Control in Romaine Lettuce (Lactuca sativa L., var. Romana)

Lettuce is one of the most consumed leafy greens. Depending on the variety, it is ready for harvesting 40–80 days after sowing, and therefore several growth cycles can be concluded within a growing season. Due to its high market standards, lettuce may require intensive management. This study implemented a critical period of weed interference (CPWI) trial to understand at which moment of the cropping cycle weeds can be tolerated without impacting crop yield to decrease the time needed for weeding and assess the potential support weeds can give to biological pest control in lettuce. Treatments represented two gradients of weed intensity: (1) increasingly weed-free, and (2) increasingly weedy. Dose–response curves were produced to find the CPWI based on lettuce relative yield. RLQ analysis was used to explore the relationships between weeding regime and weed functional traits for biological pest control. Yield was above the 5% acceptable yield loss threshold in all plots kept weed-free for 20 days or more, indicating a necessary weed-free period of 20 days from transplanting. However, the support of beneficial insects was not guaranteed at the end of the necessary weed-free period. We suggest that it is possible to limit intense weed management to the beginning of the growing season, reducing the cost of plastic mulches and increasing on-farm biodiversity, but field margins could be better suited to deliver conservation biological control in short-term crops where this service is of primary interest.

CRITICAL PERIOD OF WEED INTERFERENCE ON SOYBEAN (GLYCINE MAX (L) MERRILL)

Weeds are one of the important factors affecting agriculture production, weeds and inadequate weed control and management pose a detrimental factor affecting crop production. The experiment was conducted at the Teaching and Research Farm of Federal University Technology, Minna, Nigeria, to determine the effectiveness of different weeding regime and critical period of weed interference in the growth and yield of soyabean. The treatments were laid out in a Randomized Complete Block Design (RCBD) and replicated three times. There are ten treatments consisting of weed infested and weed-free as follows T1= soybean + weeding for 2 weeks, T2= soybean + weeding for 4 weeks, T3= soybean + weeding for 6 weeks, T4= soybean + weeding for 8 weeks, T5= soybean + weedy for 2 weeks, T6= soybean + weedy for 4 weeks ,T7= soybean + weedy for 6 weeks, T8= soybean + weedy for 8 weeks, T9= soybean + weed-free plot till end and T10= soybean + no weeding till end. Data were collected on weed cover score, weed dry weight, plant height, pod weight and grain yield. The Data were subjected to analysis of variance using SAS, software version 9, 2002. The results showed that soyabean with weed-free plot for 4, 6 8 and weed-free throughout significantly P<0.05 suppressed weed and increases yield by 70 % compared to other treatments The use of early maturing variety of soybean in addition to weed-free plot throughout the growth stage and weed-free for 8 weeks could be recommended in controlling weed interference in soybean for better soybean growth and yield.

Interferência de plantas daninhas na implantação e rebrota de pastagem de Panicum maximum cv. Massai

O manejo inadequado de plantas daninhas é uma das principais causas da baixa produtividade das pastagens brasileiras. Nesta pesquisa, objetivou-se avaliar os efeitos da interferência de plantas daninhas na implantação da pastagem de Panicum maximum cv. Massai e na rebrotação desta após o corte. Dois ensaios foram conduzidos em blocos ao acaso com quatro repetições. No primeiro ensaio, a forrageira foi mantida em convivência com as plantas daninhas pelos períodos de 0, 7, 14, 21, 28, 35, 42, 49, 56 e 66 dias após a emergência (DAE) da pastagem, e no segundo ensaio, a forrageira foi mantida sem a convivência das plantas daninhas pelos mesmos períodos até o corte da forrageira, aos 66 DAE. As parcelas foram mantidas livres da convivência de plantas daninhas por capinas manuais, conforme tratamento. Com o aumento dos períodos de convivência da comunidade infestante com a forrageira maiores foram os danos na produção de perfilhos e no rendimento de forragem na implantação da pastagem. O período crítico de prevenção da interferência de plantas daninhas na pastagem de Panicum maximum cv. Massai foi estabelecido entre 11 e 49 DAE. A interferência de plantas daninhas também afetou a rebrota da forrageira aos 40 dias após o corte, reduzindo o perfilhamento, a cobertura da superfície do solo e a produção de massa seca, principalmente de folhas.

Interval between the application of metsulfuron-methyl and sowing soybean in different production environments

The persistence of herbicides in the soil is extremely important for controlling weeds during the critical period of weed interference, and for determining which substitute crops might be sown. The aim of this study was to evaluate the effect of metsulfuron-methyl when applied at different times in relation to sowing soybean, seeking to determine a safe interval between its application and sowing the legume under different conditions of soil and climate. Two experiments were conducted, one in the district of Campo Mourao in the state of Parana (PR) (2014/15 crop) and the other in Curitibanos in the state of Santa Catarina (SC) (2015/16 crop). Both experiments were carried out in a randomised block design with four replications. The treatments were arranged in a 2 x 6 + 1 factorial scheme, where factor A represented two doses of metsulfuron-methyl (1.98 and 3.96 g ha-1), and factor B six different intervals between applying the metsulfuron-methyl and sowing the soybean (0, 15, 30, 45, 60 and 75 days after application - DAA), in addition to a control without the application of herbicide, to serve as a standard for comparison. The following were evaluated: percentage phytotoxicity, plant height, stand, number of pods per plant, 100-grain weight and productivity. A difference was seen in the persistence of metsulfuron-methyl for the experiments in Campo Mourao PR, and Curitibanos SC, and was greater for Campo Mourao. The safe interval between applying the metsulfuron-methyl and sowing the soybean was 17 days for the experiment in Curitibanos and 40 days for Campo Mourao. Precipitation volume, pH and organic matter are the main factors to possibly have influenced this interval.

Weed Interference in Okra Crop in the Organic System During the Dry Season

ABSTRACT: In organic systems during the dry season, competition of weeds with okra increases the critical period of interference of these species and yield losses. The objective of this research was to determine the critical period of weed interference in organic okra during the dry season in São Luís - MA. The experiment was conducted from October/2014 to January/2015 in randomized blocks, with four replicates. The treatments were the periods of 07, 14, 21, 28, 35, 42 days after the transplanting of the crop with control and coexistence of the infesting community. The species with the highest importance value index were Cynodon dactylon, Eleusine indica, Amaranthus spinosus and Commelina benghalensis. The CPWI was 04 to 53 days after transplanting and yield losses were 69.5%. The organic okra cropping system during the season dry should be free of weeds until the beginning of the harvest to avoid high yield loss.

Critical period of weed interference on total polyphenol content in quinoa

Critical period of weed interference on total polyphenol content in quinoa

<b>Periods of weed interference in chickpea grown under different doses of nitrogen fertilizer topdressing

Weed interference can reduce chickpea growth and, therefore, productivity depending on the period of coexistence and the nutritional status of the crop, among other factors. A study was performed over two crop years to estimate the critical period of weed interference (CPWI) during chickpea production under three doses of nitrogen (N) fertilizer topdressing (0, 50, and 75 kg N ha-1). The experiments were conducted at 0, 7, 14, 21, 28, 35, 42, 56, 63, and 140 days after emergence (DAE) of chickpea/weed coexistence under two conditions: initially weed-free and initially weed-infested. The presence of weeds negatively affected chickpea production and reduced yields by 70% on average regardless of N rate, rendering the crop economically unfeasible. The CPWI ranged from 5 to 76 DAE and was not affected by N topdressing up to 75 kg N ha-1 in both crop years, assuming an acceptable production loss of 5%. Although the CPWI without fertilization (0 kg N ha-1) was similar to that when fertilized with 50 and 75 kg N ha-1, the two topdressing doses increased chickpea productivity by 37% and 51%, on average, respectively.

Periodo crítico de interferencia de malezas en el cultivo de zanahoria

Periodo crítico de interferencia de malezas en el cultivo de zanahoria

Response of Sugar Beet Yield and Water Use Efficiency to Deficit Irrigation and Weed Competition under Drip Irrigation System

Under drip irrigation condition, two field experiments of sugar beet (Beta vulgaris L.) were conducted, in sandy soil, at El-Bostan area, Aly Mubarak Experimental Farm, Southern El-Tahrir Region, El-Buhira Governorate, Egypt, during 2013/14 and 2014/15 winter seasons, to evaluate the impact of water deficit irrigation and its relation with the critical period of weeds infestation on sugar beet yield, quality and water use efficiency. The experimental design was a split-plot design, where three water irrigation regimes treatments, i.e. 60, 80 and 100 % of evapotranspiration (ET0), were allocated in the main plots, and the ten weed removal intervals were allocated in the sub-plots which included five weed free for 3, 6, 9, 12 weeks after planting (WAP) and weed free the whole season, and five weed infestation for 3, 6, 9, 12 (WAP) and weed infestation for the whole season. The main findings indicated that the highest significant reduction on the fresh weights of grassy, broad-leaved and total weeds was obtained by irrigation at 60 % ET0 by14.8, 16.0 and 15.6 %, respectively, in 2013/14 season and 25.0, 13.6 and 17.3 %, respectively, in 2014/15 season, as compared to 100 % ET0, which reflected in increases on root and gross sugar yield per faddan by 58.8 and 60.2 %, respectively, in 2013/14 season and 65.5 and 40.1 %, respectively, in 2014/15 season, as compared to irrigation at 100 % ET0. Furthermore, water use efficiency of irrigation at 60% ET0 gave the highest values of root and sugar yield by 7.2 and 1.2 kg/m3, respectively, in the first season and 7.1 and 1.3 kg/m3, respectively, in second season. The dominant annual weeds were the broadleaf weeds with infestation rates 3.0 kg and 3.5 kg fresh weight /m2 in the first and second seasons, respectively. Whilst, the infestation rate of the grassy weeds was 1.3 kg and 1.4 kg fresh weight/m2 in the both seasons, respectively. In the both seasons, the highest reduction on the fresh weight of the two weeds categories and their total was obtained from all weed free and weed infestation treatments (> 90 %) as compared to weed infestation for the whole season, except with weed free for 3 weeks (< 70%). These results reflected on sugar beet yields (ton/fed). In the first season, the significant increasing on dry weight of tops, roots and the gross sugar yield (ton/fed) was between 118.6, 302.5 and 353.8 %, respectively, in weed free for the whole season to 58.5 % for tops by weed free for 3 weeks, 135.2 % for roots by weed free for 6 weeks and 50.0 % for gross sugar yield by weed infestation for 9 weeks, as compared to weed infestation for the whole season. In second season, the significant increasing on dry weight of the tops, roots and gross sugar yield (ton/fed) was between 98.8, 311.3 and 288.7 %, respectively, in weed free for the whole season to 37.5 % for the tops and 35.0 % for the roots in weed free for 3 weeks and 106.5 % in weed infestation for 6 weeks, as compared to weed infestation for the whole season. While, the rest weed free and weed infestation treatments in the both seasons didn't reach to significant increasing values. For sugar beet quality i.e. TSS, sucrose and purity %, all weed free and weed infestation treatments gave the same values approximately in deferent intervals. Also, different weed removal intervals can raise water efficiency by 240-320 % compared to leave the weeds to compete sugar beet plants for whole season. Concerning the interaction effects, the data indicated that the great reduction on the fresh weight of the two weed categories and their total was obtained from irrigation at 60 % ET0 with weed free for whole season, weed competition for 3 WAP and weed free for 12 WAP, in both seasons. Also, the interactions between both 60 and 80% ET0 irrigation regimes with both weed free for 12 weeks and the whole season gave the highest increasing on the roots and gross sugar yields (ton/fed) in the both seasons. The findings also revealed that the critical period of weed interference between 3 and 12 weeks after planting and the yield losses in this period. Thus, we can conclude that to save water irrigation and maximize root and sugar yields of sugar beet (ton/fed) must be irrigate at 60% ET0 with controlling weeds until 12 week from planting.

Weed Infestation, Growth and Yield of Maize (Zea mays L.) as Influenced by Periods of Weed Interference

Field trials were conducted at the Teaching and Research Farm of the Kwara State University, Nigeria, during the 2013 and 2014 cropping seasons. The aim was to determine the effect of periods of weed interference on weed infestation, maize growth and yield. The experiment consisted of 10 treatments, namely, plots initially kept weed-free for 3, 6, 9 and 12 Weeks After Sowing (WAS) and subsequently left weedy until harvest and plots initially left weedy for 3, 6, 9 and 12 Weeks After Sowing (WAS) and subsequently kept weed--free till harvest. There were two control plots, one left weedy and the other kept weed-free till harvest. The treatments were laid out in randomized complete block design (RCBD) and replicated three times. Parameters measured were weed dry weight, maize plant height, leaf area, number of leaves/plant, cob weight, number of kernel rows/cob, 100 seed weight and grain yield. Results show that weed interference in maize for 6 WAS and beyond significantly depressed growth parameters and grain yield. Plots left weedy for only 3 WAS produced significantly higher yield which was comparable to the maximum. Therefore, it is required that maize plot be kept weed-free between 3 and 6 WAS which is the critical period of weed interference, in other to get optimal yield.

Atrazine Reduces the Critical Period of Weed Interference on Narrow Row Corn

ABSTRACT The objective was to determine whether a change occurs in the critical period of weed interference prevention in narrow row corn with the use of atrazine and whether there is influence of the herbicide on crop yield components. The treatments consisted of periods without or with an initial weed control (0, 21, 35, 49, 63, 77, and 91 days after emergence), with or without application of atrazine in spikely post-emergence. The experiment was carried out in a 2 x 7 randomized blocks design (with and without weed control and seven periods with three replications). The use or not of atrazine was arranged in a split plot design. The most important weed species were Senecio brasiliensis, Urochloa plantaginea, Conyza bonariensis, Sida rhombifolia, and Solanum spp. Corn yield reduced by 15% and 18% with and without application of atrazine, respectively. The number of grains per spike and corn yield were negatively influenced by coexistence with weeds, while the number of rows per spike, the diameter and length of spike were not affected. Corn yield components were not affected by the use of atrazine. The critical period of weed interference prevention was 35 days without atrazine and 23 days with application of atrazine. There is a reduction of the critical period of weed interference prevention on narrow row corn by using atrazine, with no influence of the herbicide on crop yield.

Weed Interference Periods in Early Wheat in the Midwest of Paraná

ABSTRACT Several factors can influence wheat crop yield, they include the interference imposed by weeds is one of the most important. The objective of this study was to evaluate the critical periods of weed interference in early wheat in the midwest of the state of Paraná, Brazil. The experiment was conducted in an experimental area located in Campo Mourão - PR, during the year 2013, using the BRS Pardela cultivar. The treatments consisted of periods of coexistence and weed control in wheat. Periods of coexistence and control were 0, 7, 14, 28, 35 and the whole cycle at days after crop emergence (DAE). Number of reproductive tillers per plant, spike length, number of spikelets per spike, plant height and wheat crop yield, were significantly affected by coexistence with prevailing infestation of Raphanus raphanistrum, therefore, a critical period of interference was determined at 16 to 24 DAE.

INTERFERENCE PERIODS AMONG WEEDS AND SOYBEAN RR TM CROPS IN THE WESTERN CENTER AREA OF THE BRAZILIAN STATE OF PARANÁ

ABSTRACT One of the factors that can influence soybeans yield is the interference imposed by weeds. This research has aimed to determine the critical period of weed interference on cv. INT 6100 RRTM soybeans. The experiment was conducted under field conditions at Campo Mourão County, Parana State, in the 2013/2014 harvest, using randomized blocks, arranged in a 2 x 8 factorial, with four replications. In the first factor, the coexistence (period before weed interference) and control (total period of weed interference prevention) periods were assessed. The second factor consisted of management times of weed species (0, 7, 14, 28, 35, 49, 56 and 130 days after emergence - DAE). The evaluations performed were density and shoot dry matter of the weed community, height, number of pods, thousand grain weight and soybean yield. Among the weed species in soybean crops, there was predominance of eudicotyledonous ones (82%). The yield results allowed establishing, for cv. INT 6100 RRTM soybeans at Campo Mourão County, Parana State, a critical period for preventing interference between 24-38 DAE.

English

The objective of this research was to identify the weed species and to determine the critical periods of weed interference in upland rice in Maranhao State, northeastern Brazil. The experiment was laid out in a randomized complete block design with 16 treatments and four replications in two growing seasons. Treatments were increasing periods of control and coexistence of the crop with weeds, for every 10 days. Weeds were sampled with a 0.5 × 0.3 m metal rectangle which was randomly thrown four times in each plot. Phytosociological parameters computed were Density, Frequency, Dominance and Importance Value Index of each species. The more important families in both growing seasons were Poaceae and Cyperaceae. Cyperus spp., Phyllanthus niruri L., Alternanthera tenella Colla and Digitaria spp. reached higher values of relative importance than the other species. Coexistence of weeds with rice during the whole crop cycle in both growing seasons decreased rice grain yield by 83.4 and 72.0%, respectively. Taking into account 5% tolerance in yield reduction in cropping seasons 2010/2011 and 2011/2012, the periods before interference (PBI) were 15 and 13 days after emergence (DAE), the total periods of interference prevention (TPIP) were 25 and 45 DAE and the critical periods of interference prevention (CPIP) were from 15 to 25 and from 13 to 45 DAE, respectively. It was concluded that the weed control in upland rice must be carried out from 13 till 45 DAE to promote weed free development since the crop has low natural competitive capacity. Key words: Competition, critical period, Oryza sativa L., weed community.

Interferência de plantas daninhas na cultura do sorgo sacarino

Este trabalho teve como objetivo o estudo fitossociológico da comunidade infestante ao longo do ciclo de desenvolvimento do sorgo sacarino e a determinação do período crítico de prevenção à interferência das plantas daninhas na cultura. O delineamento experimental foi de blocos ao acaso com três repetições. Os tratamentos foram constituídos por períodos crescentes de controle ou convivência das plantas daninhas em diferentes estádios fenológicos da cultura: 0-3 (V3), 0-5 (V5), 0-7 (V7), 0-9 (V9), 0-11(V11) folhas completamente expandidas e 0-R5 (colheita). A comunidade infestante foi avaliada por meio do número de indivíduos e da massa seca acumulada correspondente, para cada população de planta daninha nos diferentes períodos de convivência. O sorgo sacarino foi colhido aos 101 dias após a emergência, quando se avaliaram altura, diâmetro, teor de sólidos solúveis totais (°Brix) em função dos períodos de convivência da cultura com as plantas daninhas, além do rendimento de colmos nos diferentes tratamentos. Commelina benghalensis e Panicum maximum foram as duas espécies de maior importância relativa na área, no momento da colheita. A ausência de controle da comunidade infestante, durante todo o ciclo do sorgo sacarino, ocasionou aumento no teor de sólidos solúveis totais (°Brix) e redução de, respectivamente, 9% e 25% na altura e diâmetro de colmo da cultura, quando comparado com a testemunha capinada durante todo o ciclo. Considerando a tolerância de 5% na redução da produtividade de colmos, observou-se que o período crítico de prevenção a interferência correspondeu ao intervalo do estádio fenológico V3 a V11.

Determination of the critical period of weed control in potato (Solanum tuberosum L.)

Field studies were conducted in north-eastern Iran in 2010 and 2011 to establish the critical period of weed interference in potato (Solanum tuberosum L.) and to investigate the effects of weed interference on weed biomass. The critical period for weed control in potato based on a 5% acceptable yield loss level was calculated by fitting logistic and Gompertz equations to relative yield data. Total dry biomass and total number of weeds increased as the duration of weed infestation increased. The beginning of the critical period for weed control was 19 days after potato emergence in both years. The end of the critical period for weed control in 2011 was 22 days after potato emergence, whereas in 2010 the beginning and end of the critical period for weed control occurred simultaneously. Tuber yields of potato were reduced by prolonged delays in weed removal in both years. The practical implication of this study is that weeds must be controlled during the first 3 weeks of the crop's growing season. Such an approach would keep yield loss levels below 5%.

English

This study was carried out in Botucatu, State of Sao Paulo, Brazil in order to evaluate the interference periods of weeds on potato crop. The experimental design was a randomized complete blocks, with four replications, and treatments were arranged in two groups: 1) the crop was kept free from weeds through the periods of 7, 14, 21, 28 and 35 days after emergence, after each period weeds were allowed to grow; 2) the crop was kept weedy for the same periods of the first group, and afterwards the crop was kept weed-free besides a control maintained weed free and another maintained in coexistence with the weeds at 98 days (harvest). Urochloa plantaginea, Cyperus esculentus, Raphanus raphanistrum, Sida rhombifolia, and Galinsoga parviflora were the main weeds in the experimental area, being U. plantaginea the weed with the highest dry matter accumulation. Tuber size and yield were affected by interference of weed community. The total period of weed interference was 35, while the period previous of interference was 7; consequently, the critical period of weed interference was from 7 to 35 after crop emergence. Key words: Competition, Solanum tuberosum, weed periods, weed management.

Weed Interference in the Sugarcane (Saccharum officinarum L.) Plantations of Ethiopia

Field experiments involving sprawling and erect cultivars of sugarcane and 12 weed competition periods were conducted in randomized complete block design in four replications for two cropping seasons at three sugarcane plantations of Ethiopia. Sugarcane was either kept free of weeds or weeds were allowed to grow for 0, 3, 6, 9, 12 and 15 weeks after planting (WAP). The sprawling sugarcane cultivars (‘B41227’ and ‘N14’) suppressed weed growth more and gave higher cane yield than the erect cultivar ‘NCo334’. The cane yield loss in unweeded plots compared to weed free plots ranged from 69.7% for sprawling cultivar ‘B41227’ at Methara to 83.5% at Wonji-Shoa for the erect cultivar ‘NCo334’. The beginning and end of critical periods of weed interference on 5% acceptable cane yield loss levels ranged from about 2.5 to 14 WAP for the erect cultivar and from 3 to 13.5 WAP for the sprawling cultivars implying the need to use herbicides or other weed control methods in sugarcane plantations of Ethiopia during these periods to keep cane yield loss levels below 5%.