Incident photosynthetically active radiation as a basis for integrated management of purple nutsedge (Cyperus rotundus)

Weed Science ◽  
1997 ◽  
Vol 45 (6) ◽  
pp. 777-783 ◽  
Author(s):  
Christophe Neeser ◽  
Renan Aguero ◽  
Clarence J. Swanton
Keyword(s):  
Costa Rica ◽  
Photosynthetically Active Radiation ◽  
Integrated Management ◽  
Soil Surface ◽  
Cyperus Rotundus ◽  
Purple Nutsedge ◽  
Active Radiation ◽  
Tuber Production ◽  
Reproductive Rates ◽  
Artificial Shading

Artificial shading studies indicated that competition for photosynthetically active radiation (PAR) will limit tuber production in purple nutsedge. There were no data available to test whether there is a relationship between incident PAR underneath crop canopies and tuber production of this weed. In this study, the effect of crop competition on net reproductive rates of purple nutsedge tubers was measured under field conditions. Purple nutsedge plants were grown in association with bush beans, maize, maize and beans intercropped, sweet potato, pole beans, and bell pepper in a 2-yr field study in Costa Rica. Measurements were taken on the number of tubers produced during the growing season of each crop, and PAR transmittance was monitored weekly for the duration of the respective cropping cycles. Data on transmittance and incident solar radiation were used to calculate the daily average amount of PAR, available 15 cm above the soil surface. Regressions indicated that average incident PAR accounted for 95% of the variation in net reproductive rates. Average incident PAR also allowed a more precise competitive ranking of crops than either average or minimum transmittance. Bush beans had consistently the lowest average incident PAR values and therefore ranked as the most competitive crop in both years. Our data suggest that no net increase in tuber populations occurs if average incident PAR is below 2.7 MJ m−2d−1. Differences in the duration of the cropping cycle accounted only for a small proportion of the overall variation in net reproductive rates of purple nutsedge tubers. Information on the competitive ranking of different crops can be used to design crop rotations that could reduce reliance on herbicides on small farms in Costa Rica.

Response of purple (Cyperus rotundus) and yellow nutsedges (C. esculentus) to selective placement of sulfentrazone

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 382-387 ◽  
Author(s):  
Glenn R. Wehtje ◽  
Robert H. Walker ◽  
Timothy L. Grey ◽  
H. Gary Hancock
Keyword(s):  
Soil Ph ◽  
Soil Surface ◽  
Hydroponic Culture ◽  
Cyperus Rotundus ◽  
Purple Nutsedge ◽  
Yellow Nutsedge ◽  
Selective Placement

A series of greenhouse studies examined the effectiveness of PRE- and POST-applied sulfentrazone in controlling purple and yellow nutsedge as influenced by selective tissue exposure. In addition,14C-sulfentrazone was utilized to contrast absorption and translocation resulting from these exposures. Consistent control with preemergence applications to germinating tubers was obtained with a combined root and shoot zone exposure. Yellow nutsedge was more susceptible than purple nutsedge. Performance of the separate root and shoot zone exposure was soil pH- and nutsedge-species dependent. POST-foliar applications to established nutsedge were more effective when sulfentrazone was allowed to contact the soil surface.14C-sulfentrazone was readily absorbed by the roots and translocated to the foliage of both species in hydroponic culture.

Effect of Five Thiocarbamate Herbicides on Purple Nutsedge(Cyperus rotundus)

Weed Science ◽  
1978 ◽  
Vol 26 (2) ◽  
pp. 127-131 ◽  
Author(s):  
D. J. Rincon ◽  
G. F. Warren
Keyword(s):  
Soil Surface ◽  
Cyperus Rotundus ◽  
Silt Loam ◽  
Initial Activity ◽  
Purple Nutsedge ◽  
Effective Reduction ◽  
Basal Bulb ◽  
Higher Doses

Five thiocarbamate herbicides, butylate(S-ethyl diisobutylthiocarbamate), EPTC(S-ethyl dipropylthiocarbamate), molinate(S-ethyl-hexahydro-1H-azepine-1-carbothioate), pebulate(S-propyl butylethyl-thiocarbamate), and vernolate(S-propyl dipropylthiocarbamate) were used in the greenhouse at doses of 0.5 to 5 kg/ha incorporated 6 cm deep in a silt loam. Purple nutsedge(Cyperus rotundusL.) tubers were planted 5 cm deep. Three and 9 weeks after treatments were applied, nutsedge plants were harvested. EPTC also was used at doses of 0.25 to 10 kg/ha and plants were harvested every 2 days up to 20 days and every 3 weeks up to 24 weeks. The most effective reduction in the number of sprouts above ground was given by butylate, EPTC, and vernolate followed by pebulate and molinate. Persistence was directly related to level of initial activity. No effect was observed on the number of tubers which sprouted. However, all the thiocarbamates stimulated the number of sprouts produced per nondormant tuber. These sprouts were abnormal and did not reach the soil surface. Treated tubers produced approximately twice as many sprouts as controls. The number of rhizomes produced from the basal bulb was reduced with all the thiocarbamates used, even 24 weeks after treatment for the higher doses.

Glyphosate Hinders Purple Nutsedge (Cyperus rotundus) and Yellow Nutsedge (Cyperus esculentus) Tuber Production

Weed Science ◽  
2008 ◽  
Vol 56 (5) ◽  
pp. 735-742 ◽  
Author(s):  
Theodore M. Webster ◽  
Timothy L. Grey ◽  
Jerry W. Davis ◽  
A Stanley Culpepper
Keyword(s):  
Multiple Shoots ◽  
Cyperus Rotundus ◽  
Cyperus Esculentus ◽  
Management Options ◽  
Third Order ◽  
Purple Nutsedge ◽  
Yellow Nutsedge ◽  
Tuber Production ◽  
Primary Means ◽  
Phase Out

The phase-out of methyl bromide requires alternative nutsedge management options in vegetable systems. Options that target tuber production, the primary means of reproduction, will be most beneficial. A study was conducted to evaluate the response of purple nutsedge and yellow nutsedge foliar growth and tuber production to a range of glyphosate rates. Glyphosate was applied at six rates between 0.41 and 2.57 kg ae ha−1to 5-wk-old nutsedge plants with multiple shoots. The rate of glyphosate needed to reduce growth 50% (I50) was similar for purple nutsedge foliar growth (0.58 kg ha−1) and tuber biomass (0.55 kg ha−1). In contrast,I50for yellow nutsedge foliar growth was 0.73 kg ha−1, which was greater than theI50for tuber biomass (0.41 kg ha−1). First-order tubers, those directly attached to the initial tuber, had anI50of 0.70 and 0.44 kg ha−1of glyphosate for purple nutsedge and yellow nutsedge tuber biomass, respectively. For all higher-order tubers,I50values ranged from 0.29 to 0.60 and 0.14 to 0.30 kg ha−1of glyphosate for purple nutsedge and yellow nutsedge tuber biomass, respectively. Glyphosate at 0.74 kg ha−1prevented fourth-order purple nutsedge and third-order yellow nutsedge tuber production (terminal tubers for yellow nutsedge). Fifth- and sixth-order purple nutsedge tuber production was eliminated by the lowest tested rate of glyphosate (0.41 kg ha−1). Effective nutsedge management options will require consistent control between spring and autumn crops. Glyphosate is economical, poses no herbicide carryover issues to vegetables, and minimizes nutsedge tuber production; therefore, it is a suitable candidate to manage nutsedges.

scholarly journals A Mobile Platform for Measuring Canopy Photosynthetically Active Radiation Interception in Orchard Systems

2012 ◽  
Vol 22 (2) ◽  
pp. 237-244 ◽  
Author(s):  
Bruce D. Lampinen ◽  
Vasu Udompetaikul ◽  
Gregory T. Browne ◽  
Samuel G. Metcalf ◽  
William L. Stewart ◽  
...  
Keyword(s):  
Photosynthetically Active Radiation ◽  
Juglans Regia ◽  
Soil Surface ◽  
Mobile Platform ◽  
Seasonal Development ◽  
Remotely Sensed Data ◽  
Data Logger ◽  
Yield Data ◽  
Canopy Development ◽  
Active Radiation

A mobile platform was developed for measuring midday canopy photosynthetically active radiation (PAR) interception in orchards. The results presented are for almond (Prunus dulcis) and walnut (Juglans regia), but the mobile platform can be used in other orchard crops as well. The mobile platform is adjustable to accommodate orchard row spacing from 4.8 to 7.8 m and is equipped with a global positioning satellite (GPS) receiver and radar for positional assessment as well as three IR thermometers for measuring soil surface temperature. Data from the mobile platform are logged at 10 Hz and stored on a data logger. Custom software has been developed to process the data. The mobile platform was used extensively for mapping midday canopy PAR interception in almond and walnut orchards in 2009 and 2010. The mobile platform produced comparable results to those collected with a handheld light bar with the advantage of being able to cover much larger areas and compare these data to mechanically harvested yield data over the same area. For almond orchards, midday canopy PAR interception peaked at ≈70% at an orchard age of ≈12 years. For walnut orchards, midday canopy PAR interception continued to increase to ≈15 years of age and peaked at a level above 80%. The mobile platform was also able to follow seasonal development of midday canopy PAR interception in young and mature orchards. This technology has potential for evaluating new varieties in terms of productivity per unit PAR intercepted, in evaluating hand pruning or mechanical hedging practices in terms of impact on PAR interception/productivity as well as evaluating effectiveness of insect or disease management treatments. It also has potential as a reference point for grower self-assessment to evaluate orchard canopy development compared with other orchards of similar variety, spacing, etc. Finally, this technology could be used as ground truth referencing for remotely sensed data.

Growth of Purple Nutsedge (Cyperus rotundus) in Response to Interference with Direct-Seeded Rice

2012 ◽  
Vol 26 (3) ◽  
pp. 506-509 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
Jhoana Opeña
Keyword(s):  
Belowground Biomass ◽  
Cyperus Rotundus ◽  
Shoot Biomass ◽  
Leaf Biomass ◽  
Total Biomass ◽  
Purple Nutsedge ◽  
Rice Plants ◽  
Shoot Number ◽  
Tuber Production ◽  
Direct Seeded

The biology of purple nutsedge was studied by growing it alone and in competition with 12 and 24 rice plants in a pot experiment. Compared with the weedy plants grown alone, competition from rice reduced purple nutsedge leaf number, shoot number, tuber production rate, and leaf biomass. At 10 wk after planting, interference from 12 and 24 rice plants reduced purple nutsedge leaf area by 79 and 86%, respectively, compared with weedy plants grown without rice interference. On the same date, purple nutsedge aboveground shoot biomass was 26.8 g plant−1without interference, whereas in interference with 12 and 24 rice plants, purple nutsedge produced aboveground biomass of 4.8 and 2.2 g plant−1, respectively. A total of 95 tubers plant−1were produced by purple nutsedge when grown alone. Growth with 12 and 24 rice plants reduced tuber production to 33 and 17 tubers plant−1, respectively. Without interference, purple nutsedge produced 40 g plant−1of total biomass of tuber plus root plus rhizome, whereas in interference with 12 and 24 rice plants, purple nutsedge produced 14 and 5 g plant−1of total belowground biomass, respectively.

Gibberellic Acid Plus Cytokinins Induced Basal Bulbs of Purple Nutsedge Above Ground

Weed Science ◽  
1974 ◽  
Vol 22 (1) ◽  
pp. 55-58 ◽  
Author(s):  
Ritchie S. Chetram ◽  
Leo E. Bendixen
Keyword(s):  
Gibberellic Acid ◽  
Soil Surface ◽  
Cyperus Rotundus ◽  
Purple Nutsedge ◽  
Surface Control

Benzyladenine (BA), kinetin, and gibberellic acid (GA) at concentrations of 6 × 10−4and 4 × 10−3M, respectively, were used to induce formation of basal bulbs above ground in rhizomes of purple nutsedge (Cyperus rotundusL.). BA plus GA induced a tropistic response in all of the rhizomes and only above ground bulbs were produced, while kinetin plus GA induced a tropistic response and bulbs formed above and below the soil surface. Control plants as well as those treated with GA, kinetin, or BA produced underground bulbs and rhizomes but no bulbs above ground. Height of above ground secondary bulbs induced by kinetin plus GA was significantly greater than those induced by BA plus GA. Transformation of primary rhizomes to shoots in the control plants did not differ significantly from transformation of those originating from plants of the various treatments. Height of primary plants of all treatments differed significantly from the controls.

scholarly journals Efecto de tipos de labranza sobre la población de malezas en caña de azúcar (Saccharum officinarum L.).

2006 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Ramón León ◽  
Renán Agüero
Keyword(s):  
Nutrient Uptake ◽  
Surface Coverage ◽  
Soil Surface ◽  
Saccharum Officinarum ◽  
Soil Disturbance ◽  
Cyperus Rotundus ◽  
The Other ◽  
Purple Nutsedge ◽  
Rottboellia Cochinchinensis

Experiments were conducted in two sugarcane fields, one with low weed pressure (plot 1) and the other with high weed pressure (plot 2). Four treatments were established in each study: green harvest that left plant mulch on soil surface (VCR), green harvest without plant mulch on soil surface (VSR), burning the crop before harvest without soil disturbance (QSL) and burning the crop before harvest with soil disturbance (QCL). Evaluations were made 75 days after harvest. The evaluations were conducted separately in rows and between rows. In addition, sugarcane population and height were measured. Differences in weed populations were not observed for the field with low weed pressure (plot 1). In the field with high weed pressure (plot 2), weeds were favored by burning and soil disturbance caused by fertilizer incorporation. Thus the treatments QSL and QCL showed the highest percentage of surface coverage. Also, the QCL treatment had the greatest weed populations resulting in reduced sugarcane population and height. Purple nutsedge (Cyperus rotundus L.) and itchgrass (Rottboellia cochinchinensis (Lour.) Clayton) had the greatest percentage surface coverage, especially in QCL. Weed populations were larger in rows than between rows. Apparently in rows, weeds found better conditions for germination and nutrient uptake.

scholarly journals Purple Nutsedge (Cyperus rotundus) Tuber Production and Viability Are Reduced by Imazapic

Weed Science ◽  
2016 ◽  
Vol 65 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Theodore M. Webster ◽  
Timothy L. Grey ◽  
Jason A. Ferrell
Keyword(s):  
Weed Management ◽  
Cropping Systems ◽  
Cyperus Rotundus ◽  
Economic Losses ◽  
Purple Nutsedge ◽  
Time Of Application ◽  
Growing Seasons ◽  
Aerial Shoot ◽  
Tuber Production

Weeds exploit underutilized space, causing economic losses in cropping systems. Weed management tactics alter that underutilized space until the crop can mature and efficiently use that space. One tactic is to reduce the weed propagules (e.g., seeds and tubers) that persist quiescently in the soil, which includes minimizing production and addition of new propagules to the soil. Purple nutsedge is a problematic weed around the globe, persisting between growing seasons as tubers in the soil. Imazapic is a peanut herbicide often used in Georgia for control of purple nutsedge. The objective of the experiment was to evaluate the effect of various rates of imazapic on purple nutsedge tuber production. Single presprouted purple nutsedge tubers were transplanted into outdoor microplots and treated after 6 wk of growth with six rates of imazapic (5 to 140 g ai ha−1) POST. A nontreated control was included. All emerged shoots at the time of application were marked with plastic rings; this allowed for classification of tubers at exhumation as (1) tubers attached to shoots that were emerged at time of application, (2) tubers attached to shoots that emerged after application, and (3) tubers without an aerial shoot during the study. At 7 wk after application, the tubers in the microplots were exhumed, classified, and quantified, and their ability to sprout was evaluated. In the nontreated control, there were 544 total tubers, with a log-logistic regression model describing the declining tuber population with increasing imazapic rate. The rate of imazapic that reduced total tuber population 50% (I50) was 36 g ha−1. In the nontreated control, there were 161 tubers attached to shoots that emerged, as when compared with plots that received an imazapic application that had an I50=60 g ha−1. Viability of purple nutsedge tubers was 44% at 70 g ha−1imazapic, suggesting the action of the herbicide may have rendered the tubers nonviable after new shoots were produced. The final classification of tubers included those that did not have an aerial shoot during the study. These were tubers in which apical dominance suppressed shoot development or were likely the most recent tubers to develop. Of the three classes, the tubers without shoots were the most prevalent in the nontreated control, with 358 tubers and an I50=18 g ha−1. Imazapic controls purple nutsedge foliage but also reduces the number of new tubers produced, and overall tuber viability and is a valuable tool in management of the long-term population density of this weed.

scholarly journals Ground level photosynthetically active radiation dynamics in stands of Acacia mearnsii De Wild

2015 ◽  
Vol 87 (3) ◽  
pp. 1833-1845 ◽  
Author(s):  
SYLVIO PÉLLICO NETTO ◽  
CARLOS R. SANQUETTA ◽  
BRAULIO O. CARON ◽  
ALEXANDRE BEHLING ◽  
AUGUSTO A. SIMON ◽  
...  
Keyword(s):  
Photosynthetically Active Radiation ◽  
Inflection Point ◽  
Soil Surface ◽  
Ground Level ◽  
Height Growth ◽  
Rio Grande Do Sul ◽  
Acacia Mearnsii ◽  
Active Radiation ◽  
Breast Height ◽  
Closed Canopy

ABSTRACTThe objective is to study the dynamics of photosynthetic radiation reaching the soil surface in stands of Acacia mearnsii De Wild and its influence on height growth in stands. This fact gives rise to the formulation of the following hypothesis for this study: "The reduction of the incidence of light inside the stand of black wattle will cause the inflection point in its height growth when this reaches 4 to 5 m in height, i.e. when the stand is between 2 and 3 years of age". The study was conducted in stands in the state of Rio Grande do Sul, Brazil, where diameters at breast height, total height and photosynthetically active radiation available at ground level were measured. The frequency tended to be more intense when the age of the stands increases. It was evident that a reduction of light incidence inside the forest occurred, caused by canopy closure. Consequently, closed canopy propitiated the competition of plants. This has affected the conditions for growth in diameter and height of this species, reason why it becomes possible to conceive the occurrence of an inflection point in the growth of these two variables, confirming the formulated hypothesis.

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