scholarly journals Control Recommendations for Black Medic (Medicago lupulina) Based on Growth and Development in Competition with Strawberry

Weed Science ◽  
2017 ◽  
Vol 66 (2) ◽  
pp. 226-233 ◽  
Author(s):  
Shaun M. Sharpe ◽  
Nathan S. Boyd ◽  
Peter J. Dittmar ◽  
Greg E. MacDonald ◽  
Rebecca L. Darnell ◽  
...  
Keyword(s):  
Growth And Development ◽  
Plant Size ◽  
Control Measures ◽  
Stem Length ◽  
Plastic Mulch ◽  
Flower Buds ◽  
Medicago Lupulina ◽  
Hand Weeding ◽  
Spray Timing ◽  
Time Frames

Strawberries are an important horticultural crop in Florida. Black medic is among the most problematic weeds within the production system. To better coordinate control measures, black medic growth and development while in competition with strawberry was studied. Twelve plants were randomly selected at each of four field sites in Hillsborough County, FL, in 2014. Plants were repeatedly measured over the growing season for stem length and number of primary branches, flower buds, flowers, and seed clusters. Growing degree days (GDD) were calculated (Tbase=0 C) starting from the hole-punch application of the plastic mulch (October 8, 2014, to October 10, 2014) from weather station data generated from the Florida Automated Weather Network. Strawberry height and width increased consistently across all sites, but black medic growth and development varied considerably. Strawberry suppressed black medic growth up to 1,805 cumulative GDD at three of four sites where black medic remained beneath the strawberry canopy. After 1,805 GDD, the black medic stems still remained below but experienced exponential growth for total stem length and, in turn, flower buds, inflorescence, and immature seed clusters. Ideal clopyralid spray timing based on susceptible plant size was 890 to 1,152 GDD. Optimal hand-weeding time frames would likely occur as the plant stems expand beyond the strawberry canopy (to improve visibility) and before flower production to prevent seed return to the seedbank. First seed production was observed at 1,200 GDD at the earliest site and between 1,966 to 2,365 GDD across all the other sites. Overall, consistent trends were observed across sites, but between-site variability was observed that could not be accounted for by differences in temperature.

Black Medic (Medicago lupulina) Emergence and Emergence Predictors within Florida Strawberry Fields

Weed Science ◽  
2018 ◽  
Vol 67 (2) ◽  
pp. 253-260 ◽  
Author(s):  
Shaun M. Sharpe ◽  
Nathan S. Boyd
Keyword(s):  
Current Control ◽  
Control Measures ◽  
Model Fit ◽  
Burial Depth ◽  
Factors Affecting ◽  
Control Techniques ◽  
Medicago Lupulina ◽  
Controlled Environments ◽  
Field Emergence ◽  
Hand Weeding

AbstractBlack medic (Medicago lupulinaL.) infestations are a concern for Florida strawberry [Fragaria×ananassa(Weston) Duchense ex Rozier (pro sp.) [chiloensis×virginiana] producers. Current control techniques rely on hand weeding or clopyralid application. Coordinating POST control measures with emergence timing can reduce crop competition duration and increase control. The objective of this study was to evaluateM. lupulinaemergence in response to burial depth and temperature and to modelM. lupulinacumulative field emergence under subtropical Florida conditions using growing degree days (GDDs) as a predictor. Two studies were in controlled environments and looked at factors affecting emergence, burial depth, and temperature. A third experiment was a 2-yr emergence study conducted on four commercial strawberry fields in Hillsborough County, FL. Emergence was modeled as a function of accumulated standard and restricted daily GDD accounting, based onM. lupulinadormancy and germination. In Experiment 1,M. lupulinaonly emerged when seed was deposited on the surface. In Experiment 2, there was three-way interaction among temperature, burial depth, and measurement timing (P<0.0001).Medicago lupulinaemerged from as deep as 2 cm at a temperature range between 15 and 25 C.Medicago lupulinafield emergence was not consistent between years, although emergence was consistent across four sites in year 1, with 0 emergence in year 2. Dormancy and germination restrictions increased calibration and validation model fit and reduced GDD inflation, making models usable between years.Medicago lupulinaprimarily emerged during crop establishment, between mid-November and late-December, which corresponds to an ideal timing for control measures before the harvest period.

Phenology and growth in four annual species grown in ambient and elevated CO2

1991 ◽  
Vol 69 (11) ◽  
pp. 2475-2481 ◽  
Author(s):  
E. G. Reekie ◽  
F. A. Bazzaz
Keyword(s):  
Key Words ◽  
Growth And Development ◽  
Stem Elongation ◽  
Plant Size ◽  
Annual Species ◽  
Flower Buds ◽  
Rate Of Development ◽  
Competitive Outcome ◽  
Number Of Leaves ◽  
Induced Changes

The objectives of this study were (i) to test the hypothesis that changes in phenology with CO2 are a function of the effect of CO2 upon growth and (ii) to determine if CO2-induced changes in phenology can influence competitive outcome. We examined the effect of 350, 525, and 700 μL∙L−1 CO2 on Guara brachycarpa, Gailardia pulchella, Oenothera laciniata, and Lupinus texensis. Plants were grown as individuals in 150-, 500-, or 1000-mL pots and in competition in 1000-mL pots. Growth and development were monitored at twice-weekly intervals by recording the number of leaves and noting the presence or absence of stem elongation, branching, flower buds, and open flowers. Elevated CO2 affected both growth and phenology, but the direction and magnitude of effects varied with species and soil volume. Elevated CO2 did not appear to affect development through its effect on growth. Those treatments in which there were significant effects of CO2 on growth were generally different from those treatments in which CO2 affected phenology. Rather than affecting phenology by changing plant size, CO2 appeared to affect phenology by modifying the size at which plants switched from one stage to the next. The level of CO2 changed competitive outcome; the importance of Lupinus increased whereas that of Oenothera decreased with increased CO2. These changes were more closely related to the effect of CO2 on growth than its effect on phenology. Key words: time of flowering, size at flowering, competition, photoperiod, rate of development.

scholarly journals Response Mechanism of Cotton Growth to Water and Nutrients under Drip Irrigation with Plastic Mulch in Southern Xinjiang

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Meng Li ◽  
Jun Xiao ◽  
Yungang Bai ◽  
Yingji Du ◽  
Fucang Zhang ◽  
...  
Keyword(s):  
Plant Height ◽  
Cotton Plant ◽  
Seed Yield ◽  
Growth And Development ◽  
Deficit Irrigation ◽  
Control Measures ◽  
Fertilizer Treatment ◽  
Plastic Mulch ◽  
Flowering Stage ◽  
Nutrient Control

The effects of water and nutrient control measures on the cotton plant height, stem diameter, biomass, seed yield, and soil moisture under an irrigated plastic mulch production system were studied. Using field experiments in the 2018 cotton-growing season, 6 fertilization treatments (30-10.5-4.5 (N-P2O5-K2O), 24-8.4-3.6 (N-P2O5-K2O), 20-7-3 (N-P2O5-K2O), 16-5.6-2.4 (N-P2O5-K2O), 10-3.5-1.5 (N-P2O5-K2O), and 0-0-0 (N-P2O5-K2O) kg/mu) and 6 deficit irrigation treatments (40% PET, 60% PET, and 80% PET) were established at the cotton budding and flowering stages. Analysis of variance (ANOVA) (P<0.05) was used to evaluate the significant differences among the treatments. The results showed that the effects of the water and nutrient control measures were obvious. The irrigation water use efficiency (IWUE) was the highest under the 80% deficit irrigation (T7) treatment at the flowering stage (2.62 kg/m3). Increases in cotton plant height and stem diameter were promoted by mild or moderate deficit irrigation at the flowering stage, but normal growth and development were affected by severe deficit irrigation at any growth stage. The growth indexes of cotton increased with increasing fertilization, but significant differences between each fertilization gradient were not obvious. At the same time, excessive fertilization not only had a positive effect on the LAI (leaf area index) and yield but also caused fertilizer waste and unnecessary cotton growth. The cotton seed yield and single boll yield reached their highest values (566 kg/mu) under the 1.2 times fertilizer treatment (T9), but the 0.8 times fertilizer treatment had the highest IWUE among the nutrient control treatments (1.91 kg/m3). Therefore, it is suggested that deficit irrigation at 60~80% of the potential evapotranspiration (PET) at the flowering stage and 16-5.6-2.4 (N-P2O5-K2O) fertilizer be applied as an optimal water and nutrient management strategy to maximize the seed cotton yield, IWUE, and overall growth and development of cotton.

scholarly journals Release of Postsenescent Dormancy in Leafy Spurge (Euphorbia esula) by Chilling

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 784-786 ◽  
Author(s):  
Stephen J. Harvey ◽  
Robert M. Nowierski
Keyword(s):  
Growth Rate ◽  
North America ◽  
Growth And Development ◽  
Leafy Spurge ◽  
Climatic Conditions ◽  
Euphorbia Esula ◽  
Flower Buds ◽  
Significant Growth ◽  
Number Of Stems

The growth and development of leafy spurge (Euphorbia esulaL. #3EPHES) collected during postsenescent dormancy and grown in the greenhouse was increasingly stimulated by chilling treatments longer than 14 days duration at 0 to 6 C. Production of stems with flower buds, primary flowers, and secondary flowers was greater in plants chilled for 42 days or more. The effects of chilling on total number of stems, number of strictly vegetative stems, or number of stems with vegetative branching were not significant. The height of the tallest stem per pot was influenced by chilling longer than 42 days. Growth rate also increased as a function of chilling duration. Based on our findings, we believe that there is little possibility that any significant growth can occur in the postsenescent period because of the prevailing climatic conditions found in areas of leafy spurge distribution in North America.

The growth and development of the leaf in tomato (Lycopersicon esculentum). I. The plastochron index, a suitable basis for description

1976 ◽  
Vol 54 (21) ◽  
pp. 2421-2428 ◽  
Author(s):  
Warren K. Coleman ◽  
Richard I. Greyson
Keyword(s):  
Lycopersicon Esculentum ◽  
Seasonal Variability ◽  
Growth And Development ◽  
Growth Analysis ◽  
Growth Habit ◽  
Leaf Growth ◽  
Growth Stages ◽  
Flower Buds ◽  
Morphological Status ◽  
Plastochron Index

Growth analysis indicates that the plastochron index (PI) is consistently applicable for describing the morphological status of the vegetative tomato shoot in quantitative terms, and pronounced seasonal variability in the growth habit is minimized. However, the PI is not applicable to tomato shoots after flower buds are produced at the vegetative apex. True leaf no. 3 goes through four growth stages which can be characterized in terms of the leaf plastochron index (LPI3). A basipetal trend in leaf growth and development is evident.

scholarly journals Identification and expression of the trehalose-6-phosphate synthase gene family members in tomato exposed to different light spectra

2017 ◽  
Vol 69 (1) ◽  
pp. 93-101
Author(s):  
Zexiong Chen ◽  
Juan Lou
Keyword(s):  
Plant Growth ◽  
Blue Light ◽  
White Light ◽  
Growth And Development ◽  
Light Quality ◽  
Red Light ◽  
Floral Transition ◽  
Stem Length ◽  
Pcr Analysis ◽  
Phosphate Synthase

Light is the source of energy for plants. Light wavelengths, densities and irradiation periods act as signals directing morphological and physiological characteristics during plant growth and development. To evaluate the effects of light wavelengths on tomato growth and development, Solanum lycopersicum (cv. micro-Tom) seedlings were exposed to different light-quality environments, including white light and red light supplemented with blue light (at ratios of 3:1 and 8;1, respectively). Tomatoes grown under red light supplemented with blue light displayed significantly shorter stem length, a higher number of flower buds and rate of fruit set, but an extremely late flowering compared to white-light-grown plants. To illustrate the mechanism underlying the inhibition of stem growth and floral transition mediated by red/blue light, 10 trehalose-6-phosphate synthase (TPS) genes were identified in tomato, and bioinformatics analysis was performed. qRT-PCR analysis showed that SlTPSs were expressed widely throughout plant development and SlTPS1 was expressed at extremely high levels in stems and buds. Further analysis of several flowering-associated genes and microRNAs showed that the expressions of SlTPS1, SlFT and miR172 were significantly downregulated in tomato grown under red and blue light compared with those grown under white light, whereas miR156 transcript levels were increased. A regulatory model underlying vegetative growth and floral transition regulated by light qualities is presented. Our data provide evidence that light quality strongly affects plant growth and phase transition, most likely via the TPS1-T6P signaling pathway.

Clopyralid Dose Response for Two Black Medic (Medicago lupulina) Growth Stages

2016 ◽  
Vol 30 (3) ◽  
pp. 717-724 ◽  
Author(s):  
Shaun M. Sharpe ◽  
Nathan S. Boyd ◽  
Peter J. Dittmar
Keyword(s):  
Dose Response ◽  
Growth Stage ◽  
Plant Size ◽  
Stem Length ◽  
Effective Dosage ◽  
Growth Stages ◽  
Response Curves ◽  
Measured Range ◽  
Large Growth ◽  
Small Growth

Black medic is a troublesome weed in commercial strawberry fields in Florida. It emerges during crop establishment from the planting holes punched in plastic mulches that are installed on raised beds. Clopyralid is registered for posttransplant applications at 140 to 280 g ae ha−1but growers typically report suppression, not control. An outdoor potted experiment was designed to model the black medic dose-response curve and determine the effect of plant size at application on control. Two plant sizes were selected: designated small (0.5- to 1-cm stem length) and large (3- to 6-cm stem length). Dose-response curves were generated using a log-logistic four-parameter model. At 22 d after treatment (DAT), there was a significant interaction between clopyralid rate and black medic growth stage on both epinasty (P = 0.0022) and chlorosis (P = 0.0055). The effective dosage to induce 90% (ED90) epinasty were 249.5 and 398.3 g ha−1for the small and large growth stages, respectively. The ED90 for chlorosis was 748.2 for the small growth stage, whereas the estimated value for the large was outside the measured range. For necrosis there was no significant effect of growth stage, and the ED90 was 1,856.3 g ha−1. The aboveground dry biomass ED90 for the small growth stage was 197.3 g ha−1, and the estimated ED90 value for the large was not within the measured range. Results indicate that clopyralid adequately controls black medic when applied at maximum label rates when stems were 0.5 to 1 cm long but not when plants were larger. Poor efficacy typically observed in commercial fields is likely due to black medic plant size or lack of herbicide coverage via shielding by strawberry plants.

Yellow Nutsedge (Cyperus esculentus) Competition and Control in Corn (Zea mays)

Weed Science ◽  
1979 ◽  
Vol 27 (1) ◽  
pp. 32-37 ◽  
Author(s):  
E. W. Stoller ◽  
L. M. Wax ◽  
F. W. Slife
Keyword(s):  
Zea Mays ◽  
Control Measures ◽  
Effective Control ◽  
Yield Reduction ◽  
Cyperus Esculentus ◽  
Yellow Nutsedge ◽  
Effective Combination ◽  
Percentage Yield ◽  
Hand Weeding ◽  
And Control

Competition of yellow nutsedge (Cyperus esculentusL.) with corn (Zea maysL.) was evaluated in the field at various yellow nutsedge densities over a 3-yr period. A relationship between yellow nutsedge density (shoots/m2) and percentage yield reduction revealed an 8% yield reduction for every 100 shoots/m2. Two 3-yr studies were conducted to determine the most effective combination of preplant-incorporated, postemergence, or postemergence-directed treatments for yellow nutsedge control in corn. The preplant incorporated treatments were alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], EPTC (S-ethyl dipropylthiocarbamate), or nothing; postemergence treatments were bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4) 3H-one 2,2-dioxide], two cultivations, or nothing; and the postemergence-directed treatments were ametryn [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine] or nothing. One preplant-incorporated treatment of EPTC or alachlor prevented yield reductions from yellow nutsedge competition. When no control was practiced, yields were reduced 17% in a moderate yellow nutsedge infestation (initially infested with 300 tubers/m2) and 41% in a heavy infestation (initially infested with 1200 tubers/m2). Yields were reduced 7 to 8% in the moderate infestation when no preplant-incorporated treatments were used regardless of whether postemergence or postemergence-directed treatments were also used. After 1 yr, all control measures resulted in less tuber density than no control measures, but all control treatments had essentially similar tuber densities. After the second year, several herbicide treatments were as effective as hand weeding in reducing tuber density. At least 2 yr of effective control treatments were required to reduce tubers to 20% of the original density, and 3 yr of treatment to reduce the density to 15% of the original density. No combination of treatments, including hand weeding, eliminated tubers after 3 yr.

scholarly journals The Effect of Different Weed Management Strategies on the Growth and Yield of Direct-Seeded Dry Rice (Oryza sativa)

2016 ◽  
Vol 34 (1) ◽  
pp. 57-64 ◽  
Author(s):  
S. MUHAMMAD ◽  
I. MUHAMMAD ◽  
A. SAJID ◽  
L. MUHAMMAD ◽  
A. MAQSHOOF ◽  
...  
Keyword(s):  
Weed Control ◽  
Crop Yield ◽  
Weed Management ◽  
Management Strategies ◽  
Control Measures ◽  
Growth And Yield ◽  
Primary Concern ◽  
Herbicide Treatment ◽  
Direct Seeded ◽  
Hand Weeding

Weed management is a primary concern in direct seeded rice (DSR) cropping because weed growth becomes a major constraint on crop yield. A two year field study was set up to evaluate the effect of various weed control measures on crop growth, grain yield and grain quality of DSR. The experiment involved five different weed control measures: hand weeding, hoeing, inter-row tine cultivation, inter-row spike hoeing and herbicide treatment (Nominee 100 SC). The extent of weed control (compared to a non-weeded control) ranged from 50-95%. The highest crop yield was obtained using hand weeding. Hand weeding, tine cultivation and herbicide treatment raised the number of fertile rice tillers formed per unit area and the thousand grain weight. Tine cultivation provided an effective and economical level of weed control in the DSR crop.

STRAWBERRY DAUGHTER PLANT SIZE ALTERS TRANSPLANT GROWTH AND DEVELOPMENT

2000 ◽  
pp. 121-126 ◽  
Author(s):  
E.B. Bish ◽  
D.J. Cantliffe ◽  
C.K. Chandler
Keyword(s):  
Growth And Development ◽  
Plant Size
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