scholarly journals Sex Lability and Dimorphism in Dioecious Palmer Amaranth (Amaranthus palmeri)

2019 ◽  
Author(s):  
Mohsen B. Mesgaran ◽  
Maor Matzrafi ◽  
Sara Ohadi
Keyword(s):  
Water Stress ◽  
Sex Ratio ◽  
Sex Expression ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Dioecious Species ◽  
Relative Growth ◽  
Male And Female ◽  
Secondary Sex Characters

AbstractDioecious weeds (separate sexes) may benefit from a maximized outcrossing and optimal sex-specific resource allocation but there are costs associated with the evolution of this breeding system which can be exploited for long-term management of dioecious weeds. That is, seed production in dioecious species is contingent upon the co-occurrence and co-flowering of the two genders and can be further complicated by biases in sex ratio. We therefore explored the sex ratio and dimorphism in secondary sex characters in three populations of Palmer amaranth (Amaranthus palmeri) from California, Kansas and Texas and tested if water stress can change the sex expression and/or the synchrony of flowering (anthesis) between male and female plants. Sex ratio (proportion of males) was balanced and did not deviate from 1:1 in all experiments and populations (California, Kansas, Texas) when plants received normal watering. Male and female plants of A. palmeri did not differ in timing of emergence, plant height and relative growth rate. While the initiation of flowering (emergence of inflorescence) occurred earlier in males than females, females preceded males in timing of anthesis. Water stress delayed anthesis in males to a larger extent than females giving rise to an anthesis mismatch as large as seven days between the two sexes. Water stress induced a female sex expression in Kansas population giving rise to a female to male ratio of 1.78 which significantly differed from the equal 1:1 sex ratio. Our data provide the first evidence of sex lability and environment sex determination (ESD) in A. palmeri, suggesting manipulation of sex expression and phenological asynchrony as novel tools for ecological management of dioecious weeds.

scholarly journals Sex dimorphism in dioecious Palmer amaranth (Amaranthus palmeri) in response to water stress

Planta ◽  
2021 ◽  
Vol 254 (1) ◽  
Author(s):  
Mohsen B. Mesgaran ◽  
Maor Matzrafi ◽  
Sara Ohadi
Keyword(s):  
Water Stress ◽  
Weed Management ◽  
Amaranthus Palmeri ◽  
Ecological Management ◽  
State University ◽  
Dioecious Species ◽  
Seed Output ◽  
Flowering Asynchrony ◽  
Secondary Sex Characters ◽  
Response To Water

Abstract Main conclusion Phenological isolation can potentially reduce seed output and may be exploited as a novel tool for ecological management of dioecious weeds. Abstract Dioecious plants may benefit from a maximized outcrossing and optimal sex-specific resource allocation; however, this breeding system may also be exploited for weed management. Seed production in dioecious species is contingent upon the co-occurrence and co-flowering of the two genders and can be further disturbed by flowering asynchrony. We explored dimorphism in secondary sex characters in Amaranthus palmeri, and tested if reproductive synchrony can be affected by water stress. We have used seeds of A. palmeri from California, Kansas and Texas, and studied secondary sex characters under natural conditions and in response to water stress. Seeds of A. palmeri from California (CA) and Kansas (KS) were cordially provided by Dr. Anil Shrestha (California State University, Fresno, California) and Dr. Dallas E. Peterson (Kansas State University, Manhattan, Kansas), respectively. Seeds of a third population were collected from mature plants (about 30 plants) from a set-aside field in College Station, Texas. A. palmeri showed no sexual dimorphism with regard to the timing of emergence, plant height, and relative growth rate. While the initiation of flowering occurred earlier in males than females, females preceded males in timing of anthesis. Water stress delayed anthesis in males to a greater extent than females increasing the anthesis mismatch between the two sexes by seven days. Our data provide the first evidence of environment-controlled flowering asynchrony in A. palmeri. From a practical point of view, phenological isolation can potentially reduce seed output and may be exploited as a novel tool for ecological management of dioecious weeds.

Evaluating Effect of Degree of Water Stress on Growth and Fecundity of Palmer amaranth (Amaranthus palmeri) Using Soil Moisture Sensors

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 738-745 ◽  
Author(s):  
Parminder S. Chahal ◽  
Suat Irmak ◽  
Mithila Jugulam ◽  
Amit J. Jhala
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Seed Germination ◽  
Crop Production ◽  
Growth Index ◽  
The United States ◽  
Palmer Amaranth ◽  
Maximum Height ◽  
Amaranthus Palmeri ◽  
Soil Moisture Sensors

AbstractPalmer amaranth (Amaranthus palmeriS. Watson) is the most problematic weed in agronomic crop production fields in the United States. The objective of this study was to determine the effect of degree of water stress on the growth and fecundity ofA. palmeriusing soil moisture sensors under greenhouse conditions. TwoA. palmeribiotypes collected from Nebraska were grown in loam soil maintained at 100%, 75%, 50%, 25%, and 12.5% soil field capacity (FC) corresponding to no, light, moderate, high, and severe water stress levels, respectively. Water was regularly added to pots based on soil moisture levels detected by Watermark or Decagon 5TM sensors to maintain the desired water stress level.Amaranthus palmeriplants maintained at ≤25% FC did not survive more than 35 d after transplanting.Amaranthus palmeriat 100%, 75%, and 50% FC produced similar numbers of leaves (588 to 670 plant−1) based on model estimates; however, plants at 100% FC achieved a maximum height of 178 cm compared with 124 and 88 cm at 75% and 50% FC, respectively. The growth index (1.1×105to 1.4×105cm3plant−1) and total leaf area (571 to 693 cm2plant−1) were also similar at 100%, 75%, and 50% FC.Amaranthus palmeriproduced similar root biomass (2.3 to 3 g plant−1) at 100%, 75%, and 50% FC compared with 0.6 to 0.7 g plant−1at 25% and 12.5% FC, respectively. Seed production was greatest (42,000 seeds plant−1) at 100% FC compared with 75% and 50% FC (14,000 to 19,000 seeds plant−1); however, the cumulative seed germination was similar (38% to 46%) when mother plants were exposed to ≥50% FC. The results of this study show thatA. palmerican survive ≥50% FC continuous water stress conditions and can produce a significant number of seeds with no effect of on seed germination.

scholarly journals Sexual ratio and floral biology of the dioecious Neea theifera Oerst. (Nyctaginaceae) in a cerrado rupestre of central Brazil

2011 ◽  
Vol 25 (4) ◽  
pp. 785-792 ◽  
Author(s):  
Felipe Wanderley Amorim ◽  
Clesnan Mendes-Rodrigues ◽  
Pietro Kiyoshi Maruyama ◽  
Paulo Eugênio Oliveira
Keyword(s):  
Resource Allocation ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Reproductive Strategy ◽  
Pollen Viability ◽  
Floral Biology ◽  
Pollinator Limitation ◽  
Dioecious Species ◽  
Male And Female ◽  
Pollination Success

Dioecy is characterized by a complete separation of sexual functions on male and female plants. It has evolved many times in flowering plants and is widespread among distinct Angiosperm families. It is viewed as a reproductive strategy to reduce endogamy, and to promote optimal resource allocation between male and female sexual functions. Neea theifera is a common species in Cerrado, neotropical savannas in Brazil, but information regarding its reproductive biology is still incomplete. In order to investigate how environmental conditions possibly affect this dioecious species, we studied its floral biology, sex ratio and spatial distribution of sexual morphs along a soil-altitudinal gradient. The sex ratio did not significantly deviate from the expected 1:1 ratio. However, flower abundance in the population was significantly biased towards staminate flowers. Female individuals were larger than male individuals and plant size was negatively correlated with altitude, but did not differ between sexual morphs. The population did not show spatial segregation of sexes and male individuals were sexually mature earlier than female ones. Staminate flowers were larger than pistillate flowers and presented high pollen viability. Meliponini bees, small flies and thrips were potential pollinators, but pollination success was very low. Dioecy in N. theifera corroborates many general features of this reproductive strategy, such as woody habit, inconspicuous flowers, pollination by small generalist insects and differential resource allocation between male and female plants. However, reproduction in this species seems to be impaired by pollinator limitation. The results showed that the soil-altitude gradient influenced the growth pattern of the species and may play an important role in its reproductive biology but did not affect dioecy directly.

scholarly journals Influence of plant growth regulators on vegetative growth, sex expression and yield of summer bottle gourd

2020 ◽  
Vol 44 (4) ◽  
pp. 577-590
Author(s):  
M Moniruzzaman ◽  
R Khatoon ◽  
M Moniruzzaman ◽  
AKM Qamruzzaman
Keyword(s):  
Sex Ratio ◽  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Female Flower ◽  
Sex Expression ◽  
Fruit Weight ◽  
Bottle Gourd ◽  
Male And Female ◽  
Female Flowers

Field experiments on bottle gourd variety ‘BARI Lau -4’ were conducted at the Plant Physiology field of Horticulture Research Center, Bangladesh Agricultural Research Institute, Gazipur during two consecutive summer seasons of 2015 and 2016 to investigate the effect of plant growth regulators on growth, sex expression, yield and yield components of the crop. The experiment consisted of different concentrations of Gibberellic acid (GA3), Naphthalene acetic acid (NAA), Maleic hydrazide (MH) and single concentration of cycocel (CCC) viz., GA3 @ 10 ppm, GA3 @ 30 ppm, NAA @100 ppm, NAA @ 150 ppm, MH @ 50 ppm, MH @ 150 ppm and CCC @ 500 ppm along with distilled water considered as control. All growth regulators were sprayed to the seedlings at two-leaf stage and 4 days after the first spray. Growth regulator treatments had significant effect on primary branches/plant, node number of 1st male and female flower appearance, number of days to 1st male and female flower appearance, number of male and female flowers, sex ratio (male:female flower) number of fruits/plant, individual fruit weight and fruit yield. Spraying of MH @ 150 ppm gave the highest primary branches/plant (17.0 and 18.0 in first and 2nd year, respectively) and induced maximum female flowers (37.3 and 40.0 in first and 2nd year, respectively) at lower nodes followed by CCC @ 500 ppm (36.3) in the first year and MH @ 50 ppm (40.0) in the 2nd year. Application of MH @ 150 ppm caused early appearance of female flowers on the nearest node (from bottom). Application of MH @ 150 ppm gave the lower number of male flowers (81.7 and 96.0 in first and 2nd year, respectively) and the highest number of female flowers/plant, thereby producing lower male:female sex ratio (2.2 and 2.5 in first and 2nd year, respectively) and the maximum number of fruits/plant (12.0 and 14.0 in first and 2nd year, respectively). The maximum fruit weight/plant was obtained from the application of MH @ 150 ppm (29.3 and 35.8 in first and 2nd year, respectively) followed by CCC @ 500 ppm (26.0 in the 1st year and 29.0 in 2nd year). The highest fruit yield per hectare was recorded significantly with the application of MH @ 150 ppm (97.6 t/ha and 89.6 t/ha in first and 2nd year, respectively) closely followed by CCC @ 500 ppm (88.5 t/ha in 2015) and GA3 @ 30 ppm (75.3 t/ha in 2016), as compared to other treatments. The highest mean yield over the years was also recorded at MH @ 150 ppm (93.6 t/ha) followed by CCC @ 150 ppm (80.6 t/ha) and GA3 30 (74.1). Application of MH @ 150 ppm gave the maximum gross return and net return with the highest BCR of 5.24 followed by CCC 500 ppm (4.15) and GA3 30 ppm (3.86). Bangladesh J. Agril. Res. 44(4): 577-590, December 2019

Phenology of Five Palmer amaranth (Amaranthus palmeri) Populations Grown in Northern Indiana and Arkansas

Weed Science ◽  
2018 ◽  
Vol 66 (4) ◽  
pp. 457-469 ◽  
Author(s):  
Douglas J. Spaunhorst ◽  
Pratap Devkota ◽  
William G. Johnson ◽  
Reid J. Smeda ◽  
Christopher J. Meyer ◽  
...  
Keyword(s):  
Planting Date ◽  
Palmer Amaranth ◽  
Maximum Height ◽  
Amaranthus Palmeri ◽  
Male And Female ◽  
Late Season ◽  
Extension Center ◽  
Male To Female ◽  
Latitudinal Range ◽  
Growth And Reproduction

AbstractPalmer amaranth (Amaranthus palmeriS. Watson) is a problematic weed encountered in U.S. cotton (Gossypium hirsutumL.) and soybean [Glycine max(L.) Merr.] production, with infestations spreading northward. This research investigated the influence of planting date (early, mid-, and late season) and population (AR, IN, MO, MS, NE, and TN) onA. palmerigrowth and reproduction at two locations. All populations planted early or midseason at Throckmorton Purdue Agricultural Center (TPAC) and Arkansas Agriculture Research and Extension Center (AAREC) measured 196 and 141 cm or more, respectively. Amaranthus palmeriheight did not exceed 168 and 134 cm when planted late season at TPAC and AAREC, respectively. Early season plantedA. palmerifrom NE grew to 50% of maximum height 8 to 13 d earlier than all other populations under TPAC conditions. In addition, the NE population planted early, mid-, and late season achieved 50% inflorescence emergence 5, 4, and 6 d earlier than all other populations, respectively. All populations established at TPAC produced fewer than 100,000 seeds plant−1. No population planted at TPAC and AAREC produced more than 740 and 1,520 g plant−1of biomass at 17 and 19 wk after planting, respectively. Planting date influenced the distribution of male and female plants at TPAC, but not at AAREC. Amaranthus palmerifrom IN and MS planted late season had male-to-female plant ratios of 1.3:1 and 1.7:1, respectively. Amaranthus palmeriintroduced to TPAC from NE can produce up to 7,500 seeds plant−1if emergence occurs in mid-July. An NEA. palmeripopulation exhibited biological characteristics allowing it to be highly competitive if introduced to TPAC due to a similar latitudinal range, but was least competitive when introduced to AAREC. AlthoughA. palmerioriginating from different locations can vary biologically, plants exhibited environmental plasticity and could complete their life cycle and contribute to spreading populations.

Maternal water stress reduces sensitivity of offspring to herbicides in Amaranthus palmeri (Palmer amaranth)

Weed Research ◽  
2021 ◽  
Author(s):  
O. Adewale Osipitan ◽  
Maor Matzrafi ◽  
Sara Ohadi ◽  
Mohsen B. Mesgaran
Keyword(s):  
Water Stress ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri

scholarly journals Effect of PPO-Inhibiting Herbicides on the Growth and Sex Ratio of a Dioecious Weed Species Amaranthus palmeri (Palmer Amaranth)

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 275 ◽  
Author(s):  
Mafia M. Rumpa ◽  
Ronald F. Krausz ◽  
David J. Gibson ◽  
Karla L. Gage
Keyword(s):  
Sex Ratio ◽  
Seed Production ◽  
Sex Ratios ◽  
Rapid Evolution ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Weed Species ◽  
Herbicide Treatments ◽  
Underlying Mechanisms ◽  
Sites Of Action

Amaranthus palmeri S. Watson (Palmer amaranth) is a fast-growing, dioecious, highly competitive agricultural weed species, which is spreading across the US Midwest. Population sex ratios are an important consideration in the management of A. palmeri populations as this species has become resistant to several herbicide sites of action, and there is need to minimize seed production by female plants. Environmental conditions, particularly stressors, may influence sex ratios, and herbicides act as major stressors and evolutionary filters in agricultural fields. Amaranthus spp. have shown a tendency for rapid evolution of herbicide resistance, with the frequency of protoporphyrinogen oxidase (PPO)-inhibitor resistance increasing across the Midwestern US. A greenhouse experiment was conducted to investigate the effect of two PPO-inhibiting herbicide treatments of either lactofen or fomesafen on four different Illinois populations (Cahokia, Collinsville, Rend Lake, and Massac). Plants raised from seed from the Massac population were tallest, and both males and females from this population also had the highest vegetative biomass. Female plants from the Collinsville population had more reproductive biomass than male plants. Control populations were male-biased (Cahokia, Collinsville), female-biased (Masaac), and 1:1 (Rend Lake). Lactofen shifted the male-biased populations to female-biased or 1:1 and the female-biased population to 1:1. Fomesafen-treated populations were male-biased or 1:1. This study suggests that PPO-inhibiting herbicide treatments may influence the growth and sex ratio of A. palmeri populations, which is an underlying factor in the rate of herbicide evolution in this species. An understanding of the underlying mechanisms of how external factors influence sex ratios may eventually provide an opportunity to reduce seed production in populations by shifting sex ratios towards a male bias.

Biology and Management of Glyphosate-Resistant and Glyphosate-Susceptible Palmer Amaranth (Amaranthus palmeri) Phenotypes from a Segregating Population

Weed Science ◽  
2017 ◽  
Vol 65 (6) ◽  
pp. 755-768 ◽  
Author(s):  
Sushila Chaudhari ◽  
David L. Jordan ◽  
Alan C. York ◽  
Katherine M. Jennings ◽  
Charles W. Cahoon ◽  
...  
Keyword(s):  
North Carolina ◽  
Drought Stress ◽  
Geographical Location ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Relative Growth ◽  
Yield Information ◽  
Basic Biology ◽  
Pressure Resistance ◽  
Segregating Population

Palmer amaranth is the most economically damaging glyphosate-resistant (GR) weed in the southern United States. An understanding of the basic biology, including relative growth and competitiveness of GR and glyphosate-susceptible (GS) Palmer amaranth phenotypes from a segregating population collected from the same geographical location, may yield information helpful in the management of resistant populations. A segregating population of Palmer amaranth collected in North Carolina during 2010 was used as a plant source for both GR and GS traits. Research was conducted in the greenhouse to compare the following: level of resistance and shikimate accumulation in GR and GS phenotypes following glyphosate application; interference from GR and GS phenotypes on early-season vegetative growth of corn, cotton, and peanut; effect of various durations of imposed drought stress on GR and GS phenotypes; and response of GR and GS phenotypes to POST-applied herbicides. The GR50(glyphosate rate providing 50% reduction in shoot dry biomass) was 17 times greater with the GR phenotype compared with the GS phenotype. Shikimate accumulated in both GR and GS phenotypes following glyphosate application, but greater concentrations were found in GS plants. The GR and GS phenotypes responded similarly when subjected to drought stress; grown with corn, cotton, and peanut; or treated with 2,4-D, atrazine, dicamba, fomesafen, glufosinate, paraquat, tembotrione, and thifensulfuron. These results indicate that in the absence of glyphosate selection pressure, resistance to glyphosate does not influence the growth and competitiveness of GR and GS Palmer amaranth phenotypes collected from the same geographical location.

scholarly journals In-Culture Selection and the Potential Effects of Changing Sex Ratios on the Reproductive Success of Multiannual Delayed Gametophytes of Saccharina latissima and Alaria esculenta

2021 ◽  
Vol 9 (11) ◽  
pp. 1250
Author(s):  
Alexander P. J. Ebbing ◽  
Gregory S. Fivash ◽  
Nuria B. Martin ◽  
Ronald Pierik ◽  
Tjeerd J. Bouma ◽  
...  
Keyword(s):  
Life Cycle ◽  
Reproductive Success ◽  
Sex Ratio ◽  
Female Gametophyte ◽  
Sex Ratios ◽  
Saccharina Latissima ◽  
Male And Female ◽  
Alaria Esculenta

Multiannual delayed gametophyte cultures can stay vegetative for years, while also having the ability to grow. This study aims to investigate whether male and female multiannual delayed gametophyte strains of the species Saccharina latissima and Alaria esculenta grow at different rates in culture. We furthermore assessed how changing sex ratios can affect the reproductive yields of these cultures. The results indicate that the reproductive yield of cultures declines with decreasing male:female ratios, a correlation that becomes especially apparent at higher culture densities for both species. Female gametophyte densities in particular affected the observed reproductive yield of the cultures, with S. latissima cultures showing a clear reproductive optimum (sporophytes·mL−1) at 0.013 mg·mL−1 DW female gametophyte biomass, while the reproductive success of A. esculenta peaked at a density of 0.025 mg·mL−1 DW of female gametophyte biomass, after which the reproductive yield started to decline in both species. The results show that the sex ratio of a gametophyte culture is an important biotic life cycle control, with higher amounts of female gametophyte biomass halting gametophyte reproduction. Understanding how these changing sex ratios in gametophyte cultures affect reproduction is especially important in the aquaculture of kelp, where reliable preforming cultures are key to long-term success.

Long-Term Management of Palmer Amaranth (Amaranthus palmeri) in Dicamba-Tolerant Cotton

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 161-169 ◽  
Author(s):  
Matthew D. Inman ◽  
David L. Jordan ◽  
Alan C. York ◽  
Katie M. Jennings ◽  
David W. Monks ◽  
...  
Keyword(s):  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Soil Cores ◽  
Alternative Mode ◽  
Similar Frequency ◽  
Weed Population Dynamics ◽  
Herbicide Programs ◽  
Pollen Movement ◽  
Term Management

Research was conducted from 2011 to 2014 to determine weed population dynamics and frequency of glyphosate-resistant (GR) Palmer amaranth with herbicide programs consisting of glyphosate, dicamba, and residual herbicides in dicamba-tolerant cotton. Five treatments were maintained in the same plots over the duration of the experiment: three sequential POST applications of glyphosate with or without pendimethalin plus diuron PRE; three sequential POST applications of glyphosate plus dicamba with and without the PRE herbicides; and a POST application of glyphosate plus dicamba plus acetochlor followed by one or two POST applications of glyphosate plus dicamba without PRE herbicides. Additional treatments included alternating years with three sequential POST applications of glyphosate only and glyphosate plus dicamba POST with and without PRE herbicides. The greatest population of Palmer amaranth was observed when glyphosate was the only POST herbicide throughout the experiment. Although diuron plus pendimethalin PRE in a program with only glyphosate POST improved control during the first 2 yr, these herbicides were ineffective by the final 2 yr on the basis of weed counts from soil cores. The lowest population of Palmer amaranth was observed when glyphosate plus dicamba were applied regardless of PRE herbicides or inclusion of acetochlor POST. Frequency of GR Palmer amaranth was 8% or less when the experiment was initiated. Frequency of GR Palmer amaranth varied by herbicide program during 2012 but was similar among all herbicide programs in 2013 and 2014. Similar frequency of GR Palmer amaranth across all treatments at the end of the experiment most likely resulted from pollen movement from Palmer amaranth treated with glyphosate only to any surviving female plants regardless of PRE or POST treatment. These data suggest that GR Palmer amaranth can be controlled by dicamba and that dicamba is an effective alternative mode of action to glyphosate in fields where GR Palmer amaranth exists.

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