The reproductive biology of the introduced root holoparasite Orobanche ramosa subsp. mutelii (Orobanchaceae) in South Australia

2015 ◽  
Vol 63 (5) ◽  
pp. 426
Author(s):  
Jane Prider
Keyword(s):  
Seed Production ◽  
Invasive Plant ◽  
South Australia ◽  
Reproductive Traits ◽  
Soil Surface ◽  
Flower Senescence ◽  
Self Pollination ◽  
Orobanche Ramosa ◽  
Large Populations ◽  
Successful Control

An understanding of the timing and constraints on seed production is necessary for the successful control of many invasive plant species. In the present study, we investigated the reproductive traits of the annual root holoparasite, Orobanche ramosa L. subsp. mutelii (F.W.Shultz) Cout. (branched broomrape), which occurs in the western Murray mallee area of South Australia. Flowering stems emerge above the ground from early September. Each flower spike has from 2 to 24 flowers and the first flower opens on the base 8 days after emergence and senesces 6 days later. An additional flower opens acropetally every 1–2 days. The species is autogamous and self-pollination can occur before anthesis. Mature seeds were observed from 9–10 days after flower senescence and capsules dehisced 12 days later. Although each plant is in flower only for an average of 20 days, in large populations or multi-branched plants, the flowering period extends over several weeks, with a peak in mid-October. Seed production in sampled populations was highly variable, ranging from 1000 to over 200 000 per plant. Large plants with several branching stems produced the most seeds, although capsules produced per stem and seeds per capsule were also variable. There is a brief window of opportunity for control of O. ramosa subsp. mutelii after it emerges above the soil surface and before it sets seed. Weedy root parasites such as Orobanche ramosa can have devastating impacts on host crops, but are difficult to control because most growth occurs underground. We identified key characters that contribute to the success of this introduced plant, including self-pollination, rapid maturation of the reproductive stages and high seed output. Vigilance is required so that plants can be controlled before they set seed.

Reproductive biology of the endangered Brachycome muelleri (Asteraceae), an endemic herb of Eyre Peninsula, South Australia

2003 ◽  
Vol 51 (2) ◽  
pp. 179 ◽  
Author(s):  
Manfred Jusaitis ◽  
Birgitte Sorensen ◽  
Lesley Polomka
Keyword(s):  
Seed Dispersal ◽  
Seed Production ◽  
Reproductive Biology ◽  
Field Experiments ◽  
Soil Seed Bank ◽  
Seed Viability ◽  
South Australia ◽  
Soil Surface ◽  
Long Distance ◽  
Pollinator Visitation

The reproductive biology of Brachycome muelleri Sonder (Asteraceae) was studied from 1995 to 1997 by using nursery and field experiments. Reproductive development and seed dispersal occupied approximately half of the 4-month growth cycle. Flowers of B. muelleri did not have any obvious self-incompatibility systems and were readily selfed to produce viable seed. It appeared that B. muelleri may be preferentially cross-pollinated under ideal conditions of pollinator visitation, but could revert to self-pollination in the event of outcross failure. Seed dispersal was assisted by the epinastic curvature of peduncles as fruit matured, bringing capitula into contact with the soil a short distance away from the parent plant. Slight wind-stimulated movement of the capitulum was sufficient to dislodge seed directly onto the soil surface. Seed was shed in the immediate vicinity of parent plants and although some short-range movement facilitated by rain splash, water flow and gravity was observed, no long-distance dispersal mechanisms were apparent. Annual seed production of the single extant population of B. muelleri in South Australia was estimated at about 5 million seeds. Immediately after dispersal, the soil seed bank in the vicinity of B. muelleri plants contained, on average, over 1700 germinable seeds m–2. Many of these seeds germinated or died within a year, the remainder persisting into a second or third year. Seed viability under field-burial conditions declined to less than 10% over that time. Population size did not appear to be limited by seed production, but rather by seed dispersal syndrome.

Digitaria ciliaris (southern crabgrass).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval ◽  
Pedro Acevedo-Rodríguez
Keyword(s):  
Seed Production ◽  
Farmyard Manure ◽  
Soil Surface ◽  
Post Harvest ◽  
Fluctuating Temperatures

Abstract As an annual weed, D. ciliaris depends on seed production for its spread. There is some post-harvest dormancy which may last several months. Germination then occurs at temperatures above 20°C and is perhaps greatest under fluctuating temperatures of 20 and 35°C (Holm et al., 1977). Most germination occurs at or close to the soil surface (Osa et al., 1988), but some may occur from 5 cm depth (Takabayashi and Nakayama, 1979). Seeds can survive passage through cattle and thus contaminate farmyard manure (Takabayashi et al., 1979).

scholarly journals Effect of EPSPS Gene Copy Number and Glyphosate Selection on Fitness of Glyphosate-Resistant Bassia Scoparia in The Field

2021 ◽  
Author(s):  
Charlemagne Ajoc Lim ◽  
Prashant Jha ◽  
Vipan Kumar ◽  
Alan T. Dyer
Keyword(s):  
Sugar Beet ◽  
Seed Production ◽  
Great Plains ◽  
Copy Number ◽  
Gene Copy Number ◽  
Reproductive Traits ◽  
Gene Copy ◽  
Epsps Gene ◽  
Gene Copies

Abstract The widespread evolution of glyphosate-resistant (GR) Bassia scoparia in the U.S. Great Plains poses a serious threat to the long-term sustainability of GR sugar beet. Glyphosate resistance in B. scoparia is due to an increase in the EPSPS (5-enolpyruvyl-shikimate-3-phosphate) gene copy number. The variation in EPSPS gene copies among individuals from within a single GR B. scoparia population indicated a differential response to glyphosate selection. We tested the hypothesis of reduced GR B. scoparia fitness (reproductive traits) to increasing glyphosate rates (applied as single or sequential applications) potentially experienced within a GR sugar beet field. The variation in EPSPS gene copy number and total glyphosate rate (single or sequential applications) did not influence any of the reproductive traits of GR B. scoparia, except seed production. Sequential applications of glyphosate with a total rate of 2,214 g ae ha− 1 or higher prevented seed production in B. scoparia plants with 2–4 (low levels of resistance) and 5–6 (moderate levels of resistance) EPSPS gene copies. Timely sequential applications of glyphosate (full recommended rates) can potentially slow down the evolution of GR B. scoparia with low to moderate levels of resistance (2–6 EPSPS gene copies), but any survivors (highly-resistant individuals with ≥ 8 EPSPS gene copies) need to be mechanically removed before flowering from GR sugar beet fields. This research warrants the need to adopt ecologically based, multi-tactic strategies to reduce exposure of B. scoparia to glyphosate in GR sugar beet.

Growth, seed production and effect of defoliation in an early flowering perennial grass, Alloteropsis semialata (Poaceae), on Cape York Peninsula, Australia

2001 ◽  
Vol 49 (6) ◽  
pp. 735 ◽  
Author(s):  
Gabriel M. Crowley ◽  
Stephen T. Garnett
Keyword(s):  
Plant Growth ◽  
Seed Production ◽  
Perennial Grass ◽  
Soil Surface ◽  
Plant Size ◽  
Perennial Grasses ◽  
Wet Season ◽  
Cape York ◽  
Seed Dynamics

Alloteropsis semialata (R.Br.) A.Hitchc. is one of the first perennial grasses in monsoonal Australia to produce seed at the start of the wet season. Patterns of growth and seed production and seed dynamics of Alloteropsis semialata were examined in this study, along with the effects of partial defoliation. Growth of Alloteropsis semialata tussocks started with the first pre-wet-season rains, and was then interrupted during a period with little rain. Growth ceased before the end of the wet season, indicating that factors other than moisture availability were limiting. Seeds of Alloteropsis semialata were germinable on production, but did not remain viable or persist on the soil surface through the dry season. Most seeds and young seedlings were harvested and no seedlings were recruited. Inflorescence production increased with plant size. Moderate defoliation in the early wet season had no impact on plant growth, but reduced inflorescence and seed production for at least 2 years. Absence of a seed bank and early wet-season flowering mean that Alloteropsis semialata is likely to be sensitive to long-term over-grazing.

Hand-Tripped Flowers Promote Seed Production in Arachis lignosa, a Wild Peanut1

1990 ◽  
Vol 17 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Donald J. Banks
Keyword(s):  
Seed Production ◽  
Growth Chamber ◽  
Self Incompatibility ◽  
Self Pollination ◽  
Reproductive Sterility ◽  
High Degree

Abstract In trials conducted in the greenhouse, growth chamber, and outdoors, no pegs or pods were produced when A. lignosa (Chod. et Hassl.) Krap. et Greg. nom. nud. plants were allowed to pollinate naturally. However, hand tripping flowers, especially in the greenhouse, resulted in significant increases in pod production. The results suggest that the high degree of reproductive sterility usually noted for A. lignosa in culture is due to pollination failure rather than to physiological self incompatibility. The somewhat truncated shape of the stigma and its elevated position relative to the anthers probably restricts natural self-pollination without the aid of pollinating vectors such as bees.

Izmir subterranean clover (Trifolium subterraneum L. var. subterraneum)

2007 ◽  
Vol 47 (2) ◽  
pp. 226 ◽  
Author(s):  
P. G. H. Nichols ◽  
G. A. Sandral ◽  
B. S. Dear ◽  
C. T. de Koning ◽  
D. L. Lloyd ◽  
...  
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
New South ◽  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Good Seed ◽  
Improvement Program ◽  
South Wales ◽  
Pasture Legume

Izmir is a hardseeded, early flowering, subterranean clover of var. subterraneum (Katz. et Morley) Zohary and Heller collected from Turkey and developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It is a more hardseeded replacement for Nungarin and best suited to well-drained, moderately acidic soils in areas with a growing season of less than 4.5 months. Izmir seed production and regeneration densities in 3-year pasture phases were similar to Nungarin in 21 trials across southern Australia, but markedly greater in years following a crop or no seed set. Over all measurements, Izmir produced 10% more winter herbage and 7% more spring herbage than Nungarin. Its greater hardseededness and good seed production, makes it better suited to cropping rotations than Nungarin. Softening of Izmir hard seeds occurs later in the summer–autumn period than Nungarin, giving it slightly greater protection from seed losses following false breaks to the season. Izmir is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. Izmir has been granted Plant Breeders Rights in Australia.

Management of ACCase-Inhibiting Herbicide-Resistant Smooth Barley (Hordeum glaucum) in Field Pea with Alternative Herbicides

2016 ◽  
Vol 30 (2) ◽  
pp. 441-447 ◽  
Author(s):  
Lovreet S. Shergill ◽  
Benjamin Fleet ◽  
Christopher Preston ◽  
Gurjeet Gill
Keyword(s):  
Seed Production ◽  
Negative Relationship ◽  
South Australia ◽  
Field Pea ◽  
Forage Yield ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Large Yield ◽  
High Level ◽  
The Impact

Smooth barley is an annual weed species that is infesting crops and pastures in South Australia. Complicating control options is the presence of herbicide-resistant biotypes. A field trial was conducted to identify alternative herbicides for the management of acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicide-resistant smooth barley in field pea. Preplant (PP) soil applications of pyroxasulfone; prosulfocarb plus S-metolachlor; dimethenamid-P; propyzamide; trifluralin alone or with triallate or with diuron; or imazamox applied POST were evaluated for their effectiveness and crop safety. Propyzamide, pyroxasulfone, or imazamox applied POST provided a high level of smooth barley control, did not cause any crop injury, and increased field pea grain or forage yield compared with the nontreated. Furthermore, propyzamide or pyroxasulfone reduced panicle density and seed production in smooth barley, whereas the effectiveness of POST imazamox varied over the two seasons. Dimethenamid-P reduced the impact of smooth barley on field pea yield, but cause stunting, and was less effective than propyzamide, pyroxasulfone, and imazamox in reducing smooth barley seed production. Negative relationship between field pea yield and smooth barley panicle density indicated that smooth barley is highly competitive in field pea crops and can cause large yield losses. The results of this investigation suggest that propyzamide or pyroxasulfone applied PP and imazamox applied POST could be used effectively in the field for the management of ACCase-inhibiting herbicide-resistant smooth barley in South Australia.

Impact of Clipping Timing on Japanese Hedgeparsley (Torilis japonica) Seed Production and Viability

2014 ◽  
Vol 7 (3) ◽  
pp. 511-516
Author(s):  
Mark J. Renz ◽  
R. Menyon Heflin
Keyword(s):  
United States ◽  
Seed Production ◽  
Management Strategy ◽  
Invasive Plant ◽  
Vegetative Stage ◽  
Effective Management ◽  
Viable Seed ◽  
Torilis Japonica ◽  
Forested Areas ◽  
Viable Seeds

AbstractJapanese hedgeparsley is a biennial plant that invades roadsides, rights-of way, and forested areas in the midwestern United States. Interest in managing populations by mechanical or hand-clipping techniques exists, but no information is available on the appropriate timing to maximize mortality and prevent the production of viable seed. To assess that, we applied clipping treatments at five periods throughout the summer to three Japanese hedgeparsley populations in southern Wisconsin and measured the number and viability of seeds produced by each plant during the year of treatment and the survival of plants clipped. Japanese hedgeparsley plants began producing seed by mid-July, but production was not maximized until early August. Viable seeds were not produced until early or mid-August, coinciding with the presence of ripened brown fruit. Clipping at any timing resulted in > 95% mortality by the fall of the treatment year. All plants that resprouted were in the vegetative stage when clipped, and no plants survived the following year. Results indicate that clipping Japanese hedgeparsley plants when they are in a reproductive phase before fruit turns brown is an effective management strategy for this invasive plant.

scholarly journals Construction of a male sterility system for hybrid rice breeding and seed production using a nuclear male sterility gene

2016 ◽  
Vol 113 (49) ◽  
pp. 14145-14150 ◽  
Author(s):  
Zhenyi Chang ◽  
Zhufeng Chen ◽  
Na Wang ◽  
Gang Xie ◽  
Jiawei Lu ◽  
...  
Keyword(s):  
Male Sterility ◽  
Seed Production ◽  
Environmental Conditions ◽  
Hybrid Rice ◽  
Rice Breeding ◽  
Male Sterile ◽  
Red Fluorescence ◽  
Cytoplasmic Male Sterile ◽  
Cross Pollination ◽  
Self Pollination

The breeding and large-scale adoption of hybrid seeds is an important achievement in agriculture. Rice hybrid seed production uses cytoplasmic male sterile lines or photoperiod/thermo-sensitive genic male sterile lines (PTGMS) as female parent. Cytoplasmic male sterile lines are propagated via cross-pollination by corresponding maintainer lines, whereas PTGMS lines are propagated via self-pollination under environmental conditions restoring male fertility. Despite huge successes, both systems have their intrinsic drawbacks. Here, we constructed a rice male sterility system using a nuclear gene named Oryza sativa No Pollen 1 (OsNP1). OsNP1 encodes a putative glucose–methanol–choline oxidoreductase regulating tapetum degeneration and pollen exine formation; it is specifically expressed in the tapetum and miscrospores. The osnp1 mutant plant displays normal vegetative growth but complete male sterility insensitive to environmental conditions. OsNP1 was coupled with an α-amylase gene to devitalize transgenic pollen and the red fluorescence protein (DsRed) gene to mark transgenic seed and transformed into the osnp1 mutant. Self-pollination of the transgenic plant carrying a single hemizygous transgene produced nontransgenic male sterile and transgenic fertile seeds in 1:1 ratio that can be sorted out based on the red fluorescence coded by DsRed. Cross-pollination of the fertile transgenic plants to the nontransgenic male sterile plants propagated the male sterile seeds of high purity. The male sterile line was crossed with ∼1,200 individual rice germplasms available. Approximately 85% of the F1s outperformed their parents in per plant yield, and 10% out-yielded the best local cultivars, indicating that the technology is promising in hybrid rice breeding and production.

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