Mechanical scarification technique breaks seed coat-mediated dormancy in wild oat (Avena fatua)

Abstract Wild oat is a herbicide resistance-prone global weed species that causes significant economic losses in dryland and horticultural agriculture. As a result, there has been a significant research effort in controlling this species. A major impediment to this research is the seed coat-mediated dormancy of wild oat, requiring a labor-intensive incision or puncturing of the seed coat to initiate seed germination. This study defines the most efficient settings of a mechanical thresher to overcome wild oat seed dormancy and then validates these settings using multiple populations collected from the Western Australian grain belt. We also compare the effects of rapid mechanical scarification and known germination stimulus tactics such as scarification with sulfuric acid (H2SO4), partial endosperm removal, sandpaper scarification of the seed coat, and immersion in sodium nitroprusside (NO donor SNP) solution on wild oat seedling growth rate. Threshing treatment of 1,500 rpm for 5 s provides equivalent germination compared with manually puncturing individual wild oat seeds, with no difference in seedling relative growth rate. The mechanical scarification of seeds using the thresher resulted in greater germination (66%) than H2SO4 scarification (0%), partial endosperm removal (10%), sandpaper seed coat scarification (25%), and exposure to NO donor SNP (34%). This study demonstrates that the physical dormancy of wild oat can be rapidly overcome using a commercially available mechanical thresher.

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Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

Weed Technology ◽

10.1017/wet.2020.142 ◽

2020 ◽

pp. 1-22

Author(s):

Michael J. Walsh ◽

Annie E. Rayner ◽

Annie Rutledge ◽

John C. Broster

Keyword(s):

Cropping Systems ◽

Seedling Emergence ◽

Field Studies ◽

Wild Oat ◽

Weed Seed ◽

Weed Species ◽

Environment Effect ◽

Seed Survival ◽

Cropping Seasons ◽

Rigid Ryegrass

Abstract Chaff lining and chaff tramlining are harvest weed seed control (HWSC) systems that involve the concentration of weed seed containing chaff material into narrow (20 to 30 cm) rows between or on the harvester wheel tracks during harvest. These lines of chaff are left intact in the fields through subsequent cropping seasons in the assumption that the chaff environment is unfavourable for weed seed survival. The chaff row environment effect on weed seed survival was examined in field studies, while chaff response studies determined the influence of increasing amounts of chaff on weed seedling emergence. The objectives of these studies were to determine 1) the influence of chaff lines on the summer-autumn seed survival of selected weed species; and 2) the influence of chaff type and amount on rigid ryegrass seedling emergence. There was frequently no difference (P>0.05) in survival of seed of four weed species (rigid ryegrass, wild oat, annual sowthistle and turnip weed) when these seed were placed beneath or beside chaff lines. There was one instance where wild oat seed survival was increased (P<0.05) when seed were placed beneath compared to beside a chaff line. The pot studies determined that increasing amounts of chaff consistently resulted in decreasing numbers of rigid ryegrass seedlings emerging through chaff material. The suppression of emergence broadly followed a linear relationship where there was approximately a 2.0% reduction in emergence with every 1.0 t ha-1 increase in chaff material. This relationship was consistent across wheat, barley, canola and lupin chaff types, indicating that the physical presence of the chaff was more important than chaff type. These studies indicated that chaff lines may not affect the over summer-autumn survival of the contained weed seeds but the subsequent emergence of weed seedlings will be restricted by high amounts of chaff (>40 t ha-1).

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Seed germination biology of sweet acacia (Vachellia farnesiana) and response of its seedlings to herbicides

Weed Science ◽

10.1017/wsc.2021.54 ◽

2021 ◽

pp. 1-19

Author(s):

Bhagirath S. Chauhan ◽

Shane Campbell ◽

Victor J. Galea

Keyword(s):

Sodium Chloride ◽

Seed Germination ◽

Development Stage ◽

Hot Water ◽

Control Treatment ◽

Similar Species ◽

Weed Species ◽

Physical Dormancy ◽

Seed Biology ◽

Wide Range

Abstract Sweet acacia [Vachellia farnesiana (L.) Willd.]is a problematic thorny weed species in several parts of Australia. Knowledge of its seed biology could help to formulate weed management decisions for this and other similar species. Experiments were conducted to determine the effect of hot water (scarification), alternating temperatures, light, salt stress, and water stress on seed germination of two populations of V. farnesiana and to evaluate the response of its young seedlings (the most sensitive development stage) to commonly available POST herbicides in Australia. Both populations behaved similarly to all the environmental factors and herbicides; therefore, data were pooled over the populations. Seeds immersed in hot water at 90 C for 10 min provided the highest germination (88%), demonstrating physical dormancy in this species. Seeds germinated at a wide range of alternating day/night temperatures from 20/10 C (35%) to 35/25 C (90%) but no seeds germinated at 15/5 C. Germination was not affected by light, suggesting that seeds are nonphotoblastic and can germinate under a plant canopy or when buried in soil. Germination was not affected by sodium chloride concentrations up to 20 mM and about 50% of seeds could germinate at 160 mM sodium chloride, suggesting its high salt tolerance ability. Germination was only 13% at −0.2 MPa osmotic potential and no seeds germinated at −0.4 MPa, suggesting that V. farnesiana seeds may remain ungerminated until moisture conditions have become conducive for germination. A number of POST herbicides, including 2,4-D + picloram, glufosinate, paraquat and saflufenacil, provided >85% control of biomass of young seedlings compared with the nontreated control treatment. Knowledge gained from this study will help to predict the potential spread of V. farnesiana in other areas and help to integrate herbicide use with other management strategies.

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Effects of Different Pretreatments and Seed Coat on Dormancy and Germination of Seeds of Senna obtusifolia (L.) H.S. Irwin & Barneby (Fabaceae)

International Journal of Biology ◽

10.5539/ijb.v8n2p77 ◽

2016 ◽

Vol 8 (2) ◽

pp. 77

Author(s):

Stephen I. Mensah ◽

Chimezie Ekeke

Keyword(s):

Sulfuric Acid ◽

Seed Dormancy ◽

Water Uptake ◽

Seed Coat ◽

Critical Factor ◽

Potassium Nitrate ◽

Ex Situ ◽

Mechanical Resistance ◽

Physical Dormancy ◽

Senna Obtusifolia

The seed dormancy of Senna obtusifolia was investigated through various methods, namely pretreatments in concentrated sulfuric acid, 2% potassium nitrate (KNO3), 99% ethanol, 99% methanol, and in hydrogen perioxide; examination of the seed coverings; and the determination of water uptake by the seeds in order to ascertain the most effective technique for breaking dormancy and also determine the dormancy type. The results showed that sulfuric acid treatment recorded the highest germination (100%); followed by 2% hydrogen peroxide treatment (24%) in 15minutes immersion. The methanol and ethanol pretreatments gave 18.33% and 16.5% germinations respectively. Pretreatment in 2% potassium nitrate gave the lowest germination (8.50%), while the intact seeds of S. obtusifiolia (control) gave 0% germination. The anatomy of the seed coat indicated the presence of hard, thickened and specialized cells of cuticle, macrosclereids, osteoscereids, and disintegrated parenchyma layers. The water uptake of intact seeds was low (13.5%) after 24 hr imbibitions. These findings revealed that the seed coat acts as barrier to germination by preventing water absorption, possibly gaseous diffusion in and out of the seed and conferring mechanical resistance to the protrusion of embryo. Pretreatments, such as immersion in H2SO4 will soften the seed coat and permit germination. Seed dormancy in S. obtusifolia can be considered of physical nature and classified as physical dormancy. The results obtained in this study may serve as useful information in the production and improvement of S. obtusifolia seedlings, as knowledge on seed dormancy and germination is a critical factor and requirements to the understanding of the propagation of this plant either in situ or ex-situ, in view of the economic potentials/attributes of this species.

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Germination Biology of Sesbania (Sesbania cannabina): An Emerging Weed in the Australian Cotton Agro-environment

Weed Science ◽

10.1017/wsc.2018.62 ◽

2018 ◽

Vol 67 (1) ◽

pp. 68-76 ◽

Cited By ~ 2

Author(s):

Nadeem Iqbal ◽

Sudheesh Manalil ◽

Bhagirath S. Chauhan ◽

Steve W. Adkins

Keyword(s):

Seed Germination ◽

Management Strategies ◽

Moisture Stress ◽

Integrated Weed Management ◽

Burial Depth ◽

Weed Species ◽

Physical Dormancy ◽

Sesbania Cannabina ◽

Wide Range ◽

The Impact

AbstractSesbania [Sesbania cannabina(Retz.) Pers.] is a problematic emerging weed species in Australian cotton-farming systems. However, globally, no information is available regarding its seed germination biology, and better understanding will help in devising superior management strategies to prevent further infestations. Laboratory and glasshouse studies were conducted to evaluate the impact of various environmental factors such as light, temperature, salt, osmotic and pH stress, and burial depth on germination and emergence of two Australian biotypes ofS. cannabina. Freshly harvested seeds of both biotypes possessed physical dormancy. A boiling-water scarification treatment (100±2 C) of 5-min duration was the optimum treatment to overcome this dormancy. Once dormancy was broken, the Dalby biotype exhibited a greater germination (93%) compared with the St George biotype (87%). The nondormant seeds of both biotypes showed a neutral photoblastic response to light and dark conditions, with germination marginally improved (6%) under illumination. Maximum germination of both biotypes occurred under an alternating temperature regime of 30/20 and 35/25 C and under constant temperatures of 32 or 35 C, with no germination at 8 or 11 C. Seed germination of both biotypes decreased linearly from 87% to 14% with an increase in moisture stress from 0.0 to −0.8 MPa, with no germination possible at −1.0 MPa. There was a gradual decline in germination for both biotypes when imbibed in a range of salt solutions of 25 to 250 mM, with a 50% reduction in germination occurring at 150 mM. Both biotypes germinated well under a wide range of pH values (4.0 to 10.0), with maximum germination (94%) at pH 9.0. The greatest emergence rate of the Dalby (87%) and St George (78%) biotypes was recorded at a burial depth of 1.0 cm, with no emergence at 16.0 cm. Deep tillage seems to be the best management strategy to stopS. cannabina’s emergence and further infestation of cotton (Gossypium hirsutumL.) fields. The findings of this study will be helpful to cotton agronomists in devising effective, sustainable, and efficient integrated weed management strategies for the control ofS. cannabinain cotton cropping lands.

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A Review of Herbicide Resistance in Iran

Weed Science ◽

10.1614/ws-d-15-00139.1 ◽

2016 ◽

Vol 64 (4) ◽

pp. 551-561 ◽

Cited By ~ 10

Author(s):

Javid Gherekhloo ◽

Mostafa Oveisi ◽

Eskandar Zand ◽

Rafael De Prado

Keyword(s):

Herbicide Resistance ◽

Crop Production ◽

Arable Land ◽

Wheat Crop ◽

Wild Oat ◽

Weed Species ◽

Wild Mustard ◽

Development Of Resistance ◽

Resistance To Herbicides ◽

Continuous Use

Continuous use of herbicides has triggered a phenomenon called herbicide resistance. Nowadays, herbicide resistance is a worldwide problem that threatens sustainable agriculture. A study of over a decade on herbicides in Iran has revealed that herbicide resistance has been occurring since 2004 in some weed species. Almost all the results of these studies have been published in national scientific journals and in conference proceedings on the subject. In the current review, studies on herbicide resistance in Iran were included to provide a perspective of developing weed resistance to herbicides for international scientists. More than 70% of arable land in Iran is given over to cultivation of wheat, barley, and rice; wheat alone covers nearly 52%. Within the past 40 years, 108 herbicides from different groups of modes of action have been registered in Iran, of which 28 are for the selective control of weeds in wheat and barley. Major resistance to ACCase-inhibiting herbicides has been shown in some weed species, such as winter wild oat, wild oat, littleseed canarygrass, hood canarygrass, and rigid ryegrass. With respect to the broad area of wheat crop production and continuous use of herbicides with the sole mechanism of action of ACCase inhibition, the provinces of West Azerbaijan, Tehran, Khorasan, Isfahan, Markazi, and Semnan are at risk of resistance development. In addition, because of continuous long-term use of tribenuron-methyl, resistance in broadleaf species is also being developed. Evidence has recently shown resistance of turnipweed and wild mustard populations to this herbicide. Stable monitoring of fields in doubtful areas and providing good education and training for technicians and farmers to practice integrated methods would help to prevent or delay the development of resistance to herbicides.

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Postharvest losses of cabbages from retail to consumer and the socio-economic and environmental impacts

British Food Journal ◽

10.1108/bfj-08-2014-0280 ◽

2016 ◽

Vol 118 (2) ◽

pp. 286-300 ◽

Cited By ~ 5

Author(s):

Karen Munhuweyi ◽

Umezuruike Linus Opara ◽

Gunnar Sigge

Keyword(s):

Environmental Impacts ◽

Research Effort ◽

Economic Losses ◽

Ambient Conditions ◽

Environment Impact ◽

Coverage Area ◽

Content Type ◽

Postharvest Losses ◽

High Incidence ◽

Parameter Approach

Purpose – The purpose of this paper is to quantify the incidence of postharvest losses of cabbage at retail purchase and during consumer simulated storage. Design/methodology/approach – Physical losses, changes in quality and nutritional value were determined using produce from three different retail outlets in South Africa. Economic losses and the environment impact associated with postharvest losses of cabbage were estimated. Findings – After seven days in storage, high incidence of postharvest losses occurred, ranging from 12 per cent under cold storage to 46 per cent under ambient conditions. These losses were equivalent to over R10 million (∼US$1 million) per annum, while the equivalent wasted fresh water was estimated to be sufficient to meet the needs of over 217,000 per annum. Research limitations/implications – Study was only conducted in one town and to get the real impact of the losses the research should cover a wider coverage area. Originality/value – Cabbage is one of the most widely consumed vegetables globally and this is the first research effort to quantify the magnitude of postharvest losses. A multi-parameter approach was applied to estimate the socio-economic and environmental impacts of losses.

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Overcoming seed dormancy and rooting in air-layering polyembryonic seedlings of sapucaia (Lecythis pisonis Cambess.)

Australian Journal of Crop Science ◽

10.21475/ajcs.20.14.05.p2262 ◽

2020 ◽

pp. 816-821

Author(s):

Caroline Palacio de Araujo ◽

Rodrigo Sobreira Alexandre ◽

Thuanny Lins Monteiro Rosa ◽

Edilson Romais Schmildt ◽

José Carlos Lopes ◽

...

Keyword(s):

Seed Dormancy ◽

Seed Coat ◽

Block Design ◽

Adjacent Region ◽

Physical Dormancy ◽

Functional Elements ◽

Lateral Region ◽

Design Environments ◽

Randomized Complete Block Design ◽

Edible Seeds

Lecythis pisonis produces edible seeds rich in nutritional and functional elements such as selenium and are a great alternative to Brazilian nuts. The seeds have low germination, which may be related to physical dormancy imposed by tegument, meaning that polyembryonic seedlings can be a strategy to increase final stand. The objective of this work was to study methods to overcome seed dormancy and auxin induction in polyembryonic seedlings of pisonis. The experiment to break dormancy consisted of seven treatments: T1: intact seeds; T2: seeds scarified on hilum’s opposite side; T3: seeds scarified hilum’s adjacent region; T4: seeds scarified in lateral region; T5: seeds scarified in both opposite and adjacent region to the hilum; T6: T2 + immersion in water at 40 °C/20 minutes; T7: T2 + immersion in water at 60 °C/5 minutes. The experiment to induce rooting was arranged in a 2 x 6 factorial randomized complete block design (environments: A. greenhouse and B. greenhouse covered with black polyolefin (80% shading) x concentrations of indole-3-butyric acid (IBA): 0; 1000; 2000; 3000; 4000 and 5000 mg L-1), with four replicates of eight polyembryonic seedlings. Seed coat scarification in hilum’s adjacent (T3) and lateral regions (T4) was the most efficient methods for breaking physical dormancy. IBA at 5000 mg L-1 promoted the greatest rhizogenesis of L. pisonis layers.

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Basis for Interactions of Ethofumesate1and Desmedipham on Sugarbeets and Weeds

Weed Science ◽

10.1017/s0043174500063074 ◽

1976 ◽

Vol 24 (6) ◽

pp. 619-626 ◽

Cited By ~ 12

Author(s):

Y. Eshel ◽

R.L. Zimdahl ◽

E.E. Schweizer

Keyword(s):

Beta Vulgaris ◽

Avena Fatua ◽

Synergistic Interaction ◽

Wild Oat ◽

Weed Species ◽

Synergistic Interactions ◽

Wild Mustard ◽

Weed Growth ◽

Spray Volume ◽

Brassica Kaber

A synergistic interaction occurred when sugarbeets (Beta vulgarisL. ‘Mono-Hy Al’) were treated with mixtures of ethofumesate (2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulphonate) and desmedipham [ethylm-hydroxycarbanilate carbanilate (ester)]. Depending on the stage of weed growth synergistic interactions were also observed on two weed species: wild mustard [Brassica kaber(DC.) L.C. Wheeler ‘pinnatifida’ (Stokes) L.C. Wheeler] and wild oat (Avena fatuaL.). Desmedipham penetrated the foliage more slowly than did ethofumesate. The rate of desmedipham penetration was positively correlated with the concentration of its formulants (solvents and adjuvants) in the spraying emulsion, and to a lesser extent with the formulants of ethofumesate. Increasing the spray volume also increased desmedipham penetration. None of these factors affected penetration by ethofumesate.14C-labeled ethofumesate and desmedipham did not translocate out of treated leaves regardless of the concentration of formulants or active ingredients. These data suggest that the synergistic interaction is mainly due to the increased penetration by desmedipham when applied with ethofumesate.

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Physiological trade-offs associated with methyl jasmonate - induced resistance in Pinus radiata

Canadian Journal of Forest Research ◽

10.1139/x07-193 ◽

2008 ◽

Vol 38 (4) ◽

pp. 677-684 ◽

Cited By ~ 23

Author(s):

Nick Gould ◽

Tony Reglinski ◽

Mike Spiers ◽

Joe T. Taylor

Keyword(s):

Growth Rate ◽

Disease Resistance ◽

Methyl Jasmonate ◽

Water Potential ◽

Seedling Growth ◽

Pinus Radiata ◽

Transpiration Rate ◽

Meja Treatment ◽

Seedling Growth Rate ◽

The Impact

Methyl jasmonate (MeJA) can induce defence responses in plants to pathogen attack, but it can also have consequences for plant growth. The transient effects of exogenous MeJA treatment on the resistance of Monterey pine ( Pinus radiata D. Don) seedlings to Diplodia pinea (Desm.) Kickx. and some physiological parameters affecting the impact of treatment on seedling growth were investigated. Following foliar application of 4.5 mmol·L–1 MeJA, disease resistance was greatest 1–2 weeks after treatment and declined with time thereafter. Elevated disease resistance was accompanied by a reduction in seedling growth rate the second week following MeJA treatment. Thereafter, seedling growth rate recovered and exceeded that of the control seedlings 4–5 weeks after MeJA treatment. Within hours of MeJA treatment, reductions in both the capacity of photosystem II and transpiration rate were observed, resulting in a concomitant reduction in net CO2 uptake rate. The slight reduction in transpiration rate was also associated with an increase in needle water potential. Longer term measurements showed no effect of MeJA on photosynthetic rate, transpiration rate, chlorophyll content, or shoot water potential and thus could not account for the elevated growth rate observed 4–5 weeks after treatment.

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ECONOMIC LOSSES CAUSED BY WEED COMPETITION IN MANITOBA GRAIN FIELDS. I. WEED SPECIES, THEIR RELATIVE ABUNDANCE AND THEIR EFFECT ON CROP YIELDS

Canadian Journal of Plant Science ◽

10.4141/cjps60-060 ◽

1960 ◽

Vol 40 (3) ◽

pp. 457-467 ◽

Cited By ~ 43

Author(s):

G. Friesen ◽

L. H. Shebeski

Keyword(s):

Relative Abundance ◽

Crop Yields ◽

Economic Losses ◽

Weed Competition ◽

Weed Species ◽

Grain Crops ◽

Annual Loss ◽

Average Annual Loss ◽

Apparent Decrease

Economic losses caused by weed competition in Manitoba grain crops were studied on 142 farm fields during a 3-year period, 1956 to 1958 inclusive. Fields were located at intervals of 6 miles along main roads and were all within a 60-mile radius of Winnipeg. Immediately after seeding, ten paired plots, each 4 feet square, were staked in each field. One member of each pair of plots was kept free of weeds by hand pulling at weekly intervals. The species of weeds present and the relative numbers were recorded. As the crops reached maturity a square-yard sample from each plot was harvested for yield determinations.Twenty-eight species of weeds were found growing in the fields. Weed counts ranged from 0 in the cleanest field to 2,143 weeds per square yard in the weediest field, with an over-all recorded average of 224 weeds per square yard. Reductions in crop yields due to weed competition in individual fields ranged from no apparent decrease to 61.5 per cent. The average reduction in crop yields for all fields over the 3-year period was 15.25 per cent. This represents an average annual loss in Manitoba of 28,657,070 bushels of grain, valued at approximately $32,379,537.

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