Growth and physiological responses of balansa clover and burr medic to low levels of salinity

2008 ◽  
Vol 59 (7) ◽  
pp. 605 ◽  
Author(s):  
Emmanuel Mapfumo ◽  
Mohammed A. Behdani ◽  
Zed Rengel ◽  
Edward G. Barrett-Lennard
Keyword(s):  
Biomass Yield ◽  
Physiological Responses ◽  
Net Photosynthesis ◽  
Sodium Concentration ◽  
Control Treatment ◽  
Shoot Biomass ◽  
Saline Control ◽  
Δ13c And Δ15n ◽  
Wide Range ◽  
Burr Medic

This study investigated a wide range of morphological and physiological responses of burr medic (Medicago polymorpha L. cv. Scimitar) and balansa clover (Trifolium michelianum L. cv. Frontier) to different levels of salinity. Balansa clover and burr medic plants were grown in the greenhouse at 25°C day temperature and 16°C night temperature. Salt treatments were applied 6 weeks after germination, and plants were grown for a further 6 weeks before harvest. The salt treatments included a control, 20 mm, 40 mm, and 80 mm of NaCl. The shoot biomass yield was significantly affected by the species × salt interaction (P = 0.04). For balansa clover, the shoot biomass yield was greatest for the control treatment and lowest for the 20 mm NaCl treatment. For burr medic, the shoot biomass yield did not differ among salt treatments. Sodium (Na+) and potassium (K+) concentrations in leaves and stems increased with salinity. Compared with a non-saline control, sodium concentration in leaves in the 80 mm NaCl treatment was 3-fold higher for balansa clover and 2-fold higher for burr medic. Under various saline treatments, leaf Na+/K+ ratio stayed relatively constant in balansa clover (0.3–0.4) and burr medic (0.4–0.5), whereas stem Na+/K+ ratios for both species increased with salinity. The most sensitive parameters to salinity were Na+/K+ and Na+/Ca2+ ratios, whereas biomass, chlorophyll fluorescence, net photosynthesis, stomatal conductance, transpiration, and δ13C and δ15N discrimination were least sensitive. Therefore, accumulation of sodium in the plant tissues did not reach the threshold for causing reduction in growth.

scholarly journals Photosynthesis and Growth of Rhamnus caroliniana during Drought and Flooding: Comparisons to the Invasive Rhamnus cathartica

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1278-1282 ◽  
Author(s):  
J. Ryan Stewart ◽  
William R. Graves
Keyword(s):  
Soil Water ◽  
Carbon Fixation ◽  
Root Zone ◽  
Net Photosynthesis ◽  
The United States ◽  
Control Treatment ◽  
Severe Drought ◽  
Rhamnus Cathartica ◽  
Potted Plants ◽  
Wide Range

Rhamnus caroliniana Walt. (carolina buckthorn or indian cherry) is an attractive small tree or shrub found in diverse habitats in the United States. Because the species occurs in both mesic and xeric soils, we questioned whether selections of carolina buckthorn could be marketed as new nursery crops resistant to both drought and flooding. Our first objective was to characterize how soil water affects growth and gas exchange of carolina buckthorn. We studied potted plants subjected to soil moistures that ranged from complete submersion of the root zone to severe drought (7% soil water by volume). The maximal photosynthetic rate occurred at 27% soil water content, and complete submersion killed plants. Our second objective was to compare responses of carolina buckthorn to those of the invasive common buckthorn (Rhamnus cathartica L.) when potted plants were treated with partial flooding of root zones and drought. Carolina buckthorn resisted deleterious effects of partial flooding. In contrast, leaves of common buckthorn became epinastic, and rates of photosynthesis were low (2.14 μmol CO2/m2/s) after 17 days of treatment. Mean photosynthesis of common buckthorn increased to 5.52 μmol CO2/m2/s, a rate similar to that of carolina buckthorn, after 55 days of treatment. Drought reduced net photosynthesis by 52% and 68%, respectively, for carolina buckthorn and common buckthorn relative to rates of plants in the control treatment. We conclude that carolina buckthorn is capable of maintaining carbon fixation and growth over a wide range of soil water contents, and unlike common buckthorn, is not dependent upon morphological, anatomical, or physiological adjustments to optimize growth and net photosynthesis in extremely wet soil. Use of carolina buckthorn as an ornamental is warranted if invasiveness and other potential problems with the species are not identified.

Some influence of the hormonal components in nutrient medium onthe induction of novel structures when obtaining rapeseed haploids through in vitro culture

2018 ◽  
pp. 30-37
Keyword(s):  
Anther Culture ◽  
Hormonal Regulation ◽  
Control Plant ◽  
Pollen Grains ◽  
Control Treatment ◽  
Basic Medium ◽  
Nutrient Media ◽  
Oilseed Crops ◽  
Wide Range

Growth regulators, phytohormones, both natural and artificial, are the main means to control plant ontogenesis. They are involved in regulating the processes of cell differentiation and cell divisions, the formation of tissues and organs, the changes in the rate of growth and development, the duration of the certain stages of ontogenesis. The main classes of phytohormones used in plant biotechnology, in particular, in the induction of haploid structures, are auxins and cytokinins. The mechanism of action of phytohormones on a cell is rather complicated and may have a different character. Understanding the characteristics of the action of phytohormones is complicated by the fact that the system of hormonal regulation of plant life is multicomponent. This is manifested in the fact that the same physiological process is most often influenced not by one, but by several phytohormones, covering a wide range of aspects of cell metabolism. In connection with the foregoing, the purpose of our work was to test a set of nutrient media with different basic composition and different proportions of phytohormones to determine the patterns of their influence on the processes of haploid structure induction in rape anther culture using accessions, developed at the Institute of Oilseed Crops NAAS. The material used was two accessions of winter rapeseed (No. 1 and No. 2) and one sample of spring rapeseed, provided by the Rapeseed Breeding laboratory of the Institute of Oilseed Crops. Incised inflorescences were kept against the background of low temperature of 6–8 ° C for several days, and then, under aseptic conditions, anthers with unripe pollen grains were isolated and planted on nutrient media differing in both basic mineral composition and content of phytohormones. MS (Murashige & Skoog 1962) and B5 (Gamborg et al 1968) media were used as basic media. Phytohormones were added to the basic media in various combinations – BA, 2,4-D, NAA at the concentrations of 0.1-0.6 mg/l. In each treatment up to 300 anthers were cultivated. Differences between treatments were evaluated using standard t-test. Studies have shown that in the anther culture of rapeseed on the tested nutrient media, morphogenic structures of different types (embryoids and callus) were originated. Synthetic auxin 2,4-D, regardless of the composition of the basic medium, caused the formation of structures of both types, though with a low frequency. Phytohormone BA of the cytokinin type had a similar effect. In this case, the frequency of structures was slightly higher, and the developed structures were represented mainly by embryoids. The joint action of cytokinin and auxin was the most favorable for the initiation of morphogenic structures. Such combination of phytohormones caused the formation of these structures with a frequency of 24.5-14.7% in the studied genotypes of winter rape. A similar effect of phytohormones on the induction and development of morphogenic structures was also observed in spring rape. In this case, a single basic MS medium was used. The experiment included treatments where phytohormones were absent (control), as well as various combinations of auxin and cytokinin. In the control treatment, the formation of new structures was not noted. In treatments with phytohormones, in addition to the medium with the combination of auxin and cytokinin, the medium in which only cytokinin was present was also rather effective. The treatment in which the action of auxin 2,4-D was combined with the action of another auxin, NAA, turned out to be practically ineffective. Thus, it was found that for the induction of morphogenic structures from microspores in rape anther culture of the tested genotypes, the combination of cytokinin with auxin, or the use of only single cytokinin BA without other phytohormones, had the most positive effect.

scholarly journals Application of Hydrochar, Digestate, and Synthetic Fertilizer to a Miscanthus x giganteus Crop: Implications for Biomass and Greenhouse Gas Emissions

2020 ◽  
Vol 10 (24) ◽  
pp. 8953
Author(s):  
Toby Adjuik ◽  
Abbey M. Rodjom ◽  
Kimberley E. Miller ◽  
M. Toufiq M. Reza ◽  
Sarah C. Davis
Keyword(s):  
Greenhouse Gas ◽  
Nutrient Management ◽  
Agricultural Land ◽  
Biomass Yield ◽  
Ghg Emissions ◽  
Hydrothermal Carbonization ◽  
Control Treatment ◽  
Miscanthus X Giganteus ◽  
Synthetic Fertilizer ◽  
Ghg Fluxes

Miscanthus x giganteus (miscanthus), a perennial biomass crop, allocates more carbon belowground and typically has lower soil greenhouse gas (GHG) emissions than conventional feedstock crops, but best practices for nutrient management that maximize yield while minimizing soil GHG emissions are still debated. This study evaluated the effects of four different fertilization treatments (digestate from a biodigester, synthetic fertilizer (urea), hydrochar from the hydrothermal carbonization of digestate, and a control) on soil GHG emissions and biomass yield of an established miscanthus stand grown on abandoned agricultural land. Soil GHG fluxes (including CH4, CO2, and N2O) were sampled in all treatments using the static chamber methodology. Average biomass yield varied from 20.2 Mg ha−1 to 23.5 Mg ha−1, but there were no significant differences among the four treatments (p > 0.05). The hydrochar treatment reduced mean CO2 emissions by 34% compared to the control treatment, but this difference was only statistically significant in one of the two sites tested. Applying digestate to miscanthus resulted in a CH4 efflux from the soil in one of two sites, while soils treated with urea and hydrochar acted as CH4 sinks in both sites. Overall, fertilization did not significantly improve biomass yield, but hydrochar as a soil amendment has potential for reducing soil GHG fluxes.

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

Weed Science ◽  
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.

195 Does Feeding a Protease and Probiotic (Bacillus Subtilis) Combination (Syncra® SWI) Result in Improved Growth Performance and Mortality in a Commercial Wean-to-finish Swine Feeding Program?

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 77-78
Author(s):  
Trey A Kellner ◽  
Josh Ellingson ◽  
Ana L P de Souza ◽  
Janet C Remus
Keyword(s):  
Growth Performance ◽  
Experimental Period ◽  
Feed Additives ◽  
Control Treatment ◽  
Experimental Unit ◽  
Gut Health ◽  
Wide Range ◽  
Feeding Program ◽  
Feed Costs ◽  
Combined Feed

Abstract The response to probiotics and enzymes is often documented in research facilities with a high degree of control and via pigs with no insults to health or feed intake. However, in commercial conditions, the response to feed additives promoting advanced gut health and improved digestion must be consistent and defined over a wide range of health statuses, stocking densities, feed intakes, environments, and diet formulations. The objective of this experiment was to determine if a combined feed protease and probiotic system (Syncra® SWI 201, DuPont, Wilmington, DE) would improve growth performance and mortality under commercial conditions. A total of 127,092 pigs (6.0 ± 0.1 kg; PIC 337 sired, Hendersonville, TN) from a sow farm producing porcine reproductive and respiratory virus and rotavirus positive weaned pigs were placed in 53 2,400-head commercial wean-to-finish barns that were alternated to 1 of 2 treatments (a control treatment without Syncra® SWI (SSWI) or with SSWI included at 72.6 g/ton of finished feed from 22.7 kg of BW to harvest) in a rolling allotment over a 12-month period. Pigs were on the experiment for an average of 162 ± 1.0 days (until harvest). Throughout the 12-month experimental period, diets (outside of the SSWI inclusion) could change in order to maximize return over feed costs. Data were analyzed using Proc MIXED (SAS 9.4; Cary, NC) with treatment as the main effect and barn as the experimental unit. Compared to the control, adding SSWI improved mortality by 1.9% and percent grade 1 marketed pigs by 2.2% (P ≤ 0.025). Compared to the control, SSWI did not improve ADG (control = 0.75 vs. SSWI = 0.78 kg) or gain:feed (control = 0.401 vs. SSWI = 0.396). In conclusion, the inclusion of the SSWI combined feed protease and probiotic system can improve mortality and grade 1 marketed pigs, but not growth performance under commercial conditions.

scholarly journals Alarm substance from adult zebrafish alters early embryonic development in offspring

2010 ◽  
Vol 6 (4) ◽  
pp. 525-528 ◽  
Author(s):  
S. Mourabit ◽  
S. D. Rundle ◽  
J. I. Spicer ◽  
K. A. Sloman
Keyword(s):  
Embryonic Development ◽  
Inclusive Fitness ◽  
Heart Function ◽  
Physiological Responses ◽  
Early Embryonic Development ◽  
Alarm Substance ◽  
Adult Zebrafish ◽  
Skin Injury ◽  
Wide Range ◽  
Alarm Substances

Alarm substances elicit behavioural responses in a wide range of animals but effects on early embryonic development are virtually unknown. Here we investigated whether skin injury-induced alarm substances caused physiological responses in embryos produced by two Danio species ( Danio rerio and Danio albolineatus ). Both species showed more rapid physiological development in the presence of alarm substance, although there were subtle differences between them: D. rerio had advanced muscle contraction and heart function, whereas D. albolineatus had advanced heart function only. Hence, alarm cues from injured or dying fish may be of benefit to their offspring, inducing physiological responses and potentially increasing their inclusive fitness.

scholarly journals FÓSFORO NA SOLUÇÃO DO SOLO EM RESPOSTA À APLICAÇÃO DE FERTILIZANTES FLUIDOS MINERAL E ORGANOMINERAL

Irriga ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 14-27 ◽  
Author(s):  
Dirceu Maximino Fernandes ◽  
Marco André Grohskopf ◽  
Edilson Ramos Gomes ◽  
Natália Rodrigues Ferreira ◽  
Leonardo Teodoro Bull
Keyword(s):  
Electrical Conductivity ◽  
Soil Solution ◽  
Phosphorus Content ◽  
Swine Manure ◽  
Mineral Fertilizer ◽  
Control Treatment ◽  
Shoot Biomass ◽  
Phosphorus Fertilization ◽  
E Mail ◽  
Over Time

FÓSFORO NA SOLUÇÃO DO SOLO EM RESPOSTA À APLICAÇÃO DE FERTILIZANTES FLUIDOS MINERAL E ORGANOMINERAL  DIRCEU MAXIMINO FERNANDES1; MARCO ANDRÉ GROHSKOPF2; EDILSON RAMOS GOMES3; NATÁLIA RODRIGUES FERREIRA2 E LEONARDO TEODORO BÜLL1 1Professor do Programa de Pós-Graduação em Agronomia, – Universidade Estadual Paulista “Júlio Mesquita Filho”, Faculdade de Ciências Agronômicas (UNESP/FCA) - Rua José Barbosa de Barros, no 1780, CEP: 18160-307 - Botucatu, SP, bolsista de produtividade em pesquisa do CNPq. E-mail: [email protected]; [email protected] do Programa de Pós-Graduação em Agronomia (Agricultura) – UNESP/FCA, bolsista CAPES. E-mail: [email protected]; [email protected] do Programa de Pós-Graduação em Agronomia (Irrigação e Drenagem) – UNESP/FCA, bolsista CNPq. E-mail: [email protected].  1 RESUMO Pouco se conhece sobre a dinâmica da solução do solo em resposta a aplicação de diferentes fertilizantes no solo, principalmente, em relação à adubação fosfatada. Nesse sentido, avaliou-se o teor de fósforo, pH e condutividade elétrica na solução do solo e, a produção de biomassa de parte aérea de plantas em resposta a aplicação de fertilizantes fluidos mineral e organomineral a base de dejeto suíno e, mineral sólido. Os tratamentos foram: testemunha geral caracterizada pela ausência de nutrientes, testemunha de fósforo (P) caracterizada pela ausência apenas de P, fertilizantes fluido mineral (MF-P) e organomineral (OF-P) e, sólido (MS-P) aplicados em Latossolo Vermelho distroférrico (LV) e Neossolo Quartzarênico Órtico típico (NQ). O experimento foi conduzido em vasos em casa de vegetação em delineamento experimental de blocos casualizados com quatro repetições. A solução do solo foi captada através de extratores de solução instalados nos vasos, realizando-se dez coletas no período de 137 dias após a aplicação dos fertilizantes, abrangendo dois cultivos consecutivos de aveia preta (cultivo I e cultivo II). Em ambos os solos o rendimento de matéria seca no cultivo I foi maior no OF-P e no cultivo II semelhante no MS-P, MF-P e OF-P, sendo os maiores rendimentos demonstrados no LV em relação ao NQ. Os teores de P na solução do solo variaram ao longo do tempo apenas no OF-P no LV, enquanto que no NQ houve variação em todos os tratamentos, sendo em ambos os solos os maiores teores a partir do cultivo II.  Para os valores de pH e condutividade elétrica (CE) também houve variação ao longo do tempo em ambos os solos, sendo que no pH os valores aumentaram e na CE os valores diminuíram no cultivo II em relação ao cultivo I em todos os tratamentos. Palavras-chave: adubo líquido e sólido, resíduo, esterco.   FERNADES, D. M.; GROHSKOPF, M. A.; GOMES, E. R.; FERREIRA, N. R.; BÜLL, L.T.PHOSPHORUS IN SOIL SOLUTION IN RESPONSE TO THE APPLICATION OF MINERAL AND ORGANOMINERAL FLUID FERTILIZERS  2 ABSTRACT Little is known about the dynamics of soil solution in  response to  the application of different soil fertilizers, mainly in relation to phosphorus fertilization.  Using this approach, the study evaluated phosphorus content, pH and electrical conductivity in soil solution as well as shoot biomass production in response to mineral and organomineral fluid fertilizers containing swine manure and solid mineral.  Treatments were as follows: a control treatment consisting of absence of nutrients, phosphorus (P) control characterized by absence   only of  P, mineral (MF-P) and organomineral (OF-P) fluid fertilizers , and solid mineral fertilizer (SM-P) applied to Oxisol   (LVd) and Typic Quartzipsamments  (TQ) soils. The experiment was carried out   using pots in a greenhouse with a randomized block  experimental design  and  four replicates. Soil solution was collected by solution extractors installed in pots. Ten collections were performed over 137 days after fertilizer application, which included two crops in a row of black oat (cultivation I and cultivation II). In both soils, yield of dry matter in cultivation I was higher in OF-P, and  it was similar in  (SM-P), (MF-P) and (OF-P) in cultivation II. Higher yield was obtained in LVd in relation to TQ.  Phosphorus content in soil solution ranged over time just in OF-P in LVd, whereas  variation was observed in all treatments in TQ. In both soils, higher content was observed as of cultivation II.   Also, variation over time was observed for pH and electrical conductivity (EC) values in both soils. Values of pH increased and values of EC decreased in cultivation II as compared with those in cultivation I in all treatments. Keywords: liquid and solid fertilizer, residue, manure.

scholarly journals Genotype and within-pod bean position microenvironment effect on seed choice for raising cocoa (Theobroma cacao L.) seedlings

2020 ◽  
Vol 115 (2) ◽  
pp. 247
Author(s):  
Daniel B. ADEWALE ◽  
Beatrice A. NDUKA
Keyword(s):  
Biomass Yield ◽  
Cocoa Bean ◽  
Shoot Biomass ◽  
Seedling Vigour ◽  
Periodic Data ◽  
Length Width ◽  
Probable Role ◽  
Number Of Leaves ◽  
Theobroma Cacao L

<p>The probable role of within-pod microenvironment on seed sizes, seedling vigour and biomass yield of four cocoa genotypes was investigated for two years. The respective main, sub and sub-sub plots in the split-split plot experimental design were years, genotypes and within-pod bean positions. Data were taken on cocoa bean length, width and thickness after each pod was opened. Four weekly periodic data were obtained for plant height (PH), stem girth (SG) and number of leaves (NOL); root and shoot biomass yield were also recorded. Analysis of variance revealed significant (p ≤ 0.05) bean position, genotypes, years and some interaction on the studied traits. Means of the levels of the three factors differed significantly (p ≤ 0.05). Proximal, middle and distal positions were distinct within-pod microenvironments. The pod middle cavity housed the longest, widest and heaviest beans. Trend analysis of the growing sequences of NOL, PH and SG by the four genotypes differed with bean locations. For bean length, GGE biplot respectively identified CRIN Tc1, CRIN Tc2 and CRIN Tc3 as the best genotype for middle, proximal and the distal positions. The intra-locular space within the pod enhanced differential seed development and maturation; this was evident in the seedling vigour.</p>

scholarly journals Baccharis trimera (Less.) DC responses to water restriction

2021 ◽  
Vol 16 (3) ◽  
pp. 229-237
Author(s):  
Francine Falcão de Macedo Nava ◽  
Vilson Conrado da Luz ◽  
Lucas Antonio Stempkowski ◽  
Lenir Fátima Gotz ◽  
Fabiana Tonial ◽  
...  
Keyword(s):  
Root Growth ◽  
Water Saturation ◽  
Pearson Correlation ◽  
Physiological Responses ◽  
Shoot Biomass ◽  
Guaiacol Peroxidase ◽  
Water Restriction ◽  
Low Levels ◽  
Baccharis Trimera ◽  
Harsh Conditions

Climate change can cause imbalances in plants. Baccharis trimera is a specie usually found in harsh conditions and has medicinal and agricultural properties. Thus, this study aimed to evaluate the biochemical and physiological responses of this plant under water restriction (WR) levels. B. trimera samples were identified and collected in Erechim/RS and propagated in a greenhouse. When acclimated, they were subjected to 0, 25, 75 and 100% WR, determined according to the water saturation in the soil by capillary action. After 30 days of treatment, the physiological responses: growth, and fresh and dry biomass; and the biochemical responses: activity of superoxide dismutase (SOD), guaiacol peroxidase (GP) and ascorbate peroxidase (APX) enzymes, proline, protein and hydrogen peroxide content, and lipid peroxidation, were determined. Data were submitted to regression analysis and Pearson correlation. The WR of 27.37%, on average, induced an increase in physiological parameters, but the root growth was impaired in conditions above 50% of WR. With the increase in WR there was an increase in the activity of SOD in the shoot and APX in the root. In low WR conditions, proline contents were maintained. Therefore, with low levels of WR, around 27%, B. trimera has increase in root growth and root and shoot biomass. Proline, and SOD and APX activity are a pathway that scavenging the stress generated by WR on B. trimera.

Seed germination ecology of Sumatran fleabane (Conyza sumatrensis) in relations to various environmental parameters

Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Gulshan Mahajan ◽  
Asheneel Prasad ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Germination ◽  
Light Intensity ◽  
Chloride Concentration ◽  
Soil Surface ◽  
Control Treatment ◽  
Effect Of Temperature ◽  
Burial Depth ◽  
Germination Ecology ◽  
Wide Range ◽  
Dark Conditions

Abstract Sumatran fleabane [Conyza sumatrensis (Retz.) Walker] is an emerging weed in the Australian cropping region. Populations resistant to glyphosate have evolved in Australia, creating the demand for information regarding the seed germination ecology of glyphosate-resistant (R) and glyphosate susceptible (S) populations of C. sumatrensis. A study was conducted to examine the effect of temperature, light intensity, salt stress, osmotic stress, and burial depth on the germination and emergence of two populations (R and S) of C. sumatrensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C). In light/dark conditions, the R population had higher germination than the S population at 20/10 and 35/25 C. In the dark, the R population had higher germination than the S population at 25/15 C. In the dark, germination was inhibited at 30/20 C and above. Averaged over populations, seed germination of C. sumatrensis was reduced by 97% at zero light intensity (completely dark conditions) compared with full light intensity. Seed germination of C. sumatrensis reduced by 17 and 85% at an osmotic potential of −0.4, and −0.8 MPa, respectively, compared with the control treatment. The R population had lower germination (57%) than the S population (72%) at a sodium chloride concentration of 80 mM. Seed germination was highest on the soil surface and emergence was reduced by 87 and 90% at burial depths of 0.5 and 1.0 cm, respectively. Knowledge gained from this study suggests that a shallow-tillage operation to bury weed seeds in conventional tillage systems, and retention of high residue cover in a zero-till system on the soil surface may inhibit the germination of C. sumatrensis. This study also warrants that the R population may have a greater risk of invasion over a greater part of a year due to germination over a broader temperature range.

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