Seedbanks and seedling emergence of saffron thistle (Carthamus lanatus) in eastern Australian pastures

2002 ◽  
Vol 53 (12) ◽  
pp. 1327 ◽  
Author(s):  
B. S. Grace ◽  
A. W. Sheppard ◽  
R. D. B. Whalley ◽  
B. M. Sindel
Keyword(s):  
Weed Management ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
First Year ◽  
Seed Loss ◽  
Eastern Australia ◽  
Mesh Bags ◽  
Second Year ◽  
Number Of Seeds ◽  
Over Time

Weed management has often proved difficult because of persistent seedbanks that allow recruitment to occur for many years after the weed has otherwise been controlled. The number of seeds in seedbanks of Carthamus lanatus, a widespread and troublesome weed, has not been investigated. Little is known about longevity of its seedbanks in pastures of eastern Australia.The numbers of seeds in the soil and the rate of seed loss were investigated at 3 sites in eastern Australia. Seedbanks were found to be patchy, and they had mean densities between 815 and 2290 seeds/m2 after the main germination flush. These seedbanks decreased over time and between 11 and 15% of seeds remained in the soil after 2 years without further input. More seeds were lost in the first year than in the second year, and pasture cover did not affect the rate of seed loss.Seeds buried in mesh bags and exhumed regularly showed that dormancy was lost, induced, then lost again within the 2-year experiment. Maximum seed germinability coincided with peak germination times. The likelihood of a seed producing a seedling was reduced when seeds were sown at high density. C. lanatus seeds appear to be well adapted for persistence in eastern Australian pastures by maintaining a bank of seeds that generally germinate when conditions favour seedling survival.

Ecological segregation in a subterranean reptile assemblage in arid Australia

1989 ◽  
Vol 10 (3) ◽  
pp. 277-295 ◽  
Author(s):  
Klaus Henle
Keyword(s):  
National Park ◽  
Reproductive Effort ◽  
Arid Zone ◽  
Daily Maximum ◽  
First Year ◽  
Lizard Species ◽  
Eastern Australia ◽  
Food Size ◽  
Late Maturity ◽  
Second Year

AbstractThe organisation of the subterranean component of an arid zone reptile community was studies in Kinchega National Park (Eastern Australia) from September 1985 to May 1987. Three species of fossorial or semifossorial lizards and two species of snakes were found in Kinchega. All species were habitat generalists, but microhabitat, food size and food taxon clearly separated them. All species were primarily nocturnal although Lerista xanthura was occasionally active during the day. All three lizard species were active from September to May. Activity of Eremiascincus richardsonii and L. xanthura were significantly correlated with monthly mean daily maximum and minimum temperatures. The optimum temperature of L. punctatovittata was 28.8 °C in daytime retreats. Biomass ranged from 505-900 g/ha in E. richardsonii and from 968-1152 g/ha in L. punctatovittata. All three lizard species produced only one clutch per year. L. punctatovittata and E. richardsonii reached sexual maturity at the end of their second year, L. xanthura matured in its first year. The data show that subterranean lizard guilds have a different structure than diurnal and non-fossorial noctunal lizard assemblies. The data also indicate a correlation of late maturity and low reproductive effort in fossorial lizards.

scholarly journals Modeling the emergence of North African knapweed (Centaurea diluta), an increasingly troublesome weed in Spain

Weed Science ◽  
2020 ◽  
Vol 68 (3) ◽  
pp. 268-277 ◽  
Author(s):  
Carlos Sousa-Ortega ◽  
Aritz Royo-Esnal ◽  
Antonio DiTommaso ◽  
Jordi Izquierdo ◽  
Iñigo Loureiro ◽  
...  
Keyword(s):  
Cropping Systems ◽  
Seedling Emergence ◽  
Management Strategies ◽  
First Year ◽  
Weibull Function ◽  
Limited Information ◽  
North African ◽  
High Predictability ◽  
Second Year ◽  
Base Water Potential

AbstractNorth African knapweed (Centaurea diluta Aiton) is an annual weed that is widespread in southern Spain and is of increasing concern in dryland cropping systems. Despite its expanding range in Spain, there is limited information on the emergence timing and pattern of this species, knowledge of which is critical for developing more timely and effective management strategies. Therefore, there is a need to develop simple and reliable models to predict the timing and emergence of this annual weed under dryland conditions. A multi-location field experiment was established across Spain in 2016 to 2017 to assess the emergence of C. diluta. At each of 11 locations, seeds were sown in the fall, and emergence was recorded. Overall emergence averaged 39% in the first year across all sites and 11% in the second year. In both years, the main emergence flush occurred at the beginning of the growing season. A three-parameter Weibull function best described seedling emergence of C. diluta. Emergence models were developed based on thermal time (TT) and hydrothermal time (HTT) and showed high predictability, as evidenced by root mean-square error prediction values of 10.8 and 10.7, respectively. Three cardinal points were established for TT and HHT at 0.5, 10, and 35 C for base, optimal, and ceiling temperatures, respectively, while base water potential was estimated at −0.5 MPa.

Influence of rotation and time of germinating rains on the productivity and composition of annual pastures in Western Australia

1998 ◽  
Vol 49 (2) ◽  
pp. 225 ◽  
Author(s):  
C. J. Thomson ◽  
C. K. Revell ◽  
N. C. Turner ◽  
M. A. Ewing ◽  
I. F. Le Coultre
Keyword(s):  
Western Australia ◽  
Plant Density ◽  
Seedling Survival ◽  
Subterranean Clover ◽  
Annual Rainfall ◽  
First Year ◽  
Botanical Composition ◽  
Pasture Production ◽  
Bromus Diandrus ◽  
Second Year

A long-term rotation experiment located in south-western Australia was used to measure the effect of rotation and time of germinating rains on the productivity and botanical composition of grazed annual pastures in 2 contrasting seasons in an environment with an average annual rainfall of 325 mm. The density of self-regenerating seedlings of subterranean clover (Trifolium subterraneum), capeweed (Arctotheca calendula), and grasses (Lolium rigidum, Hordeum leporinum, Bromus diandrus) was greatly increased (approx. 3 times the density) when there was a second year of pasture after crop compared with the first year after crop. The lower plant density resulted in first-year pastures having only about 33% of the autumn biomass accumulation of second-year pastures. This difference in early pasture growth had no effect on total pasture production in 1992, but in 1993 total pasture production was 30% greater in second-year pastures compared with first-year pastures. Botanical composition varied between and within seasons with the percentage of subterranean clover increasing throughout the season and the percentage of capeweed decreasing throughout the season. Grasses comprised <20% of the biomass in all seasons and treatments. Production of subterranean clover seed in 1993 was higher in a 1 : 2 crop-pasture rotation than in a 1 : 1 crop-pasture rotation and direct drilling in the cropping phase increased seed set compared with conventional tillage in both 1 : 1 and 1 : 2 crop-pasture rotations. Capeweed seedlings emerged in large numbers after rainfall between February and May and subsequently showed a relative growth rate twice that of subterranean clover and the grasses, but exclusion of rainfall until June resulted in a significant reduction in the emergence of capeweed seedlings. Additionally, capeweed had a lower rate of seedling survival compared with other pasture species, and this is contrary to observations by other researchers that capeweed is highly resistant to moisture stress during early growth.

Changes with time in the germination of buried scentless chamomile (Matricaria perforata Mérat) seeds

1995 ◽  
Vol 75 (1) ◽  
pp. 277-281 ◽  
Author(s):  
G. G. Bowes ◽  
A. G. Thomas ◽  
L. P. Lefkovitch
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Growing Season ◽  
Early Spring ◽  
First Year ◽  
Temperature Regimes ◽  
Buried Seed ◽  
Second Year ◽  
Persistent Seed Bank

Change with time in the germination of scentless chamomile (Matricaria perforata Mérat) seeds was investigated. Seeds were placed in nylon net bags, buried 7 cm deep in soil, exhumed at monthly intervals for 2 yr and allowed to germinate in temperature regimes of 10/2 °C, 20/5 °C, 25/10 °C and 35/20 °C (16/8 h), simulating temperatures found during early spring or late fall, spring or fall, summer and mid-summer on the soil surface, respectively. Exhumed and refrigerator-stored (2 °C) check seeds exhibited no yearly dormancy/nondormancy germination cycle, but mortality of buried seed increased to 36%, after 10 mo in contrast with that of the check seeds which remained low for two years. Light was required for germination during the first year but was not required for a portion of the seed during the second year. The retention of viability in buried seed explains the persistent seed bank and seedling emergence throughout the growing season when moisture and temperature are nonlimiting. Key words: Seed burial, germination, Matricaria perforata Mérat

Survival and seasonal germination of seeds of Avena fatua and A. ludoviciana

1968 ◽  
Vol 19 (5) ◽  
pp. 721 ◽  
Author(s):  
PH Quail ◽  
OG Carter
Keyword(s):  
Soil Type ◽  
Dominant Species ◽  
First Year ◽  
Moisture Regime ◽  
Seed Type ◽  
Wild Oats ◽  
Eastern Australia ◽  
Buried Seed ◽  
Second Year ◽  
Better Than

The effects of soil type, temperature, and moisture on the survival and seasonal germination of seeds of A. fatua and A. ludoviciana, buried at five depths in the soil, were studied in a glasshouse experiment. Seeds of both species germinated only when mean weekly minimum temperatures were below 20°C and mean weekly maxima below 28°. A. fatua germinated better than A. ludoviciana in the 20–30° range and was therefore the dominant species in autumn germinations of wild oats. Both species germinated throughout winter. Only 30% of the seeds sown produced seedlings. Of these 90% emerged in the first year after seeding and the remainder in the second year. Only 2% of the seeds sown remained viable after 18 months. The depth at which the seeds were buried, seed type, soil type. and moisture regime all affected the survival of seeds and the percentage that produced seedlings. An explanation is offered for the dominance of A. ludoviciana in the northern wheat-belt of eastern Australia.

scholarly journals Integrated Weed Management Systems to Control Common Ragweed (Ambrosia artemisiifolia L.) in Soybean

2021 ◽  
Vol 2 ◽  
Author(s):  
Shawn C. Beam ◽  
Charles W. Cahoon ◽  
David C. Haak ◽  
David L. Holshouser ◽  
Steven B. Mirsky ◽  
...  
Keyword(s):  
Weed Management ◽  
Planting Date ◽  
Ambrosia Artemisiifolia ◽  
Integrated Weed Management ◽  
First Year ◽  
Weed Seed ◽  
Common Ragweed ◽  
Late Planting ◽  
Winter Cover ◽  
Second Year

As resistance to herbicides limits growers' weed management options, integrated weed management (IWM) systems that combine non-chemical tactics with herbicides are becoming critical. A 2 year integrated weed management (IWM) study was conducted at three locations in VA, USA. The factorial study evaluated: (1) soybean planting date (early or late planted) (2) with or without winter cover (cereal rye/wheat or no cover), and (3) with or without harvest weed seed control (HWSC). Prior to soybean planting in the first year, winter cover resulted in a 22% reduction in common ragweed density compared to no cover. At soybean harvest in the first year, the lowest common ragweed densities were in the late planted plots following winter wheat, and common ragweed aboveground biomass was reduced by 46 and 22% at two locations in late planted compared to early planted soybean. To evaluate the impact of the first year's treatments and HWSC, full season soybeans were planted across the trial in the second year. Prior to soybean planting in the second year, late planting in the first year common ragweed density was reduced by 83% at one location, but significant reductions were not observed elsewhere. When comparing winter cover to no cover, common ragweed densities were reduced by 31 and 49% at two locations and densities were similar at the third location. Harvest weed seed control reduced common ragweed density by 43% at one location compared to the conventional harvest plots but no significant reductions were observed at the other locations or at other rating timings. However, there was a significant location by planting date by winter cover interaction and the overall lowest common ragweed densities (4.1 to 10.3 plants m−2) were in the late planted plots with winter cover. This research indicated that winter cover, late planting, and HWSC can reduce common ragweed populations with late planting being the most influential. Therefore, double-cropping soybean after wheat is likely the most viable means to better control common ragweed using IWM as it combines both winter cover and late planting date.

scholarly journals Rotating Vegetables and Peanuts

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 670f-671
Author(s):  
V.M. Russo
Keyword(s):  
Bell Pepper ◽  
First Year ◽  
Navy Bean ◽  
Second Year ◽  
Over Time

Monoculture can lead to reduced yields due to pressure from biotic or abiotic sources. This pressure may be reduced by rotating crops. In the first year, a 0.5-ha of a Bernow fine-loamy, siliceous, thermic Glossic Paleudalf soil was planted to peanuts at Lane, Okla. In each of the following 5 years, the area was subdivided in to four rotations that were replicated four times. Bell pepper, cucumber, navy bean and cabbage were planted after 1, 2, or 3 years of peanuts. The first vegetable planting in each rotation was followed by either vegetables or peanuts, and these crops were planted in 3 of the 6 years in each rotation. Half of each plot was treated with soil fungicides, and half of the peanut plots were treated with foliar fungicides. Sclerotia, likely in the genera Sclerotia and Sclerotinia, were counted in the spring of each year starting in the second year. Peanut yields in the first year were 6.6 Mg·ha–1 but were <2.5 Mg·ha–1 thereafter. Yields of vegetables planted to follow 1 or 2 years of peanuts were normal for this location. Yields in later vegetable plantings in these rotations were reduced by 50%, and yields of vegetables planted after 3 years of peanuts were significantly less than vegetables planted after 1 or 2 years of peanuts. Numbers of sclerotia fluctuated over time, but numbers in the spring of the second year were the same as in the spring of the sixth year. The vegetables tested here should not be planted after >2 years of peanuts at this location.

scholarly journals PATH COEFFICIENT IN SAFFLOWER AS AFFECTED BY HARVEST DATES

2017 ◽  
Vol 48 (4) ◽  
Author(s):  
Wuhaib & et al.
Keyword(s):  
Plant Height ◽  
Total Yield ◽  
Dry Weight ◽  
Phenotypic Correlation ◽  
First Year ◽  
Path Coefficient ◽  
Seed Plant ◽  
Harvest Dates ◽  
Second Year ◽  
Number Of Seeds

In order to determine the traits that correlate to yield to rely on them as selection criteria for high yield in safflower; seeds of five cultivars .2081, Gelser Almais , Ordini, and rabia 500 planted in the field of Field Crop Dept. College of Agriculture –Uni. Of Baghdad during 2010and 2011.The design  of experiments is randomize complete block design  with split plot arrangement with three replication. Data were recorded for traits: yield/ plant, total yield, harvest index, oil%, number of seed/plant, number of seeds/capsules, seed weight,dry weight of plant, number of capsules/plant, number of primary and secondary branches and plant height. Results of statistical analysis illustrate that the genotypic and phenotypic correlation and direct and indirect effects were different due to differences in harvest dates and tow years of planting.The highest positive genetic correlation and direct effects with yield were for plant height and total yield for first harvest  in first year, for second year were dry weight, number  of capsules/ plant, number of seed/ plant and total yield. For second harvest in first year was total yield only. and number of capsule/ plant, dry weight, total yield and number of seeds/ plant, in second year. Also only total yield in third harvest in first year, and dry weight and total yield in second year. In fourth harvest first year the traits were number of capsules\plant and total yield, dry weight and total yield in second year. For that we can rely these traits as criteria for selection in breeding programs to improve the yield of safflower.   

scholarly journals 25 Determining stability of genomic predictivity in future generations in commercial pig populations

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 21-21
Author(s):  
Mary Kate Hollifield ◽  
Daniela Lourenco ◽  
Jeremy Howard ◽  
Yijian Huang ◽  
Ignacy Misztal
Keyword(s):  
Selection Pressure ◽  
Predictive Ability ◽  
Single Step ◽  
First Year ◽  
Training Population ◽  
Data Set ◽  
Validation Population ◽  
Related Individuals ◽  
Second Year ◽  
Over Time

Abstract Genomic predictivity is expected to decay over time as predictions are evaluated to more distant generations. More data increases predictive ability; however, data from distant ancestors may not add a significant amount of value compared to the data from closely related individuals. The objective of this study was to evaluate the decay in genomic predictivity over time and to compare the magnitude of decay when including ancestral data versus data from 2 and 3 most recent generations for body weight at off-test (BW). The data set included 211,812 phenotypic records. The pedigree included 406,983 animals from 2001 to 2020, of which 55,118 were genotyped. A single-trait model was used with all ancestral data and sliding subsets of two- and three-generation intervals. Single-step GBLUP was used to calculate GEBVs. Predictive abilities were calculated by the correlation between GEBVs and adjusted phenotypes. Validation populations consisted of single generations succeeding the training population and continued for all generations available. Predictive ability was slightly higher, with all ancestral data in the training population compared to three- and two-generation intervals. The decay of predictivity was similar when comparing the three training population subsets. The average predictivity for the validation population immediately following the training population was 0.40 for 2016, 0.39 for 2017, 0.35 for 2018, and 0.29 for 2019. Predictive ability reached a maximum in the year 2017 (0.45) for the ancestral training population, 2017 (0.43) for the 3-year training population, and 2016 (0.38) for the 2-year training population. The average decay of predictive ability from the first year after the training population to the second year was -0.08. Realized predictivity is affected by selection pressure. The drop in predictive ability suggests declining heritability. With more data and with consistent selection pressure, predictive abilities should increase.

Seed production of cut-leaved teasel (Dipsacus laciniatus) in central Missouri

Biologia ◽  
2011 ◽  
Vol 66 (5) ◽  
Author(s):  
Diego Bentivegna ◽  
Reid Smeda
Keyword(s):  
Linear Regression ◽  
Seed Production ◽  
Native Species ◽  
Field Studies ◽  
First Year ◽  
Invasive Weed ◽  
Seed Field ◽  
Second Year ◽  
Total Seed ◽  
Number Of Seeds

AbstractCut-leaved teasel is an invasive weed in Missouri that reduces the diversification of native species along roadsides and impairs traffic visibility. Teasel is a biennial and grows as a rosette in the first year and flowers the second year. Reproduction is only by seed. Field studies were conducted in 2004 and 2005 at two locations to assess the seed production of cut-leaved teasel. From a natural stand, fifteen plants were tagged at the onset of flowering. Selected plants included those considered growing in a group and those growing alone; a plant was considered alone when no other plant was adjacent for at least 60 cm. Whenever a seedhead completed flowering, it was covered with a cellophane bag and harvested one month later. Linear regression was used to correlate the weight of seeds from a single seedhead and number of seeds to estimate the total seed production per seedhead. The number of seedheads per plant varied from 3 to 56. On average, plants growing alone had 64% more seedheads per plant than plants occurring in a group. Seed numbers in the primary seedhead ranged from 511 to 1,487. Total seed production per plant ranged from 1,309 to 33,527. Seed production was 61% greater for plants growing alone versus those growing in a group and was more prolific in 2005 than in 2004. In addition, seed production per plant varied between locations for plants growing alone, but seed yield per plant was similar for plants growing in groups. Colonization of teasel in new areas is facilitated by higher seedhead numbers per plant and total seed production compared to reproduction of plants in areas of intraspecific competition.

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