Seed production by skeleton weed (Chondrilla juncea L.) in Western Australia in relation to summer drought

1987 ◽  
Vol 38 (4) ◽  
pp. 689 ◽  
Author(s):  
J Dodd ◽  
FD Panetta
Keyword(s):  
Soil Water ◽  
Seed Production ◽  
Western Australia ◽  
Summer Rainfall ◽  
Soil Water Storage ◽  
First Year ◽  
Root Penetration ◽  
Summer Drought ◽  
Air Temperatures ◽  
Viable Seeds

Seed production in Forms A and C of C. juncea was measured at 11 wheatbelt sites in Western Australia and under glasshouse conditions. Most field-grown plants produced abundant viable seeds, even without substantial summer rainfall. Up to 27.6 x l03 seeds per plant were recorded, and their viability was frequently between 80 and 90%. Even in their first year, some plants produced more than 10000 seeds each. Through the summer, seed production often followed either a positively skewed, or a bimodal curve. Falls of rain in summer did not increase seed output or affect its quality in established plants. Exceptionally high air temperatures appeared to depress seed numbers and/or viability at several, but not all, sites. At the end of summer, when young plants were 9-12 months old, soil water extraction had occurred to 310 cm, indicating root penetration to this depth. Conservative water use by C. juncea during summer was indicated by low values of soil water depletion. In glasshouse-grown plants, simulated drought reduced seed numbers, viability, primary dormancy and seed weight, although the two forms responded differently. Given adequate winter rainfall to recharge soil water storage, C. juncea appears capable of producing large quantities of viable seeds throughout the Western Australian wheatbelt.

Wheat root penetration and total available water on a range of soil types

1976 ◽  
Vol 16 (81) ◽  
pp. 570 ◽  
Author(s):  
D Tennant
Keyword(s):  
Shallow Water ◽  
Soil Water ◽  
Western Australia ◽  
Sandy Loam ◽  
Soil Surface ◽  
Wheat Root ◽  
Consistent Pattern ◽  
Clay Soils ◽  
Soil Types ◽  
Root Penetration

Depth of root penetration was examined over three years on a range of soil types in Western Australia. A consistent pattern was recognized. Roots penetrated rapidly to 5 to 10 cm from the soil surface within the first week from planting. Subsequent penetration was slow to 6 weeks, at which stage, depending on soil types, depth of root penetration was 15 to 30 cm. Rates of root penetration increased after 6 weeks from planting with greatest penetration occurring between 8 to 13 weeks. Respective maximum depths of root penetration in the deep sand, sandy loam, grey clay and sand over clay soils investigated were 169, 173, 31 and 73 cm. These depths were reached between 10 to 14 weeks after planting. Potential available soil water to maximum depths of root penetration were 2.6, 20.1, 5.6 and 8.1 cm for the deep sand, sandy loam, grey clay and sand over clay respectively. More than half of this available soil water was accessible for crop exploitation over the 9 to 14 week period after planting, except with shallow water and root penetration in the grey clay.

Ecotypic variation for seed dormancy contributes to the success of capeweed (Arctotheca calendula) in Western Australia

1999 ◽  
Vol 50 (8) ◽  
pp. 1451 ◽  
Author(s):  
Matthew T. Dunbabin ◽  
P. S. Cocks
Keyword(s):  
Seed Dormancy ◽  
Western Australia ◽  
Late Summer ◽  
Soil Surface ◽  
Summer Rainfall ◽  
Early Summer ◽  
Effect Of Temperature ◽  
First Year ◽  
Buried Seed ◽  
Dormancy Pattern

The seed dormancy characteristics of 2 capeweed [Arctotheca calendula (L.) Levyns] ecotypes from Western Australia were studied to determine aspects of seed dormancy that contribute to the success of this species in southern Australia. Short- and long-term dormancy pattern of buried and soil surface seed, effect of summer temperatures on afterripening, and effect of temperature on seed germination were investigated using seed produced in a common environment. There were large differences in the seed dormancy pattern of the 2 ecotypes studied. On the soil surface, >95% of seed of the Mt Barker ecotype became non-dormant and germinated in the first year, the remainder germinating the following season. In contrast, only 5% of Mullewa seed germinated in the first year, with 75% germinating in the second year and 20% of seed remaining dormant after 2 years. Cycling of dormancy was observed for buried seed of both ecotypes, with periods of non-dormancy corresponding with the likely timing of the break of the season. Dormancy cycling was also apparent in seed stored under constant conditions in the laboratory. Burial prevented germination of both ecotypes; however, the ability to resist germination while buried was lost in 30% of the Mt Barker seed in the second season. Differences in the duration of dormancy of soil surface and buried capeweed seed have evolved as an adaptation to the different environments likely to be experienced by plants at their site of collection. All seeds possessed primary dormancy at maturity, with any afterripening during the first year occurring by the end of summer. Afterripening was enhanced by exposure to typical soil surface temperatures, providing some protection against germination during early summer rainfall. Protection from late summer rains is insured by the inability of seed to germinate at temperatures >30°C and a relatively slow rate of germination. These features of capeweed seed dormancy, combined with the ability to evolve genetically distinct populations suited to particular environments, help explain why capeweed is so widespread and abundant across southern Australia.

Soil water extraction and biomass production by lucerne in the south of Western Australia

2005 ◽  
Vol 56 (4) ◽  
pp. 389 ◽  
Author(s):  
P. J. Dolling ◽  
R. A. Latta ◽  
P. R. Ward ◽  
M. J. Robertson ◽  
S. Asseng
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Biomass Production ◽  
Western Australia ◽  
Root Zone ◽  
Clay Content ◽  
Water Extraction ◽  
Soil Water Storage ◽  
The South ◽  
Structure Variation

To understand the factors involved in lucerne reducing drainage below the root-zone and influencing lucerne biomass production and water extraction were analysed in the south of Western Australia. The lucerne was grown for 3 years before removal. The factors investigated as part of the water extraction analysis included the rate of advance of the extraction front or extraction front velocity (EFV, mm/day), the soil plant-available water-holding capacity (PAWC, mm/m soil), and the temporal change in soil water deficit (drainage buffer, mm). The drainage buffer is related to the EFV and PAWC. A site with deep sand had the highest EFV (mean of 9.2 mm/day) but the lowest PAWC (mean of 32 mm/m soil) to a depth of 4 m. In the duplex soils the EFV was 18–34% of the deep sand EFV and the PAWC was 60–222% higher than the deep sand PAWC to a depth of 1.6–2.1 m. The EFV was reduced by the higher clay content and sodicity in the B horizon of the duplex soils. The highest drainage buffer measurements occurred in the deep sand site and the better structured duplex soils and therefore these soils will have the greater effect on reducing drainage below the root-zone. However, lucerne was able to create a drainage buffer to at least a depth of 1.5 m over 3 years and therefore contribute to a reduced drainage even on the most sodic and saline sites. Low soil pH did not affect the drainage buffer as much as soil texture and structure. Variation in biomass production of lucerne-based pastures was positively related to rainfall and water use (taking into account soil water storage and drainage losses) across sites, explaining approximately 50% of the biomass variation. Rainfall and water use could therefore be used for predicting lucerne biomass production in Western Australia. Biomass water use efficiency was highest in spring (15 kg/ha.mm) and least during autumn (4.5 kg/ha.mm).

Characterisation of a windbreak system on the south coast of Western Australia. 3. Soil water and hydrology

2002 ◽  
Vol 42 (6) ◽  
pp. 729 ◽  
Author(s):  
D. J. M. Hall ◽  
R. A. Sudmeyer ◽  
C. K. McLernon ◽  
R. J. Short
Keyword(s):  
Ground Water ◽  
Soil Water ◽  
Western Australia ◽  
Surface Soil ◽  
Water Storage ◽  
Time Domain Reflectometry ◽  
Water Levels ◽  
Soil Water Storage ◽  
Neutron Moisture ◽  
Water Contents

This paper describes changes in soil water and ground water at various distances from a Pinus pinaster windbreak in south-western Australia. Soil water contents were measured by neutron moisture meter and time domain reflectometry at distances from a windbreak ranging from 1 to 20 tree heights (H). Within 3 H of the windbreak, soil water storage was reduced by 100–153 mm/1.8 m when compared to unsheltered conditions (20 H) over the 4 years of the experiment. Beyond 3 H, no significant differences in soil water storage were found which could be related to microclimate modification. Relationships between surface soil water storage (mm/0.4 m) at <6�H and 12–24 H were 1 : 1 regardless of the technique used. Similarly, soil water depletion within the crop rootzone (mm/0.6 m) was similar at distances >3 H. Reductions in the depth and duration of perched water levels occurred within 4 H of the windbreak. Despite this, the windbreaks had no effect on the regional ground-water levels.

Water use and drainage under phalaris, annual pasture, and crops on a duplex soil in Western Australia

2001 ◽  
Vol 52 (2) ◽  
pp. 305 ◽  
Author(s):  
P. J. Dolling
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Western Australia ◽  
Water Storage ◽  
Growing Season ◽  
Early Summer ◽  
Late Spring ◽  
Soil Water Storage ◽  
Annual Rainfall ◽  
Annual Crops

Rising water tables in southern Western Australia are causing waterlogging and salinity problems. These issues are related to a lower level of water use by annual plants than by the native vegetation. Phalaris can use more water than annual pastures and crops because of deeper rooting characteristics and longer growing season. However, there is limited information on the water use of phalaris in the Western Australian environment. There is also very little information on water balances under annual crops and pastures outside the growing season. A field experiment was carried out on a duplex soil between March 1994 and March 1999. Annual rainfall varied between 321 and 572 mm. The study examined soil water content, deep drainage, and productivity of phalaris-based pasture, continuous annual pasture, annual pasture–wheat rotation, and a wheat–lupin rotation. The results showed that the phalaris-based pasture after the establishment year was 25% (1.9 t dry matter/ha) more productive than continuous annual pasture, with the main difference occurring in late spring–early summer. The phalaris-based pasture used, on average, 45 mm/year more water and reduced drainage below 1 m by 44 mm/year compared with the annual pastures and crops. Total drainage below 1 m was 30 mm under the phalaris-based pasture and 74 mm under annual pasture. The greater water use in the phalaris-based pasture occurred in late spring and early summer. Although differences in total biomass per year occurred between wheat in different rotations there was no difference in the soil water storage prior to the break of the season. There was also no difference in the soil water balance between any of the annual crops and pastures. Differences in soil water storage did occur in some years in October but disappeared by May the following year.

Conservation biology of banksias: insights from natural history to simulation modelling

2007 ◽  
Vol 55 (3) ◽  
pp. 280 ◽  
Author(s):  
Byron B. Lamont ◽  
Neal J. Enright ◽  
E. T. F. Witkowski ◽  
J. Groeneveld
Keyword(s):  
Seed Production ◽  
Western Australia ◽  
Seed Set ◽  
Conservation Management ◽  
Fire Regime ◽  
Simulation Modelling ◽  
Detailed Knowledge ◽  
Long Distance ◽  
Viable Seeds ◽  
Growing Conditions

We have studied the ecology and conservation requirements of Banksia species in the species-rich sandplains of south-western Australia for 25 years. Loss of habitat through land-clearing has had the greatest impact on their conservation status over the last 50 years. Ascertaining optimal conditions for conservation management in bushland requires detailed knowledge of the species under consideration, including demographic attributes, fire regime, growing conditions and interactions with other species. Where populations have been fragmented, seed production per plant has also fallen. The group most vulnerable to the vagaries of fire, disease, pests, weeds and climate change are the non-sprouters, rather than the resprouters, with population extinction so far confined to non-sprouting species. Recent short-interval fires (<8 years) appear to have had little impact at the landscape scale, possibly because they are rare and patchy. Fire intervals exceeding 25–50 years can also lead to local extinction. Up to 200 viable seeds are required for parent replacement in Banksia hookeriana when growing conditions are poor (low post-fire rainfall, commercial flower harvesting) and seed banks of this size can take up to 12 years to be reached. Seed production is rarely limited by pollinators, but interannual seasonal effects and resource availability are important. Genetic diversity of the seed store is quickly restored to the level of the parents in B. hookeriana. Florivores and granivores generally reduce seed stores, although this varies markedly among species. In Banksia tricuspis, black cockatoos actually increase seed set by selectively destroying borers. Potential loss of populations through the root pathogen Phytophthora cinnamomi also challenges management, especially in the southern sandplains. Prefire dead plants are a poor source of seeds for the next generation when fire does occur. Harvesting seeds and sowing post-fire have much to commend them for critically endangered species. Bare areas caused by humans can result in ideal conditions for plant growth and seed set. However, in the case of B. hookeriana/B. prionotes, disturbance by humans has fostered hybridisation, threatening the genetic integrity of both species, whereas fine-textured soils are unsuitable for colonisation or rehabilitation. Few viable seeds become seedlings after fire, owing to post-release granivory and herbivory and unsuitable germination conditions. Seedling-competitive effects ensure that season/intensity of fire is not critical to recruitment levels, except in the presence of weeds. Water availability during summer–autumn is critical and poses a problem for conservation management if the trend for declining rainfall in the region continues. Our simulation modelling for three banksias shows that the probability of co-occurrence is maximal when fire is stochastic around a mean of 13 years, and where fire-proneness and post-fire recruitment success vary in the landscape. Modelling results suggest that non-sprouting banksias could not survive the pre-European frequent-fire scenario suggested by the new grasstree technique for south-western Australia. However, we have yet to fully explore the conservation significance of long-distance dispersal of seeds, recently shown to exceed 2.5 km in B. hookeriana.

Corrigendum to: Soil water extraction and biomass production by lucerne in the south of Western Australia

2005 ◽  
Vol 56 (9) ◽  
pp. 1010
Author(s):  
P. J. Dolling ◽  
R. A. Latta ◽  
P. R. Ward ◽  
M. J. Robertson ◽  
S. Asseng
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Biomass Production ◽  
Western Australia ◽  
Root Zone ◽  
Clay Content ◽  
Water Extraction ◽  
Soil Water Storage ◽  
The South ◽  
Structure Variation

To understand the factors involved in lucerne reducing drainage below the root-zone and influencing lucerne biomass production and water extraction were analysed in the south of Western Australia. The lucerne was grown for 3 years before removal. The factors investigated as part of the water extraction analysis included the rate of advance of the extraction front or extraction front velocity (EFV, mm/day), the soil plant-available water-holding capacity (PAWC, mm/m soil), and the temporal change in soil water deficit (drainage buffer, mm). The drainage buffer is related to the EFV and PAWC. A site with deep sand had the highest EFV (mean of 9.2�mm/day) but the lowest PAWC (mean of 32�mm/m soil) to a depth of 4�m. In the duplex soils the EFV was 18.34% of the deep sand EFV and the PAWC was 60.222% higher than the deep sand PAWC to a depth of 1.6.2.1�m. The EFV was reduced by the higher clay content and sodicity in the B horizon of the duplex soils. The highest drainage buffer measurements occurred in the deep sand site and the better structured duplex soils and therefore these soils will have the greater effect on reducing drainage below the root-zone. However, lucerne was able to create a drainage buffer to at least a depth of 1.5�m over 3 years and therefore contribute to a reduced drainage even on the most sodic and saline sites. Low soil pH did not affect the drainage buffer as much as soil texture and structure. Variation in biomass production of lucerne-based pastures was positively related to rainfall and water use (taking into account soil water storage and drainage losses) across sites, explaining approximately 50% of the biomass variation. Rainfall and water use could therefore be used for predicting lucerne biomass production in Western Australia. Biomass water use efficiency was highest in spring (15 kg/ha.mm) and least during autumn (4.5 kg/ha.mm).

scholarly journals Regression Models for Soil Water Storage Estimation Using the ESA CCI Satellite Soil Moisture Product: A Case Study in Northeast Portugal

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Tomás de Figueiredo ◽  
Ana Caroline Royer ◽  
Felícia Fonseca ◽  
Fabiana Costa de Araújo Schütz ◽  
Zulimar Hernández
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Regression Models ◽  
Meteorological Data ◽  
Water Storage ◽  
Model Performance ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
The Relationship

The European Space Agency Climate Change Initiative Soil Moisture (ESA CCI SM) product provides soil moisture estimates from radar satellite data with a daily temporal resolution. Despite validation exercises with ground data that have been performed since the product’s launch, SM has not yet been consistently related to soil water storage, which is a key step for its application for prediction purposes. This study aimed to analyse the relationship between soil water storage (S), which was obtained from soil water balance computations with ground meteorological data, and soil moisture, which was obtained from radar data, as affected by soil water storage capacity (Smax). As a case study, a 14-year monthly series of soil water storage, produced via soil water balance computations using ground meteorological data from northeast Portugal and Smax from 25 mm to 150 mm, were matched with the corresponding monthly averaged SM product. Linear (I) and logistic (II) regression models relating S with SM were compared. Model performance (r2 in the 0.8–0.9 range) varied non-monotonically with Smax, with it being the highest at an Smax of 50 mm. The logistic model (II) performed better than the linear model (I) in the lower range of Smax. Improvements in model performance obtained with segregation of the data series in two subsets, representing soil water recharge and depletion phases throughout the year, outlined the hysteresis in the relationship between S and SM.

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