Wongan Hills Research Articles

Variation in skikelet initiation and ear development of old and modern Australian wheat varieties

A chronological series of 14 economically important varieties of wheat was sown at two sites in Western Australia. Frequent samples were taken until the terminal spikelet stage. At each sampling, the stage of apex development of the main shoot was scored and number of emerged leaves and total number of primordia were counted. At terminal spikelet stage, numbers of leaves and spikelets were counted separately. Development was faster at Perth, which was on average more than 1 °C warmer than Wongan Hills. When analysed in terms of thermal time, development of varieties with an intermediate-length life-cycle was similar at both sites, as were rates of primordium initiation. Development of the earliest varieties was also similar at both sites until about the double-ridge stage, when herbicide was applied to the Wongan Hills experiment. This caused malformation of the floral apex and slowed down development compared with Perth. The latest varieties developed more quickly at Wongan Hills, possibly because they may have a vernalisation response. Thermal time from sowing to double-ridge stage ranged from 424 to 958°Cd and to terminal spikelet from 591 to 1196°Cd. Between 8 and 14 leaves were initiated, the number of leaves being strongly correlated with the time to double-ridge and terminal-spikelet stage. The rate of spikelet initiation varied from 0.08 to 0.03 (°Cd) −1, and both rate and duration of spikelet initiation were also strongly correlated with number of leaves. There was no correlation with number of spikelets. The association between number of leaves and shoot apex development may have important implications for breeding high-yielding early genotypes, as further reduction in the number of leaves on the main shoot may reduce tillering potential. It may be possible to use thermal time to predict both stages and rates of development in the earlier varieties. Differences in response of the later varieties between sites needs further investigation.

Microflora of soil and wheat rhizosphere in a field following fumigation

Light sand and heavier sandy loam wheat-growing soils at Wongan Hills, W.A. were fumigated (2: 1 mixture of chloropicrin and methyl bromide) to study its effect on the soil microflora. In fumigated soil, numbers of bacteria and fungi, after an initial reduction, remained high and low, respectively, in comparison to untreated soil, throughout the period of study. In the fumigated soil Trichoderma species rapidly recolonized the soil, becoming the dominant fungus by 15 days and remaining so to the end of the experiment (145 days after fumigation). There was no difference in the total numbers of bacteria, actinomycetes or fungi in the rhizosphere of wheat grown in fumigated and non-fumigated soils. The numbers of some fungal species were lower in the rhizosphere of wheat grown in the fumigated soil, these included Aspergillus glaucus, A. fumigatus, Beauveria bassiana, Cladosporium cladosporoides, Embellisia tumida, Fusarium oxysporum, Penicillium patulum, P. tardum, Phialophora mutabilis and Trichoderma saturnisporurn. The only fungi found to be significantly higher in the rhizosphere of plants in fumigated soil were F. merismoides, T. koningii and T. viride.

Effects of fumigation on soil nitrogen, plant nitrogen and root disease incidence in wheat at Wongan Hills, Western Australia

Fumigation of three Western Australian wheat field soils with a mixture of chloropicrin and methyl bromide (2:l) caused changes in soil nutrients and microflora which resulted in increased vegetative growth at all sites, leading to increased grain yields on the two light soils (33 and 49% respectively) but not on the heavy soil, probably because of dry conditions during the grain filling period. Soil fumigation increased concentrations of mineral nitrogen in soil early in the season. Ammonium nitrogen in fumigated soil 49 days after treatment ranged from 18.2 to 26.5 ppm, compared with 1.4-2.2 ppm in untreated soil, while nitrate nitrogen ranged from 0.3 to 2.1 ppm and 1.5 to 7.9 ppm respectively. Much of the growth increases appear to be due to this nitrogen and to a lesser extent the reduction of Gaeumannomyces graminis var. tritici. The possibility that minor pathogens like Fasarium avenaceum, Microdochium bolleyi and weakly pathogenic forms of Rhizoctonia spp. contributed to yield reduction is considered to be unlikely.

An introduction to a series of papers describing new species from the Wongan Hills and surrounding district

An introduction to a series of papers describing new species from the Wongan Hills and surrounding district

An investigation of reduction in wheat yields after use of a high level of ammonium sulphate for a number of years

Investigations were carried out to determine reasons for reduced yields in two out of three multiple wheat cropping trials, where ammonium sulphate (S/A) was applied each year at 376 kg ha-1 (76 kg N ha-1). These included chemical analysis of soil and plant samples from the trials, and a pot trial on soil from the two affected sites at Merredin and Wongan Hills. At all three sites the SIAtreatment lowered soil pH and exchangeable bases and increased exchangeable H in the soil. Available Al was markedly increased at Merredin and Wongan Hills, the sites where yields were reduced, but to a much lesser degree on the third site at Beverley. Available Mn was increased at Beverley. The reductions in soil Mg and K were reflected in the contents of these nutrients in wheat tops from the sites, but Ca content was affected only at Merredin. Plant Mn levels were increased by S/A at Wongan Hills and Beverley, but Al levels did not show any consistent effects. The level of plant Mo was reduced by S/A at all sites. In pots, on soil from the high S/A plots at Merredin and Wongan Hills a large growth response to lime was obtained, but no growth responses to Ca, Mg or K. The response to lime was associated with a decrease in Al in the plants at both sites and an increase in P at Merredin. It was considered that Al toxicity was the most likely cause of the yield reductions, but that levels of K and Mo could also be marginal for healthy growth.

Selective chemical control of doublegee (Emex australis) in legume pasture

Seven chemicals were evaluated for selective control of doublegee (Emex australis) in legume pasture in 14 field trials conducted at several sites in Western Australia over three years. The effect of removing doublegee on pasture growth was studied in four field trials over the same period. Three hundred and fifty to 700 g a.i. methabenzthiazuron ha-1 gave good selective control of this weed except at Chapman and Wongan Hills in 1974 where the beginning of the growing season was poorly defined. The selectivity of bromoxynil and WL 6361 1 in one year of trials was similar to methabenzthiazuron but that of asulam and metoxuron was too restricted for practical use when doublegees were sprayed at the 2-4 leaf growth stage, 2,4-DB showed selectivity on doublegees with 12 leaves, and no herbicides were satisfactory on doublegees with more than 12 leaves at the time of spraying. Pasture growth and clover seed production was not substantially increased by controlling doublegee.

Effect of successive cropping with nitrogenous fertilizers on wheat yields

Wheat was grown for twelve successive years at three sites with five rates of nitrogen either as calcium ammonium nitrate, ammonium sulphate or urea applied each year to the same plots. There was a long term yield decline, with and without nitrogen, on the site at Wongan Hills, but not at Merredin or Beverley. At each of the three sites there was no indication of a need for higher rates of nitrogen fertilizers with time to maintain yields. At Wongan Hills and Merredin, yields were depressed in most years when the highest rate of ammonium sulphate was used each year. Grain protein contents were low and did not decrease with time.

The Redfields meteorite—A unique iron from Western Australia

SummaryA metallic mass brought to the Western Australian Museum from the Wongan Hills district N.W. of Perth has been identified as an iron meteorite of unique type. It has graphite inclusions about I mm across distributed throughout the metal giving a ‘raisin bread’ appearance. Its nickel content (6·65 %) is comparable with that of coarse octahedrites but the kamacite grain structure is anomalous. Its gallium, germanium, and nickel contents place it close to, but outside, Wasson's chemical group IIb. Taenite is absent and troilite is rare. Neumann bands in the kamacite are distorted and the kamacite has flowed around large schreibersite inclusions. The latter have an exceptionally low nickel content (7·0 %) and probably formed at an unusually high temperature. The kamacite contains more phosphorus than normal iron meteorites, and small schreibersite grains in the kamacite are relatively nickel-poor (22 %). The unusual structure of this iron is thought to be due to one or more of the factors high carbon, high phosphorus, and relatively rapid cooling.

Association of premating liveweight to lambing performance of medium wool Merinos ewes

Analysis of data collected at Merredin and Wongan Hills between 1964 and 1969 showed that premating liveweight and lambing performance of medium woolled Merino ewes were correlated. For each 10 lb increase in liveweight of ewes there was: 1. a 2.9 per cent increase in lambs born at May-June lambing, 379 2. a 6.4 per cent increase in lambs born at July-August lambing, 3. a 3.2 per cent increase in twin births at May-June lambing, 4. a 5.6 per cent increase in twin births at July-August lambing. Equations for per cent ewes lambing demonstrated a reduction in ewes lambing both at low and high premating 1ive.weights for ewes lambing in July-August but not for those lambing in May-June. Significant interactions of premating liveweight and time of lambing were noted for both the per cent lambs born and the per cent ewes bearing twins.

THE INFLUENCE OF VARIOUS ROTATIONS ON COARSE‐TEXTURED SOILS AT CHAPMAN AND WONGAN HILLS RESEARCH STATIONS, WESTERN AUSTRALIA

SummaryThe effect of four wheat rotations on the water stability of the aggregates, organic carbon, porosity relations, and depth of penetration of a penetrometer at Chapman and Wongan Hills Research Stations is discussed. These rotations compare continuous wheat, fallow‐wheat, fallow‐wheat‐pasture, and fallow wheat‐z years lupins. The soils are coarse‐textured.Significant correlations were obtained between several measurements of structure. These include organic carbon and aggregation, organic carbon, and capillary porosity. Non‐capillary porosity is correlated with penetrometer readings.No such relation was found with total porosity. Wetting and drying of the soil and the action of growing plant roots are considered the two main factors contributing to the physical condition of the soil, and fallowing is considered to be the principal agent causing loss of structure.Water‐stable aggregates were demonstrated in the lateritic sandplain soils from Wongan Hills. These soils have been usually regarded as structureless. Variations in the content of coarse sand considerably obscured the results from this locality.

THE INFLUENCE OF VARIOUS ROTATIONS ON COARSE‐TEXTURED SOILS AT CHAPMAN AND WONGAN HILLS RESEARCH STATIONS, WESTERN AUSTRALIA

SummaryThe effect of four wheat rotations on soil organic carbon and nitrogen in two long‐term experiments at Chapman and Wongan Hills Research Stations is discussed. The experiments compare continuous wheat, fallow‐wheat, fallowwheat‐pasture, and fallow‐wheat‐z years lupins.On the assumption that adjacent uncultivated soils were comparable in carbon and nitrogen to the original virgin soils, the four‐course rotation is at each site the only one which maintained soil nitrogen at levels approaching those of the virgin soils. The two‐ and three‐course rotations, including in each case a year of fallow, by contrast, produced serious losses in both carbon and nitrogen at both localities, but particularly at Chapman. The soil‐nitrogen data support the hypothesis of Shier and Cullinane (1948) that these levels are influencing wheat yield and the flour quality of the grain.The data emphasize, also, the very low nitrogen and carbon contents of these soils both in the virgin condition and after zz years of a four‐course rotation in which half of each +year period was occupied by a leguminous crop.It is concluded that much longer periods under legumes are necessary if the carbon and nitrogen levels of these soils are to approach those typical of known highly fertile soils elsewhere.

The Birds of Wongan Hills, W.A.

The Birds of Wongan Hills, W.A.

Notes on a Trip to the Wongan Hills, Western Australia

Notes on a Trip to the Wongan Hills, Western Australia

Notes on a Trip to the Wongan Hills, Western Australia, with a Description of a New Ptilotis

Notes on a Trip to the Wongan Hills, Western Australia, with a Description of a New Ptilotis