Historically, few articles have addressed the use of district level mill production data for analysing the effect of varietal change on sugarcane productivity trends. This appears to be due to lack of compiled district data sets and appropriate methods by which to analyse these data. Recently, varietal data on tonnes of sugarcane per hectare (TCH), sugar content (CCS), and their product, tonnes of sugar content per hectare (TSH) on a district basis, have been compiled. This study was conducted to develop a methodology for regular analysis of such data from mill districts to assess productivity trends over time, accounting for variety and variety x environment interaction effects for 3 mill districts (Mulgrave, Babinda, and Tully) from 1958 to 1995. Restricted maximum likelihood methodology was used to analyse the district level data and best linear unbiased predictors for random effects, and best linear unbiased estimates for fixed effects were computed in a mixed model analysis. In the combined analysis over districts, Q124 was the top ranking variety for TCH, and Q120 was top ranking for both CCS and TSH. Overall production for TCH increased over the 38-year period investigated. Some of this increase can be attributed to varietal improvement, although the predictors for TCH have shown little progress since the introduction of Q99 in 1976. Although smaller gains have been made in varietal improvement for CCS, overall production for CCS decreased over the 38 years due to non-varietal factors. Varietal improvement in TSH appears to have peaked in the mid-1980s. Overall production for TSH remained stable over time due to the varietal increase in TCH and the non-varietal decrease in CCS.

Mungbeans are susceptible, following rainfall, to weather damage which reduces their value for food uses. Cultivars differ in their resistance to weathering, but selection for resistance based on field response has been unsuccessful. Three controlled experimental systems (immersion in water, exposure to simulated rainfall, and exposure to cyclic wetting and drying in a mist chamber) were evaluated for their ability to reproduce the symptoms of weather damage and to differentiate among the responses of cultivars known from field experience to differ in resistance. When seeds were immersed, the susceptible green gram cv. Berken absorbed water faster and had less impermeable seed than the resistant black gram cv. Regur. The green gram cv. Celera showed an intermediate response consistent with its intermediate resistance to weathering. The rainfall simulator produced more realistic conditions for weathering than seed immersion, and symptoms typical of weather damage were produced. However, the responses of cultivars were relatively poorly differentiated and the method showed poor repeatability. The exposure of podded racemes to wetting and drying cycles under controlled conditions of temperature and humidity in a mist chamber provided the most reliable method for simulating weather damage. The degree of damage increased with duration of exposure and the relative resistance of cultivars was consistent with field observation. The extent of weather damage was best measured as reduction in seed viability and as change in the appearance and permeability of the testae of seeds following exposure. The combined use of the mist chamber and these measurement criteria constitute a successful system for the selection and breeding of mungbeans for resistance to pre-harvest weathering.

The expansion of mungbean production in Australia is severely limited by the susceptibility of current cultivars to weather damage in the field. The aim of this research was to describe the causes, process, and effects of weathering in mungbean as the first step toward the breeding of resistant cultivars. Symptoms of weather damage were produced by exposing plants to simulated rainfall/high humidity and by subjecting seeds to cycles of wetting and drying. In both cases, symptoms progressed from discolouration, wrinkling, and cracking of the testa, to germination of the seed. Symptoms produced in controlled experiments were the same as those observed in the field. Only seeds that imbibed during the wetting phase developed symptoms of weather damage on drying. Exposure to one cycle of weathering also advanced the timing and degree of damage to seeds during subsequent cycles. This was associated with an increased rate of water absorption in weathered seeds. The lowering of apparent resistance to weather damage with prior exposure to rainfall suggested that only protected material be screened for weathering resistance. The death of seeds remained the ultimate expression of the changes induced by weathering.

Weather-damaged seeds of mungbean are unsuitable for the production of bean sprouts and some other food uses. The breeding of resistant cultivars requires an understanding of the weathering process and the use of suitable criteria for measuring the degree of weather damage. The aim of this research was to describe the effect of weathering on the electrical conductivity of leachate from exposed seeds and to evaluate this technique as a means of discriminating among levels of weather damage. Seeds were weathered in the field or immersed in water in the laboratory for varying durations during one or more cycles of wetting and drying. Leachate conductivities generally increased with increasing visual damage and decreasing viability of seeds. When measurements of conductivity were delayed, the results appeared to be confounded by the extent to which solutes were lost during previous exposure/s to weathering. Measurements soon after immersion tended to reduce this effect and to better reflect the level of weather damage in seeds of mungbean. It was concluded that leachate conductivity technique can provide a reliable assay of weather damage in mungbean. When seeds have been exposed to severe weathering, however, the relationship breaks down, and the technique can give misleading results.

The objective of this study was to use classification methodology to characterize the genotypic variation and line by environment (L x E) interaction for grain yield of a sample of advanced CIMMYT wheat lines and three local check cultivars tested over six Queensland environments. The environments were managed to differ in the magnitude of water stress they imposed on the lines at the critical developmental stage of anthesis. The grouping of lines was based on grain yield. The yield differences among the groups were investigated in terms of yield components and dry matter production and partitioning attributes. Groups of CIMMYT lines which outyielded the two groups which contained the three Queensland cultivars were identified. The yield advantage of the groups of CIMMYT lines decreased with increasing severity of water stress at anthesis and in the environment where the most severe stress was characterized there were no yield differences among the groups of lines. The yield advantage of the groups of CIMMYT lines was generally associated with a higher number of grains per unit area and in some cases a higher grain size. While phenology variation could account for some of the yield differences among the line groups there was considerable yield variation among line groups with similar phenology patterns across the environments. Additional measurements taken on the lines to characterize differences in dry matter production and the partitioning of the dry matter to yield components were not effective in explaining the yield variation among the groups of lines after the effects of phenology were taken into account. While the incidence of the large L x (water-stress) interactions encountered in this study would complicate selection for yield, the identification of groups of advanced CIMMYT lines which outyielded the Queensland cultivars in five of the six environments suggests that the L x (water stress) interactions do not preclude scope for further improvement of grain yield of wheat in Queensland.

Irrigated grain sorghum was cropped immediately following irrigated soybean, to establish whether there were any residual effects on sorghum from the previous management of soybean. Results of experiment 1 showed that, where soybean residues were incorporated, sorghum DM accumulation and grain yields were greatest where soybean had been least frequently irrigated (after about 240 mm cumulative open pan evaporation), and least where the soybean had been grown with saturated soil culture (SSC). Extractable mineral nitrogen (N) at sowing of the sorghum was also least following the SSC soybean and greatest following the least-frequently irrigated soybean. The subsequent availability of N during sorghum growth appeared greater where the soybean was more frequently irrigated, although the release occurred too late to influence grain yield.In experiments 2 and 3 residual effects of conventional irrigation of soybean after 60 mm evaporation were compared with those of SSC. Where soybean stubble was uniformly removed (experiment 2), no significant effects of previous irrigation were observed. Where soybean stubble was either removed or incorporated (experiment 3), sorghum yields were lower following the SSC soybean. The incorporation of soybean stubble delayed the release of soil N, although this was not reflected in lower sorghum yields.Taken together, the studies suggested that, for a sorghum crop following soybean, more N fertiliser will be needed at sowing where the soybean stubble is incorporated; where the soybean had been well-irrigated; and the sooner after soybean harvest the sorghum is sown. Conversely, there were indications that more N may be available late in the growth of the sorghum crop where soybean had been well irrigated.

Australian wheat breeding programs are currently evaluating and using advanced breeding lines from the International Centre for Wheat and Maize Improvement (CIMMYT). A more coordinated and efficient procedure for identifying useful lines for Australian breeding programs was evaluated by assessing the potential for exploiting correlated response to selection for grain yield between CIMMYT international and Australian evaluation trials. The genetic correlation, based on 40 common lines, between average line performance across 18 international and six Australian environments was high (0.813±0.049), indicating considerable potential for exploiting correlated response to selection for broad grain yield adaptation to the Australian environments for selection on broad adaptation in the international environments. The potential to select for specific grain yield adaptation to the individual Australian environments was investigated and individual international environments were identified which expressed a higher genetic correlation with the Australian environments than did average performance over all of the international environments. Therefore, opportunity exists for Australian wheat breeders to use the principles of indirect selection to select among advanced CIMMYT wheat lines on grain yield performance in international performance trials for both broad and specific grain yield adaptation to Australian environments prior to the introduction of this material to Australia. Since genotype by environment interaction for yield in the international trials is large and its causes are not well understood, selection for specific adaptation on the results from individual trials will require further investigation of the individual relationships.

Studies were conducted over several years at field sites in south east Queensland to evaluate the response of diverse soybean genotypes to saturated soil culture (SSC), relative to that in conventional irrigation (CI). In an initial study at Dalby, 56 accessions from 12 countries were tested, and all exhibited the ability to acclimate to, and grow in SSC. The chance occurrence of residual picloram herbicide on the site confounded interpretation of differential genotypic responses, but highlighted the potential vulnerability of the SSC system to chemical residues in the surface soil. In more detailed studies with representative subsets of lines at Lawes, there was large genotypic variation in relative responsiveness (RR, defined as {[Response in SSC-Response in CI]/Response in CI}) of yield to SSC, with seed yields reduced by up to 52%, enhanced by up to 37%, or unchanged, depending on genotype and agronomic management. Genotypic variation in RR was generally consistent across seasons, and was variously associated with genotypic differences in phenology when grown under CI. In general, the most positively responsive genotypes were those that started flowering late enough for the plants to have already acclimated to SSC, and that then flowered for a longer duration. Negatively responsive genotypes were those in which the pre-flowering period was sufficiently short for flowering to have commenced before acclimation was complete, i.e. where the acclimation phase intruded into reproductive ontogeny. Very late genotypes were also less responsive, perhaps because of greater lodging under the very favourable growth conditions provided by SSC. The studies indicated the potential for predicting responsiveness to SSC from knowledge of genotypic responses under conventional irrigation.

Barley progeny lines (201) derived from F2 plants of the cross cv. Triumph x cv. Grimmett were evaluated at 7 environments in Queensland. Cluster analysis and principal component analysis were used to examine the variation in response for grain yield. The relationship between days to anthesis and these responses was investigated.The variance component for genotype x environment (GE) interaction for grain yield was of similar magnitude to that for line main effects. Groups of lines formed using cluster analysis exhibited substantial differences in ranking across environments, indicating that selection would be affected by choice of test environments. The components of grain yield, harvest index (HI), and total dry matter (TDM) had large variation for GE interaction. However, for days to anthesis, the variance component for GE interaction was small compared with that for the line main effects.There were significant differences in mean days to anthesis for groups of lines that were classified on the basis of grain yield. Early flowering was associated with high grain yield in some environments but with low grain yield in the 2 irrigated environments.The first component from principal component analysis of grain yield was only weakly related to days to anthesis. This component appeared to be related to performance in favourable environments, suggesting that an important source of variation in grain yield among the progeny lines was associated with their responsiveness to favourable conditions.

The ability to acclimate to, and grow well under saturated soil culture conditions (SSC) is a ubiquitous trait in soybean (Glycine max) but little information has been reported about this novel adaptive trait in wild Glycine spp. The ability of 39 diverse accessions from one wild annual and eight wild perennial Glycine spp. to acclimate to, and grow in SSC was therefore evaluated, and responses compared with those of three cultivars of soybean. Plants were exposed to SSC 26 days after sowing, and measurements made, after a further month, of the number of nodules, leaf area, and dry matter accumulation of roots, stems and leaves. None of the wild perennial Glycine spp.(subgenus Glycine) acclimated to SSC. Necrotic tissue developed in some perennial accessions as soon as six days from the imposition of SSC, and all of the perennial accessions died during the experiment. In contrast, both of the annual species within subgenus Soja (soybean, and its presumed wild progenitor, G. soja) acclimated to SSC. The subsequent rate of recovery tended to be slower in G. soja than soybean. The responses are consistent with the hypothesis that the ability to acclimate to SSC is a wild-type trait, expression of which was amplified in soybean during domestication in rice-based agriculture.

Plant and soil water status, crop water use and water use efficiency, as affected by irrigation treatment, were monitored over two seasons for soybean cv. Ross, sown in the late wet season in the Ord Irrigation Area in north Western Australia. Irrigation treatments were, in both seasons, furrow irrigation after cumulative open pan evaporative losses of 30, 60 120 and 240 mm, and in the second year, an additional treatment, saturated soil culture (continuous furrow irrigation, analogous to irrigation after 0 mm pan evaporation). As expected, during periods of strong evaporative demand plant water status, as indicated by leaf water potential and leaf conductance of water vapour, was consistently greater in the more frequently irrigated treatments, while soil water depletion occurred to greater extent and depth in the less frequently irrigated treatments. However, total soil water use was directly proportional to crop growth, so that there was little evidence that water use efficiency was enhanced by restricting water supply in this environment. Indeed, efficiency of water use even under the continuous furrow irrigation system was comparable with that from other irrigation treatments. The responses are interpreted to imply that there is unlikely to be any economic advantage to the use of limited supplemental irrigation in this environment.

The response of soybeans to saturated soil culture (SSC), achieved through continuous furrow irrigation, was evaluated in two studies in the Ord Irrigation Area in north Western Australia. In the first study, the effect of SSC on 14 genotypes was compared with conventional irrigation after every 60 mm pan evaporation (CI60), in an early wet season sowing. Averaged across genotypes, seed yields with SSC were increased by 0.74 t ha-1 or 21 % above the mean yield of 3.47 t ha-1 with the CI60 treatment. Among genotypes, the advantage with SSC ranged from 2 to 49%. In the second study, the effect of SSC on growth and yield of three cultivars of different maturity was evaluated in a late wet season sowing, where crop durations were shorter than in the first study. There was a strong interaction between irrigation method and cultivar. Average seed yields of the latest maturing cultivar Durack were 10% greater with SSC, average yields of the intermediate cultivar Ross were relatively unchanged, while average yields of the earliest cultivar Buchanan were reduced by 24% with SSC. In both studies, and regardless of time of application of the SSC treatment, a transient chlorotic phase developed which tended to be more severe when SSC was applied earlier in crop growth. Where the chlorosis had dissipated by flowering, and providing crop duration was sufficient to compensate for the initial depression in shoot growth, seed yields were promoted by SSC. Taken together, the two studies indicate that substantial yield increases are possible with SSC in this environment, with the extent of the increases depending on genotype, crop duration, and the timing of application of the treatment.

The effect of frequency of irrigation on the growth, development and yield of soybeans was studied in two experiments at the Irrigation Research Station, Ord Irrigation Area'(15-degrees 39' S., 128-degrees 43' E.), Western Australia. Irrigation frequencies were based on Class A pan evaporation and involved irrigation after every 30, 60, 120 or 240 mm of cumulative pan evaporation. An additional treatment, saturated soil culture (SSC) or continuous furrow irrigation (analogous to 0 mm pan evaporation), was included in one of the experiments. Seed yields increased linearly with increasing irrigation frequency with the highest yields being obtained with SSC. Increasing the frequency of irrigation increased seed yields through the promotion and prolongation of crop growth. Growth rates of all plant components, viz. vegetative, reproductive, roots and nodules were enhanced by more frequent irrigation, senescence was delayed, and leaf area retained later in the growing period. Greater yields were reflected mainly in larger seed. The physiological basis for the observed responses is discussed.

Eight soybean genotypes were sown at weekly intervals in three tropical dry season environments to examine genotypic and environmental effects on growth and seed yield per plant. In general, dry matter (DM) at maturity increased exponentially with crop duration and so was greater with later maturing genotypes and sowing dates where photothermal conditions slowed development. Across environments, thermal time provided a better description of DM accumulation than did crop duration, indicating direct effects of temperature on growth rates. Among genotypes, the relationship between seed yield and DM production was strongly linear, implying that under the wide spacings of the study, DM production was the main basis of genotypic differences in seed yield. Among environmental means, the relationship was both weaker and curvilinear, suggesting that environmental effects on vegetative growth were not necessarily reflected in seed yield. Further, where photothermal regime delayed flowering and maturity, vegetative growth was often excessive, and harvest index (HI) smaller. HI was also smaller where flowering coincided with cool night temperatures (< c. 14-degrees-C) and podset was reduced. Overall, HI was negatively correlated with crop duration. Responses are discussed in terms of the implications for soybean improvement for the tropical dry season.

Eight soybean genotpes were sown at weekly intervals in three tropical dry season environments to examine genotypic and environmental effects on phenology. A series of simple linear models was used to test the relationships, for individual genotypes, between rate of development for the vegetative (Rf) and reproductive (Rr) phases and photoperiod and temperature. For each genotype, most (> 85%) of the variation across sites, years and sowing dates in Rf and more than half the variation in Rr could be accounted for by variation in photoperiod and/or temperature. Rf was generally negatively associted with mean maximum temperature and mean photoperiod, and positively with mean minimum temperature. Rr was generally positively associated with either mean, or mean maximum, temperature and negatively with mean photoperiod. It was concluded that variations in photothermal regime across sites, years and sowing dates within the tropical dry season are sufficiently large to induce instability in time to flowering of most present soybean cultivars. Most genotypes are also poorly adapted to the relatively long day-warm temperature conditions experienced by dry season crops during podfilling, presumably because they have been developed as summer crops. Breeding soybeans for the dry season will therefore need to place strong emphasis on photothermal effects during post-flowering as well as pre-flowering development.

Soybean cultivars developed for the tropical wet season performed poorly when grown in the dry season in north-west Australia. The proposition that breeding for later flowering time might enhance yields was tested by using artificial photoperiod extension (14 h day-1 for 28 days post-emergence) to delay flowering of field plots of agronomically improved genotypes. Canopy development and interception of photosynthetically active radiation (PAR), dry matter (DM) accumulation, seed yield and seed composition were examined, and compared with that from plants grown under natural photoperiods. Photoperiod extension delayed flowering an average 24 days, and maturity by an average 14.5 days, the effect being greater in the earlier-flowering genotypes. Differences among genotypes and photoperiod treatments in above-ground DM at the beginning and end of flowering were almost entirely due to the consequences of differences in phenology for cumulative PAR interception. DM at maturity was a simple linear function of crop duration (r2 = 0.95**), while seed yield exhibited an optimum-type response with DM (R2 = 0.79**). The net consequence was that photoperiod extension increased DM production by an average 2.23 t ha-1 and seed yield by an average 0.65 t ha-1. The analyses suggested that a crop duration of c. 143-146 days would be needed to maximize seed yield under the agronomic conditions of the study, whereas the longest duration among the agronomically improved genotypes under natural photoperiod conditions was 136 days. It was concluded that breeding to constrain precocious flowering under short day conditions would be a viable strategy to improve the yield potential of soybean in the dry season.

Phytophthora root and stem rot, caused by Phytophthora megasperma Drechs. f. sp. glycinea Kuan & Erwin, is an important disease of soybean in several major growing areas across the world. Susceptible genotypes can be completely devastated, but cultivars with a high level of field resistance are available. Although high soil moisture is known to predispose to infection by Phytophthora, in the absence of this disease soybean is relatively tolerant to soil waterlogging, and has been shown to respond positively to continuous watering in the Saturated Soil Culture (SSC) system. The impact of Phytophthora on plants grown in SSC was investigated at two sites in south-east Queensland. At both sites, there were no differences between plants grown in SSC and conventional furrow-irrigated treatments in the rate or ultimate extent of disease development: susceptible cultivars succumbed to the disease, while cultivars with field resistance remained free of symptoms. A fungicidal seed dressing improved emergence and reduced initial disease infection, and improved seed yield in some cultivars. It was concluded that Phytophthora root and stem rot is not a limitation to the use of Saturated Soil Culture in soybean providing resistant cultivars are available.

An analysis was undertaken of the development, growth and seed yield of irrigated soybean crops grown during the dry season of the semi-arid tropics in north-western Australia, to establish yield potentials and identify major climatic or physiological constraints. Ten tropically adapted genotypes were grown at three sowing times, using agronomic management practices designed to maximize productivity and minimize constraints due to water supply, fertility, weeds and insects. In addition to phenology, seed yield, dry matter (DM) accumulation, and seed and plant morphological traits, measurements were made at the beginning and end of flowering of DM accumulation, leaf area development and interception of photosynthetically active radiation (PAR). Harvest indices were generally large, but maximum seed yields were only c. 3 t ha-1, apparently because of inadequate biomass production. The analysis of growth and development suggested that DM accumulation during the vegetative phase was limited primarily by cumulative PAR interception by the crop canopy rather than the efficiency of conversion of intercepted PAR. In turn, both cumulative PAR interception, and canopy leaf area development, were constrained by precocious flowering, induced by the comparatively short-day/warm temperature conditions of the dry season. It was concluded that yield improvement strategies for the dry season will need to be based on agronomic and/or breeding strategies to enhance canopy development and improve biomass production.

An analysis was undertaken of the development, growth and seed yield of irrigated soybean crops grown during the dry season in the semi-arid tropics of north-western Australia, to establish whether constraints to seed yield induced by precocious flowering could be overcome agronomically by manipulating sowing date and/or sowing density. Three agronomically improved cultivars and a later-flowering landrace cultivar were tested using irrigation, fertility and pest management practices designed to minimize constraints to yield. Maximum seed yields were 3.5-4.0 t ha-1, with large genotype x sowing date x sowing density interaction. Analysis of vegetative growth showed that higher sowing densities stimulated more rapid leaf area development and earlier canopy closure, and enhanced total biomass production. However, very high sowing densities were needed to maximize yields of most genotypes, while lodging precluded high yield being realized from the greater biomass production of high density sowings of the landrace genotype. Delaying sowing from April to June delayed flowering, increased biomass production and marginally enhanced yields, but not sufficiently to offset potential problems caused by maturation into hot dry conditions prior to the wet season. It was concluded that agronomic strategies alone were insufficient to overcome the constraints to yield of present soybean genotypes in the dry season.

Pachytene Chromosome Inversion Loops with Misaligned and Paired Centromeres: Their Significance in Pigeonpea X Atylosia acutifolia Hybrids Get access I. S. Dundas, I. S. Dundas 1The Department of Agronomy, Waite Agricultural Research Institute, University of Adelaide, Glen OsmondSouth Australia Search for other works by this author on: Oxford Academic PubMed Google Scholar E. J. Britten, E. J. Britten 2The Department of Agriculture, University of Queensland, St. Lucia Search for other works by this author on: Oxford Academic PubMed Google Scholar D. E. Byth, D. E. Byth 3Queensland Agricultural CollegeLawes via Gatton Search for other works by this author on: Oxford Academic PubMed Google Scholar G. H. Gordon G. H. Gordon 4NewDor Consultancy Pty. Limited, Chippendale, New South WalesAustralia Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Heredity, Volume 81, Issue 2, March 1990, Pages 139–143, https://doi.org/10.1093/oxfordjournals.jhered.a110945 Published: 01 March 1990