Australian Journal of Agricultural Research

PIP As part of a study on ovine infertility in agricultural regions of Western Australia, the production of cervical mucus in fertile and infertile ewes was examined between February and July 1970. In the first test, 15 Corriedal ewes (5-6 years old) were implanted with Silastic implants containing 375 mg of progesterone for a period of 16 days to synchronize the onset of estrus. All ewes grazed on nonestrogenic pastures or were hand-fed grain during the test period. During a second 16-day study, ewes were injected intramuscularly daily with 10 mg progesterone in 1 ml of oil. 48 hours after the last progesterone injection, ewes were injected with estradiol benzoate in 1 ml of oil. After both tests, mucus samples were collected on cylindrical cotton swabs at 6-hour intervals. The first progesterone test revealed a significant (p less than .05) difference in the total weight of mucus between fertile (23.3 g) and infertile (34.6 g) ewes. After the second progesterone treatment, fertile ewes again produced significantly less mucus than the infertile ewes (25.7 vs. 37.2 g; p less than .05). Production of mucus in infertile ewes was 1.5% greater than that produced by fertile ewes at both a synchronized and a natural estrus. Both groups of ewes showed similar responses to exogenous estrogen following ovariectomy. Data indicated that the increase in the total weight of mucus is due to an increase in fluid content. As the rheological properties of cervical mucus contribute to sperm transport, production of a thinner watery mucus in ewes may account for infertility.

PIP In view of the impairment of transport and survival of spermatozoa i n the genital tract of progestagen-treated spayed ewes compared with tha t observed in normal animals and the possible relationship with the prod uction of cervical mucus, 2 experiments were conducted to study the pattern of response to exogenous progesterone and estrogen. The production of cervical mucus was measured at intervals of 6 hours about the onset of estrus in ewes treated with exogenous progestagen administered intramuscularly or intervaginally. There was a quadratic pattern of production with peak values early in the estrous period. Although there were no differences between groups in the total amount of mucus produced, levels recorded in untreated ewes were lower in the preestrous period. Within the intravaginal progestagen group, those ewes which exhibited estrus within 42 hours of sponge withdrawal produced greater quantities of cervical mucus than did animals which came into heat after this time. This relationship was not evident within the intramuscular progesterone group. It was concluded that the variable cervical mucus response observed after the cessation of treatment may contribute to the lowered fertility commonly observed following the synchronization of estrus. The cervical mucus response to injected steroids was recorded in spayed ewes. This was a specific line ar response to exogenous estrogen. Progesterone priming resulted in higer levels of cervical secretions from 24 to 42 hours after the admini stration of estradiol benzoate (ODB). Intravenous administration of OBD caused an earlier but short-lived response.

PIP An experiment designed to study the effects of PMSG (pregnant mare serum gonadotrophin) and HCG (human chorionic gonadotrophin) on ovulation and subsequent fertility in the cyclic Merino ewe is described. 360 cyclic Merino ewes, 16 vasectomized rams, and 6 entire rams of proven fertility were used. PMSG (0v750iu) was injected into the ewes on the twelfth day after service by vasectomized rams. HCG (0v400v800iu) was injected immediately after the ewes were observed in estrus. The ewes were artificially inseminated. Each received .1 ml of semen of good motility containing 200-500x1,000,000 spermatozoa. 3-15 hours after the detection of estrus. PMSG induced multiple ovulation and speeded up ovulation 203 hours. A reflection of the ovulation rate increase was the increase in multiple births. HCG increased the proportion of ruptured follicles and this effect was accompanied by an increase in number of ovulations. The number of ewes which lambed increased with increase in the HCG dosage. HCG given alone or after PMSG increased the incidence of birth to a lesser extent than PMSG.

PIP The ovarian responses of 2 groups of Merino ewes, 63 ewes of high (T) and 67 of low (0) fecundity, to 0, 375, 750, or 1500 intrauterine injections of pregnant mare's serum gonadotrophin (PMSG) on Day 13 or 15 of the estrous cycle were compared. 5 or 12 9 group ewes injected with PMSG failed to show estrous compared with 1 of the T ewes. Untreated T ewes ovulated significantly more frequently than 0 ewes (p.01). Response to PMSG was significantly higher in the T group (p.001). Plasma progesterone and luteal tissue weight was greater in T ewes. Loss of potential embryos by 20 days was similar in both groups and increased with increasing doses of PMSG. It is not known whether the between-group differences in fecundity arose through changes in pituitary gonadotrophin secretion, ovarian sensitivity changes, or both.

Seventy 14-day-old male pigs that were either heavy (6.0 kg) or light (3.6 kg) for age were weaned into individual pens and fed 1 of 7 diets containing 9.2-21.0 g lysine/kg feed in a study designed to determine the effect of dietary lysine and weight on lysine requirements of pigs. Five pigs from each weight group were used to determine initial body composition. When pigs reached 10 kg they were slaughtered and empty body composition was analysed to determine protein tissue accretion rates. Protein deposition rate was not affected by weight at weaning but increased with dietary lysine content before reaching a plateau. The relationship between protein deposition (PD, g/day) and dietary lysine (L, g/kg) was described by 3 models. The rectilinear model, which had a linear ascending phase (PD = 4.84 + 1.948L, R2 = 0.935, P = 0.002) and a horizontal component representing maximum protein deposition rate of 32.3 g/day, revealed that maximum protein deposition occurred at 14.1 g lysine/kg. The quadratic function (PD = - 2.74 + 3.74L - 0.099L2, R2 = 0.916, P = 0.003) provided an estimate of the lysine requirement of 14.9 g lysine/kg occurring at a point where PD reached 95% of the maximum protein deposition rate (32.5 g/day). Use of an asymptotic model (PD = 32.60 - 186 x 0.727L, R2 = 0.919, P = 0.003) provided an estimate of 14.9 g lysine/kg occurring at a point where PD reached 95% of the maximum protein deposition rate (32.6 g/day). These data indicate that early weaned pigs should be fed a highly digestible diet containing 14-15 g lysine/kg to maximise protein deposition.

A survey for mycotoxins and fungal damage in maize (Zea mays L.) grown during 1982 in Far North Queensland is reported. This season had a rainfall distribution which was typical for the reglon. The 293 samples examined came from 11 1 farms in eight maize-growing districts. The samples were first subjected to rapid screening tests for fungal damage. Aflatoxins B,, B,, GI, G,, ochratoxin A, T-2 toxin, and sterigmatocystin were not detected, but zearalenone was found in 85% of the samples. The concentrations of zearalenone were correlated with the extent of Gibberella zeae cob rot as indicated by the proportion (up to 2%) of kernels in each sample having a reddish-purple discoloration. In four samples the zearalenone concentration exceeded 1 mg kg-', but the mean + s.d. (n = 293) concentration in all samples was 0.17 _f 0.225 mg kg-'. Concentrations were highest in districts with the highest rainfall during the period of maize growth.

A survey for various mycotoxins was carried out on samples of all wheat delivered to nine storage and marketing depots in south-eastern Queensland, selected as most likely to receive mycotoxin-contaminated grain. All wheat was surveyed during 1983, when the degree of weather damage was high. Samples of the poorest grade of wheat from these depots were also surveyed in 1984 and 1985. The surveys included all regions where head scab of wheat caused by Fusariurn graminearurn Schwabe Group 2 had been reported to occur at significant levels. 4-Deoxynivalenol was detected in nearly all pooled samples representing bulk wheat at concentrations ranging from traces of <0.01 up to 1.7 mg kg-1. The highest concentration of zearlenone detected in a pooled wheat sample was 0.04 mg kg-1. In a few samples representing individual wheat deliveries and with up to 2.8% by weight of pink grains, 4-deoxynivalenol concentrations ranged up to 11.7 mg kg-' and zearalenone up to 0.43 mg kg-l. Aflatoxins B,, B2, G1 and G2 were detected in only one pooled sample of wheat, at a total aflatoxin concentration of 0.003 mg kg-'. Ochratoxin A, sterigmatocystin and T-2 toxin were not detected. Higher concentrations of mycotoxins were found in the poorer grades of wheat.

A rapid and reliable polymerase chain reaction (PCR)-based protocol was developed for detecting zygosity of the 1BL/1RS translocation in hexaploid wheat. The protocol involved a multiplex PCR with 2 pairs of oligonucleotide primers, rye-specific Ris-1 primers, and consensus 5S intergenic spacer (IGS) primers, and digestion of the PCR products with the restriction enzyme, MseI. A small piece of alkali-treated intact leaf tissue is used as a template for the PCR, thereby eliminating the necessity for DNA extraction. The test is simple, highly sensitive, and rapid compared with the other detection systems of 1BS1RS heterozygotes in hexaploid wheat. PCR results were confirmed with AFLP analyses. Diagnostic tests for 1BL/1RS translocation based on Sec-1-specific ELISA, screening for chromosome arm 1RS controlled rust resistance locus Yr9, and the PCR test differed in their ability to detect heterozygotes. The PCR test and rust test detected more heterozygotes than the ELISA test. The PCR test is being used to facilitate S1 family recurrent selection in the Germplasm Enhancement Program of the Australian Northern Wheat Improvement Program. A combination of the PCR zygosity test with other markers currently being implemented in the breeding program makes this test economical for 1BL/1RS characterisation of S1 families.

The leguminous shrub Leucaena leucocephala (leucaena) iswidely used as a forage species for cattle in tropical agriculture. However,leucaena contains the toxic amino acid mimosine. Both mimosine and its primaryruminal degradation product 3-hydroxy-4(1H)-pyridone (DHP) are toxic and theiraccumulation in the animal’s system results in hair loss, reducedliveweight gain, and goitre. The ruminal bacteriumngle cultivar bywithholding water. In Expt 2, plants of EP and MK were grown together in thesame container and received water daily with gradation in intensity of waterdeficit achieved by varying the daily water ration per container. All cultivars in each experiment exhibited commonly reported responses towater deficit, characterised by diminished evaporative surface area andincreased root : shoot ratio. The response of MK was primarily morphologicaland MK plants had smaller plant size, higher root : shoot ratio,

The ‘dehesas’ are savannah-like semiarid grasslands typical of western Spain that are subject to strong inter-annual variations in biomass production. Over a 20-year period, from 1986 to 2005, aboveground biomass and the nutritional quality of these grasslands in the province of Salamanca (western Spain) were evaluated to determine the relationships between interannual variations in grassland parameters and climate variables (precipitation and temperature). Herbage samples were collected from several sites, along a topographic gradient that differentiated two types of herbaceous communities on the upper and lower part of the slope. Nutritional quality was assessed by determining on the basis of protein, acid detergent fibre, neutral detergent fibre, lignin and digestibility. On both the upper and lower zones total biomass and biomass of grasses were correlated with annual precipitation calculated from the previous October to the current June. Biomass of legumes and forbs, on the upper zones, was correlated with spring precipitation. Stepwise multiple regression analysis provided different models for grasses, legumes, forbs and total biomass for the upper and lower zones. Protein concentration was negatively correlated with annual precipitation in both zones of slope. The number of days in spring with precipitation (≥ 1 mm or ≥ 10 mm) was a good predictor of the lignin content and digestibility in both zones of the slope, and of the acid detergent fibre content on the upper zones and the neutral detergent fibre content on the lower zones. The present work was funded by several research projects that were begun in 1987 (European Union, Spanish Ministry of Education and Science, Regional Goverment -Junta de Castilla y León) Peer reviewed

A study of the effect of soil-water stress and phosphorus level on the efficiency of phosphorus absorption (micrograms phosphorus per milligram oven-dry root per day) and growth by young wheat plants grown on a lateritic podzolic soil showed that absorption was not affected by increasing soil-water stress, provided the plants were not damaged by wilting. In experiments where the water-stress treatment was imposed for only a few days it was found that the rate of phosphorus absorption was reduced after the plants had been subjected to a period of wilting. The results indicate that available soil phosphorus was derived mainly from fine pores undrained at suctions approaching 15 atm. The concentration of available phosphate in these pores may have been considerably higher than earlier estimates of the phosphate concentration in the soil solution. The absorption of phosphorus increased with increasing soil phosphorus potential for all levels of water stress.

Root and shoot attributes of 12 indigenous perennial accessions of the wild mungbean (Vigna radiata ssp. sublobata) were evaluated in early and late summer sowings in the field in SE Queensland. All but one of the accessions were obtained from the Townsville-Charters Towers region of NE Queensland. In both sowings, the accessions developed thickened tap and lateral roots, the taproot thickening extending to a depth of 0.20-0.30m below the soil surface, depending on accession. The thickened lateral roots emerged from the taproot within 0.10m of the soil surface, and extended laterally up to 1.10 m, remaining close to the soil surface. Differences among the accessions in gross root morphology and phenology were relatively small. There were differences among the accessions in the production of seed, tuberised root, and recovered total plant biomass. Depending on accession and sowing date, the tuberised roots accounted for up to 31% of recovered plant biomass and among accessions, the root biomass was positively correlated with total plant biomass. In contrast, seed biomass represented only a small proportion of recovered plant biomass, up to a maximum of 14%, depending on accession and sowing date. Among accessions, the proportion of seed biomass tended to be negatively correlated with that of tuber biomass. The perennial trait appears to be unique to Australian accessions of wild mungbean obtained from coastal-subcoastal, speargrass-dominant woodlands of NE Queensland. Although the ecological significance of the trait remains conjectural, field observation indicates that it facilitates rapid plant re-growth following early summer rainfall, especially where dry-season. re has removed previous-season above-ground growth.

The wild mungbean, Vigna radiata ssp. sublobata, is an 'old world' tropical species indigenous throughout the better watered areas of northern Australia. Variation among 115 accessions, mainly from Australia, West Timor, and Papua New Guinea, was evaluated for several diverse traits. The plants were cultivated in the field at 2 sowing dates, at both a tropical and a subtropical location, with 6 accessions from India and a mungbean cultivar for comparison. Substantial variation was identified for traits of potential agronomic, adaptive, or taxonomic interest. For some traits, like phenology, the variation appeared to be systematic, with plausible underlying physiological and/or adaptive explanation. Among accessions, wild type traits, like prostrate habit, more gracile morphology, twining form, and small hard seeds, tended to be associated. There was a general geographic trend for lines collected from locations more remote from where mungbean has historically been cultivated to show greater expression of wild type traits, with few 'traits of domestication' evident in the Australian accessions. Some of the identified variation, e. g. higher seed protein content, hardseededness, and putative disease resistance, may be of value in mungbean variety improvement. A more targetted evaluation of the collection would likely reveal other adaptations, especially tolerance to environmental stresses. As such, the wild accessions are a potentially valuable if under-utilised germplasm resource.

Summer-dormant, cool-season perennial grasses are being used in place of traditional, summer-active cultivars for high-quality winter forage. One reason for this change is the ability of cultivars with summer-dormant attributes to tolerate increasing annual temperature, decreasing precipitation, and repeated severe summer droughts. The mechanism of summer dormancy is still not understood in detail. Cultivar development for summer dormancy typically is conducted under field conditions in environments where summer-active types do not survive summer weather conditions. We developed a method based on germination responses to photoperiod to differentiate summer-dormant from summer-active types of tall fescue [Lolium arundinaceum (Schreb.) S. J. Darbyshire] and orchardgrass (Dactylis glomerata L.). Seed of cultivars with known summer dormancy characteristics was germinated at a constant temperature of 24°C under a range of photoperiods (0-24h) for 14 days. Total germination, modelled cumulative germination, instantaneous rate of germination, and relative germination (to that in the dark) were analysed. Germination of summer-dormant orchardgrass was similar in the dark and short photoperiods (4-12h), but it was inhibited by a photoperiod longer than 12h. Germination of summer-active orchardgrass was promoted by any photoperiod compared with the control (0h). Short photoperiods (4-12h) promoted germination of summer-dormant tall fescue, while long photoperiods (>12h) inhibited germination compared with germination in the dark. Summer-active types of tall fescue did not respond to photoperiod, regardless of length. A validation test using two Mediterranean origin cultivars of orchardgrass with contrasting summer dormancy characteristics and experimental lines of Mediterranean origin tall fescue with known expression of summer dormancy characteristics supported the use of seed germination analysis to differentiate among lines for this trait.

The ability to predict accurately dry matter (DM) accumulation, partitioning, and thus final grain yield is crucial in crop simulation models. The objectives of the study were to measure radiation interception and radiation use efficiency, to quantify the distribution of DM among the various plant parts, and to develop improved methods of modelling DM accumulation and partitioning among plant parts. Five cultivars of maize differing widely in maturity and adaptation were planted in October 1993 in southeastern Queensland, and grown under non-limiting conditions of water and plant nutrient supplies. Data on DM accumulation, light interception, and canopy development were collected. The light extinction coefficient (k) did not differ among the cultivars. Radiation use efficiency was constant in each cultivar until close to physiological maturity, when a small decline was observed. Partitioning of DM between leaves and stems (until 90% of leaf tips had appeared) was described by a linear relationship between the proportion of DM allocated to leaves and the number of leaves present. Ear growth was described by a thermal-time-dependent equation from 150 degree-days (base temperature 8 degrees C) before silking to 115 degree-days after silking. Predictions of accumulation of grain yield by either components of yield (grain number per plant and individual grain weight) or daily increase in harvest index were assessed, but neither was entirely satisfactory, the former because of inaccurate prediction of grain number per plant, and the latter because of differences among cultivars in the daily increase in harvest index and terminal harvest index. Thus, the use of genotype-specific coefficients remains necessary. Throughout crop life, DM in stems can be predicted by difference, once DM is allocated to other plant parts. The relationships presented where leaf number mediates DM partitioning before silking simplify modelling of DM accumulation and partitioning in maize.

Comparisons among species can be a valuable approach to identifying traits important for plant breeding. Differences between 2 durum wheat (Duilio and Creso) and 1 triticale (Antares) cultivar have been analysed in a 2-year field trial in Sardinia (Italy), in order to define a more productive durum wheat ideotype for Mediterranean-type environments. The greater grain yield (569 v. 447 g/m²) and the lower protein percentage (9.2 v. 10.6%) of triticale cv. Antares compared with the durum wheat cultivars, at a similar level of biomass produced at heading, were analysed in terms of number of grains per unit surface and rate and duration of dry matter (DM) and nitrogen (N) accumulation, calculated from a logistic curve. When the single grains were considered, Antares showed a lower rate but a longer duration of DM and N accumulation in the more favourable season, resulting in lower DM (40 v. 54 mg) and N (0.7 v. 1.0 mg) contents in the grain. On the other hand, when data were expressed on a per unit surface basis, the greater spike fertility of Antares (53 v. 39 grains per spike) and its longer duration of accumulation, were responsible for similar or even greater amounts of DM and N accumulated in the grains per m². Growth rate of single grains, although able to explain differences in single grain weight, cannot explain differences in grain weight per m² and hence in yield, which mainly result from variation in the number of grains per spike. Nitrogen percentage of the grains decreased from the maximum values observed at the beginning of grain filling, until a constant final value attained before the end of DM and N accumulation. Rate is more important than duration in determining the quality characteristics of grains, as higher grain weights and protein percentages correspond to higher rates of DM and N accumulation.

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.

As sowing dates are critical for appropriate yield forecasting, a national survey of Australian wheat farmers was undertaken. This revealed that wheat sowing generally takes 2-4 weeks to complete between the middle of May and the middle of June. Distinct regional differences occur in the way sowing is completed and these are related to soil and climatic effects. In Western Australia, sowing follows a more distinct &grave;break in the season" and the midpoint of farm sowing is fairly uniform across cropping areas. As one progresses into south-eastern and then north-eastern cropping areas the spatial variability in sowing increases. The combination of fallowing practices, unreliable autumn rainfall, and heavier soils (that delay operations when conditions are wet or dry), all add to the variability in sowing date and sowing duration in north-eastern areas. The range of midpoint in sowing (between years) generally decreases as the progression is made from a farm, to a State, to a national scale. Reduced variability at a national scale is enhanced by broad-scale weather patterns causing sowing opportunities to contrast markedly on different sides of the country. During the 1980s, sowing progressed a day earlier per year at a national scale. The most pronounced changes occurred in Queensland and Western Australia, where a 2-3-week shift to earlier sowing was recorded. Coinciding with this was a trend in all areas to reduced or minimum tillage techniques. Late opening rains in South Australia restricted early sowing opportunities during this time.

A network of rainfall stations was selected across the Australian wheatbelt and monthly rainfall regressed with wheat yields from the surrounding shires for the period 1976-87. Yields were found to be strongly related to fluctuations in total rainfall amount and the seasonal distribution of rainfall through the year. These temporal relationships vary spatially and appear to be regulated by the water-holding capacity of regional soils. Sixteen agrometeorological zones were defined with similar rainfall-yield relationships. In all these, autumn rains that permit an early sowing, and finishing rains after July, are most important for higher yields. As the rainfall distribution becomes more winter-dominant, both crop yield variability and the usefulness of high winter rainfall decreases. Heavy rainfall in the month after sowing can have a negative effect in southern Australia, as plants are more prone to suffer potential yield losses from a wet soil profile. Waterlogging has a large negative effect in the south-west of Western Australia, such that the rainfall distribution can be more important than the rainfall amount. Rainfall-yield correlations are generally more positive in drier regions, and are enhanced by persistent rainfall anomalies between April and November during El Niño Southern Oscillation years.

Analyses of variance and co variance were carried out on the activities of three lysosomal enzymes in mononuclear blood cells from Brahman cattle. These were hexosaminidase (HEX), beta-D-galacto-sidase (GAL) and acid alpha-glucosidase (GLU) which had been measured in blood mononuclear cells from 1752 cattle from 6 herds in a Pompe's disease control programme. Herd of origin and date of bleeding significantly affected the level of activity of all enzymes. In addition, HEX and GAL were affected by age and HEX by the sex of the animal bled. Estimates of heritability from sire variances were 0.29:t 0.09 for HEX, 0.31 :t 0.09 for GAL and 0.44:t 0.09 for GLU. Genetic correlations between all enzymes were positive. The data indicate the existence of a major gene causing Pompe's disease and responsible for 16% of the genetic variation in GLU. One standard deviation of selection differential for high GLU should almost eliminate Pompe's disease from the population. The effi-ciency of selection would be aided by estimating the breeding value for GLU using measurements of HEX and GLU and taking account of an animal's sex, age, date of bleeding and herd of origin.

Breeding methodologies for cultivated lucerne (Medicago sativa L.), an autotetraploid, have changed little over the last 50 years, with reliance on polycross methods and recurrent phenotypic selection. There has been, however, an increase in our understanding of lucerne biology, in particular the genetic relationships between members of the M. sativa complex, as deduced by DNA analysis. Also, the differences in breeding behaviour and vigour of diploids versus autotetraploids, and the underlying genetic causes, are discussed in relation to lucerne improvement. Medicago falcata, a member of the M. sativa complex, has contributed substantially to lucerne improvement in North America, and its diverse genetics would appear to have been under-utilised in Australian programs over the last two decades, despite the reduced need for tolerance to freezing injury in Australian environments. Breeding of lucerne in Australia only commenced on a large scale in 1977, driven by an urgent need to introgress aphid resistance into adapted backgrounds. The release in the early 1980s of lucernes with multiple pest and disease resistance (aphids, Phytophthora, Colletotrichum) had a significant effect on increasing lucerne productivity and persistence in eastern Australia, with yield increases under high disease pressure of up to 300% being recorded over the predominant Australian cultivar, up to 1977, Hunter River. Since that period, irrigated lucerne yields have plateaued, highlighting the need to identify breeding objectives, technologies, and the germplasm that will create new opportunities for increasing performance. This review discusses major goals for lucerne improvement programs in Australia, and provides indications of the germplasm sources and technologies that are likely to deliver the desired outcomes.

Agenetic experiment was conducted using 80 full-sib families in irrigated and dryland treatments under the summer moisture stress conditions of the Northern Tablelands of New South Wales, over 3 years. This paper reports on the effects of climatic and soil moisture conditions, the genetic variation for stolon attributes and seasonal herbage yield, and the development of new recombinant genotypes in relation to the association between stolon attributes and herbage yield. Large components of variance were estimated for genotype-by-environment-by-year interactions for the attributes stolon density, number of branches, number of nodes, number of rooted nodes, stolon thickness, root diameter, internode length, and summer herbage yield. The combined analysis of variance across environments and years indicated the presence of genetic variation for the stolon attributes stolon density, number of branches, number of nodes, stolon thickness, internode length, and herbage yield. Crossing of the morphologically contrasting cultivars El Lucero x Tahora x Duron, and Barbian x El Lucero, resulted in generating genotypic recombinants with new associations between herbage yield and stolon density, number of branches, number of nodes, and number of rooted nodes. Evaluation of the full-sib families and check cultivars (cvv. Haifa and Huia) identified 5 full-sib families with relatively higher herbage yield, stolon density, number of branches, number of nodes, and number of rooted nodes than cultivars Haifa and Huia.

Phytophthora root rot, caused by Phytophthora medicaginis, is a major limitation to lucerne ( Medicago sativa L.) production in Australia and North America. Quantitative trait loci (QTLs) involved in resistance to P. medicaginis were identified in a lucerne backcross population of 120 individuals. A genetic linkage map was constructed for tetraploid lucerne using 50 RAPD ( randomly amplified polymorphic DNA), 104 AFLP (amplified fragment length polymorphism) markers, and one SSR ( simple sequence repeat or microsatellite) marker, which originated from the resistant parent (W116); 13 markers remain unlinked. The linkage map contains 18 linkage groups covering 2136.5 cM, with an average distance of 15.0 cM between markers. Four of the linkage groups contained only either 2 or 3 markers. Using duplex markers and repulsion phase linkages the map condensed to 7 homology groups and 2 unassigned linkage groups. Three regions located on linkage groups 2, 14, and 18, were identified as associated with root reaction and the QTLs explained 6 - 15% of the phenotypic variation. The research also indicates that different resistance QTLs are involved in conferring resistance in different organs. Two QTLs were identified as associated with disease resistance expressed after inoculation of detached leaves. The marker, W11-2 on group 18, identified as associated with root reaction, contributed 7% of the phenotypic variation in leaf response in our population. This marker appears to be linked to a QTL encoding a resistance factor contributing to both root and leaf reaction. One other QTL, not identified as associated with root reaction, was positioned on group 1 and contributed to 6% of the variation. This genetic linkage map provides an entry point for future molecular-based improvement of lucerne in Australia, and markers linked to the QTLs we have reported should be useful for marker-assisted selection for partial resistance to P. medicaginis in lucerne.

The effect of interspecific heterosis in crosses between Medicago sativa subsp. sativa and M. sativa subsp. falcata was assessed. Three sativa and 3 falcata plants were crossed in a diallel design. Progeny dry matter yield and natural plant height were assessed in a replicated field experiment at Gatton, Queensland. Yield data were analysed using the method of residual maximum likelihood (REML) and Griffing's model 1. There were significant differences between the reciprocal, general combining ability (GCA), and specific combining ability (SCA) effects. As expected, S-1 populations were lower yielding than their respective intraspecific cross and falcata x falcata crosses were significantly lower yielding than sativa x sativa crosses. Some of the interspecific crosses indicated substantial SCA effects, yielding at least as well as the best sativa x sativa crosses. We have demonstrated the potential usefulness of unselected M. sativa subsp. falcata as a heterotic group in the improvement of yield in northern Australian adapted lucerne material, and discuss how it could be incorporated into future breeding to overcome the yield stagnation currently being experienced in Australian programs.

The phenology of 11 diverse accessions of wild mungbean was observed under natural and artificial photoperiod - temperature conditions, in order to examine whether genotypic differences might be attributed to adaptive responses to photo-thermal conditions. There was large variation in phenological response among accessions and across environments, much of which was due to differences in the duration of the pre-flowering phase. Accessions that flowered earlier tended to flower for longer, apart from 2 earlier flowering, inland Australian lines that were also earlier maturing. The patterns of response in time from sowing to flowering over environment were consistent with quantitative short-day photoperiodic adaptation, a conclusion supported by the effects of artificial day-length extension and by 'goodness of fit' of the observed responses to standard models relating rate of development to photoperiod and temperature. The fitted models indicated that rate of development towards flowering was hastened by warmer temperatures, and delayed by longer day lengths, with differential sensitivity between accessions to both factors. The models also suggested that photoperiod was more important for accessions collected closer to the equator, which were generally later flowering as a consequence. Conversely, temperature was relatively more important in lines from higher latitudes. Modelling also suggested that the period from first flowering to maturity was sensitive to photoperiod and temperature. Again, longer days appeared to prolong growth and delay maturity. However, cooler temperatures accelerated rather than slowed maturity, by suppressing further vegetative growth. The variation observed indicated that there is considerable scope for using the wild population to broaden the adaptation of cultivated mungbean. In particular, the unusual response of a late-flowering, photoperiod-insensitive accession warrants further study to establish whether the wild population contains a unique 'long juvenile' trait analogous to that being used for improving phenological adaptation in soybean.

The leaf growth, dry matter production, and seed yield of 11 wild mungbean ( Vigna radiata ssp. sublobata) accessions of diverse geographic origin were observed under natural and artificial photoperiod temperature conditions, to determine the extent to which genotypic differences could be attributed to adaptive responses to photo-thermal environment. Environments included serial sowings in the field in SE Queensland, complemented by artificial photoperiod extension and controlled-environment growth rooms. Photo-thermal environment influenced leaf growth, total dry matter production ( TDM), and seed yield directly, through effects of ( mainly cool) temperature on growth, and indirectly, through effects on phenology. In terms of direct effects, leaf production, leaf expansion, and leaf area were all sensitive to temperature, with implied base temperatures higher than usually observed in cultivated mungbean ( V. radiata ssp. radiata). Genotypic sensitivity to temperature varied systematically with accession provenance and appeared to be of adaptive significance. In terms of the indirect effects of photo-thermal environment, genotypic and environmental effects on TDM were positively related to changes in total growth duration, and harvest index was negatively related to the period from sowing to flowering, similar to cultivated mungbean. However, seed yield was positively related to the duration of reproductive growth, reflecting the indeterminate growth habit of the wild accessions. As a consequence, the wild accessions are more responsive to favourable environments than typically observed in cultivated mungbean, which is determinate in habit. It is suggested that the introduction of the indeterminate trait into mungbean from the wild subspecies would increase the responsiveness of mungbean to favourable environments, analogous to that of black gram ( V. mungo). Although the wild subspecies appeared more sensitive to cool temperature than cultivated mungbean, it may provide a source of tolerance to the warmer temperatures experienced during the wet season in the tropics.

The effects of microbial phytase supplementation of phosphorus-adequate, wheat-based diets with available lysine : energy density ratios ranging from 0.75 to 0.90 g available lysine/MJ DE on growth performance of weaner pigs were investigated in 3 studies. In the first study, increasing levels of dietary phytate depressed growth rates (P<0.08) and efficiency of feed conversion (P<0.01) and phytase supplementation enhanced growth rates (P<0.05) and tended to improve feed efficiency (P<0.15). There were no significant interactions between dietary phytate and phytase inclusion to support the hypothesis that dietary substrate levels of phytate govern responses to phytase. However, in this and other studies, percentage increases in efficiency of feed conversion generated by phytase were positively correlated to dietary phytate concentrations to a significant extent (P<0.005), so it is possible that dietary substrate levels are of importance to the magnitude of responses following phytase supplementation. Diets with 3 levels of protein, expressed as 0.80, 0.85, and 0.90 g available lysine/MJ DE, were offered to pigs without and with phytase in the second study. Protein/amino acid levels or lysine : energy density ratios did not influence growth performance, which was not expected. However, phytase tended to increase growth rates (P<0.08) and improved feed efficiency (P<0.01). Although it is believed that phytase may have a positive influence on protein utilisation, this was not demonstrated in this experiment. In the third study, the simultaneous inclusion of phytase and xylanase feed enzymes in wheat-based weaner diets did not increase growth performance responses in comparison with phytase alone. Individually, phytase improved feed efficiency (P<0.05) and numerically increased growth rates (P<0.25). Although responses in growth performance of weaner pigs following phytase supplementation lacked consistency, they were generally positive and indicative of anti-nutritive properties of phytate that are unrelated to P availability. That these positive responses were observed in diets with suboptimal available lysine : energy density ratios is consistent with the possibility that phytate has a negative influence on protein utilisation, which is ameliorated by phytase. However, these antinutritive effects and their underlying mechanisms need to be better defined if full advantage of the potential protein-sparing effects of microbial phytase is to be taken.

Most sugarcane breeding programs in Australia use large unreplicated trials to evaluate clones in the early stages of selection. Commercial varieties that are replicated provide a method of local control of soil fertility. Although such methods may be useful in detecting broad trends in the field, variation often occurs on a much smaller scale. Methods such as spatial analysis adjust a plot for variability by using information from immediate neighbours. These techniques are routinely used to analyse cereal data in Australia and have resulted in increased accuracy and precision in the estimates of variety effects. In this paper, spatial analyses in which the variability is decomposed into local, natural, and extraneous components are applied to early selection trials in sugarcane. Interplot competition in cane yield and trend in sugar content were substantial in many of the trials and there were often large differences in the selections between the spatial and current method used by the Bureau of Sugar Experiment Stations. A joint modelling approach for tonnes sugar per hectare in response to fertility trends and interplot competition is recommended.

Spot form of net blotch (SFNB) (Pyrenophora teres f. maculata) is an economically damaging foliar disease of barley in many of the world's cereal-growing areas. The gene Rpt4 that confers seedling resistance to SFNB has been mapped on the long arm of chromosome 7H, but no genes for adult plant resistance (APR) have been identified. A lack of field resistance to SFNB in breeders' lines selected for Rpt4 led us to investigate the genetics of APR to this disease. Five doubled-haploid populations were phenotyped for seedling and adult plant reaction. Markers linked to Rpt4 explained a large part of the seedling variation, but little of the APR. In 2 mapped populations, major quantitative trait loci (QTLs) for APR distal to Rpt4 on chromosome 7H were identified. QTLs contributing to APR on chromosomes 4H or 5H were also identified in each population. Association of the 5H QTL with a gene for cereal cyst nematode resistance and the probable effect of this linkage on the historical development of cultivars with adult plant resistance to SFNB is discussed.

In a glasshouse study, two experiments were conducted to understand how inherent variability, such as the seed size or mass, and formation of adventitious nodal roots might influence the tolerance of various wheat and triticale cultivars at different growth stages to waterlogging. Waterlogging at germination resulted in 11% seedling mortality, but the waterlogged seedlings had a 19% increase in shoot mass per plant, with no difference in root mass compared with non-waterlogged seedlings. Waterlogging at the 3-leaf stage was deleterious to only a few cultivars. On average, larger seed resulted in greater plant growth for most of the cultivars, and seed mass was positively related to the plant biomass and adventitious nodal root mass under waterlogged conditions. A decreasing oxygen concentration with increasing duration of waterlogging and soil depth did not affect the plant growth and visual stress symptoms, chlorosis, until the oxygen concentration decreased to less than 10% in the bottom depths. The highest yielding triticale cultivar, Muir, and wheat cultivars Brookton and Frame had the greatest seed mass, plant biomass, and relative growth rates under waterlogged conditions, compared with the lowest yielding wheat cultivars, Amery, Silverstar, and More. However, the degree of 'waterlogging tolerance', expressed as the percent ratio of plant biomass or growth rates under waterlogged conditions relative to the non-waterlogged control conditions, appeared to be greatest for the low-yielding cultivars, indicating a 'cautious approach' when screening tolerant cultivars.

Root-lesion nematodes (Pratylenchus thornei Sher and Allen and P. neglectus ( Rensch) Filipijev and Schuurmans Stekhoven) cause substantial yield loss to wheat crops in the northern grain region of Australia. Resistance to P. thornei for use in wheat breeding programs was sought among synthetic hexaploid wheats (2n= 6x = 42, AABBDD) produced through hybridisations of Triticum turgidum L. subsp. durum ( Desf.) Husn ( 2n= 4x = 28, AABB) with Aegilops tauschii Coss. ( 2n= 2x = 14, DD). Resistance was determined for the synthetic hexaploid wheats and their durum and Ae. tauschii parents from the numbers of nematodes in the roots of plants grown for 16 weeks in pots of pasteurised soil inoculated with P. thornei. Fifty-nine (32%) of 186 accessions of synthetic hexaploid wheats had lower numbers of nematodes than Gatcher Selection 50a (GS50a), a partially resistant bread wheat. Greater frequencies of partial resistance were present in the durum parents (72% of 39 lines having lower nematode numbers than GS50a) and in the Ae. tauschii parents (55% of 53 lines). The 59 synthetic hexaploids were re- tested in a second experiment along with their parents. In a third experiment, 11 resistant synthetic hexaploid wheats and their F-1 hybrids with Janz, a susceptible bread wheat, were tested and the F(1)s were found to give nematode counts intermediate between the respective two parents. Synthetic hexaploid wheats with higher levels of resistance resulted from hybridisations where both the durum and Ae. tauschii parents were partially resistant, rather than where only one parent was partially resistant. These results suggest that resistance to P. thornei in synthetic hexaploid wheats is polygenic, with resistances located both in the D genome from Ae. tauschii and in the A and/or B genomes from durum. Five synthetic hexaploid wheats were selected for further study on the basis of ( 1) a high level of resistance to P. thornei of the synthetic hexaploid wheats and of both their durum and Ae. tauschii parents, ( 2) being representative of both Australian and CIMMYT ( International Maize and Wheat Improvement Centre) durums, and ( 3) being representative of the morphological subspecies and varieties of Ae. tauschii. These 5 synthetic hexaploid wheats were also shown to be resistant to P. neglectus, whereas GS50a and 2 P. thornei-resistant derivatives were quite susceptible. Results of P. thornei resistance of F(1)s and F(2)s from a half diallel of these 5 synthetic hexaploid wheats, GS50a, and Janz from another study indicate polygenic additive resistance and better general combining ability for the synthetic hexaploid wheats than for GS50a. Published molecular marker studies on a doubled haploid population between the synthetic hexaploid wheat with best general combining ability ( CPI133872) and Janz have shown quantitative trait loci for resistance located in all 3 genomes. Synthetic hexaploid wheats offer a convenient way of introgressing new resistances to P. thornei and P. neglectus from both durum and Ae. tauschii into commercial bread wheats.

The understanding of the interaction between thermo-photoperiodic conditions and the genetic control of anthesis date is fundamental in explaining the environmental adaptation of durum wheat and triticale cultivars. The development of 8 durum wheat ( Triticum turgidum L. var. durum ) and 2 triticale (x Triticosecale Wittmack) cultivars was studied at 3 sowing dates (September, November, and March) by observations on apex development, number and rate of leaf appearance, spike fertility, and number and length of elongated internodes. Variation in anthesis date was mostly explained by the total number of leaves, which ranged between 8.3 and 15, and hence by the duration of the phase of leaf primordium production. Total leaf number also affected the length of the subsequent phase until flag leaf appearance. The phyllochron was influenced by both sowing date and genotype, and was minimum in the March sowing (87 degree-days). The genotypic variability in phyllochron was due either to the variations in leaf number or to genotypic intrinsic differences. Time to terminal spikelet stage was related to the number of spikelets per spike and to the number of elongated internodes, although stem length depended more on internode length than on internode number. The number of spikelets per spike was associated with leaf number, but their relationship was affected by the thermal conditions during spikelet primordium initiation. No differences were observed between wheat and triticale cultivars, apart from the number of spikelets per spike.

Quality of grain, next to yield, is the most important factor for rice (Oryza sativa L.) production in semi-arid tropical Australia. Studies were undertaken in the Burdekin River Irrigation Area of northern Australia to improve rice grain quality through nitrogen fertilisation. This paper reports the results of 4 experiments comparing the response of 3 rice genotypes differing in maturity and stature to 5 rates of applied nitrogen (0, 70, 140, 210, and 280 kg/ha) over 4 seasons (2 wet and 2 dry seasons). The components of grain quality studied were endosperm chalkiness, whole grain millout, grain size, alkali digestion (gelatinisation temperature), and grain protein. This paper also examines the suitability of the 3 genotypes as parental material in breeding programs aimed at selecting for specific grain quality attributes. Starbonnet was identified as a potential parent in breeding programs which aim to specifically select for reduced chalkiness and high millout in low N environments. Selection for lower chalkiness, and higher millout and protein concentration, should occur in a wide range of target environments to account for the seasonal variation observed in these parameters. Grain size appeared to be affected more by genetic than agronomic factors, since grain length and breadth were largely unaffected by N rate, yet genotypic differences were found for both parameters in all experiments. Newbonnet grain was long and slender, suggesting this genotype would be a suitable parent in breeding programs aimed at improving grain appearance. The response of alkali digestion to N rate and genotype was small for all seasons. The importance of developing N fertiliser strategies that optimise both grain yield and quality was highlighted by differences in the responses of grain protein and grain yield to N rate. A number of linkages were examined among various components of grain quality. However, the magnitude of these linkages was small, suggesting that selection for one quality component should not be at the expense of selection for another.

The variable nature of rainfall in north-eastern Australia confounds the process of selecting sorghum hybrids that are broadly adapted. This paper uses a crop simulation model to characterise the drought environment types (ET) that occur in the target population of environments (TPE) for dryland sorghum. Seventy seasons (1921-1990) of simulations of the yield of a sorghum genotype and the associated within-season sequence of a stress index were conducted for a small TPE of 6 locations and also for a large TPE of 211 locations that attempted to represent the entire sorghum region. Previously, using the small dataset of 6 locations, pattern analysis enabled us to group seasonal stress indices from each trial into major ETs: 'low terminal stress' (ET1), severe terminal stress (ET2), and intermediate mid-season/terminal stress (ET3) in the ratio 33 : 38 : 29. When the dataset was broken into a sequence of 16 multi-environment trials (METs), each of 3 years and 6 locations, the ratios of ET1 : ET2 : ET3 differed greatly among METs, i.e. any single MET was not randomly sampling the TPE. Hence, for any MET, the average yield (GV(u)) was not the same as the overall mean of the entire 70-year dataset. If the trial yields were weighted according to the ratio of ET1 : ET2 : ET3 in the overall TPE, then GV(w) (s.d. = 0.13) for a single MET was much closer to the overall mean than was GV(u) (0.38). For different METs, the values of GV(w) were up to 30% higher or 15% lower than GV(u). Across METs, the difference between GV(u) and GV(w) was positively correlated (r = 0.88, n = 16, P < 0.05) with the frequency of ET1 ('low terminal stress') encountered within the MET and negatively correlated (r = -0.82) with the frequency of ET2. The value of weighting was confirmed by its ability to verify that two simulated genotypes had the same mean yield over many trials, even though they differed in their specific adaptation to the different ETs. The large TPE consisted of more than 15 000 simulations and was classified in 2 stages (within/among locations), repeated for each of 3 soil types. In years in which the simulation sowing criteria were met, the ratios of ET1 : ET2 : ET3 were about 4 : 2 : 4, 4 : 5 : 1, and 6 : 3 : 1 in the shallow, intermediate, and deep soils, respectively. Hence, over all soil types and locations, the sorghum TPE for northern Australia consists of at least 30% each of low terminal stress (ET1) or severe terminal stress (ET2) and these environment types need to be sampled. The incidence and nature of the 'intermediate midseason/terminal stress' environment type (ET3) varies with soil type and location. Weighting genotype performance should improve the precision of the estimate of its broadly adapted value, and be of practical use in breeding programs in these variable environments. Although the 'boundary conditions' of the TPE are not yet resolved, this paper also shows that simulation and pattern analyses can be used to determine the structure of the abiotic TPE. Taking other factors into account (e.g. soil type distribution, shire production levels, and farm profit), selection trials could be weighted to improve selection for narrow or broad adaptation, depending on the purpose of the breeding program.

Past sorghum hybrid trials in north-eastern Australia have detected substantial genotype by environment (GxE) interactions for yield in sampling a variable target population of environments (TPE) that is affected by spatial and seasonal differences in crop water supply. Three datasets, comprising yields of commercial and final stage experimental hybrids and covering 9-17 years (Y) and up to 30 locations (L), were analysed to quantify variance components for trial error, genotypic (sigma(g)(2)), and GxE (sigma(gl)(2), sigma(gy)(2), and sigma(gly)(2)) interaction effects. Whereas trial means varied 2-3-fold across seasons, a greater range was estimated for variance components of trial error (range of 0.05-0.5), G (0->0.3), and GxL interaction (0.05->1.0). There was substantial seasonal variation in the ratio of sigma(g)(2) to (sigma(g)(2)+sigma(gl)(2)), and in two datasets, 73% of the seasonal sigma(gl)(2) was due to poor genetic correlations among locations. This implies that any given set of hybrids in a random set of locations would be ranked differently from season to season. Analysis of locations over years detected 90% of the total GxE interaction as GxLx Y, rather than GxL or GxY, although this was reduced by accounting for genotype maturity. To achieve repeatabilities of >80%, trials would need to be conducted over at least 5 years and 20 locations per year. The variable and unpredictable nature of much of the GxE interaction in the region implies that broad adaptation to different water regimes is required, unless prior knowledge of the seasonal weather can be used to choose 'narrowly adapted' cultivars. With current approaches, a large sample of environments is needed to identify such hybrids, and testing across locations and years is equally important. Alternative breeding strategies based on classifying environment types are discussed.

Genotype x environment (GxE) interactions due to variation in soil moisture and rainfall complicate the interpretation of sorghum hybrid performance trials over locations (L) and years (Y). This paper aims to use pattern analysis to explain measures of the GxL interaction for yield, and whether these can, in turn, be explained using simulation models to determine the occurrence of environment types (within-season patterns of drought). The aim of this work is to simplify the analysis of GxE by explaining it in terms of interactions of genotypes with environment types (ET) that are not 'fixed' to locations and years. In a sequential analysis of 17 seasons, 18 locations were separated into groups that tended to represent either the northern (i.e. central Queensland, CQ) or southern Queensland (SQ) regions. For a subset of 6 locations, ordination partially explained differences among locations as being related to latitude (r = 0.88) and rainfall (r = -0.46), but they were better related (r > 0.9) to the frequencies of 3 stress ETs as determined by long-term crop simulations. These 3 environment types were: (1) low stress (occurring in 33% of seasons); (2) severe terminal stress with an early-season (9%) or midseason time (29%) of onset; and (3) intermediate terminal stress with a midseason (9%) or late-season (20%) time of onset. Low stress ETs were more common in two SQ locations than in CQ. Stress ETs as defined by simulation models and pattern analysis had more consistent relationships with simulated yields than did the fixed descriptors of locations and years. Sorghum hybrid trials for broad adaptation in Queensland should include locations at least from each of the 2 regions and the results should be interpreted in the context of the season in which they are conducted. To match the long-term patterns in the 6 locations of the analysis, trial yields would need to sample from at least 3 yield ranges: <1 t/ha, 1-3.5 t/ha, and >3.5 t/ha. Additional seasons of testing are likely to be required when the locations used during a season do not adequately represent the target population of environments over all locations and years.

The importance of awns in durum wheat ( Triticum turgidum L. var. durum ) has to be evaluated whenever an increase in grain yield is expected due to a greater photosynthetic capacity of the awned ear. Awned and awnless isolines of durum wheat were compared in a 3-year field trial in Sardinia (Italy). Ear and flag-leaf size, radiation interception, canopy temperature, yield, and yield components were measured. Awns increased the ear surface area from 36 to 59%, depending on their length, which ranged from 5.5 to 13.8 cm. This resulted in an average 4% more radiation intercepted by the awned ears. Canopy temperature was 0.9°C lower, on average, in the awned isolines, and was negatively correlated with kernel weight ( r = –0.85**, n = 10), although consistent and marked effects of awns on canopy temperature were only observed in the long-awned lines. Awns positively affected grain yield, with an average increase of 10 and 16%, respectively, in the 2 years in which they affected kernel weight. The irrelevant effect of awns on yield in the year characterised by a severe drought was a consequence of their early desiccation. The effects of awns on grain yield and kernel weight strongly depend on the genetic background, on awn length and functionality, and on the environmental conditions during grain filling.

Molecular diversity among 421 clones of cultivated sugarcane and wild relatives was analysed using AFLP markers. Of these clones, 270 were Saccharum officinarum and 151 were either cultivars produced by the Australian breeding program or important parents used in the breeding program. The S. of. cinarum clones were obtained from a collection that contained clones from all the major regions where S. of. cinarum is grown. Five AFLP primer combinations generated 657 markers ofwhich 614 were polymorphic. All clones contained a large number of markers; a result of the polyploid nature and heterozygosity of the genome. S. of. cinarum clones from New Guinea displayed greater diversity than S. of. cinarum clones from other regions. This is in agreement with the hypothesis that New Guinea is the centre of origin of this species. The S. of. cinarum clones from Hawaii and Fiji formed a separate group and may correspond to clones that have been introgressed with other members of the ` Saccharum complex'. Greater diversity was found in the cultivars than in the S. of. cinarum clones due to the introgression of S. spontaneum chromatin. These cultivars clustered as expected based on pedigree. The major contribution of clones QN66- 2008 and Nco310 to Australian sugarcane cultivars divided the cultivars into 2 main groups. Although only a fewS. of. cinarum clones are known to have been used in the breeding of current cultivars, about 90% of markers present in the S. of. cinarum clone collection ( 2n= 80) were also present in the cultivar collection. This suggests that most of the observed genetic diversity in S. of. cinarum has been captured in Australian sugarcane germplasm.

Assay methods for the alkaloids of sorghum ergot (Claviceps africana) are described and compared. Sorghum ergot bodies (sclerotia/sphacelia) from various regions of Queensland and New South Wales were collected in 1997 and 2001 and assayed by spectrophotometry, thin layer chromatography, or high performance liquid chromatography (HPLC). All contained dihydroergosine (DHES) as the main alkaloid component (about 80%), with smaller amounts of dihydroelymoclavine and festuclavine. The preferred method of assay for infected sorghum and mixed feeds involved extraction into dichloromethane:methanol:ethyl acetate:ammonium hydroxide (50:5:25:1) using an ultrasonic bath. After solvent removal, the extract was dissolved in diethyl ether and partitioned into 0.5 M hydrochloric acid. After adjusting the pH to 8–10 with ammonium hydroxide, the alkaloids were extracted into dichloromethane, the solvent evaporated, and the residue dissolved in methanol. HPLC separation was on a C18 column, 150 × 3.9 mm, run isocratically at 40°C, with acetonitrile:0.1% ammonium acetate:methanol (31:50:20) as the mobile phase. Detection was either by UV at 280 nm or by fluorescence with excitation at 235 nm and absorbance at 340 nm. Levels of quantitation for DHES in sorghum approached 0.1 mg/kg (UV) and 0.01 mg/kg (fluorescence). Method recoveries for DHES in the range of 0.025–7 mg/kg averaged 75%. The total alkaloid content of ergot bodies (sclerotia/sphacelia) from different batches of grain varied from 100 to 7900 mg/kg (0.79%). Within batches, there was much less variation in the alkaloid content of ergot bodies, but larger ergots tended to contain more alkaloid than smaller ergots, and those infected with Cerebella species contained even less; this probably related to the ratio of sclerotial/sphacelial tissue present. Honeydew also contained DHES (1–10 mg/kg) and might contaminate clean grain at significant levels. Tests on 4 farms showed that substantial amounts of ergot bodies and alkaloids were removed during grain harvesting.

The influences of temperature, time, and moisture on the germination of macroconidia and secondary conidia of Australian isolates of Claviceps africana were studied in vitro. The optimum temperature for germination of both macroconidia and secondary conidia of C. africana was 20degreesC. Although germination of macroconidia ceased near 31degreesC, approximately 30% of secondary conidia germinated at 37degreesC after 48 and 72 h of incubation. Sorghum flower extract agar stimulated macroconidium and secondary conidium germination, irrespective of temperature. Germination of macroconidia and secondary conidia on water agar started after 4 h of incubation at 20degreesC, reaching a maximum after 16-24 h and 14 h, respectively. Maximum germination of both macroconidia and secondary conidia was at greater than or equal to-5 bars at 20degreesC. Germination of secondary conidia ceased at -35 bars, whereas macroconidia germinated at water potentials as low as -55 bars at 20degreesC.

Isolates of Claviceps africana from Australia, Africa, Asia, and America were tested for the production of dihydroergosine (DHES), and its biogenic precursors dihydroelymoclavine (DHEL) and festuclavine (FEST), in culture. Several growth media were evaluated to optimise alkaloid production with little success. The best of these involved 2-stage culturing on high-sucrose substrate. Australian C. africana isolates varied widely and inconsistently in alkaloid production, with DHES concentrations in mycelium ranging from: <0.1 to 9 mg DHES/kg; <0.1 to 1.6 mg DHEL/kg; and <0.1 to 0.4 mg FEST/kg. In a separate experiment using similar culturing techniques, DHES was produced by 2 of 3 Australian isolates, 1 of 3 USA isolates, 1 of 4 Indian isolates, the sole Puerto Rican isolate, the sole Japanese isolate, but not the sole South African isolate. In this experiment, DHES concentrations detected in mycelium of Australian isolates (0.1-1.0 mg DHES/kg) were of similar magnitude to isolates from other countries (0.2-1.8 mg DHES/kg). Three C. africana isolates, including one that produced only traces of alkaloid in culture after 8 weeks, were inoculated onto panicles of sterile male sorghum plants. After 8 weeks, all 3 isolates produced 10-19 mg DHES/kg in the panicles, demonstrating that the growing plant favoured more consistent alkaloid production than culture medium.

A key controversy in negotiating the International Treaty on Plant Genetic Resources for Food and Agriculture, and the likely long-term effectiveness of the agreement, is the way in which the intellectual property provisions are interpreted and applied to the key genetic resources forming the Consultative Group on International Agricultural Research (CGIAR) system of International Agricultural Research Centres' (IARC) collections. This paper reviews the intellectual property provisions in the treaty and examines the likely consequences from patenting under the Patents Act 1990 over materials derived from these collections. The consequence is argued to be significant and, over time, these practices are likely to deplete the usefulness of these collections and undermine the relevance of the treaty. The paper concludes that Australia's interests might best be served by arguing that access to these collections, and the other materials under the treaty, be subject to a non-exclusive, royalty free licence for any use of the derived materials to develop useful new plant varieties. Yes Yes

This paper reports on several studies conducted to better understand the variability between lucerne cultivars and lines, and use this to predict persistence in dryland grazing pastures in eastern Australia. Morphological traits of 20 cultivars/lines were measured in irrigated and dryland spaced plant experiments. Studies were also conducted to describe variation among lucernes in their utilisation of starch and responses to water deficit, pests and diseases. Multiple regression analyses were used to develop simple models where the measured traits could be used to predict persistence of lucerne lines in dryland evaluation experiments. Although there was significant variation among cultivars/lines in most measured traits, no single trait reliably predicted persistence of cultivars/lines in dryland evaluation experiments. However, variation in persistence at both sites could be explained by models developed by multiple regression using differences in the mean lengths of the longest stems at 10% flower in summer and winter. Persistent lucernes were those that had relatively long stems in summer and short stems in winter. Water use efficiencies, starch utilisation patterns and resistances to pests and diseases of different lucernes provided some improvement to this simple model, but these improvements were not consistent.

Two populations between the German malting variety Alexis and the Australian malting variety Sloop were constructed, mapped, phenotyped, and subjected to quantitative trait loci analysis. One population consisted of 153 F4-derived recombinant inbred lines and the other of 111 doubled haploid lines. This paper describes 18 field and laboratory experiments conducted with the populations and summarises the traits mapped and analysed. The genetic basis of 5 traits (malt extract, resistance to leaf rust, resistance to powdery mildew, early flowering, plant stature) important to Australian efforts to improve malting barley varieties was elucidated. Detailed maps for these populations are shown in this paper, while a consensus map incorporating these maps and further experiments on the populations are described elsewhere in this issue.

The absence of expression of the granule-bound starch synthase I (GBSSI) allele from chromosome 4A of wheat is associated with improved starch quality for making Udon noodles. Several PCR-based methods for the analysis of GBSS alleles have been developed for application in wheat. A widely applied approach has involved a simple PCR followed by electrophoretic separation of DNA products on agarose gels. The PCR amplifies one band from each of the loci on chromosomes 4A (Wx-B1), 7A (Wx-A1), and 7D (Wx-D1), and the band from the Wx-B1 locus is diagnostic for the occurrence of the null Wx-B1 allele that is associated with improved starch quality. The reliable detection of the null Wx-B1 allele has been important in identifying wheat breeding lines. Allele-specific PCR has also been used to successfully detect the occurrence of the null Wx-B1 allele. In the present paper the various protocols were evaluated by testing a segregating double haploid population from a cross between Cranbrook and Halberd and the tests gave good agreement in different laboratories. The application of the DNAbased tests applied in wheat breeding programs provides one of the first examples of a molecular marker selection for a grain quality trait being successfully applied in an Australian wheat breeding program.

Good growth in acid soils suggests that sweet potato may be tolerant of acid soil infertility factors such as Al toxicity or Ca deficiency. In a conventional solution culture experiment, 4 cultivars responded positively when solution Ca concentration was increased from approximately 4 to 1300 &square;М. However, a subsequent flowing solution culture (FSC) experiment showed no significant (P > 0.05) differences in growth by most of the 15 cultivars studied when solution Ca concentration was increased from 45 to 400 &square;М. Hence, it was concluded that sweet potato could be fairly tolerant of low Ca supply. In contrast, soluble Al markedly decreased growth of the 15 sweet potato cultivars studied. The results of the present study indicate that Al rather than low Ca supply would be more important in limiting sweet potato growth in acid soils. Furthermore, tolerance to low Ca and soluble Al appears to be linked in sweet potato. These results highlight the importance of selecting sweet potato cultivars for specific soil conditions such as soil acidity.

This study aimed to: (1) determine the effect of P depletion and presence of Al on root and shoot growth of representative cover crops, and on their nutrient uptake; (2) characterise the composition of root exudation under P and Al stress in nutrient solution; (3) evaluate the ability of aqueous extracts of composts in reducing Al phytotoxicity. Plants of cowpea (Vigna unguiculata subsp. unguiculata), black oat (Avena strigosa), and lablab (Lablab purpureous) were cultivated in different nutrient solution compositions and concentrations for 3 weeks. It was found that Al at concentration of 20 and 200 μmol/L increased citrate exudation at least 8 and 24 times, respectively, for cowpea and 18 and 36 times, respectively, for lablab, as compared with the blank. However, no release of organic acids occurred due to P deprivation, suggesting that citrate exudation was a specific response to excess Al. No response in organic acid release was observed for black oat under the stress of P deficiency or Al toxicity. Although the presence of Al in solution did not significantly affect chlorophyll content in leaves, it decreased root and shoot weight, as well as root length, surface area, volume, and number of tips. Organic extracts alleviated aluminum toxicity, improving plant growth and ameliorating plant nutrition status. Yard waste extract was more effective in enhancing plant growth than GreenEdge extract in plants under Al stress.

Despite extensive research since pathogenicity was first established in 1919, no cultural or chemical control strategy has proven effective against Fusarium wilt of bananas. The efficacy of cultural control is attributed to the suppression of pathogen activity. Yet, amending naturally infested soil with aged chicken manure has been shown to enhance disease severity, without any change in the activity of the pathogen Fusarium oxysporum f. sp. cubense (Foc) in the soil. In this study, the effect of amending soil with composted sawdust, and of solarising soil, was compared with the effect of amending soil with chicken manure. Bioassays comparing the activity of Foc in the soil with the extent of invasion of banana pseudostem tissue by Foc were used to investigate why strategies targetting pathogen survival have not proven successful in controlling this disease. The enhancement of Foc invasion of the banana plantlets was reproduced with the addition of chicken manure to the naturally infested soil. However, changes in the activity of Foc in the soil were not associated with changes in the frequency of invasion of the plantlets. Invasion of banana pseudostems in the sawdust and solarisation treatments was not significantly different from invasion in the respective control treatments, despite a reduction in the activity of Foc in the sawdust-amended soil and an enhancement in the solarised soil. Moreover, the increase in Foc activity in the solarised soil recorded during the bioassays occurred despite the effectiveness of solarisation in reducing the survival of Foc in pre-colonised banana root tips buried in the soil. Changes in the frequency of invasion were associated with changes in the availability of mineral nitrogen, particularly ammonium N. These results suggest that the physiological response of banana cultivars to ammonium N may be associated with their susceptibility to Fusarium wilt. Accordingly, cultural strategies for controlling Panama disease will only be effective if they enhance the ability of the host to resist invasion.

Based on morphological features alone, there is considerable difficulty in identifying the 5 most economically damaging weed species of Sporobolus [viz. S. pyramidalis P. Beauv., S. natalensis (Steud.) Dur and Schinz, S. fertilis (Steud.) Clayton, S. africanus (Poir.) Robyns and Tourney, and S. jacquemontii Kunth.] found in Australia. A polymerase chain reaction (PCR)-based random amplified polymorphic DNA (RAPD) technique was used to create a series of genetic markers that could positively identify the 5 major weeds from the other less damaging weedy and native Sporobolus species. In the initial RAPD profiling experiment, using arbitrarily selected primers and involving 12 species of Sporobolus, 12 genetic markers were found that, when used in combination, could consistently identify the 5 weedy species from all others. Of these 12 markers, the most diagnostic were UBC51490 for S. pyramidalis and S. natalensis; UBC43310.2000.2100 for S. fertilis and S. africanus; and ORA20850 and UBC43470 for S. jacquemontii. Species-specific markers could be found only for S. jacquemontii. In an effort to understand why there was difficulty in obtaining species-specific markers for some of the weedy species, a RAPD data matrix was created using 40 RAPD products. These 40 products amplified by 6 random primers from 45 individuals belonging to 12 species, were then subjected to numerical taxonomy and multivariate system (NTSYS pc version 1.70) analysis. The RAPD similarity matrix generated from the analysis indicated that S. pyramidalis was genetically more similar to S. natalensis than to other species of the 'S. indicus complex'. Similarly, S. jacquemontii was more similar to S. pyramidalis, and S. fertilis was more similar to S. africanus than to other species of the complex. Sporobolus pyramidalis, S. jacquemontii, S. africanus, and S. creber exhibited a low within-species genetic diversity, whereas high genetic diversity was observed within S. natalensis, S. fertilis, S. sessilis, S. elongates, and S. laxus. Cluster analysis placed all of the introduced species (major and minor weedy species) into one major cluster, with S. pyramidalis and S. natalensis in one distinct subcluster and S. fertilis and S. africanus in another. The native species formed separate clusters in the phenograms. The close genetic similarity of S. pyramidalis to S. natalensis, and S. fertilis to S. africanus may explain the difficulty in obtaining RAPD species-specific markers. The importance of these results will be within the Australian dairy and beef industries and will aid in the development of integrated management strategy for these weeds.