Evaluation of teff (Eragrostis tef [Zucc.] Trotter) lines for agronomic traits in Australia

Teff (Eragrostis tef [Zucc.] Trotter) is a native cereal crop widely grown in Ethiopia as the main grain for local consumption. With the increasing challenge by climate change, there is a need for alternative cereal crops in Australia. However, despite its early introduction in the 1800's, there is limited information on teff production in the country. The purpose of this study was to evaluate 20 teff lines using the seed supplied by The Australian Tropical Germplasm Centre at Biloela Research Station (Queensland). A replicated glass house pot trial was carried out to test performance of agronomic traits related to yield. The teff lines were propagated in the glasshouse and data was collected over one growing season and analysed for days to flowering, days to maturity, plant height, peduncle length, internode length, leaf width and number of tillers. In addition, plant biomass, grain yield and 100 seed weight were determined. Results of this study displayed variability in teff traits demonstrating the potential for a future breeding program. Lines that exhibited promising outcomes were identified for further screening under field conditions. Teff lines 302136, 302135, 302131, 302126, 302127 and 302129 demonstrated higher performance in grain yield, tillering, panicle length and vegetative biomass signalling increased opportunity for better yield. Higher grain yield was associated with medium and late maturing lines. Regression analysis showed that vegetative biomass was positively correlated with higher grain yield. Further field evaluation and improvement of teff is required before the crop can be considered as an alternative for growers and provide a source of gluten free product for people with coeliac disease

Guayule Seed Production, Harvesting and Processing

Guayule (Parthenium argentatum Gray) is a source of high quality low-allergenic natural rubber. The effort to commercialise this plant has intensified in the last decade. That guayule can survive extreme environmental conditions makes it more attractive to farmers, especially under conditions of moisture stress. Recent research has indicated that guayule grows well in Australia producing high rubber and resin yield. Efficient seed production technology resulting in high quality seed is vital to full commercialisation of this crop. The main objective of this research was to investigate production, harvesting and processing of guayule seed. This included investigation on flowering nature of guayule, determination of optimum seed maturity, effect of plant population on seed yield and quality and the development of harvesting and seed processing technology. Guayule was established in the field at four plant populations. A seed harvester was developed and tested over two production seasons. A seed threshing and cleaning machine was also developed and evaluated. Flowering behaviour of guayule was studied over three years with the objective of determining when peak flowering occurs and to investigate factors affecting flower initiation and pattern of flowering. The results indicated that photoperiod is the likely main trigger for flower initiation with soil moisture and temperature also having some influence. With rainfall as the only source of moisture, flowering peaks occurred in mid-spring (October) and in Summer (February) in Southeast Queensland, Australia. After initial flowering, the flowering pattern was mainly affected by soil moisture. High summer temperatures reduced the number of flowers. The optimum harvest maturity and indicators of maturity for guayule were investigated by harvesting seed sequentially after flowering and comparing seed quality parameters. Heat units expressed as growing degree days after flowering were calculated and related to seed development stages and quality. Seed quality was assessed by germination test, capitulum dry mass, 1000-seed mass and percentage of filled seeds. Results indicated that guayule seed can safely be harvested at about 329 growing degree-days (GDD) or 28 days after flowering under south-east Queensland climatic conditions. At this date seed quality was better and seedhead colour was comparable to cinnamon (code 165C) on the Royal Horticultural Society (R.H.S) standard colour chart. Of all the parameters, GDD, 1000-seed mass and percentage of filled seeds provided more rapid and reliable measures of optimum seed maturity. The effect of plant population on seed yield and quality was studied by planting guayule at 4444, 8300, 12500 and 25000 plants/ha. Data were collected at 16 and 28 months after planting. Seed was harvested manually multiple times over 4 weeks each year following the main flowering period in spring. Harvested seed was threshed and clean seed yield was compared among different plant populations. Seed quality was also compared in terms of 1000-seed mass and seed size. Lowest plant population of 4444 plants/ha provided the highest yield at 28 months but produced the lowest yield at 16 months from planting when the plants had not yet reached full size to compensate for wider spacing. However, at both ages this treatment produced heavier and larger seeds. The difference in yield or seed quality between plant populations ranging from 8300 to 25000 plants/ha was not significant. Overall results of the study demonstrated that seed yield and seed size, which is important in direct seeding, can be affected by plant population. A single-row guayule seed harvester was developed after investigating different methods of seed dislodgement and collection. The harvester consisted of a seed dislodgement mechanism that removes seeds by vibration of spring steel rods. An axial flow fan placed directly over the vibrating rods catches the seed before it falls to the ground. The seed is then conveyed by the air stream through an inflatable canvas tube to a collection bin. The design and selection of the seed catching system was based on terminal velocity of the unthreshed seed. Vibration frequencies ranging from 9.9 to 14.5 Hz and amplitude from 4 to 5.5 cm were used to test the harvester in the field. Harvested seed was analysed for percentages of clean seed in the harvested material, seed loss and immature seeds harvested. The performance of the machine was evaluated based on harvesting capacity and efficiency. Guayule seed harvested by the machine ranged from 1.73 to 7.18 kg/ha and harvest efficiency varied from 77 to 91%. The percentage of immature seeds removed from the crop during mechanical harvesting was as low as 0.1%. Although there was a trend for better efficiency from higher vibration frequencies, the variation was not statistically significant. Nearly 21% of clean seed was obtained in the harvested material which was much higher than that reported by other researchers. The harvester can be converted into a multiple row machine to increase its capacity. A guayule seed processing system consisting of a belt thresher, a vibrating screen separator and horizontal air grading unit was developed and evaluated. The machine efficiency was up to 77% with little seed injury. Seed purity reached 98% and germination 76%. Of the 3 grades of seed collected from the machine, up to 63.5% of the seed processed was first grade with 1000-seed mass achieving 764 mg; this is highly desirable for direct seeding. The processing capacity of the threshing unit can easily be upsized by increasing belt width. Threshing clearance and belt speed affected seed quality and grade as well as overall efficiency of the machine. The greatest efficiency was obtained with a combination of clearance between 0.75 and 1 mm and belt speed of 9 m/s

Morphological characteristics of maize canopy development as affected by increased plant density

Improving crop productivity through higher plant density requires a detailed understanding of organ development in response to increased interplant competition. The objective of this paper is thus to investigate the characteristics of organ development under increased interplant competition. A field experiment was conducted to investigate organ development across 4 maize plant densities i.e. 2, 6, 12 and 20 plants m (referred to PD2, PD6, PD12 and PD20 respectively). In response to increased interplant competition, lengths of both laminae and sheaths increased in lower phytomers, but decreased in upper phytomers. Sheath extension appeared to be less sensitive to increased interplant competition than lamina extension. Extension of laminae and internodes responded to increased plant density as soon as onset of mild interplant competition, but did not respond any further to severe competition. Both lamina width and internode diameter were reduced due to a smaller growth rate in response to increased plant density. Overall, this study identified that organ expansion rate can be taken as the key morphological factor to determine the degree of interplant competition

Genotype, Row Spacing and Environment Interaction for Productivity and Grain Quality of Pigeonpea (Cajanus Cajan) in Sub-Tropical Australia

The pigeonpea (Cajanus cajan) is grown between the 45oN and 45oS as a summer food legume, and consumed by billions of people in the world. Recent renewed interest from Australian growers prompted the current study to evaluate high-yielding varieties and develop agronomic parameters for this crop. Performance of four selected pigeonpea genotypes were assessed under three row spacing (25, 50 and 100 cm) treatments and at one plant density (30 plants/m2) in two diverse Australian environments (Kingaroy and Gatton) in Queensland. Decreasing row spacing from 100cm to 25cm led to a linear increase in mean shoot dry matter (DM) at both sites. However, maximum grain yields of up to 2.9 t/ha were achieved at 50cm row spacing but the yields declined at 25cm spacing at both sites. Genotypic variation for radiation use efficiency (RUE) measured at Gatton site ranged from 1.40 to 1.76 g/MJ, which accounted for 76% of variation in DM. There was a significant effect of site and genotype on grain N and 100-seed mass. The study demonstrated that pigeonpea could be grown as a legume break crop in subtropical Australia, with potential export market opportunities

Genotype, Row Spacing and Environment Interaction for Productivity and Grain Quality of Pigeonpea (Cajanus Cajan) in Sub-Tropical Australia

The pigeonpea (Cajanus cajan) is grown between the 45oN and 45oS as a summer food legume, and consumed by billions of people in the world. Recent renewed interest from Australian growers prompted the current study to evaluate high-yielding varieties and develop agronomic parameters for this crop. Performance of four selected pigeonpea genotypes were assessed under three row spacing (25, 50 and 100 cm) treatments and at one plant density (30 plants/m2) in two diverse Australian environments (Kingaroy and Gatton) in Queensland. Decreasing row spacing from 100cm to 25cm led to a linear increase in mean shoot dry matter (DM) at both sites. However, maximum grain yields of up to 2.9 t/ha were achieved at 50cm row spacing but the yields declined at 25cm spacing at both sites. Genotypic variation for radiation use efficiency (RUE) measured at Gatton site ranged from 1.40 to 1.76 g/MJ, which accounted for 76% of variation in DM. There was a significant effect of site and genotype on grain N and 100-seed mass. The study demonstrated that pigeonpea could be grown as a legume break crop in subtropical Australia, with potential export market opportunities

Genotype, Row Spacing and Environment Interaction for Productivity and Grain Quality of Pigeonpea (Cajanus Cajan) in Sub-Tropical Australia

The pigeonpea (Cajanus cajan) is grown between the 45o N and 45o S as a summer food legume, and consumed by billions of people in the world. Recent renewed interest from Australian growers prompted the current study to evaluate high-yielding varieties and develop agronomic parameters for this crop. Performance of four selected pigeonpea genotypes were assessed under three row spacing (25, 50 and 100 cm) treatments and at one plant density (30 plants/m2 ) in two diverse Australian environments (Kingaroy and Gatton) in Queensland. Decreasing row spacing from 100cm to 25cm led to a linear increase in mean shoot dry matter (DM) at both sites. However, maximum grain yields of up to 2.9 t/ha were achieved at 50cm row spacing but the yields declined at 25cm spacing at both sites. Genotypic variation for radiation use efficiency (RUE) measured at Gatton site ranged from 1.40 to 1.76 g/MJ, which accounted for 76% of variation in DM. There was a significant effect of site and genotype on grain N and 100-seed mass. The study demonstrated that pigeonpea could be grown as a legume break crop in subtropical Australia, with potential export market opportunities