Effect of planting time on the yield of wheat at Biloela Research Station in Central Queensland

Trials conducted over a 12-year period at Biloela Research Station in Central Queensland showed that wheat planted in May and June gave consistently better yields than wheat planted outside these months. Earlier plantings faced the risk of frost damage during the susceptible stages of growth. Later plantings resulted in poor yields, mainly due to a drier growing season

Stretching water - Queensland’s water use efficiency cotton and grains adoption program

The Cotton and Grain Adoption Program of the Queensland Rural Water Use Efficiency Initiative is targeting five major irrigation regions in the state with the objective to develop better irrigation water use efficiency (WUE) through the adoption of best management practices in irrigation. The major beneficiaries of the program will be industries, irrigators and local communities. The benefits will flow via two avenues: increased production and profit resulting from improved WUE and improved environmental health as a consequence of greatly reduced runoff of irrigation tailwater into rivers and streams. This in turn will reduce the risk of nutrient and pesticide contamination of waterways. As a side effect, the work is likely to contribute to an improved public image of the cotton and grain industries. In each of the five regions, WUE officers have established grower groups to assist in providing local input into the specific objectives of extension and demonstration activities. The groups also assist in developing growers' perceptions of ownership of the work. Activities are based around four on-farm demonstration sites in each region where irrigation management techniques and hardware are showcased. A key theme of the program is monitoring water use. This is applied both to on-farm storage and distribution as well as to application methods and in-field management. This paper describes the project, its activities and successes

Soil water extraction dynamics of dryland cotton in various row configurations

The soil water extraction dynamics of dryland cotton grown in various row configurations on some major Queensland cotton soils are being quantified. The data will assist in the further development of a cotton simulation model "CERCOT". This model is to be used to determine the outcome of various management scenarios relating row configuration, planting time and plant available water supply. This paper presents some results obtained on one soil type during the 1997/98 season

Phenology of sunflower cultivars. II. Controlled-environment studies of temperature and photoperiod effects

The effects of photoperiod and temperature on the phenology of the open-pollinated sunflower cultivar, Sunfola 68-2, the hybrid, Hysun 30, and its parents, were studied in five experiments using the CSIRO Canberra phytotron. Photoperiod and temperature influenced the number of days to first anthesis (FA) mainly during the emergence (E) to head-visible (HV) stage of growth. Leaf counts and plant height measurements supported this finding. There were major differences in the responses of the two cultivars to short photoperiods and low temperatures. The differences were removed by increasing temperature to a regimen of 27/22¦C (day/night) or by increasing the photoperiod to 14 h. At low temperature, Sunfola 68-2 showed little response to photoperiods of between 10 and 14 h, whereas Hysun 30 showed a marked increase in duration of the E-HV stage for photoperiods shorter than 14 h. At photoperiods of 10 and 12 h there was a general decline in all measured attributes with increases in temperature, except the number of leaves on Sunfola 68-2 which remained relatively constant. Hysun 30 was similar to its male parent ('R' line) in response to photoperiod and temperature. The experiments suggest that the effects of radiation levels on sunflower phenology and photoperiod x temperature interactions in the 14-18 h photoperiod range require further investigation

Leaf area development in barley—model construction and response to soil moisture status

A model to simulate leaf area development for barley at the whole plant level was constructed. Data for leaf area development in the absence of soil water stress were collected from irrigated field trials grown at Hermitage Research Station, near Warwick, Queensland, in 1990. The response of leaf area expansion to soil water status was measured in a glasshouse trial. In the model, green leaf area per plant (GPLA) is derived as the difference between total leaf area produced per plant (TPLA) and senesced leaf area (SPLA). TPLA and SPLA are described by logistic functions of thermal time. Two types of senescence are included: that due to ageing of the whole plant (ontogenetic senescence) and senescence associated with the development of large canopies (light-induced senescence). The onset of ontogenetic senescence is linked to anthesis, whereas light-induced senescence occurs if the leaf area index of the crop exceeds 5.5. Leaf expansion of plants in pots varying in the fraction of transpirable soil water available (FTSW) was compared with leaf expansion of those in well-watered pots three times per week. The relationship between relative leaf expansion (RLE) and FTSW was described by a logistic function (r2 = 0.96). A 50% reduction in RLE occurred when FTSW = 0.34. Similarly, a logistic function described the relationship between relative transpiration (RT) and FTSW (r2 = 0.96). A 50% reduction in RT occurred when FTSW = 0.17. Potential leaf expansion as predicted by the non-stressed model was reduced in response to moisture stress via a ramp function relating RLE to RT. The model gave an unbiased prediction of the leaf area dynamics for 21 rainfed and irrigated crops of barley grown in southern Queensland between 1986 and 1993 (RMSD = 1.09 m2 m-2, r2 = 0.75, n = 76). Precision may have been reduced by the lack of information available on parameters for soil water balance when barley is grown on a range of soil types

Stretching water - Queensland’s water use efficiency cotton and grains adoption program

The Cotton and Grain Adoption Program of the Queensland Rural Water Use Efficiency Initiative is targeting five major irrigation regions in the state with the objective to develop better irrigation water use efficiency (WUE) through the adoption of best management practices in irrigation. The major beneficiaries of the program will be industries, irrigators and local communities. The benefits will flow via two avenues: increased production and profit resulting from improved WUE and improved environmental health as a consequence of greatly reduced runoff of irrigation tailwater into rivers and streams. This in turn will reduce the risk of nutrient and pesticide contamination of waterways. As a side effect, the work is likely to contribute to an improved public image of the cotton and grain industries. In each of the five regions, WUE officers have established grower groups to assist in providing local input into the specific objectives of extension and demonstration activities. The groups also assist in developing growers' perceptions of ownership of the work. Activities are based around four on-farm demonstration sites in each region where irrigation management techniques and hardware are showcased. A key theme of the program is monitoring water use. This is applied both to on-farm storage and distribution as well as to application methods and in-field management. This paper describes the project, its activities and successes

Phenology of sunflower cultivars. III. Models for prediction in field environments

Models of the daily rate of development for the stages emergence to head visible and head visible to first anthesis were formed for two sunflower cultivars (Helianthus annuus cvv. Sunfola 68-2 and Hysun 30). The models relate rate of development to photoperiod, daily mean temperature and relative cultivar sensitivity to photoperiod. They were derived from controlled-environment and field studies reported in the first two papers of this series. The two cultivars were found not to differ in sensitivity to temperature. The base temperature for development was found to decrease as the life cycle progressed. The models were validated on an independent data set and are applicable to the entire Australian continent, with one possible limitation on the temperature range at long photoperiods (14-18 h). The relationship of these models to the cultivar groups defined in the first paper of this series is discussed and a rapid method of determining relative cultivar sensitivity factors for new cultivars is outlined. The application of the models in planning for avoidance of frost by selecting the time of planting and the cultivar to be planted was demonstrated for three major sunflower-growing districts in Queensland. The possible use of these phenology models in conjunction with growth simulation models for studies of crop adaptation is discussed

Phenology of sunflower cultivars. I. Classification of responses

The phenology of commercial sunflower cultivars available to Queensland growers in 1979 was studied in monthly plantings over a 12-month period at Toowoomba in southern Queensland. By using pattern analysis procedures, the cultivars were classified into three maturity groups, viz. 'Very Quick', 'Quick' and 'Medium', based on the number of days from emergence to the head-visible stage of growth. Most of the cultivars belonged to the Quick and Medium maturity groups. Cultivar differences were most obvious for plantings in the cooler months (March to October). To classify new releases, one or two plantings during this period as well as one planting in summer is recommended. Sunfola 68-2 and Hysun 30 should be included in these plantings as cultivars representative of the two major maturity groups. The study showed that there was very little genetic variability in phenology in the present commercial cultivars and there was little difference in phenology among cultivars in the main summer planting period

Radiation interception, radiation use efficiency and growth of barley cultivars

Dry matter production and utilization of photosynthetically active radiation (PAR) was studied for barley (Hordeurn vulgare L.) in the field at Hermitage Research Station, Qld. In 1990, four cultivars (Gilbert, Tallon, Grimmett, Skiff) were sown at three times and grown with non-limiting soil moisture. In 1991, soil moisture limitations were imposed on one sowing of the cultivar Grimmett. The radiation extinction coefficient (k) was 0.41±0.02 and did not vary with cultivar, time of sowing or soil moisture availability. Radiation use efficiency (RUE) (based on absorbed PAR and above-ground dry matter) did not change with time of sowing but did vary between cultivars. RUE was highest for Gilbert (2.90±0.10 g MJ-1), while the other three cultivars averaged 2.60±0.04 g MJ-l. RUE of Grimmett was significantly lower in 1991 (1.48±0.07 g MJ-1) than in 1990 (2.60±0.07g MJ-1), but soil moisture differences in 1991 did not significantly affect RUE. Several factors with possible links with RUE were examined and discussed. Of the variables examined those which showed the strongest relationships with RUE were average daily vapour pressure deficit and average daily minimum temperature

Development and use of a barley crop simulation model to evaluate production management strategies in north-eastern Australia

A study was undertaken to identify improved management strategies for barley (Hordeum vulgare L.), particularly in relation to time of planting, location, and frost risk in the variable climate of north-eastern Australia. To achieve this objective, a crop growth simulation model (QBAR) was constructed to integrate the understanding, gained from field experiments, of the dynamics of crop growth as influenced by soil moisture and environmental variables. QBAR simulates the growth and yield potential of barley grown under optimal nutrient supply, in the absence of pests, diseases, and weeds. Genotypic variables have been determined for 4 cultivars commonly grown in the northern cereal production areas. Simulations were conducted using long- term weather data to generate the probabilistic yield outcome of cv. Grimmer for a range of times of planting at 10 locations in the north-eastern Australian grain belt. The study indicated that the common planting times used by growers could be too late under certain circumstances to gain full yield potential. Further applications of QBAR to generating information suitable for crop management decision support packages and crop yield forecasting are discussed