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Chen C.,CSIRO | Lawes R.,CSIRO | Fletcher A.,CSIRO | Oliver Y.,CSIRO | And 3 more authors.
Field Crops Research | Year: 2016

It is important to quantify the nitrogen (N) uptake and dinitrogen (N2) fixation of legumes and estimate the N contribution that these crops make to subsequent crops for sustainable agricultural production. The growth and development of legumes and their impact on soil N fertility can be simulated by the Agricultural Production Systems Simulator (APSIM). However, the model performance has not been evaluated in simulating the dynamic processes of N accumulation and N2 fixation. The parameterised model was tested for the simulation of N uptake and N2 fixation in above-ground biomass of four crop legumes (lupin, chickpea, field pea and peanut). The simulations varied in location, cultivar, sowing date, climate, soil type, water regime (irrigated or dryland) and starting soil N and applied fertiliser N in tropical, subtropical, semiarid and Mediterranean environments across Australia. In general, the absolute amount of N uptake and N2 fixation in above-ground biomass (unit: kgha-1) were reasonably well simulated, with 92% of the variation in observed N accumulation in above-ground biomass and 84% in N2 fixation being explained by APSIM. The model was also able to simulate the responses of N2 fixation by chickpea and peanut to differences in soil mineral N status. However, the simulations of N2 fixation efficiency (NFE, calculated as fixed N2 per unit above-ground dry matter (DM; unit: gNkg-1 DM) were much less accurate, especially for lupin. Sensitivity analysis showed that improving the definition of the model parameter of crop N2 fixing capacity (the potential to fix atmospheric N2 per unit above-ground DM; unit: gNg-1 DM) would improve the simulations of NFE. We therefore propose that to successfully simulate the absolute amount of N accumulation and N2 fixation, the above-ground biomass as the major driving factor must first be simulated well, and future work should focus on accurately determining the parameter of crop N2 fixing capacity through optimisation of N2 fixation data obtained from field or controlled experiments to fine-tune the simulations of the relative efficiency of N2 fixation. © 2015 Elsevier B.V.

Wang E.,CSIRO | Bell M.,Queensland Alliance for Agriculture and Food Innovation | Luo Z.,CSIRO | Moody P.,Information Technology | Probert M.E.,CSIRO
Field Crops Research | Year: 2014

Phosphorus (P) is one of the macro nutrients required by crops, and is deficient in many agricultural soils. Due to the low recovery and residual effects of applied P, long-term measurements are required to quantify crop response to P inputs. A modelling approach enables integration of available data to investigate response of crops to P additions in different soils. The APSIM agricultural production systems model has an ability to simulate crop response to soil P. However, the model has only been tested against a few datasets for maize, sorghum and bean crops outside Australia. It has not been applied to Australian conditions, nor against other crops. In this paper we derived the model parameters for wheat, soybean and peanut based on literature and measurement data. The parameterised model was tested for simulation of biomass growth, grain yield, P uptake and grain P contents of four crops (wheat, maize, soybean and peanut) in response to different levels of P addition in a 6-year rotation on a Red Ferrosol soil at Kingaroy, Queensland, Australia. Overall, the model could explain 87% of the variation in observed total aboveground biomass, 84% in grain yield, 75% in crop P uptake and 73% in P content in grain. It was also able to reflect the differential P recovery of crops in the rotation under the 5 different P input levels. In addition, a close relationship was found between modelled labile P and measured bicarbonate extractable P (Colwell P), which may help to initialise APSIM using Colwell P measurements in future studies. It is noted that much of the uncertainties in modelling crop response to phosphorus input arise from the uncertainties in input variables, particularly those describing soil P sorption capacities. Unless P sorption characteristics of a soil in a particular region are quantified, it remains difficult to conduct meaningful modelling research or develop model applications. © 2013.

Xu C.-Y.,Griffith University | Xu C.-Y.,University of The Sunshine Coast | Hosseini-Bai S.,Griffith University | Hosseini-Bai S.,University of The Sunshine Coast | And 6 more authors.
Environmental Science and Pollution Research | Year: 2015

Biochar has significant potential to improve crop performance. This study examined the effect of biochar application on the photosynthesis and yield of peanut crop grown on two soil types. The commercial peanut cultivar Middleton was grown on red ferrosol and redoxi-hydrosol (Queensland, Australia) amended with a peanut shell biochar gradient (0, 0.375, 0.750, 1.50, 3.00 and 6.00 %, w/w, equivalent up to 85 t ha−1) in a glasshouse pot experiment. Biomass and pod yield, photosynthesis-[CO2] response parameters, leaf characteristics and soil properties (carbon, nitrogen (N) and nutrients) were quantified. Biochar significantly improved peanut biomass and pod yield up to 2- and 3-folds respectively in red ferrosol and redoxi-hydrosol. A modest (but significant) biochar-induced improvement of the maximum electron transport rate and saturating photosynthetic rate was observed for red ferrosol. This response was correlated to increased leaf N and accompanied with improved soil available N and biological N fixation. Biochar application also improved the availability of other soil nutrients, which appeared critical in improving peanut performance, especially on infertile redoxi-hydrosol. Our study suggests that application of peanut shell derived biochar has strong potential to improve peanut yield on red ferrosol and redoxi-hydrosol. Biochar soil amendment can affect leaf N status and photosynthesis, but the effect varied with soil type. © 2014, Springer-Verlag Berlin Heidelberg.

Topp B.L.,Queensland Alliance for Agriculture and Food Innovation
Acta Horticulturae | Year: 2016

A rapid rate and high percentage of macadamia nut germination, together with production of vigorous seedlings, are required by nurseries and breeding programs. Germination of nuts is typically protracted, however, and rarely reaches 100%. Many studies have been conducted into macadamia germination, but most have assessed percent germination only. This study investigated the effects of various treatments on percent germination, germination rate, and plant, shoot and root dry weights. The treatments tested were combinations of: (i) soaking or not soaking seeds in a dilute fungicide solution prior to planting; (ii) four different planting media; and (iii) leaving seed trays open or placing them inside clear plastic bags. For freshly harvested nuts, sowing in potting mix under clear plastic and without soaking produced the highest percent germination and germination rate, the largest shoots, and longest lateral roots.

News Article
Site: phys.org

Queensland Alliance for Agriculture and Food Innovation's Dr Lee Hickey said humans domesticated wheat about 10,000 years ago. "Modern breeding and a switch to monoculture cropping has greatly improved yield and quality, but the lack of genetic variation has caused crops to become more vulnerable to new diseases and climate change," he said. "Diversity in ancient strains could hold the key to the future." Dr Hickey said disease and drought cost the industry millions of dollars every year, and climate change was likely to make the situation worse. Fortunately for today's researchers, Russian scientist Nikolai Vavilov devoted his life to the improvement of cereal crops. During the early 1900s, Vavilov travelled the world collecting seeds that he stored in a seed bank in Leningrad, now known as the N.I. Vavilov Institute of Plant Genetic Resources. "Vavilov's unique seed collection represents a snap shot of ancient wheats grown around the world prior to modern breeding," Dr Hickey said. Following in the footsteps of the Russian scientist, UQ PhD student Adnan Riaz has performed the world's first genome-wide analysis of Vavilov's seeds. "A total of 295 diverse wheats were examined using 34,000 DNA markers," Mr Riaz said. "The genomic analysis revealed a massive array of genes that are absent in modern Australian wheat cultivars. "The ancient genes could offer valuable sources of disease resistance or drought tolerance." The Hickey Lab has offers the research community open-access to this resource, including the pure seed of the ancient wheats, along with DNA marker information. "We hope this will empower scientists and wheat breeders to rediscover genetic diversity lying dormant in our seed banks," Dr Hickey said. Explore further: Ancient genes used to produce salt-tolerant wheat

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