Archive for the category: Crop physiology

Karine Chenu, Florianne Oudin

The University of Queensland, Queensland Alliance for Agriculture and Food Innovation (QAAFI), Toowoomba, QLD, Australia
Email: karine.chenu@uq.edu.au

Abstract

In recent decades, rising temperatures have increasingly affected wheat crops in major producing regions around the world. Climate models predict further increases in mean temperature and in the frequency of temperature extremes for the near to mid-future.

The impact of heat on wheat at different periods of the crop cycle was studied in two experiments conducted with finely controlled temperatures in a glasshouse. While heat shocks affected the main stem and primary tillers of a plant differently, a common response to heat was found for all stems (irrespective of their rank), when considering the timing of the stress relative to stem anthesis. The greatest impact on grain number was observed for stress applied ~10 days before stem anthesis. The impact of pre-anthesis stress on grain set were slightly compensated by an increase in individual grain weight. Overall, grain yield was substantially affected for early pre-flowering stress and early-to-mid post-flowering stress. The results of this study have been used to improve estimations of heat impact in crop modelling and thus improve the accuracy of crop simulations for future climate scenarios.

Heping Zhang, Jens Berger, Chris Herrmann, Adam Brown, Sam Flottmann

CSIRO Agriculture and Food, Private Bag 5, Wembley, WA6014

Abstract:

Canola yield is a complex trait determined by environmental and genetic factors, and their interaction. We investigated yield performance of 21 canola across multiple environments and its association with flowering time, architectural and physiological traits. Pattern analyses showed that environment discriminated varieties differently, from which two mega-environments and four variety groups were identified. Principal component analysis (PCA) revealed specific adaptation: i.e. yield was associated with early flowering in the low/medium rainfall zone (LMRZ) and with late flowering in the high rainfall zone (HRZ). A few varieties outperformed all other varieties across environments and were broadly-adapted. PCA revealed that yield was positively associated with biomass and HI but negatively with days to flowering in the LMRZ, and positively with biomass, longer days to flowering and more seeds m^-2 but negatively with HI in the HRZ. The combination of high harvest index and biomass of broadly-adapted varieties enabled them to produce high yield across the environments.

Garry O’Leary¹, Cassandra Walker¹, Joe Panozzo¹, Thabo Thayalakumaran², Malcolm McCaskill³, James Nuttall¹, Kirsten Barlow⁴, Brendan Christy⁴ and Senthold Asseng⁵

¹ Agriculture Victoria, 110 Natimuk Road, Horsham, VIC 3400 garry.oleary@ecodev.vic.gov.au gjoleary@yahoo.com, 
² AgriBio, 5 Ring Road, Bundoora, VIC 3083,
³ Agriculture Victoria, 915 Mount Napier Road, Hamilton, VIC 3300,
⁴ Agriculture Victoria, 124 Chiltern Valley Road, Rutherglen, VIC 3685 Australia Present address: Precision Agriculture, 113 High Street Rutherglen, VIC 3685,
⁵ University of Florida, Gainesville, FL 32611-0570, USA

Abstract:

Maintaining high quality grain from Australian dryland production systems is under threat from three main environmental factors.  These are rising atmospheric CO₂ concentrations, increasing frequency of drought and higher temperatures both as average increase and more frequent heat waves.   For wheat, we propose a new hypothesis and simulation model for predicting the environmental effects on the synthesis of glutenin and gliadin proteins, two important quality parameters which control end-use properties.  This model is applicable for the diverse environments encountered in Australia and France.  Mechanistically linking changes in composition of these rheologically-important proteins to environmental conditions should support targeted breeding selection of suitable genes to help maintain grain quality in wheat and provide a marketing edge for Australian grain.

Brenton Leske¹, Ben Biddulph², Mario D’Antuono², Ifeyinwa Olive Onyemaobi² and Timothy Colmer¹ 

¹ University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, brenton.leske@research.uwa.edu.au, ² Department of Primary Industries and Regional Development, 3 Baron-Hay Court, South Perth, WA 6151

Abstract:

Quantifying the grain set and floret sterility (FS) of wheat cultivars is crucial to benchmarking their susceptibility to frost and exploring cultivar differences so that genetic improvement can be made. Ensuring that the measurement of grain set and FS is accurate and adequately captures the variation within and between spikes and cultivars, is vital to making progress in this space. A field trial with eight times of sowing blocks (from mid-April to early-June) was established at Dale, Western Australia to evaluate the susceptibility to frost of 15 wheat cultivars, of which three are reported on in this paper. Variance component analysis was used to determine the optimal sample size from a sub-set of three wheat cultivars with known differences in their susceptibility to frost damage (Impose CL Plus, Kunjin and Magenta). The optimal sample size was determined to be 15 to 20 spikes per plot, when grain positions per spike ranged from 25 to 35.. Future phenotyping experiments exploring stresses or traits related to spike fertility would benefit from undertaking a variance component analysis to ensure efficient use of their resources.

Matthew T. Newell¹, Timothy E. Crews² and Richard C. Hayes³

¹ NSW Department of Primary Industries, Cowra Research and Advisory Station, Binni Creek Rd, Cowra, NSW 2795 matt.newell@dpi.nsw.gov.au,
² The Land Institute, 2440 E. Water Well Rd., Salina, KS 67401, United States of America,
³ NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, PMB, Wagga Wagga, NSW 2650

Abstract:

A redesign of current cropping systems that incorporates grain production from perennial species has been proposed as a method of sustainable staple grain production. Perennial sorghum is one such species under development as a grain crop, which has been suspected of hosting endophytic nitrogen fixing bacteria in its stems or crowns. A pilot study using isotope dilution methodology was used to measure the percent nitrogen derived from the atmosphere (%Ndfa) in perennial sorghum. Plants were grown in three metre columns over 90 days set in the field. Three treatments providing high (HN), low (LN) and zero (0N) N applied as urea were compared, with each treatment consisting of a perennial sorghum plant grown in the same column with Lolium rigidum and L.perenne. Additional nitrogen from urea significantly (P< 0.05) increased total shoot and root dry matter, compared to the 0N treatment. Interestingly, perennial sorghum plants in the 0N treatment had significantly (P< 0.05) longer roots and a higher root:shoot ratio (P< 0.05) compared to both additional N treatments. This suggests that N scarcity stimulated increased root allocation. Perennial sorghum showed no evidence of N₂ fixation under the HN and LN treatments at all sampling dates. However, over time in the 0N treatment there was a trend for increasing levels of biologically sourced N with an average of 30 %Ndfa at the final sampling date, although calculations varied with the reference species used. The current study provides evidence of N₂ fixation in perennial sorghum but highlights concerns about the adequacy of the reference plant δ¹⁵N values.

Neroli Graham¹, Annie Warren², Rosy Raman³ and Kristy Hobson^2 1

NSW DPI, 4 Marsden Park Road Calala NSW 2340, neroli.graham@dpi.nsw.gov.au,
² NSW DPI, 4 Marsden Park Road Calala NSW 2340,
³ NSW DPI, Pine Gully Road Wagga Wagga NSW 2650

Abstract:

The sensitivity of current Australian chickpea cultivars to cool temperatures during flowering and podset results in delayed and interrupted podset. In 2016 in north-western NSW, this sensitivity resulted in an estimated yield loss of 0.5 to 0.7 t/ha based on observationsin commercial paddocks. This project aimed to improve our knowledge of the response of current genotypes to cool temperatures and identify elite chickpea breeding lines with superior chilling tolerance. Twenty-four genotypes were sown at Tamworth and Wagga Wagga in early May and June to encourage flowering under suboptimal temperatures. Comparative phenology was tracked among the lines throughout the season and conversion of flowers to pods and seeds mapped on individual plants. Genetic variation in the ability of genotypes to flower and set pods under suboptimal temperatures were identified.Identification of chilling tolerance in elite breeding material will inform breeding efforts, , potentially improving the ability of future cultivars to set pods under sub optimal temperatures,  enabling shifts in the cropping window to avoid terminal heat and moisture stress.

Ariel Ferrante¹, Cesar M. Cossani^{1, 2}, Jason A. Able¹, Victor O. Sadras^{1, 2}

¹ School of Agriculture, Food and Wine. The University of Adelaide, Adelaide, Australia, ariel.ferrante@adelaide.edu.au,
² South Australian Research and Development Institute, Adelaide, Australia

Abstract:

Low temperatures during the flowering period of cereals can lead to floret sterility, yield reduction, and economic losses in Australian crops. In this study we investigated the physiological bases of yield determination in a historic set of wheat varieties grown under frost-prone field conditions in Southern Australia. We tested the hypothesis that selection for yield inadvertently improved frost tolerance. We measured yield and yield components, including the distribution of grains within the spike, in a factorial experiment combining twelve wheat varieties (released from 1973 to 2015), two sowing dates (19^th April and 22^nd May 2017), and two thermal regimes, ambient control and frost-protected. To protect crops from frost we used moveable, lightweight passive heating systems before each frost event (≤ 0°C). Phenotypic plasticity of yield, grain number and grain weight were analysed. We found a positive relationship between phenotypic plasticity of grain yield and phenotypic plasticity of grain number, but no correlation between yield and year of release. Across varieties, the average numbers of grains per spike was 35.1 ± 0.3 in frost-protected crops compared to 16.1±0.1 in frosted controls in the first sowing, and 29.7 ± 0.3 and 22.9 ± 0.2 respectively in the second sowing. Preventing frost improved spike fertility by increasing the proportion of grains in distal positions within spikelets in relation to controls.