Genotype × management strategies to stabilise the flowering time of wheat in the south-eastern Australian wheatbelt

Growers in the wheatbelt of south-eastern Australia need increases in water-limited potential yield (PYw) in order to remain competitive in a changing climate and with declining terms of trade. In drought-prone regions, flowering time is a critical determinant of yield for wheat (Triticum aestivum L.). Flowering time is a function of the interaction between management (M, establishment date), genotype (G, development rate) and prevailing seasonal conditions. Faced with increasing farm size and declining autumn rainfall, growers are now sowing current fast-developing spring wheat cultivars too early. In order to widen the sowing window and ensure optimum flowering dates for maximum yield, new G × M strategies need to be identified and implemented. This study examined the effect of manipulating genotype (winter vs spring wheat and long vs short coleoptile) and management (sowing date, fallow length and sowing depth) interventions on yield and flowering date in high-, medium- and low-rainfall zones in south-eastern Australia. Twelve strategies were simulated at nine sites over the period 1990–2016. At all sites, the highest yielding strategies involved winter wheats with long coleoptiles established on stored subsoil moisture from the previous rotation, and achieved a mean yield increase of 1200 kg/ha or 42% relative to the baseline strategy. The results show promise for winter wheats with long coleoptiles to widen the sowing window, remove the reliance on autumn rainfall for early establishment and thus stabilise flowering and maximise yield. This study predicts that G × M strategies that stabilise flowering may increase PYw.

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Effect of sowing time on yield and agronomic characteristics of wheat in south-eastern Australia

Australian Journal of Agricultural Research ◽

10.1071/ar9951381 ◽

1995 ◽

Vol 46 (7) ◽

pp. 1381 ◽

Cited By ~ 70

Author(s):

H Gomez-Macpherson ◽

RA Richards

Keyword(s):

Grain Yield ◽

Flowering Time ◽

Barley Yellow Dwarf Virus ◽

Maximum Yield ◽

Sowing Date ◽

High Yield ◽

Sowing Time ◽

South Eastern ◽

Eastern Australia ◽

South Eastern Australia

The main environmental constraints to the yield of dryland wheat in south-eastern Australia are: a low and erratic rainfall throughout the growing season, the chance of frost at flowering time, and high temperatures during the grain-filling period. The aims of this work were threefold. Firstly, to determine which sowing period minimizes these constraints and results in the highest yields. Secondly, what is the optimum flowering time for a given sowing date so that maximum yield is achieved. The third aim was to determine whether any crop characteristic was associated with high yield or may limit yield in the different sowings. The experiments were conducted at three sites in New South Wales that were representative of dry (Condobolin) and cooler and wetter (Moombooldool, Wagga Wagga) sites in the south-eastern wheatbelt. In this study several sets of isogenic material, involving a total of 23 genotypes, that were similar in all respects except for flowering time, were sown early (mid-April and early May), normal (mid to late May) and late (June to mid July). Characteristics of the highest-yielding lines in each experiment are presented. The average flowering time of the highest yielding lines in all sowings had a range of only 12 days at the driest site, but a range of over 20 days at the coolest and wettest site. The optimum anthesis date (day of year, y) was related to sowing date (day of year, doy) at the cooler sites such that: y = 245+0.32 doy (r2 = 0.86) and at Condobolin, y = 253+0.19 doy (r2 = 0.91). Optimum anthesis date expressed in thermal time (�C days) after sowing (y) was related to sowing time (doy) as follows: y = 2709 -8-3 doy (r2 = 0.84). It is suggested that these relationships are likely to be quite robust and should hold true for similar thermal environments in eastern Australia. There was little variation in grain yield between the earliest sowing in mid-April (108 doy) and sowings throughout May (up to 147 doy). Grain yield declined 1.3% per day that sowing was delayed after late May. Aboveground biomass was substantially higher in early sown crops. However, this did not translate into higher yields. From the evidence presented it is argued that the principal reason that greater yields were not obtained in the early sowings, particularly in the April sowing, was the greater competition for assimilates between the growing spike and the elongating stem. It is suggested that a way of overcoming this competition is to genetically shorten the stems of winter wheats. This should capitalize on the considerable advantages in terms of water use efficiency that early sowing offers and result in greater yields. Barley yellow dwarf virus, although present at the cooler, wettest site in one year, was more frequent in the later sowings than in the early sowing and was not likely to have contributed to the lower than expected yields in the early sowings.

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Water and temperature stress define the optimal flowering period for wheat in south-eastern Australia

10.1101/115287 ◽

2017 ◽

Author(s):

B.M. Flohr ◽

J.R. Hunt ◽

J.A. Kirkegaard ◽

J.R. Evans

Keyword(s):

Cropping Systems ◽

Supply And Demand ◽

Maximum Yield ◽

Wheat Yield ◽

Flowering Period ◽

Critical Determinant ◽

South Eastern ◽

Flowering Date ◽

Systems Model ◽

Eastern Australia

AbstractAcross the Australian wheat belt, the time at which wheat flowers is a critical determinant of yield. In all environments an optimal flowering period (OFP) exists which is defined by decreasing frost risk, and increasing water and heat stress. Despite their critical importance, OFPs have not been comprehensively defined across south eastern Australia’s (SEA) cropping zone using yield estimates incorporating temperature, radiation and water-stress. In this study, the widely validated cropping systems model APSIM was used to simulate wheat yield and flowering date, with reductions in yield applied for frost and heat damage based on air temperatures during sensitive periods. Simulated crops were sown at weekly intervals from April 1 to July 15 of each year. The relationship between flowering date and grain yield was established for 28 locations using 51-years (1963-2013) of climate records. We defined OFPs as the flowering period which was associated with a mean yield of ≥ 95% of maximum yield from the combination of 51 seasons and 16 sowing dates. OFPs for wheat in SEA varied with site and season and were largely driven by seasonal water supply and demand, with extremes of heat and temperature having a secondary though auto-correlated effect. Quantifying OFPs will be a vital first step to identify suitable genotype x sowing date combinations to maximise yield in different locations, particularly given recent and predicted regional climate shifts including the decline in autumn rainfall.

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