Deep Soil Water-Use Determines the Yield Benefit of Long-Cycle Wheat
Bonnie M Flohr1, James R Hunt2, John A Kirkegaard3
1The Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Adelaide, SA, Australia.
Frontiers in Plant Science
|June 6, 2020
Summary
Long-cycle wheat cultivars offer yield benefits in southern Australia when sown early, particularly in dry conditions with stored soil water. This strategy enhances deep water extraction and grain production, outperforming short-cycle varieties in specific environments.
Area of Science:
- Agricultural Science
- Agronomy
- Plant Physiology
Background:
- Southern Australian wheat production typically relies on autumn rainfall for crop establishment.
- Early sowing with slower-developing cultivars (long-cycle) is a strategy to utilize summer/autumn rainfall, but yield responses are variable.
- The mechanism behind yield variability in long-cycle wheat, especially concerning water stress, remains unclear.
Purpose of the Study:
- To compare yield performance of short-cycle versus long-cycle wheat cultivars under different sowing times and seasonal rainfall conditions.
- To investigate the environmental factors influencing yield advantages of long-cycle wheat cultivars.
- To identify conditions under which long-cycle wheat provides a yield benefit over current practices.
Main Methods:
- Field experiments comparing short- and long-cycle wheat cultivars with varied sowing times over four seasons (2011, 2012, 2015, 2016) in Temora, NSW.
- Monitoring of summer fallow rainfall, initial plant-available water, and rainfall during the critical pre-flowering period.
- A simulation study to extend findings and assess yield benefits with increased starting soil water.
Main Results:
- Yield benefits for long-cycle treatments were observed only in 2011 and 2012, characterized by stored deep soil water and low rainfall during the critical period.
- Higher yields in these conditions were linked to increased deep soil water extraction (<1.0 m), dry matter production, and grain number.
- In seasons with high in-crop rainfall (2016) or no stored water (2015), no significant yield difference was found between cultivar types.
Conclusions:
- Long-cycle wheat cultivars provide a yield advantage under specific environmental conditions: adequate stored soil water and limited rainfall during the critical yield-determining period.
- Deep soil water extraction is a key mechanism contributing to the yield benefit of long-cycle wheat in water-limited environments.
- Findings quantify the frequency of conditions favoring long-cycle wheat, informing strategic sowing decisions for improved wheat production.
