Crop Growth In The High Rainfall Zone (Transcript)

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Scene one

Shows an animation of a paddock; five spheres appear in the sky, one for each of the months of January, March, June, August and November. Each sphere fills in a 24 hour clock illustration of the number of hours of daylight per day (white), and the number of hours of darkness per day (black).

January shows 14.5 hours of daylight and 9.5 hours of darkness per day; March shows 11 hours of daylight and 13 hours of darkness per day; June shows 9 hours and 35 minutes of daylight and 13 hours and 25 minutes of darkness per day; August shows 10 hours and 40 minutes of daylight and 13 hours and 20 minutes of darkness per day; and November shows 14 hours of daylight and 10 hours of darkness per day. These average daily hours of daylight are for a landscape in the high rainfall zone of southern Australia.

This scene is accompanied with the text "Over a year, the hours of daylight per day and the average daily temperature varies greatly. How long a variety of wheat needs to complete its growth cycle largely depends on day length and temperature."

Scene two

The scene is set for the month of April, with an average daily temperature of 23.9°C. A fence appears dividing the landscape into two paddocks. On the left is Chris' farm, on the right is Pat's farm. A seeding machine sows Chris' paddock with a long-season winter wheat.

The scene is accompanied with the text "Time of sowing is critical for grain production and depends on the wheat variety. In southern Australia, wheat varieties that take longer to grow are sown early in the season. Our farmer, Chris, chooses to grow a long-season winter wheat used to feed livestock."

Scene three

It is now June, with an average daily temperature of 13.1°C, and Chris' wheat has germinated and is tillering. The Zadocks scale (Z0-Z99) is used to name the stage of wheat growth and Chris' wheat is a Z21. Pat chooses to now sow the same variety of winter wheat as Chris. A seeding machine is shown on the screen sowing Pat's paddock.

This scene is accompanied with the text "Zadoks scale is used in agriculture to name the stages of wheat growth. The scale ranges from Z0-Z99. By June, Chris' wheat has germinated and is tillering (Z21). Chris' neighbour, Pat, chooses to sow the same variety of winter wheat in an adjoining paddock. The animation will demonstrate the differences in the stage of development and the risks to sowing the same wheat at two different times."

Scene four

In July, the average daily temperature is 12.5°C. Pat's wheat has a rating of Z13, while Chris' wheat has progressed to a Z25. Two zoomed (magnified by 10) bubbles appear on the screen to show the difference in development between Z13 and Z25.

This scene is accompanies with the text "By July, Pat's wheat is sown but has missed out on eight weeks of the season. Therefore, Pat's wheat is only at Z13. Chris' wheat is now advancing through tillering (Z25)."

Scene five

In August, the average daily temperature is 13.6°C but the chance of frost is high and day lengths are short. The two zoomed bubbles from the previous scene remain on the screen as the Zadok scale for Chris' and Pat's wheat has not changed since July.

The scene is accompanied with the text "It is now very cold with a high chance of frost and day lengths are short. The crops do not grow very much during this time. This is a valuable time for winter wheat as it needs a long cold period to trigger flowering. This period is called vernalisation and happens in both crops."

Scene six

In October, with an average daily temperature of 18.1°C, Chris' wheat has progressed to a Z65 and is flowering. Frost is shown to damage the flowers on Chris' wheat. As Pat's wheat is less advanced with a Z31 and not yet flowering, Pat's wheat is shown to be unlikely to be damaged by frost.

The scene is accompanied with the text "In October, Chris' wheat is flowering (Z65) and is vunerable to frost that will damage the flowers and reduce grain yield if temperatures get below O°C. Pat's wheat is less advanced (Z31) and therefore unlikely to be damaged by frost."

Scene seven

November shows an average daily temperature of 20.8°C, and the two zoomed bubbles reappear on the screen to show Chris' wheat has progressed to grain filling stage (Z75) while Pat's wheat is flowering (Z65). Two additional zoom bubbles appear to show the difference in the grain between the frost damaged grain and undamaged grain on Chris' wheat.

The scene is accompanied with the text "In November, Chris' wheat is at grain-filling stage (Z75). Any area of Chris' crop that is damaged by frost produces less grain. Pat's wheat is now flowering (Z65) and the time of greatest frost risk has passed. However, summer is approaching, soil water is being depleted and there is now a risk Pat's crop will be damaged by excessive heat if temperature gets above 30°C."

Scene eight

In December the average daily temperature is 23.7°C and Chris' wheat is shown to be brown and then harvested by machinery. In Pat's crop, wheat is still growing.

The scene is accompanied with the text "Chris' wheat is ready to harvest (Z93) in late December. In frost affected areas, the grain is shrivelled and yield is reduced. In areas no affected by frost the grain is plump."

Scene nine

By January, Pat's wheat is ready to harvest, is shown to brown and harvested by machinery. Chris' paddock is bare after being harvested the month prior.

The scene is accompanied with the text "Pat's wheat is ready to harvest (Z93) only a few weeks later than Chris' wheat despite being sown much later. Pat's wheat catches up because there was only a short time between sowing and vernalisation, and this type of wheat is somewhat sensitive to day length. As the days get longer, the crops development quickens in an effort to reach maturity."

Scene ten

Scene ten shows two trucks being filled with grain from Chris' and Pat's harvest. Chris' truck fill with more grain that Pat's because of a greater yield from Chris' paddock.

The scene is accompanied with the text "The late sowing means Pat's wheat has less time to fill the grain. This leads to lower grain yields. The delay in crop maturity by a couple of weeks pushes harvest into January."

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