This model calculates the Peak viscosity (PV) of rice starch as a function of the average air temperature experienced by the crop during the whole ripening period. The final value of PV is then corrected by a factor accounting for the effect of maximum air temperature perceived by the crop in the first 20 days after flowering.

The PV value (BU) at maturity (DVS = 3) is calculated as follow:

Where:

PVTavg (BU) is the Peak viscosity of rice starch calculated as function of average temperature perceived by the crop during the whole ripening period;

FTmax (BU) represents the effect of average maximum air temperature experienced by the crop during the first 20 days after flowering on starch viscosity.

The PVTavg value (BU) is calculated as:

Where:

Tavg (°C) is the average temperature experienced by the crop during the whole ripening period;

Tmin (°C) is the temperature threshold below which the PV response to temperature is linear;

Tmax (°C) is the temperature threshold beyond which the rates of PV response to temperature start to decrease with a logarithmic pattern;

ai (22.082 for Loto variety, 17.505 for Gladio variety; unitless), bi (650 for Loto variety, 750 for Gladio variety; unitless), ci (11.8199 for Loto variety, 13.7658 for Gladio variety; unitless), di (464.1795 for Loto variety, 607.3935  for Gladio variety; unitless), ei (5622.0032 for Loto variety, 7701.0670 for Gladio variety; unitless), gi (434.85 for Loto variety, 846.6 for Gladio variety; unitless), mi (-164.87 for Loto variety, -1641.6 for Gladio variety; unitless), are coefficients of the equations.

The effect of average maximum air temperature experienced by the crop during the first 20 days after flowering on starch viscosity is computed as follow:

Where:

Tmax (°C) is the average maximum temperature experienced by the crop during the first 20 days after flowering;

Tmaxmin, Tmaxmax (°C) represent the minimum and maximum threshold triggering the effect of maximum air temperature on peak viscosity;

ni (-4.8869 for Loto variety, 4.523 for Gladio variety; unitless), oi (279.49 for Loto variety, -257.52 for Gladio variety; unitless), pi (-3944.2 for Loto variety, 3616.5 for Gladio variety; unitless), qi (-51.294 for Loto variety, 43.887 for Gladio variety; unitless).

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