# Actual Yield

&#x20;       The harvest index predicted with equation 5:2.4.1 is affected by water deficit using the relationship:

&#x20;               $$HI_{act}=(HI-HI_{min})*\frac{\gamma _{wu}}{\gamma _{wu}+exp[6.13-0.883*\gamma _{wu}]}+HI_{min}$$                             5:3.3.1

where $$HI_{act}$$ is the actual harvest index, $$HI$$ is the potential harvest index on the day of harvest calculated with equation 5:2.4.1, $$HI_{min}$$ is the harvest index for the plant in drought conditions and represents the minimum harvest index allowed for the plant, and $$\gamma _{wu}$$ is the water deficiency factor. The water deficiency factor is calculated:

&#x20;                  $$\gamma_{wu}=100*\frac{\sum^m_{i=1} E_a}{\sum ^m_{i=1} E_o}$$                                                                                          5:3.3.2

where $$E_a$$ is the actual evapotranspiration on a given day, $$E_o$$ is the potential evapotranspiration on a given day, $$i$$ is a day in the plant growing season, and $$m$$ is the day of harvest if the plant is harvested before it reaches maturity or the last day of the growing season if the plant is harvested after it reaches maturity.
