One-year old crowns of cvs.
Brocks, Larac, Tainan No.1 and UC157 were grown in growth cabinets to examine spear yield and fern development at high temperatures (28°C, 33°C and 36°C).
In one study, spears were harvested for 2 months and measurement of spear weight, spear yield, spear diameter and spear number were taken.
In another study the spears were not harvested, but were left to develop into fern, and the height during development from spear to fern was measured.
Not only did high temperature depress spear yield, but also depressed the total fern weight of the whole plant and individual fern height.
When fern height was fitted to the Richard's Growth Equation, the Gompertz function was preferred to the monomolecular or the logistic function.
The higher the temperature the faster the fern growth, but lower the final height of the fern.
The spear growth (up to 20 cm high) was exponential, but faster at 33°C than at 28°C and 36°C. The criterion of fern or spear heat adaption with the parameters of Richard's Equation and relative spear growth rates was in order of Tainan No.1 > Brocks > UC157 > Larac.