Fiber Elongation Rates in Five Varieties of Cotton (Gossypium hirsutum L.) as Influenced by Night Temperature1

Five cotton varieties were grown in the field under four different night temperature regimes (10, 15, 20, and 25 C). The influence of temperature on the rate and extent of fiber elongation was studied. Temperatures below 20 C reduced fiber length; and generally, the reduction was greater in varieties having the longer fibers. Lowering night temperature increased the fiber elongation period and slowed the fiber growth rate. The temperature coefficients of elongation indicated the rate of elongation for all varieties was extremely temperature‐sensitive up to 15 days age. Beyond 15 days age, however, the coefficlents of elongation quickly approached one, indicating temperature independence.