01278naa a2200217 a 450000100080000000500110000800800410001910000170006024501170007726000090019452006440020365000210084765000160086865000100088465000180089465300190091265300160093170000190094770000220096677300720098812785962024-05-21       1989    bl uuuu     u00u1 u    #d1 aGREER, D. H.  aPhotoperiod control of the initial phase of frost hardiness development in Pinus radiata.h[electronic resource]  c1989  aFrost hardiness was measured in outdoor-grown seedlings, and in seedlings in controlled environments exposed to photoperiods shortening by 1, 3 or 5 min/d from 13 h to 9.5 h or constant at one of five periods from 9 to 12 h. Frost hardiness developed at a constant rate in response to shortening photoperiod once it had declined to about 12 h. Hardening stopped when photoperiod became constant. Rate of hardening increased with rate of change of photoperiod. Once max. hardiness was reached, frost hardiness was inherently unstable. Dehardening occurred when photoperiod lengthened and could occur spontaneously under constant conditions.  afrost resistance  aphotoperiod  aGeada  aPinus Radiata  aCold hardening  aFotoperiodo1 aSTANLEY, C. J.1 aWARRINGTON, I. J.  tPlant, Cell and Environment, Oxfordgv. 12, n. 6, p. 661-668, 1989.