PHOTOSYNTHETIC APPARATUS IN COLD-STORED CONIFER SEEDLINGS IS AFFECTEDBY NURSERY AND STORAGE PHOTOPERIOD

The photosynthetic apparatus of outdoor grown seedlings of white spruc e (Picea glauca [Moench] Voss) and lodgepole pine (Pinus contorta Doug l. var. latifolia Englem.) responded in different ways to similar nurs ery and storage photoperiod treatments. Seedlings of both species were (1) exposed to natural or short days (SD: 8-hr photoperiod for 4 or 8 wk) during late summer, (2) returned to natural conditions, and (3) s ubsequently put in indoor storage at 2-degrees-C in the dark or with a low intensity photoperiod (less-than-or-equal-to 15 mumol m-2-s-1, 8 hr daylength) for a 6 mo storage period starting October, December, or January. Poststorage measurements of chlorophyll (chl) a fluorescence in light-stored white spruce showed, relative to dark controls, incre ased variable fluorescence and decreased photochemical quenching (qP), with little increase in nonphotochemical quenching (qN). In contrast, qP was relatively unaffected in lodgepole pine seedlings, although th e combination of SD treatment followed weeks later by light in storage induced an increase in qN. The sequentially applied SD treatment plus light during storage also led to the accumulation of a foliar 23kD pr otein in pine seedlings. The above foliar responses to the treatments were only weakly related to effects of treatments on diameter and heig ht increase assessed 3 mo after spring planting. The interaction of th e treatments shows that the pine foliage was able to integrate environ mental signals received months apart.