Daylength and temperature during seed production interactively affect adaptive performance of Picea abies progenies.

Adaptive traits in Picea abies (Norway spruce) progenies are influenced by the maternal temperatures during seed production. Here, we have extended these studies by testing the effects of maternal photoperiod and temperature on phenology and frost hardiness on progenies. Using eight phytotron rooms, seeds from three unrelated crosses were made in an environmental 2 x 2 factorial combination of long and short days and high and low temperatures. The progenies were then forced to cease growth rapidly at the end of the first growing season. An interactive memory effect was expressed the second growth season. Progenies from high temperature and short days, and from low temperatures and long days, started growth later in spring, ceased shoot growth later in summer, grew taller and were less frost hardy in the autumn than their full siblings from low temperatures and short days, and from high temperatures and long days. Norway spruce has developed a memory mechanism, regulating adaptive plasticity by photoperiod and temperature, which could counteract harmful effects of a rapidly changing climate.

Sexual reproduction in a greenhouse and reduced autumn frost hardiness of Picea abies progenies.

In 1989, identical crosses (2-3 females within males) were performed with Picea abies (L.) Karst. in a greenhouse seed orchard at Biri nursery and in an outdoor seed orchard at Huse, 32 km north of Biri. Pollination began 17 days earlier in the greenhouse than outdoors at Huse. The potted grafts in the greenhouse were moved outdoors when the seed cones were no longer receptive. Twelve full-sib family pairs (Biri and Huse) from these crosses were grown in a phytotron and tested for height and autumn frost hardiness during their first growing season. No significant difference was found between the indoor (Biri) and outdoor (Huse) progenies for height growth. However, the progenies from the greenhouse seed orchard were significantly more susceptible to frost than their full-sibs from the outdoor seed orchard. There was no significant interaction between males and the flowering environment, but a significant female x flowering environment interaction was present as a result of greater differences in frost hardiness between progenies from females in the greenhouse seed orchard than in the outdoor seed orchard. Although seeds from the outdoor seed orchard generally had a greater biomass than seeds from the greenhouse seed orchard, the difference in seed weight did not explain the difference in frost hardiness. We hypothesize that temperature and photoperiod during pollination and fertilization affect the frost hardiness of the progenies.