The effects of temperature, photoperiod and chilling on the leafing‐out of Norway spruce, Picea abies (L.) Karst. were studied. High temperature promotes breakage of post‐dormancy, long photoperiods having no such effect. Photoperiod and chilling cause the breakage of true dormancy. However, under field conditions, photoperiod will have no effect on leafing‐out date in the spring. By use of clonal material it was possible to show substantial genetic differences between individuals in response to temperature and photoperiod. When the effect of clones was accounted for, treatments could be compared more precisely. Differences between clones were apparent in heat‐sum required for leafing‐out, in rapidity of response to favorable post chilling conditions, and in chilling requirement This latter quantity was given a new definition, applicable when both chilling and post chilling temperatures are controlled and specified. This is that period beyond which a further 10 days of chilling accelerates leafing‐out by less than one day, i.e. the point at which the slope of the line relating days till leafing‐out to chilling period, is equal to minus 0.10. Differences in leafing‐out date were shown between provenances taken from throughout the range of Picea abies. These differences were related to latitude with provenances of high latitude leafing‐out first.

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A mixture of apple pomace and sawdust was tested as a substrate for production of shiitake [Lentinula edodes (Berk.) Pegler] and oyster mushroom [Pleurotus ostreatus (Jacq. ex Fr.) Kummer and P. sajor-caju (Fr.) Sing.] on synthetic logs. MyCelia grew faster and more densely in logs containing apple pomace than in sawdust alone. Five shiitake isolates and two Pleurotus spp. produced higher fresh weights on a mixture of equal parts (by weight) of apple pomace and sawdust than on either substrate alone. An alternative substrate based on sawdust, millet (Panicum miliaceum L.), and wheat (Triticum aestivum L.), bran gave almost identical overall yield as pomace-sawdust medium, but there was a significant differential effect of the substrates on yield of the two tested shiitake isolates. Analyses and experiments in vitro suggested that optimal N levels provided by apple pomace account in part for its effectiveness.

Controlled-environment experiments were conducted on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings during their 1st year. Hardiness of foliage was assessed by visually estimating injury after freezing tests.Germinants (1 week) were unable to attain any freezing tolerance under 8-h days at 2 °C even after 9 weeks but were killed whenever ice formed. Their ability to supercool increased by 5 °C during this treatment. However, seedlings older than 3 weeks (1 to 2 cm of epicotyl) could develop true hardiness under the influence of either short days (less effective) or low positive temperatures, independently of lignification, bud setting, or entry into rest. Ability to acclimate increased gradually with age and was inversely related to growth and maturation, apparently because the latter processes had higher temperature optima. Photoperiod affected growth and bud formation only above about 15 °C but influenced hardiness at 1 °C. The optimum photoperiod for inducing hardiness was longer at low light intensities than at high ones, presumably because of a minimum requirement for photosynthesis.Interruption of the long inductive dark period with 15 min of red light (650 nm) caused a small decrease in hardiness and bud set and an increase in growth. This effect was not reversed, but was enhanced by an isoenergetic burst of far-red (FR) light immediately after. FR interruptions alone had no effect. Night frosts (−7 °C) caused significant dehydration and rapidly increased hardiness only if both the warm, short day and chilling "stages" had been supplied first and the daily supply of light continued.