Decline and physiological response to foliar-deposited salt in Norway spruce genotypes: a comparative analysis

Severe spruce decline in Denmark at the end of the 1980s led to investigati ons of the physiology and genetics of the decline and the importance of sea salt deposition. Narrow-sense heritability of health in a progeny trial wi th 8-year-old Norway spruce families (Picea abies (L.) Karst.) was 0.58. Br oad-sense heritability in a seed orchard with clones from ortets of southea stern European origin was 0.53. The health of the ortets correlated with fa mily and clone health. Health of families and clones were not correlated. T he health of three spruce provenances in the progeny trial varied from 6.3 to 7.7 on a 0-9 scale. Salt stress responses of 12 two-year-old open-ollina ted families from the above clones were investigated after dipping branches into different salt solutions. Photosynthesis and transpiration decreased with increasing salt deposition, respiration increased, and water use effic iency increased initially and decreased later. Correlations between field h ealth and physiological salt responses suggested that airborne salt predisp oses to spruce decline rather than triggers it. Health of Norway spruce is unlikely to be improved by salt-resistance selection in the laboratory but may be improved by low transpiration and high water use efficiency selectio n. Visible injuries were primarily determined by the amount of salt taken u p.