Photosynthesis and Nutrient Supply in Needles of Sitka Spruce [Picea sitchensis (Bong.) Carr.]

• Published in: The New phytologist 1993-09, Vol.125 (1), p.101-111
• Main Authors: Chandler, J. W., Dale, J. E.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Carotenoids; Chlorophylls; Coniferous forests; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Growing seasons; Metabolism; needle growth; Nitrogen; Nitrogen, phosphorus, potassium fertilizations; Nutritional deficiencies; Phosphorus; Photosynthesis; Photosynthesis, respiration. Anabolism, catabolism; photosynthetic capacity; Pine trees; Plant physiology and development; Sitka spruce; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Trees
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.1993.tb03868.x

Growth and photosynthetic development were measured for currently developing needles of young trees of Sitka spruce [Picea sitchensis (Bong.) Carr.] throughout their fourth growth season. Treatments included trees that were fully fertilized (control), trees deficient in phosphorus (-P), or nitrogen (-N), and trees initially deficient but then supplied with phosphorus (-PR) or nitrogen (-NR). Growth was measured in terms of needle projected area, and the photosynthetic components measured were pigment concentration, net photosynthetic rate, (PN), activity of ribulose-1, 5-bisphosphate carboxylase, (RuBPC), stomatal conductance to CO2, (GS), and the intercellular partial pressure of CO2, (Ci). Needle growth was rapid, beginning in early May and being complete by the end of the month or early in June. Free growth occurred in the - NR treatment. Photosynthesis increased throughout the season, reaching a peak in August, with some variables subsequently showing a decrease in value. PNincreased more rapidly during needle expansion than either chlorophyll concentration or RuBPC activity. Phosphorus deficiency led to a reduction in RuBPC activity, which was restored to the control value following refertilization with P. Nitrogen deficiency severely reduced values of all variables studied, except Ci, which was higher than for the controls. Refertilization of -N trees caused a very rapid increase in values of all variables, with an increase in Ci, representing a larger increase in mesophyll conductance to CO2, (GM), than GS. PNand RuBPC activity were significantly correlated with total chlorophyll concentration for all treatments, but PNwas not correlated with Gsor RuBPC activity.