Dry-matter Production and Photosynthesis in Pine Seedlings

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Abstract
Growth analysis and photosynthesis measurements were carried out on first-year seedlings of Pinus radiata, P. contorta, and P. nigra. P. sylvestris was also included in two growth-analysis experiments. There appeared to be no difference in relative growth-rate (RGR) between the species mentioned, except between P. radiata and P. nigra. It was found that when the level of mineral nutrition was high, P. radiata had a higher RGR than P. nigra and that the reverse was true at low mineral nutrient levels. There was no difference in net assimilation rate (NAR) between the species, but NAR appeared to increase and decrease with mineral nutrient supply. Net photosynthesis per unit of leaf was somewhat higher in P. radiata than in P. contorta; P. nigra had a lower photosynthetic rate than either P. radiata or P. contorta.