Geographical variation in apparent net photo-synthesis of Rocky Mountain Douglas-fir, Pseudotsuga menziesii var. glauca

Graduation date: 1973Rates of apparent net photosynthesis were measured on a sample\ud of Rocky Mountain Douglas-fir consisting of eleven one-year-old seedlings\ud from each of the thirteen different seed sources. Secondary\ud observations of needle length, needle weight, and needle number\ud were also obtained. A formula derived through step-wise multiple\ud regression of the secondary observations on the rate of photosynthesis\ud controlled 87 of the variation. The significance of the regression\ud formula indicated the importance of the process of mutual shading.\ud Analysis of variance of the un-adjusted rates of photosynthesis was\ud significant between and within seed sources. After adjustment only\ud seed source differences were significant. Analysis of variance of\ud the regression formula was significant between and within seed\ud sources. By the process of contrasting sums of squares, climatic factors at the origin of the seed sources were found significantly to\ud effect only the morphological factors. Therefore adaptation of the\ud photosynthetic process by morphology to an environment is probable.\ud The importance of this study is that the processes used to determine\ud the adjusted rate of photosynthesis enable a better estimate of the\ud apparent net photosynthesis than has been possible before with\ud Douglas-fir