New Zealand Journal of Botany abstracts

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Factors Regulating the Growth Rate of Lolium perenne L. cv. 'Grasslands Ruanui' and L. multiflorum Lam. cv. 'Grasslands Tama' a Tetraploid
1. Seeds, Photosynthetic Rates, Photosynthetic Products, Translocation, and Proportion of Plant Parts

A. O. Taylor, J. A. Rowley, and N. M. Jepsen

Plant Physiology Division, Department of Scientific and Industrial Research, Palmerston North

Abstract When seedlings and young plants of these ryegrass varieties are glasshouse-grown in pots with adequate nutrient and light, Tama maintains a 14-16% higher mean relative growth rate (shoot) than Ruanui. A number of developmental, physiological, and biochemical assessments have been made in an attempt to explain some of the reasons for this difference in growth rate. Some discussion on the usefulness of these assessments is given. Tama seeds are twice the weight and contain roughly 1 mg more mobilisable reserves than those of Ruanui and this presumably enables more rapid expression of the embryo's growth potential during early stages of seedling growth. The two varieties differ markedly in their proportions of leaf to root and consequently in the retention of photo-assimilated carbon in their leaves. Extrapolation from dry matter percentages of plants of 1 g dry weight showed that Tama used 54% of photo-assimilated (nonrespired) carbon in the construction of photosynthetic tissue, while Ruanui used only 43%. This appears to be the dominant factor responsible for the higher shoot growth rate (RGR) of Tama under the glasshouse conditions used in this work.

(Received 13 July, 1970) New Zealand Journal of Botany 9: 504-518.

PDF file of entire paper: medium quality (765K); (scanned from paper original: notes about this process)

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