Publications

Jacobs, BC & Pearson, CJ 1991, 'Potential yield of maize, determined by rates of growth and development of ears', Field Crops Research, vol. 27, no. 3, pp. 281-298.
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Zea mays L. hybrids which differed in their expression of prolificacy were grown in field experiments and subjected to treatments which altered the amounts of nitrogen and solar radiation available to each plant. Detailed measurements were made of growth of the tassel and ears to determine the mechanisms through which plants adjusted their grain-yield to the environment. In preliminary field experiments, increases in plant population from 5 to 20 m-1 caused increased asynchronous flowering and reduced grain-yield per plant (but not per ha), due mainly to a 47% decrease in kernel number per plant. In the main field experiment, grain-yield of XL 80 (semi-prolific) and XL 81 (single-eared) were reduced by nitrogen deficiency and defoliation by 65 and 40% respectively, relative to controls. Yield per plant was reduced through (a) 1.3-2.7-fold reductions in number of potential kernels; (b) increases in asynchronous flowering; and (c) a 25% reduction in the number of spikelets differentiated by the first ear when grown under low N. Asynchronous flowering of the first ear increased because development of the ears was delayed relative to the tassel, and the relative elongation rate of silks was reduced. Treatment effects on ear growth were greater at lower ear positions. Spikelet number appeared to be related to the size of the ear, and was not influenced directly by treatments. We conclude that the processes which determine kernel number are highly sensitive to low levels of intercepted radiation or N supply. © 1991.

MITCHELL, CA, BEALL, JA, WELLS, JRE & GRAY, PP 1991, 'GROWTH AND PROTEIN-PRODUCTION KINETICS OF A MURINE MYELOMA CELL-LINE TRANSFECTED WITH THE HUMAN GROWTH-HORMONE GENE', CYTOTECHNOLOGY, vol. 5, no. 3, pp. 223-231.
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Mukheibir, P 1991, 'Mix properties of concrete with classified Lethabo fly ash in the Western Cape', Concrete Beton, vol. 58, no. April 1991.

Mukheibir, P 1991, 'The deformation properties of hardened concrete containing classified Lethabo fly ash', Concrete Beton, vol. 61, no. Nov 1991.