Jacobs, BC & Chand, V 1992, 'Large Headsetts and Improved Cultivar Enhance Growth and Development of Taro (Colocasia esculents [L.] Schott) During Establishment', Journal of Agronomy and Crop Science, vol. 168, no. 2, pp. 119-127.
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AbstractSmall, medium and large headsetts of a traditional (Nine) and an improved (Alafua Sunrise) cultivar of taro were grown for 33 days in pots in a screenhouse.Differences between the cultivars were greatest in root growth where density of root primordia, number of primary roots and root surface area at the final harvest were 53, 82, and 60 % greater respectively in the improved over the traditional variety. Relative rate of leaf elongation and leaf appearance rate were about 30 % faster in the improved variety. Correlation between leaf area and root surface area was cultivar dependent.Large headsetts produced more primary roots and a larger root surface area than small headsetts. They also produced 46 % more leaf area than small headsetts because of larger individual leaves, but not the rate of leaf appearance.Dry matter and nitrogen content declined in petioles, remained relatively constant in corm and accumulated in new shoot and root during establishment. Losses of N were similar but accumulation was greater in new growth of Alafua Sunrise than Niue.We conclude that differences in productivity between the improved and traditional cultivars used in this experiment are at least partly attributable to differences in rate of development of new shoot and root during establishment. Previously reported correlations between corm yield and size of planting material are probably due to large headsetts producing a greater area of leaf and root than small headsetts during early growth.
JACOBS, BC & PEARSON, CJ 1992, 'Pre-flowering Growth and Development of the Inflorescences of Maize', Journal of Experimental Botany, vol. 43, no. 4, pp. 557-563.
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The growth and development of the main stem and the two uppermost axillary apices of maize were studied during the period from emergence until flowering. Plants were grown in the field under varying levels of applied nitrogen fertilizer at two times of sowing. The effects of daylength were isolated from those of temperature by making comparisons of growth and development on a thermal time basis.The growth and development of the terminal (male) apex and the two uppermost axillary (female) apices followed the same patterns, with apex volumes increasing curvilinearly with increase in number of leaf or husk primordia. The RGR(relative growth rate of volume) of the terminal apex was, however, only approximately one-tenth of the axillary apices. There was no difference in growth and development between the first and second axillary apices before flowering: Other factors, such as accumulation of dry weight, rather than primordia production, must be responsible for an axillary apex's potential to bear grain. Applied N, and to a lesser extent short days, increased the rates of growth and development of all the apices. For example, applied N increased the RGR (volume) of the apical domes, and the rate of production of spikelet primordia, by about 25%.All axillary apices and treatments showed a single relationship between number of spikelets and surface area of the ear: a favourable environment (e.g. high N) simply accelerated the progression of spikelet production and area expansion along this single path. We conclude that this path is probably determined genetically and that N and time of sowing influence potential yield of maize through effects on the surface area of the ear but not on the density of spikelets formed. © 1992 Oxford University Press.
JACOBS, BC & PEARSON, CJ 1992, 'Pre-flowering Growth and Development of the Inflorescences of Maize', Journal of Experimental Botany, vol. 43, no. 4, pp. 565-569.
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The accumulation and partitioning of dry matter and nitrogen were examined in the developing tassel and two uppermost ear shoots of field-grown maize under varying levels of applied nitrogen and times of sowing.Accumulation of dry matter and nitrogen within an axillary branch always favoured the ear over the husk and shank. Dry matter and nitrogen accumulated faster in the first ear than in the tassel or second ear and the partitioning between inflorescences of dry matter and nitrogen was not affected by treatment. The relative rate of growth, RGR(dry matter), of the first and second ear shoots increased by up to 42% at high levels of applied nitrogen and with early sowing. In contrast, the relative rate of accumulation of nitrogen (RNAR) was not sensitive to N supply, although it was reduced, on average, by 22% at the late time of sowing.We conclude that accumulation, but not partitioning, of dry matter and nitrogen between developing inflorescences of maize are altered by nitrogen application, time of sowing, and position of the inflorescence on the stem. © 1992 Oxford University Press.
Mukheibir, P 1992, 'The use of artificial wetlands to treat rural effluent', New Ground, vol. 7.
Plant, R Tauw Milieu BV 1992, Application of Support Correction Models in Soil Remediation Projects, Deventer.
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Rapportnr. 0021048, Tauw Milieu BV, Deventer
