Growth responses of clonal lines of American sycamore grown under different intensities of nutrition

1971 ◽  
Vol 49 (3) ◽  
pp. 353-358 ◽  
Author(s):  
Klaus Steinbeck

Four random clones of American sycamore supplied with four concentrations of Hoagland's solution differed in their response to and interacted with treatment as far as height and diameter growth and total dry matter production in the first growing season were concerned. Varying nutrient intensity did not affect the time of the seasonal peak of height and diameter growth; better growth was maintained subsequent to the seasonal peak at the higher concentrations, however. The proportions of the trees in terms of dry-matter distribution and branching characteristics changed with nutrient concentration.

1979 ◽  
Vol 15 (4) ◽  
pp. 339-351 ◽  
Author(s):  
J. Y. Yayock

SUMMARYAn investigation for 2 years at Kano and 1 year at Samaru evaluated the effects of plant density on vegetative growth, development and dry matter production and distribution of five varieties of groundnut. Growth and branching of individual plants were reduced at high populations but more dry matter was produced per unit area. Dense plants, particularly Spanish 205, developed a larger leaf area earlier in the season and were presumably able to make better use of light. Varieties F439.4 and 439.2 suffered the least reduction in the number of vegetative branches but the extra branches contributed few useful reproductive nodes.


2010 ◽  
Vol 61 (5) ◽  
pp. 353 ◽  
Author(s):  
L. L. Burkitt ◽  
D. J. Donaghy ◽  
P. J. Smethurst

Pasture is the cheapest source of feed for dairy cows, therefore, dairy pastures in Australia are intensively managed to maximise milk production and profits. Although soil testing commonly suggests that soils used for dairy pasture production have adequate supplies of phosphorus (P), many Australian dairy farmers still apply fertiliser P, often by applying smaller rates more frequently throughout the year. This study was designed to test the hypotheses that more frequent, but lower rates of P fertiliser applied strategically throughout the growing season have no effect on dry matter production and P concentration in perennial ryegrass (Lolium perenne L.), when soil extractable P concentrations are above the critical value reported in the literature. Three field sites were established on rain-fed dairy pasture soils ranging in P sorption capacity and with adequate soil P concentrations for maximising pasture production. Results showed that applied P fertiliser had no effect on pasture production across the 3 sites (P > 0.05), regardless of rate or the season in which the P was applied, confirming that no P fertiliser is required when soil extractable P concentrations are adequate. This finding challenges the viability of the current industry practice. In addition, applying P fertiliser as a single annual application in summer did not compromise pasture production at any of the 3 sites (P > 0.05), which supports the current environmental recommendations of applying P during drier conditions, when the risk of surface P runoff is generally lower. The current results also demonstrate that the short-term cessation of P fertiliser application may be a viable management option, as a minimal reduction in pasture production was measured over the experimental period.


1983 ◽  
Vol 61 (8) ◽  
pp. 2186-2194 ◽  
Author(s):  
Roy Turkington

Replicates of two genotypes of Trifolium repens L., collected from a Poa pratensis dominated sward and a Dactylis glomerata dominated sward, respectively, were grown in swards composed of various proportions of P. pratensis and D. glomerata. These swards represented a range of environments of neighbours; an increasing proportion of P. pratensis was considered as an increasingly alien environment for individuals of T. repens collected from the D. glomerata dominated site, and vice-versa for the individuals from the P. pratensis dominated site. The individuals of T. repens were harvested on five occasions over a period of 27 months. Both genotypes responded to increasingly alien environments by producing more inflorescences and by distributing proportionately more dry matter to inflorescence production. Some evidence is also presented which suggests that allocation to stolons and inflorescences are alternatives and the balance of the trade off is dependent on the advantages of possibly producing new, better adapted offspring from seed, against the chances of a wandering stolon encountering a less hostile environment. Results are discussed in the context of environmental alienness, a major source of which is the different relative proportions of neighbours. The various genotypes of organisms which a relatively mobile plant species encounters are a major source of this environmental, or biotic, alienness.


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