Effect of nitrogen source on growith of Eucalypts in sand culture

Abstract

Twelve species of Eucalyptus were grown in sand culture to determine their response to nitrate and ammonium nitrogen, and to different proportions of the two ions. Response was measured in terms of plant height, yields of plant parts (stems, branches, leaves, and roots), and number of branches. The results indicate a wide variation in the response of different species to form of nitrogen. A classification of species in terms of their overall response bears no relation to the accepted taxonomic classification. On the basis of the results for the 12 species, it appears that plants of similar ecological habitat tend to have similar responses. Thus, typical woodland species (E. melliodora, E. blakelyi, and E. albens) behave quite differently from typical forest species (E. rossii and E. sideroxylon). Nevertheless, there are differences within such general groupings; e.g. forest species such as E. Agglomerata and E. macrorhyncha form a distinct group, apparently unrelated to the other forest species tested. The response of E. polyanthemos, which occurs in both dry sclerophyll forests and woodlands, is similar to that of the typical forest species. When Eucalyptus species are to be grown in sand culture for nutrition or other trials, a preliminary test is necessary to determine the preferred form of nitrogen for each species. Otherwise the effects of the factor being tested may be so masked as to render the test valueless.