Premium
AN ANALYSIS OF COMPETITION BETWEEN BARLEY AND WHITE PERSICARIA
Author(s) -
ASPINALL† D.
Publication year - 1960
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1960.tb03565.x
Subject(s) - biology , competition (biology) , shoot , shading , growth rate , agronomy , population , nutrient , relative growth rate , horticulture , botany , ecology , art , geometry , mathematics , demography , sociology , visual arts
White persicaria grown with barley had a lower relative growth rate, a lower net assimilation rate, a higher leaf‐area ratio and a higher leaf‐area: leaf‐weight ratio than when grown alone. These differences were accentuated with time and with increase in the density of the surrounding barley plants. That the responses were those of plants subjected to a high degree of shading was confirmed by growing spaced plants under differing degrees of shade and from measurements of the amount of light penetrating the mixed stands. However, they do not necessarily demonstrate that light was the environmental factor in shortest supply. An attempt was made to distinguish the effect of competition between shoots from competition between the roots. Root competition appeared to reduce growth more than shoot competition although the influence of the latter increased with time. Increase in nutrient supply, which was varied by supplying, at weekly intervals, solutions of various dilutions, caused a proportionately greater increase in the growth of white persicaria than of barley in a mixed population. These results suggest that restricted nutrient supply was the factor which first decreased the growth of white persicaria. This was a direct consequence of its smaller root system arising from a smaller embryo than that of barley. The divergence between the amount of growth of the two species with time led to the white persicaria plants becoming progressively more and more shaded, and ultimately caused a further reduction in the rate of expansion of the root system and of the leaves. Although restriction in light was certainly concerned, as shown by the type of plant produced, it seemed likely that mineral nutrients were the factors always in shortest supply. The reduction in tiller number, but not in dry weight, of barley when grown with white persicaria was interpreted as a response to a lower internal concentration of nitrogen arising directly from the lower external concentration. Root extension did not appear to be significantly reduced.