Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Ultraviolet-B radiation effects on intra- and interspecific competition in broccoli (Brassica oleracea) and Chenopodium album were studied using bivariate factorial experiments. A randomized block design was used in which three monoculture densities for each species [144 (low), 256 (medium), and 400 (high) plants m−2] and all binary combinations were grown in a glasshouse at two (4 and 7 kJ m−2 day−1) UV-BBE radiation levels for 4 weeks in 1999 and 5 weeks in 2000. Inverse yield–density relationships were more discernible at 4, compared with 7 kJ m−2 day−1 UV-BBE radiation. Substitution rates, indicating the balance of intra- to interspecific competitive effects, declined for broccoli at 7, compared with 4 kJ m−2 day−1 UV-BBE radiation, largely because of reduced interspecific competitive influences. Conversely, substitution rates increased for C. album grown at 7 kJ m−2 day−1 UV-BBE radiation, as a result of both decreased intraspecific and increased interspecific competition. Interspecific competitive effects were influenced more than intraspecific competitive effects by UV-B radiation. Based on relative magnitude of substitution rates, C. album was a stronger competitor than broccoli at 4 kJ m−2 day−1 UV-BBE radiation in both years, and at 7 kJ m−2 day−1 UV-BBE radiation in 1999. In 2000, broccoli was the stronger competitor at 7 kJ m−2 day−1 UV-BBE radiation. Overall, the relative competitiveness of broccoli was enhanced, while that of C. album diminished at 7, compared with 4 kJ m−2 day−1 UV-BBE radiation. These findings indicate that above-ambient UV-B radiation has the potential to alter crop–weed competitive interactions, which could change acceptable weed threshold levels.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ecological data were analyzed to determine the environmental conditions associated with the occurrence of plants possessing C3 and C4 photosynthetic pathways. Non-parametric analysis of variance, multiple regression analysis and discriminant analysis techniques were applied to information derived from separate studies on plant species in California and central Europe. All the analyses revealed significant differences in ecology between the C3 and C4 groups. The occurrence of C4 species was greater where summer or winter temperatures were relatively high and moisture availability relatively low. Using discriminant analysis, more than 80% of the species considered were classified into the correct photosynthetic category on the basis of their distribution with respect to temperature. No significant differences between the C3 and C4 groups were found for other environmental factors, including light, soil nitrogen, soil salinity and continentality of climate. These results support the suggestion from previous physiological studies that C4 species may possess competitive advantages under conditions of high temperature and intermittent water stress. The C4 species were relatively restricted in the range of environmental conditions where they occurred, and as a group C4 species may be ecologically more specialized than C3 species.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...