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Some effects of darkness and partial defoliation on the resistance of sugar beet to downy mildew
Author(s) -
RUSSELL G. E.,
EVANS GWENLLIAN M.
Publication year - 1972
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.1744-7348.1972.tb04692.x
Subject(s) - darkness , biology , downy mildew , inoculation , spore , mildew , botany , horticulture
SUMMARY Seedlings of two susceptible sugar‐beet stocks were grown either in daylight or in darkness for 24 h before or after inoculation with Peronospora farinosa f.sp. betae . Post‐inoculation darkness did not significantly affect the percentage of inoculated plants that became infected but increased the percentage of plants on which the fungus sporulated in both stocks. The effects on sporulation of darkness before inoculation were more variable than those of post‐inoculation darkness. In the same stocks removal of all leaves, except those in the bud, before inoculation increased the percentage both of plants which became infected and of those on which P. farinosa sporulated. Infection and sporulation were not significantly affected by defoliation in a more resistant stock. Defoliation or darkness may have affected the concentration of certain sugars or amino acids in the bud leaves thereby changing the expression of polygenically‐controlled resistance to downy mildew.