Hot water treatments of carrot seeds: effects on seed-borne fungi, germination, emergence and yield.
Hermansen, A.; Brodal, G.; Balvoll, G.;
Seed Science and Technology Year: 1999 Vol: 27 Issue: 2 Pages: 599-613 Ref: 27 ref.
1999
บทคัดย่อ
The effects of hot water treatments of carrot seeds on seed-borne fungi, germination, emergence and yield were studied. Seeds infected with Alternaria dauci were hot water treated at temperatures ranging from 44 to 59 deg C at intervals of 5 deg C for periods of 5 to 40 minutes. Different grades of healthy carrot seeds were hot water treated at 50-55 deg C. In some experiments seed treatments with Trichoderma harzianum, Streptomyces griseovirides or fungicides were included. Seed germination and survival of fungi were investigated in the laboratory and emergence was determined in a growth chamber test. Emergence and yield measurements under field conditions and postharvest evaluation of carrots were made in some experiments. Hot water treatment of carrot seeds at 44, 49 and 54 deg C generally improved germination of infected seeds and reduced the incidence of A. dauci. Treatments at 54 deg C for 20 minutes eradicated A. dauci without adversely affecting germination, emergence or yield. A signifi
cant correlation (r=0,97) between the incidence of A. dauci and the occurrence of abnormal seedlings was found. Small seeds were more sensitive to hot water than larger seeds. In two field experiments seed treatment with iprodione gave higher emergence and seedling weight than hot water treatment, possibly because iprodione may have reduced attack by soil-borne fungi whereas hot water treated seeds would not have been protected against such organisms. Hot water treatment of seeds and seed treatments with the biological control agents had no effect on carrot yield and storage quality but reduced the incidence of the saprophyte Ulocladium atrum on the seeds. The germination percentages found in the laboratory correlated well with the emergence percentages in the growth chamber. It is concluded that hot water treatment is an alternative to fungicides to eradicate seed-borne pathogens in carrots in organic farming systems.