ISHS Acta Horticulturae 494: II International Symposium on Chestnut
ASSESSMENT OF RESISTANCE TO CHESTNUT INK DISEASE |
| Authors: | C.G. Abreu, L. Carvalho, M.J. Gaspar, A.L. Gomes, J. Colaço, A.O. Cardoso |
| Keywords: | Phytophthora cinnamomi, Elston index |
| Abstract:
The chestnut ink disease induced by the oomycete Phytophthora cinnamomi represents a major constraint for the actual chestnut production in Terra Fria, the cold lands of mountainous northeast Portugal. The expression of the disease is increased by a suitable environment involving dry periods during summer followed by frequent waterlogging in the wet seasons. The approach of NATO/Science for Stability PO-Chestnut Project to control the disease has involved both suitable management practices and resistance. This contribution describes a method used by the PO-Chestnut Project for testing the 3rd cycle-resistance of different chestnut selections and varieties to ink disease. Three partial resistance components (incubation period, lesion size and proanthocyanidin content) observed on the tested chestnut trees were used as traits for simultaneous consideration by the multiplicative weight-free Elston index. Incubation period means the time between leaf inoculation and first visible symptoms; lesion size refers the stem area showing necrosis after wound inoculation; proanthocyanidin content is given by the absorbance at 550 nm under standard conditions and the results expressed as A/g of fresh leaf. Ranking the chestnuts according to the highest index values gave favourable results respectively to Colutad, Castanea mollissima selection and Marsol CA 07. Three C. sativa genotypes (UTAD 14, UTAD 15 and Verdeal) had the least favourable indices. | |
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