Effect of Chestnut Ink Disease on Photosynthetic Performance

In order to evaluate the evolutionary impact of chestnut ink disease, infected trees (cv. Judia), were compared with non-infected trees, in three separate months: July, September and October. The aim of this work is to analyse the effects of the infection using parameters related to plant water relations, gas exchange and biometric data of leaves and fruits. In this period, temperatures decreased from 31 to 16 C contrarily to precipitation, which increased from 18 to 178 mm, respectively. In consequence, leaf water potential changed between )1.6 and )1.0 MPa while in infected plants the values maintained around )1.2 MPa over the referred period. Nevertheless, at the gas exchanges level, differences in stomatal conductance, transpiration and photosynthesis were only detected in October. Concerning photosynthesis rate, the infected plants showed, in relation to September, a reduction around 35% whereas in non-infected plants the decline was 25%. Alterations in the chlorophyll contents were also observed between September and October. In infected plants reduction on total amount of chlorophyll was from 18.6 to 13.4 mg/Wf, while in non-infected plants values were only decayed from 15.1 to 13.1 mg/Wf. In relation to chlorophyll a/chlorophyll b ratio, plants infected by the oomycete preserved values in the level of 2.6, whereas in healthy plants values changed from 2.5 to 2.3. Leaves and fruits from infected chestnut trees were 13 and 20% smaller, respectively than those from non-infected. Fruits from infected plants also had less starch but more crude protein.