EFFECTS OF ASCOCHYTA BLIGHT (MYCOSPHAERELLA-PINODES BERK-AND-BLOX) ONBIOMASS PRODUCTION, SEED NUMBER AND SEED WEIGHT OF DRIED-PEA (PISUM-SATIVUM L) AS AFFECTED BY PLANT-GROWTH STAGE AND DISEASE INTENSITY

The effects of ascochyta blight due to Mycosphaerella pinodes on bioma ss production, seed number and seed weight according to physiological stage and disease intensity were examined. Pea plants were grown in a glasshouse and inoculated with various concentrations of conidia befor e flowering, at flowering of the second fructifer node (FLO2), at the start of seed filling of the first fructifer node (FSSA1) or the secon d fructifer node (FSSA2). Uninoculated plants were used as controls. W hatever the stage of inoculation (FLO2 or FSSA2), the disease reduced plant growth and the decrease depended on disease intensity on foliar organs. The seed number was reduced for plants inoculated before flowe ring, at FLO2 and at FSSA1 and the reduction was linked to disease int ensity on foliar organs. At each node, seed number was reduced if the disease occurred before FSSA of the node. The mean seed weight per pla nt was decreased in plants inoculated at FSSA1 and FSSA2 and the highe r the disease intensity on aerials organs, the greater was the reducti on of the seed weight. For individual nodes, only inoculations after t he beginning of seed filling had a negative effect on mean seed weight at harvest. We found that the decrease of seed number induced by the disease was proportional to aerial biomass production before the end o f the period of seed production.