Using intracellular pH to evaluate growth inhibition of strawberry plants

At present, many strawberry plants (Fragaria x ananassa Duch.) are cold-sto red in autumn and replanted the next summer to provide good crops the follo wing spring. These plants should be dormant (low growth potential) with abu ndant nutrient reserves (e.g. carbohydrates) to withstand storage. Because no rapid test was available to assess the induction of autumnal dormancy of strawberry plants, we have evaluated the level of relative nutrient defici ency of growth organs (correlative inhibition, one cause of dormancy) by in tracellular pH measurements on Elsanta strawberry plants. To control the va lidity of this evaluation, carbohydrate accumulation in the storage parench yma was measured and the dormancy level was estimated by measuring the peti ole length of Elsanta plants under controlled conditions. The results showe d that petiole length and intracellular pH of buds were low at the beginnin g of autumn, implying that the measurements of intracellular pH can be a ma rker of dormancy induction in strawberry plants. Then, in the middle of aut umn, when the first changes occurred, growth inhibition remained even as th e intracellular pH measurements implied a break of correlative inhibition. This should suggest that another growth inhibition remains after the first chilling. (C) Elsevier, Paris.