Annals of Botany 73: 539-545, 1994
© 1994 Annals of Botany Company
Regulation of the Partitioning of Dry Matter and Calcium in Cucumber in Relation to Fruit Growth and Salinity
Horticulture Research International, Littlehampton, West Sussex BN17 6LP, UK
The regulation of the partitioning of dry matter and calcium in relation to fruit growth was investigated in cucumber plants grown in the salinity range of 3-8 mS cm-1 in NFT (Nutrient Film Culture), with or without a fruit pruning treatment. The dry weight gain of the plants was proportional to the outdoor integral irradiance, with a common daily rate of 1 g MJ-1 m-2 in two crops grown under summer (18 MJ m-2 d-1) and autumn (7 MJ m-2 d-1) conditions. Within the salinity range studied, the reduction of plant dry weight was 9% mS-1 cm-1. However, fruit dry weight was only reduced at salinities above 5·5 mS cm-1, although the daily dry matter accumulation by fruit, as a percentage of total dry matter accumulation, was increased. Salinity reduced the dry matter accumulation in the young shoot proportionally more than in the fruit. Although the total plant Ca content was reduced by 13% mS-1 cm-1, the Ca content of the young shoot was reduced by 16·6%, compared to 11% in the fruit. Pruning fruit reduced neither plant dry weight nor Ca uptake. The growth of the remaining fruit, and to a lesser degree of the young shoot, accounted for all surplus assimilates. Thus, fruit were the dominant sinks for assimilates whilst the mature leaves were the strongest sinks for Ca. Nevertheless, the fruit sustained the capacity to import Ca better than the young shoot, when supplies of both assimilates and Ca were reduced by high salinity.Copyright 1994, 1999 Academic Press
Cucumber, Cucumis sativus L., salinity, fruit pruning, dry matter and calcium