Dry matter accumulation and foliar K, Ca and Na contents in salt-stressed cape gooseberry (Physalis peruviana L.) plants

A pot experiment aimed at determining the effect of five NaCl<br />concentrations (namely 0, 30, 60, 90 and 120 mM, determining<br />respective EC values of 0.8, 3.0, 6.0, 9.0 and 12.2 dS m-1) on cape<br />gooseberry plants was set up at Humboldt University’s greenhouse<br />in Berlin, Germany. Dry weight (DW) of roots, stems<br />and leaves, as well as foliar content of ions K+, Ca2+ and Na+ and<br />the relationship they hold with one another, were determined<br />over a 75-day period. DW of all plant organs was observed<br />to decrease with increasing salinity. The lowest values of this<br />variable, which were recorded from the 120 mM NaCl plants,<br />were found to be significantly smaller than those recorded at<br />60 mM and lower salt concentrations. Salt stress effects on dry<br />matter (DM) accumulat ion were observed to increase with<br />plant age. Leaf K+ content increased with salinity and peaked<br />at 90 mM NaCl, where the value was significantly higher than<br />that observed at 120 mM. Foliar Ca2+ content remained unchanged<br />at the different salt concentrations, whilst Na+ content<br />increased together with salt stress. The relationship among ion<br />concentrations was significantly influenced only by 90 mM or<br />higher NaCl concentrations, which determined a progressive<br />increase of the Na+/Ca2+ ratio and a similar decrease of the K+/<br />Na+ ratio. According to the results, cape gooseberry can be<br />considered as moderately tolerant to salt, as shown by the 30<br />mM NaCl treatment, which did not affect DM accumulation in<br />plant organs. This tolerance is also supported by steady leaf Ca2+<br />contents at all levels of salinity, indicating that cape gooseberry<br />uses K+ as an osmoprotectant, at least up to 90 mM NaCl.