SALINITY EFFECTS ON STRAWBERRY PLANTS GROWN IN ROCKWOOL .1. GROWTH AND LEAF WATER RELATIONS

Comparison of four everbearing or day-neutral cultivars of strawberry (Rapella, Ostara, Fem and Selva) grown under glasshouse conditions in rockwool showed Rapella to accumulate the greatest shoot dry weight and leaf number together with the production of few stolons but many relatively large fruits per inflorescence. Subsequent studies with cv. Rapella found that increasing the salinity of the irrigation supply from 2.5 to 5.7 and to 8.5 mS cm-1, by the addition of NaCl, progressively reduced leaf number emerged and final leaf area by up to 36% and 48% respectively, after 100 d of treatment. Shoot dry weight, excluding fruits, was reduced by up to 47%. The number of crowns (lateral branches) was reduced from 11 in the lowest salinity to 8 and 7 at the higher salinity levels. Leaf water potential, psi(w), was reduced by up to 0.23 MPa in young leaves and 0.36 MPa in older leaves. Leaf osmotic potential, psi(pi), was decreased by up to 0.14 MPa in younger leaves following salinity treatment at 8.0 mS cm-1. Consequently leaf turgor was reduced more in older than in younger leaves. Inflorescence number was reduced from 27 to 20 and 17. Within the remaining inflorescences however, flower numbers, fruit numbers and duration of fruit ripening were not affected. A marked decrease in the fresh weight of the fruit was detected in both higher salinity treatments but fruit dry weight was only slightly reduced.