Preharvest calcium applications have little effect on mineral distribution in ripe strawberry fruit

Abstract

Supplemental Ca was supplied to 'Cardinal' and 'Fern' strawberry (Fragaria xananassa Duch.) plants grown in an Enders clayey silt loam soil as a foliar spray of Ca glutarate, as soil incorporated gypsum, as fertigated calcium nitrate (CaNO3), or as a combination of the above. Controls received no Ca. Individual fruits were partitioned into six parts: proximal, distal, inner and outer receptacle, and proximal and distal achenes. Mineral nutrient concentrations (dry mass basis) found in the inner and outer receptacle, and in achenes were, in descending order, K, P, Ca, Mg, Al, Na, Fe, Mn, Zn, B, and Cu; K, P, Ca, Mg, Na, Mn, Fe, Zn, Al, B, and Cu; and Ca, P, Mg, K, Na, Fe, Mn, Zn, Al, Cu, and B, respectively. Many nutrients, including Ca, tended to occur in greater concentrations in the proximal portion of the fruit than in the distal part. With the exception of Al, nutrient concentration gradients were lowest in the inner receptacle. Fruit Ca concentrations were highest in achenes and lowest in inner receptacle tissue. Differences among cultivars in Ca concentration were found in achenes but not in receptacle tissue. Calcium treatment had no effect on receptacle tissue Ca concentrations, regardless of cultivar, but CaNO3 and combination treatments increased Ca concentrations in the achenes in the proximal half of 'Cardinal' fruit. Concentrations of all other nutrients except Mn were unaffected by supplemental Ca treatments.