Prohexadione-calcium changes morphological and physiological traits in strawberry plants and preconditions transplants to water stress

Prohexadione-calcium (ProCa) applied as foliar spray, increases root to shoot ratio and reduces specific leaf area (SLA) in strawberry plants (Fragaria x ananassa Duch.). These effects may help treated plants to survive a transplant shock. Under mild water stress, ProCa caused a transient reduction in leaf stomatal conductance (g(s) in 'Camarosa' and 'Sweet Charlie' plants. This reduction in g, was paralleled by a decrease in transpiration in treated plants, which was not attributable to differences in plant size or leaf area. Pressure volume curves of 'Sweet Charlie' plants revealed that ProCa application lowered leaf osmotic potential at both full and zero turgor, and increased the volumetric modulus of elasticity. ProCa treatment regulated the leaf morphology of strawberry and preconditioned strawberry plants to tolerate water stress. Under field conditions in the plasticulture fruit production system, newly transplanted bare-root strawberry plants had a progressively higher water potential (psi(1)) and g(s) with a longer overhead irrigation. Plants treated with ProCa had a higher psi(1) and g(s) than control plants at the same level of overhead irrigation. Application of ProCa to strawberry transplants may in part be able to replace overhead irrigation and at the same time maintain acceptable levels of fruit yield.