K + /Ca2+ RATIO OF THE NUTRIENT SOLUTION AFFECTS GROWTH AND POSTHARVEST QUALITY TULIP

Abstract

Tulip (Tulipa gesneriana L.) is a plant species of importance for floriculture, and for the industries of cosmetics and pharmaceutics. For its production, this species needs particular soil and weather conditions and little is known about its nutritional requirements for optimal production, particulary the potassium/calcium ratios in hydroponics. In this study we evaluated the effect of nine ratios of K⁺/Ca²⁺ (5.5/7.5; 5.5/9.0; 5.5/10.5; 7.0/7.5; 7.0/9.0; 7.0/10.5; 8.5/7.5; 8.5/9.0; y 8.5/9.0 mol_c m^-3) in Steiner´s universal nutrimental solution, by measuring growth indicators and postharvest quality of tulip cv. ‘Ile de France’. This cultivar showed differential responses K⁺/Ca²⁺ ratios in the nutrient solution. The best response was produced by K⁺/Ca²⁺ of 8.5/9.0 mol_c m^-3, in which the highest and strongest flower stem, highest levels of total chlorophylls in leaves and sugars in petals, and the longest postharvest life were registered. As for K and Ca partitioning in the plant, we observed that K⁺ did not accumulate in a particular trend related to treatments, whereas. Ca²⁺ affected flower quality and postharvest life. Plants in the 8.5/9.0 ratio showed the lowest Ca²⁺ accumulation ratios both in bulb/stem and in stem/leaf, and Ca²⁺ accumulated higher in leaves than in stems, thus improving growth responses and postharvest quality.