Excessive Calcium Accumulation in the Roots Is a Key Factor in Tipburn Incidence under High Ca Supply in Lisianthus (<i>Eustoma grandiflorum</i>) Cultivars

Abstract

In lisianthus cultivars, the occurrence of tipburn is known to adversely affect quality and yield. However, information concerning the responses of tipburn incidence to different levels of Ca is limited. In addition, only a few studies have investigated the effect of potassium (K) concentration on Ca acquisition and distribution in lisianthus. To address this knowledge gap, we investigated tipburn incidence in three lisianthus cultivars (Umi honoka (UH), Reina white (RW), and Voyage peach (VP)) and the Ca and K concentrations in them under different concentrations of Ca supply (40, 80, and 120 ppm). These cultivars exhibited different responses to different concentrations of Ca supply. Tipburn was not observed in UH. In RW, tipburn incidence and severity significantly decreased with an increase in nutritional Ca concentration, because the Ca concentration in the tips of the top leaves significantly increased with Ca concentration. By contrast, in VP, tipburn incidence under all treatments was 100%, and there was no significant difference in the Ca concentration in the tips of the top leaves among the treatments, but the total Ca concentration significantly increased. VP was the only cultivar that significantly acquired and accumulated more Ca in the roots with an increase in nutritional Ca concentration. Overall, excessive Ca accumulation in the roots under high-Ca conditions inhibits the distribution of Ca to the tips of the top leaves and eventually manifests as tipburn in the cultivar. In addition, our results suggested that the content ratio of K in the nutrient solutions did not prevent Ca acquisition and distribution in lisianthus cultivars and that the K concentration has a negligible effect on the occurrence of tipburn.

Keywords

• <i>Eustoma grandiflorum</i>
• Ca acquisition
• Ca distribution
• K concentration
• antagonism