Effects on the Reproductive Development of Tomato under Conditions of Ca Deficiency up to the Re-application of Ca

Abstract

Calcium (Ca) is an essential nutrient that regulates many physical events during plant growth, such as signaling and nutrition. Ca is known as an immobile element due to its binding properties with pectin. Ca deficiency during the vegetative process of plant growth causes physical disorders such as shoot apical meristem necrosis and leaf etiolation, which inhibit plant growth. Tomato plants lacking Ca also experience impaired fruit production due to blossom end rot (BER), although the symptoms of BER have reported to be alleviated by Ca resupply through foliar application. On the other hand, the mechanism remains for this unknown. Therefore, it is important to understand the effect of Ca reapplication on overall plant growth. To analyze the effect of Ca reapplication on plant growth, especially reproductive development, an experimental system was established in which the root Ca supply was interrupted for 30 days via hydroponic cultivation, followed by reapplication of Ca at a concentration of 0.6 mM, a level comparable to the control treatment. Regarding the difference in vegetative growth performance among treatments, based on the results of leaf SPAD measurements and biomass in the 80 days after Ca deficiency treatment, there was no significant difference between Ca reapplication and the control; however, Ca deficiency resulted in lower values. As for the difference in reproductive development, Ca reapplication treatment was found to produce 52% more fruit compared to the control and 78% more fruit than Ca-deficient plants. These results indicated that Ca reapplication to Ca-deficient individuals caused an increase in fruit production and restored vegetative growth performance.