Temporal Relationship between Calcium and Fruit Growth and Development in Bell Pepper (Capsicum annuum L.)

Abstract

Bell peppers (Capsicum annuum L.) are ranked eighth in value for vegetable production in the United States (USDA-NASS, 2019). Due to the high value of bell peppers, disorders such as blossom-end rot (BER) can cause significant losses in yield by up to 35% for growers. BER is the symptom of a calcium (Ca2+) deficiency that may occur during periods of cell expansion when the supply of Ca2+ may be lower than demand. In this study, we determined the temporal patterns of the fruit Ca2+concentration ([Ca2+]) and accumulation in three separate studies under field and greenhouse conditions. In the three experiments, [Ca2+] during fruit development showed varied patterns: it remained constant, decreased transiently during the cell expansion phase, or displayed a more gradual sustained decrease. However, in the three experiments, fruit Ca2+ accumulation increased during development as fruit size increased. In two experiments, the distal part of the fruit had lower [Ca2+] than the proximal end. However, there was no correlation between [Ca2+] in various fruit sections with BER incidence. Seeds and placental tissue had increased [Ca2+] and several other macro- and micronutrients; this spatial distribution of Ca2+ coupled with subcellular Ca2+ distribution should be explored in future studies. The temporal pattern of Ca2+ accumulation in this study suggests that fruit Ca2+ uptake continues throughout fruit development. Therefore, Ca2+ application during bloom and early fruit development may prevent or minimize Ca2+ deficiency disorders in bell pepper.