Abstract
It is of great practical significance to study the development process of cut lily for regulating flowering and preservation. In this study, the developmental process of lily cut flower was explored from cellular, morphological, and physiological aspects. From a morphological aspect, the tepal edge grows faster than the midrib. The midrib groove of the flowering stage is wider than that of bud stage. The fast-growing edge of the petals results in the midrib bending outward. Moreover, the rapid growth of the stamens and stigmas also contributes to bud cracking. From the cellular aspect, in the bud stage there were more wrinkles in the outer epidermal cell wall of the tepal than those in the inner epidermal cell wall, indicating that asymmetric structural differences exist from the beginning of lily development. From a physiological aspect, from the bud cracking stage to the senescence stage, a variety of substances in the tepal cells gradually decreased, including total nitrogen, total phosphorus, total potassium, total calcium, starch, soluble sugar, and soluble protein, but not malondialdehyde. These results indicate that the asymmetric growth caused by this structural difference is responsible for flowering. The wrinkles in the cell wall can be regarded as indicators of senescent cells and are caused by the degradation of the cell wall and the loss of intracellular turgor pressure. The differences in the epidermal cells between the inner and outer tepal indicated ultrastructural changes in the tepal cells. The bud and flowering stages are maintained by the tepals acting as a sink. After flowering, the tepals gradually change from a sink to a source organ. Senescence of the cut lily flowers was caused by the decomposition of intracellular compounds in the tepals and the remobilization of nutrients from the tepals to the developing organs.
