The fitness of pelargonium cuttings affects the relationship between the photochemical activity of the photosynthetic apparatus and rooting ability

Abstract

Pelargoniums cultivated for ornamental purposes rely on efficient vegetative propagation. This study researched applicability of chlorophyll fluorescence for validating the physiological conditions of pelargonium cuttings. Results indicated a correlation between the chlorophyll fluorescence and rooting potential. The ET₀/RC values were negatively correlated with the rooting efficiency between the varieties and the duration of cold storage. A negative correlation was observed between OJIP parameters, representing energy flow in thylakoids, and chlorophyll content in cuttings with lower nutritional status. The phenomenological energy fluxes for leaf cross-sections and the number of active PSII reaction centers in the not-excited state (RC/CS₀) increase with raised chlorophyll concentration. This imply the influence of rooting ability on the demand for photoassimilates in pelargonium cuttings, which can be detected early on through chlorophyll fluorescence analysis but not chlorophyll content measurements. Chlorophyll fluorescence evaluation, along with specific OJIP test parameters such as the performance indices PI_ABS and PI_total, prove useful for predicting rooting efficiency in relation to the nutritional status of cuttings, suggesting the effects of cuttings cold storage and discerning varietal differences in rooting. This study establish the pragmatic application of chlorophyll fluorescence assessment for elucidating the physiological intricacies of pelargonium cuttings and factors influencing rooting efficiency.