Warm-night temperature delays spike emergence and alters carbon pool metabolism in the stem and leaves of Phalaenopsis aphroide

•The new and fully expanded leaf exhibited the maximum diurnal fluctuations of malate and starch concentrations on warm- and cool-night (control) treatments.•The sucrose concentrations in the stem on both treatments were significantly higher than those in the different ages of leaves.•Warm-night temperature delayed the spike emergence of Phalaenopsis.•The sucrose concentration in the stem on the warm-night treatment was significantly higher than that of the control.•The potential role of sucrose in the stem is to sustain the viability of the dormant spike bud.