Controlled atmosphere storage at high CO2 and low O-2 levels affects stomatal conductance and influence root formation in kalanchoe cuttings

摘要

Since the response of cuttings to raised CO2 concentration is not documented, controlled atmosphere (CA) storage of kalanchoe cuttings at combinations of high carbon dioxide and low oxygen levels was investigated to study the feasibility of using CA to sustain quality of cuttings prior to planting. During storage, stomata opening and plant fresh weight (FW) were measured, and root formation (RF) was recorded post storage. Storage atmosphere composition (10/2, 15/2, or 15/5; kPa CO2/kPa 02), storage duration (9 or 19 days), and cutting type (rooted or un-rooted) affected stomata conductance (G,), and influenced FW and subsequent RIF in cuttings of kalanchoe'Yellow Josefine'. In CA stored plants, G, was high, 60-160 mmol m(-2) s(-1), indicating open stomata, whereas in control plants G, was low, 514 mmol M-2 s(-1), indicating closed stomata. Generally G, values were higher for un-rooted than for rooted cuttings. Overall, cutting FW was reduced by CA storage with no significant differences in FW reduction between the CA treatments. RIF of un-rooted CA stored cuttings was comparable to that of controls, whereas for rooted cuttings controls grew better than CA stored cuttings. CA at 10 kPa CO2 and 2 kPa 02 for 2-3 weeks could sustain un-rooted cuttings, in a pests-free state whilst retaining the ability of the cuttings RF. The results showed that stomata aperture may be altered by high CO2 concentration combined with low 02, and results indicated that this effect was not only caused by high CO2 but also by low 02 concentration. In addition, the results indicated that CA storage, stomata conductance, and water stress ofkalanchoe cuttings may be correlated. Monitoring Gs ofleaves ofcuttings could be used as a nondestructive indicator of storability and quality status. Based on the novel positive preliminary results reported here, a protocol that focuses on minimising water loss should be developed and optimised for kalanchoe.