Ventilation of culture vessels. II. Increased water movement rather than reduced concentrations of ethylene and CO2 is responsible for improved growth and development of Delphinium in vitro

Summary

Delphinium plantlets were cultured during Stage III in vessels modified to give different gas exchange rates. Modifications were achieved by the fitting of a covered aperture, or by the sealing of the lids. The concentrations of CO₂ and ethylene were measured in conjunction with measurements of relative humidity, water loss, the uptake of mineral nutrients and growth. Both CO₂ and ethylene concentrations were low in intact vessels, and significantly higher in vessels sealed with parafilm. Water loss was similar in intact and in sealed vessels, indicating that the vessel lid acted as a good barrier to water but allowed high rates of gas exchange. Plant growth rate was not affected by the level of ventilation of the vessels although leaf area was greater in vessels having lower gas exchange rates. After one week of culture, tissue concentrations of calcium and magnesium were highest in the vessels having the highest gas exchange rates. Relative humidity within the culture vessels was not affected by the level of ventilation. Improved stomatal performance, growth and survival of Delphinium from ventilated vessels appears to be due to an increased flow of water, and not to amelioration of the gaseous environment.