Comparative studies of carnation micropropagation under four different ventilation rates showed that using gas-permeable filters, with gelled or liquid media and modifying the volume of culture medium, it was possible to establish a suitable hydric state to obtain good proliferation rates with gelled and liquid medium, as well as optimal acclimatization of microcuttings. The following parameters were measured: ventilation rate, gas exchange coefficients, relative water loss, increase of agar concentration, micropropagation rates, percentage of hyperhydricity, and acclimatization rates. Our results confirm that it is possible to avoid hyperhydric plants cultured in liquid medium with the use of ventilated culture vessels through the control of the water relations during the multiplication phase and, at the same time, keeping the micropropagation rate.

Explants of Actinidia deliciosa Chev. Liang and Ferguson var. Hayward were cultured in controlled CO2 atmospheres in the presence of different sucrose concentrations. Organogenesis was measured after 45 days in explants from the different assays, and quantification of photosynthesis, transpiration, chlorophylls, RUBISCO and total soluble protein content was performed in leaves from the different treatments. The best results were those of explants cultured at 600 &mgr;mol CO2 mol-1 on 20 g l-1 of sucrose for the first 20 days and then transferred to sucrose-free medium until the end of the culture period. Increasing CO2 to 2000 &mgr;mol CO2 mol-1 in the atmosphere of the culture vessel reduced all the parameters studied. Photosynthesis of autotrophically developed explants trebled that of the reference heterotrophic explants, as there was an apparent inverse relationship between photosynthesis and transpiration. Photosynthesis was saturated at 300 &mgr;mol m-2 s-1 PPFD and 600 &mgr;mol CO2 mol-1. Chlorophylls and RUBISCO presented differences between treatments, mainly between different CO2 concentrations, with the highest values in autotrophically cultured explants. Explants grown at 2000 &mgr;mol CO2 mol-1 showed the lowest RUBISCO/Prots ratio, probably due to negative adaptation of RUBISCO to long-term high CO2. In short, explants grown in a controlled microenvironment, with increased CO2 and under autotrophic conditions, developed wholly functional photosynthetic apparatus well prepared to be transferred to ex vitro conditions, which has many advantages in micropropagation.

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A method has been developed for the rapid and simultaneous extraction and analysis from plant material of 3‐indolylacetic acid (IAA), naphthalene acetic acid (NAA), abscisic acid (ABA) and the cytokinins benzyladenine (BA), zeatin, zeatin riboside, dihydrozeatin, dihydrozeatin riboside, isopentenyl adenine and isopentenyl adenosine. The method involves extraction with 80% (v/v) methanol, pre‐purification of the extracts through reversed phase C18 Sep‐Pak cartridges and immunopurification. The separation of the different compounds was accomplished by reverse‐phase high performance liquid chromatography for cytokinins, and by partition with diethyl ether for IAA, NAA and ABA. After methylation of the IAA fraction with diazomethane, quantification of all plant growth regulators (PGRs) was made by immunoassay. The percentage recovery at each step was monitored following the addition of radioactive compounds at the beginning of the process. The final recovery was 68% for IAA, 92% for NAA, 76% for ABA and 75% for BA. The method was applied to the analysis of PGRs in tissues and callus of kiwifruit (Actinidia deliciosa Liang and Ferguson).

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