he daily dynamics of CO2 concentration in the culture vessels and the photoautotrophic or photomixotrophic growth capacity of apple (Malus pumila hybrid MM 106 paradisiaca x Northern Spy) cultures were studied. The photoautotrophic cultures were grown on a sugar-free growth medium and submitted (0S+CO2) or not (0S-CO2) to periodic injections of exogenous CO2. The photomixotrophic cultures were grown in the presence of 30 g dm-3 sucrose, with (30S+CO2) or without (30S-CO2) CO2 enrichment. The photosynthetic photon flux density applied was of 210 ± 5 μmol m-2s-1. In the 0S-CO2 treatment, CO2 showed rather uniform and narrow light-dark fluctuations throughout the culturing cycle. In the 30S-CO2 treatment, the daily ratio between CO2 produced during the dark period and that uptaken during the following light period, was almost always above 1 with the only exception of a few days (from the 5 th to the 9th day) when the amount of photosynthesised CO2 was equal to or higher than that produced during dark respiration. The 0S+CO2 cultures needed to be enriched all days with exogenous CO2 to avoid periods of gas deficiency while in 30S+CO 2 the CO2 injected the first culturing day was uptaken over 5 d, thereafter, daily injections were necessary. Culture fresh and dry mass, number of newly formed shoots and number of nodes per shoot in 0S+CO 2 treatment did not statistically differ from the values obtained with 30S-CO2. The highest growth was observed in 30S+CO2 treatment. The increase in culture fresh mass due to 1 μmol of CO 2 added to the culture vessels was 1.54 and 1.36 mg for 30S and 0S respectively, while in terms of dry mass the increase was about 2.5 times higher in the sugar-enriched treatment. CO2 enrichment accounted for 77.3 % and 21.2 % of the final fresh mass in 0S+CO2 and 30S+CO 2, respectively.
|Autori:||Morini S; Melai M.|
|Titolo:||CO2 dynamics and growth in photoautotrophic and photomixotrhopich apple cultures|
|Anno del prodotto:||2003|
|Digital Object Identifier (DOI):||10.1023/B:BIOP.0000022246.09161.63|
|Appare nelle tipologie:||1.1 Articolo in rivista|