The effect of a conveyer step on gas exchange of the “lettuce - soil-like substrate” system

Inclusion of the soil-like substrate (SLS) into life support systems with a high closure degree re-quires keeping an accurate intensity record of its gas exchange as a mineralization part of plant bio-mass. The given work is aimed at comparative es-timation of CO2 gas exchange of the experimental model “lettuce-SLS” with a periodic introduction of inedible plant biomass in it. Wheat straw was used as inedible plant biomass to supply mineral sub-stances in the SLS which were taken away with ed-ible biomass of the plants grown on it earlier. Here, the amount of vegetable mass introduced in the SLS was calculated according to equivalent of ni-trogen content in wheat straw and in edible bio-mass of gathered lettuce. Two cycles of lettuce growing on the SLS were carried out. In the result of the first research gas exchange characteristics of one-age lettuce cenosis cultivated on the SLS were obtained. In the result of the second research CO2 gas exchange characteristics of the conveyors with steps of 4 days and 7 days between plant ages were registered. The plants were grown in pressur-ized vegetative chambers with continuous registra-tion of CO2 concentration. It was found out that the period of intensive CO2 emission from the SLS after inedible plant biomass introduction into it appears to be one of characterizing conditions for optimal lettuce age numbers in a conveyor. Here an interval step weakly affects the amount of plant biomass inserted in the SLS and the plant productivity, but contributes to the determination of CO2 level and quantity fluctuations in the atmosphere of the ex-perimental model “lettuce-the SLS”.