Influence of simulated microgravity on growth, yield, and quality of leafy vegetables: Lettuce and rocket.

A closed hydroponic system (Porous Tube Plant Nutrient Delivery System) combined with a horizontal uniaxial clinostat has been designed and built-up to grown leafy vegetables under simulated microgravity conditions. Two research activities were carried out to investigate the effects of clinorotation on growth, yield, and quality of rocket seedlings (Eruca saliva Mill.) and lettuce plants (Lactuca saliva L.), which may constitute a source of health), fresh food for the astronauts during space missions. The percentage of germination of rocket was affected by clinorotation with the highest value observed in the control treatment. The seedling fresh weight of the control treatment, was 19 % higher compared to that of the clinorotation treatment while the opposite trend was observed for chlorophyll a/b ratio. Clinorotation did not influence the quality (total carbohydrates, triglycerides, carotenoids and vitamin C) of the rocket seedlings. Shoot fresh and dry weight, leaf area, specific leaf dry weight, root dry weight and shoot:root ratio were lower in the clinorotated lettuce plants than those grown in the control treatment. Quality parameters (chlorophyll, total carbohydrates and vitamin C) of lettuce plants were negatively affected by clinorotation. Lettuce genotype comparison under simulated microgravity showed that 'Mortadella di primavera' should be adopted for space experiments due to the better growth and productivity.