Effects of root confinement on lemongrass (Cymbopogon citratus)

The root confinement (RC) is a stressful factor that changes metabolic and growth process in plants. Many works have demonstrated reduction in shoot growth when plants are growing in pots. Lemongrass (Cymbopogon citratus) produces essential oil used by industries for vitamin A synthesis and as flavouring, among others. This work aims to evaluate the RC effects on lemongrass growth and photosynthesis. It was used a randomized block design, with a factorial scheme 5 x 5 and 5 replications per treatment. Vegetative tillers were grown in 42; 11; 6 1.5 and 0.5 L pots, as confinement levels (CL). At 60; 90; 120; 150, and 180 days after planting (DAP) were evaluated: photosynthetic rate, number of tillers, foliage area, shoot and root dry matter. The factor confinement time (CT) was composed by the evaluating periods. It was verified that RC reduced lemongrass growth, mainly, due to tillering inhibition. Plants under RC also showed reduced foliage area, shoot and root dry matter. The photosynthetic rate was reduced in around 50% in plants grown in 11; 6; 1.5 and 0.5 L, while it was constant in plants grown in pots of 42 L. These results alert to the use of pots on scientific experiments, as treatment effects can be confused with those from RC.