EVALUATION OF A SENSOR FOR ONLINE MEASUREMENTS OF STEM DIAMETER VARIATIONS OF LEAFY VEGETABLES
Continuous monitoring of leafy vegetables in greenhouses could be of great assistance to growers to obtain optimal plant growth with little or no basal rotting and no marginal necrosis or tipburn. However, continuous measurements of plant responses have remained mainly restricted to leaf temperature for monitoring purposes for leafy vegetables. Leaf temperature measurements can give some information about the plant transpiration rate, but direct information about the plant water status remains fairly limited, and no information at all is provided about the plant growth rate. The present contribution evaluated the use of a device which allowed online measurements of the diameter (SD) of the very short and hidden stem of butterhead lettuce (Lactuca sativa L. var. capitata). We were able to measure SD variations during the whole growing cycle in an automated way, with the exception of a short period just after transplantation. No significant sensor pressure effect on growth was observed, and the recorded SD variations showed a good correlation with manual measurements on the control plants. Moreover, we found a strong correlation between SD and plant fresh weight. However, the relationship SD versus fresh weight was season-dependent. Additionally, the sensor was able to reveal stem shrinkage due to drought stress, which means these measurements can provide instantaneous information on the actual plant water status.
Bleyaert, P., Vermeulen, K., Steppe, K. and Dekock, J. (2012). EVALUATION OF A SENSOR FOR ONLINE MEASUREMENTS OF STEM DIAMETER VARIATIONS OF LEAFY VEGETABLES. Acta Hortic. 927, 571-579
Lactuca sativa L. var. capitata, butterhead lettuce, phytomonitoring, plant growth, plant water status