SIMULTANEOUS RESPONSE OF STEM DIAMETER, SAP FLOW RATE AND LEAF TEMPERATURE OF TOMATO PLANTS TO DROUGHT STRESS

One of the many opportunities of direct crop monitoring is the ability to detect suboptimal growth conditions in a very early stage, so that both productivity and quality can still be guaranteed.
In this study, eight tomato plants (Lycopersicon esculentum Mill. ‘Clothilde’) were hydroponically grown in order to modulate the root zone.
Four of these plants were subjected to drought stress by adding 200 g/L poly-ethylene glycol 6000 to the nutrient solution.
This treatment immediately resulted in a considerable reduction in sap flow rate, thereby forcing the plants to use their internal water storage to support transpiration.
Consequently, a stem diameter shrinkage of 0.1 mm was measured before visual symptoms of turgidity loss were observed.
At leaf level, the leaf temperature increased to a level above the predicted leaf temperature, which indicated that the stomata were gradually closing.
Measurements of stomatal resistance confirmed this hypothesis.
The lack of transpiration and, hence, the ceased cooling of the leaves during the treatment caused permanent damage to the leaves, which was also confirmed by a permanent reduction in sap flow rate.
In conclusion, stem diameter, sap flow rate and leaf temperature measurements detected drought stress before visual symptoms were observed, so they can be implemented in an early-warning system.
A combination of these plant responses gives a good overall picture of the water status of a tomato plant.

International Symposium on High Technology for Greenhouse System Management: Greensys2007

K. Vermeulen, K. Steppe, N.S. Linh, R. Lemeur, L. De Backer, P. Bleyaert, J. Dekock, J.M. Aerts, D. Berckmans

speaking plant, crop monitoring, early-warning, climate control

https://doi.org/10.17660/ActaHortic.2008.801.154