STOMATAL RESISTANCE AND LEAF WATER POTENTIAL MEASURED UNDER FIELD CONDITIONS

Four different soil water regimes were set up in replicated field experiments in order to investigate the relation between soil moisture and water status of sugar beet (Beta vulgaris L.; cv ‘Dymo Monopura’). Soil (_S) and leaf (_L) water potential, abaxial (R₁) and adaxial (R_u) stomatal resistance were measured from emergence to harvest.
Stomata widths and frequencies were determined both in abaxial and adaxial leaf surface.
Results showed a linear relationship between upper (R_u) and lower (R₁) leaf resistance irrespective of water regime, time of day and season.
The leaf water potential of non-irrigated plants was highly correlated with the soil moisture potential.
The daily trend of R was a quadratic curve with the minimum reached 2 hours after midday in all the treatments.
Values of R decreased during the growing season.
As the drought intensified, the differences between the treatments increased and the daily range of R and _L was the highest.
Stomatal resistance, under the conditions herein described, seems to be unable to estimate the water status of sugar beet except in extremely dry conditions.

I International Symposium on Water Relations in Fruit Crops

P. Rossi Pisa, F. Bigaran

https://doi.org/10.17660/ActaHortic.1985.171.12