PHOTOSYNTHESIS, LEAF WATER POTENTIAL, AND STOMATAL CONDUCTANCE IN OLEA EUROPAEA UNDER WET AND DROUGHT CONDITIONS

The relationship of net photosynthesis (Pn) and dark respiration (Rd) to water saturation deficit (WSD), leaf water potential, leaf conductance and transpiration rates were studied in summer on three year old potted olive trees cvs.
Arbequina, Manzanilla and Sevillana.

Stomatal conductance and transpiration were measured with a steady state porometer (LI 1600), water potential with a Scholander pressure bomb, and CO2 gas exchange in an open system with a differential IRGA (Grubb-Parson, model 120).

In well watered trees, leaf water potential varied from -7 bars in the sunrise to -25 bars at noon; maximum resistances were 0.8 cm.s-1 with 8 μg.cm-2.s-1 transpiration rate; and CO2-uptake were about 18 mg.dm-2.h-1. No significant differences were found between the three cultivars.

Moisture stress reduced the rates of Pn in the course of drying period in correspondance with a strongly decrease in WSD, leaf water potential, leaf conductance, and transpiration.
Dark respiration declined with leaf water potential.
After rewatering the photosynthetic and conductance recovery was correlated with recuperation of RWC and leaf water potential.

I International Symposium on Water Relations in Fruit Crops

J. Jorba, L. Tapia, D. Sant

https://doi.org/10.17660/ActaHortic.1985.171.21