ISHS Acta Horticulturae 470: II International Symposium on Pistachios and Almonds
EFFECT OF DRIP IRRIGATION ON LEAF GAS EXCHANGES AND STEM WATER POTENTIAL IN PISTACHIO CV. LARNAKA |
| Authors: | L. de Palma, V. Novello |
| Keywords: | Pistacia vera, leaf net CO2 uptake, stomatal conductance, leaf transpiration, plant-based water potential |
| Abstract:
The influence of irrigation treatments restoring 0, 25, 50, and 75% ETc (0, 1,500, 3,000, and 4,500 m3 ha-1 per year) was assessed in terms of leaf net CO2 assimilation, stomatal conductance, leaf transpiration, quantum yield, water use efficiency and stem water potential. Leaf gas exchange rates were influenced by normal fluctuations in the growing cycle climatic conditions rather than by the irrigation treatment. However, under dry conditions, restoring 25 and 50% ETc increased the rate of leaf net CO2 assimilation (+ 10 and +20%), more so than the rate of leaf transpiration (+ 0.5 and + 7%), and thus resulted in a markedly higher water use efficiency (+ 26 and + 30%). In the treatment restoring 75% ETc, leaf net CO2 assimilation increased only by 7%, the same extent as the transpiration increment; so that water use efficiency rose only by 9%. Stem water potential was influenced by growing cycle and seasonal climatic conditions as well as by the irrigation treatment. Under the trial conditions, lower photosynthetic rates in the maximum irrigation treatment might have been due to root sensitivity to soil oxygen depletion in saturated soils. The lack of treatment effects on stomatal conductance indicates that non-stomatal mechanisms played a role. | |
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