ISHS Acta Horticulturae 449: II International Symposium on Irrigation of Horticultural Crops
EXPERIENCES ON THE RESPONSE OF ALMOND PLANTS (AMYGDALUS COMMUNIS L.) TO WATER STRESS |
| Author: | C. Germanà |
| Keywords: | Cultivars, basin-irrigation, leaf water potential, leaf temperature, net exchange rate, transpiration rate |
| Abstract:
A research has been carried out in Eastern Sicily on six cultivars and clones of 13 years old almond trees to assess their response to various degrees of water stress. In each genotype six plants were selected; three of them were unirrigated and three were basin-irrigated twice in the course of the summer. The following parameters were monitored: leaf water potential (  ), leaf and air temperature, CO2 net exchange rate (CER), transpiration rate (TR), stomatal conductance (SC), vapour pressure deficit (VPD), photosyntetically active radiation(PAR). Results showed a remarkable difference in responses from the various genotypes to water stress.
Leaf potential in unirrigated trees ranged between noon-time values of -2.8 to -4.7 MPa, while in irrigated trees it ranged between -2.0 to -3.6 MPa.
Leaf temperature was in all cases higher than that of the atmosphere independently of VPD values.
Net photosynthetic activity was reduced to very low levels (even negative in days of high evaporative demand), only temporarily relieved after irrigation events.
Since transpiration rates were less affected by water stress than photosynthetic activity, photosynthetic water use efficiency (WUE) and quantum yield (QY) were lowest in unirrigated plants; their values however were ranking according to cultivars' sensitivity.
A matrix of correlations between the principal climatic factors and physiological responses was developed.
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