CO₂ Assimilation and Water Relations of Almond Tree (Prunus amygdalus Batsch) Cultivars Grown Under Field Conditions

Abstract

Gas exchanges and leaf water potential (ψ w ) of six-years-old trees of fourteen Prunus amygdalus cultivars, grafted on GF-677, were studied in May, when fruits were in active growing period, and in October, after harvesting. The trees were grown in the field under rain fed conditions. Predawn ψ w showed lower water availability in October compared with May. The lowest ψ w values at midday in May increased gradually afterwards, while in October they decreased progressively until night, suggesting a higher difficulty to compensate the water lost by transpiration. However, relative water content (RWC) measured in the morning was similar in both periods, most likely due to some rainfall that occurred in September and first days of October that could be enough to re-hydrate canopy without significantly increasing soil water availability. The highest net photosynthetic rate (P N ) was found in both periods early in the morning (08:00-11:00). Reductions in P N from May to October occurred in most cultivars except in José Dias and Ferrastar. In all cultivars a decrease in stomatal conductance (g s ) was observed. Photosynthetic capacity (P max ) did not significantly change from spring to autumn in nine cultivars, revealing a high resistance of photosynthetic machinery of this species to environmental stresses, namely high temperature and drought. Osmotic adjustment was observed in some cultivars, which showed reductions of ca. 23 % (Duro d' Estrada, José Dias) and 15 % (Tuono) in leaf osmotic potential (ψ π ). Such decreases were accompanied by soluble sugars accumulation. The Portuguese cultivar José Dias had a higher photosynthetic performance than the remaining genotypes.

Chlorophyll fluorescence performance of sweet almond [Prunus dulcis (Miller) D. Webb] in response to salinity stress induced by NaCl

“…---Non-stomatal effects may prevent photosynthetic activities as has been reported for eucalyptus (Rawat and Banerjee 1998), pistachio (Ranjbar et al 1999(Ranjbar et al , 2002, and almond (Matos et al 2004, Rouhi et al 2006. Salt stress can also lead to destruction of fine chloroplast structure and instability of pigment-protein complexes (Zaman et al 2002).…”

Vegetative growth, compatible solute accumulation, ion partitioning and chlorophyll fluorescence of 'Malas-e-Saveh' and 'Shishe-Kab' pomegranates in response to salinity stress

“…Thus, plants respond to salinity at nonstomatal and/or stomatal levels. Nonstomatal responses include instability of pigment-protein complexes and destruction of chloroplast structure (Zaman et al 2002), which inhibits photosynthetic activities (Matos et al 2004, Rouhi et al 2006. At the stomatal level, the stomatal activity is reduced and it limits photosynthesis (Lawlor and Cornic 2002) and photon flux energy used for photochemistry (Cornic 1994).…”

Photosynthetic responses of apricot (Prunus armeniaca L.) to photosynthetic photon flux density, leaf temperature, and CO₂ concentration

“…In recent years, photosynthesis of fruit trees has been studied in banana (Thomas and Turner 2001), mango (Shivashankara and Mathai 2000), grape (Patakas et al 2003, Cohen et al 2005, apple (Jia andLi 2002, Mierowska et al 2002), almond (De Herralde et al 2003, Matos et al 2004, jujube (Su and Liu 2005), etc. But no research has been reported on apricot acclimation in controlled environments.…”