1,721,309 research outputs found
Editor of the "Proceedings of the fourtheenth international symposium on apricot breeding and culture"
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Effetto cumulato negli anni della carenza idrica sulla crescita della parte aerea e radicale della cv. Coratina.
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Adaptative mechanisms of olive tree to drought
No full textOlive trees is able to resist drought stress by a broad range of physiological and biochemical mechanisms. Olive
trees lower the water content and water potentials of their tissues, establishing a high potential gradient between
leaves and roots. In drought conditions, olive plants stop shoot growth but not photosynthetic activity and
transpiration. This allows continued the production of assimilates as well as their accumulation in the various
plant parts, in particular in the root system, creating a higher root/leaf ratio compared to well-watered plants.
Active and passive osmotic adjustment play an important role in maintaining cell turgor and leaf activities which
depend on it. Sugars, especially mannitol and glucose, play a major part in the osmotic adjustment of leaves. In
addition, the osmotic adjustment observed in the root system allows maintenance of cell turgor, avoiding or
delaying the separation of roots from soil particles. Moreover, in trees subjected to severe drought the nonstomatal
component of photosynthesis is affected and likely a light-dependent inactivation of the photosystem II
occurs. The increase of malondialdehyde content and lipoxygenase activity, two markers of oxidative damage
related to drought stress, suggest that water deficit is associated with lipid peroxidation mechanisms at cellular
level both in leaves and roots. Finally, in olive trees, the activities of some antioxidant enzymes, such as
superoxide dismutase, catalase, ascorbate peroxidase and peroxidase, involved in the scavenging of activated
oxygen species and in other biochemical pathways, increase during a period of drought. This suggest that higher
activities of some antioxidant enzymes are required for a better protection against oxidative stress related to
water deficit
Drought resistance mechanisms in olive tree
No full textOlive trees (Olea europaea L.) are commonly grown in the Mediterranean basin and are able to resist severe and prolonged drought under environmental conditions characterized by high temperatures and high irradiance levels. This species is able to resist drought stress by a broad range of physiological and biochemical mechanisms.
Olive trees lower the water content and water potentials of their tissues, establishing a high potential gradient between leaves and roots. In drought conditions olive plants stop shoot growth but not photosynthetic activity and transpiration. This allows continued the production of assimilates as well as their accumulation in the various plant parts, in particular in the root system, creating a higher root/leaf ratio compared to well-watered plants.
Active and passive osmotic adjustment play an important role in maintaining cell turgor and leaf activities which depend on it. Sugars, especially mannitol and glucose, play a major part in the osmotic adjustment of leaves. Organic acids, such as citric and malic, also play an important role in active osmotic adjustment. In addition, the osmotic adjustment observed in the root system allows maintenance of cell turgor, avoiding or delaying the separation of roots from soil particles. The accumulation of proline in leaves and roots indicates a possible role of this aminoacid in osmotic adjustment.
Moreover, in trees subjected to severe drought the non-stomatal component of photosynthesis is affected and likely a light-dependent inactivation of the photosystem II occurs. The increase of malondialdehyde content and lipoxygenase activity, two markers of oxidative damage related to drought stress, suggest that water deficit is associated with lipid peroxidation mechanisms at cellular level both in leaves and roots.
Finally, in olive trees, the activities of some antioxidant enzymes, such as superoxide dismutase, catalase, ascorbate peroxidase and peroxidase, involved in the scavenging of activated oxygen species and in other biochemical pathways, increase during a period of drought. This suggest that higher activities of some antioxidant enzymes are required for a better protection against oxidative stress related to water deficit
Inhibition of photosynthesis in olive trees (Olea Europaea L.) during water stress and rewatering
No full textThe effect of high levels of natural light on leaf photosynthesis in olive trees (Olea europaea L. var. Coratina), grown in pots outdoors in the summer and subjected to water, stress, was studied. Net photosynthetic rates reached maximum values early in the morning in both control and stressed plants and subsequently declined gradually. This inactivation of photosynthetic activity was accompanied by changes in the fluorescence characteristics of the upper intact leaf surface. The maximum fluorescence yield (Fp) and the ratio Fv/Fp decreased at midday especially in water-stressed plants, but the initial fluorescence (Fo) rose to a maximum value at midday and declined again in the afternoon. In control plants the values of maximum fluorescence Fp and the ratio Fv/Fp increased again in the afternoon and had recovered almost completely by 8 p.m. as the leaf water potential recovered. In stressed plants this diurnal recovery was not complete, so that the photosynthetic rates and the ratio Fv/Fp declined gradually during the development of water stress. These results indicate that in olive trees subjected to severe water stress the non-stomatal component of photosynthesis was affected and perhaps a light-dependent inactivation of the primary photochemistry associated with photosystem II (PSII) occurred. Four to five days after rewatering severely stressed plants, the predawn leaf water potential, net photosynthetic rates and chlorophyll fluorescence indices recovered only partially
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