scholarly journals Physiological and biochemical parameters of apricot varieties characterized by various drought resistance

Author(s):  
I. N. Paliy ◽  
T. B. Gubanova ◽  
A. E. Paliy

The aim of the presented work was to identify the peculiarities of the photosynthetic apparatus, the activity of redox enzymes and proline content in apricot varieties with different drought tolerance. Four apricot varieties such as Kazachok, Nagycorosi Orias, Khurmai and Krymsky Amur were used as objects of the studies. To determine the effect of drought on the state of the photosynthetic apparatus, a series of experiments was carried out to analyze chlorophyll fluorescence induction (ChFI) parameters, peroxidase and polyphenol oxidase activity and proline content in apricot leaves. It was found out that in summer 2018, when the amount of precipitation exceeded the climatic norm, during the period of the maximum drought probability, catalase activity decreased, polyphenol oxidase activity increased or was unchanged and the proline content did not change significantly. Extremely arid conditions in summer 2019 resulted in peroxidase and polyphenol oxidase activation and a decrease in the proline concentration in all the studied apricot varieties. However, the drought tolerant variety Nagycorosi Orias was characterized by the most stable indexes of peroxidase activity during the entire experiment. A decrease in the leaf tissue hydration was the reason for the increase in the base fluorescence and the decrease in the correlation index of the rate constants of photochemical and nonphotochemical deactivation of excitation in PS 2. In the drought tolerant varieties Nagycorosi Orias and Kazachok changes in the ChFI parameters were reversible. It has been demonstrated that disturbances during primary photosynthetic processes were most pronounced during the restoration of turgidity. It was revealed that the most sensitive parameters of ChFI in apricot are the characteristics of the fast phase. A decrease in reparative abilities in the midsummer was probably associated with age-related changes in leaves and fruit load.

Author(s):  
O. A. Grebennikova ◽  
T. B. Gubanova

The results of the studies of proline content, peroxidase, catalase, polyphenol oxidase activity and chlorophyll fluorescence induction (ChFI) parameters in leaves of Ficus species and cultivars under controlled dehydration conditions are presented. It was shown that the ChFI parameters, the most sensitive to the lack of water availability, are the characteristics of the chlorophyll fluorescence fast phase. Proline content, peroxidase and polyphenol oxidase activity can be used to addition diagnose of drought resistance of the plants of the genus Ficus. The cultivars Sabrutsiya Rozovaya, Sary Stambulskij and the species F. palmata are relatively drought tolerant.


Author(s):  
I. N. Paliy ◽  
T. B. Gubanova ◽  
A. E. Paliy ◽  
E. A. Melkozerova ◽  
N. V. Mesyats ◽  
...  

In order to determine special features of the photosynthetic apparatus activity and the content of thread compounds in various apricot cultivars during the period of maximum drought probability on the Southern Coast of the Crimea, we studied the concentration of proline, phenolic compounds and chlorophylls, as well as the parameters of chlorophyll fluorescence induction (CFI) in some apricot cultivars ( Prunus armeniaca Lam.), characterized by various degree of drought tolerance (‘Alupkinsky’, ‘Krymskiy Amur’) are weakly resistant; Khurmai cultivar is characterized by labile resistance, and the cultivars Kazachok, Professor Smykov, Nagycorosi Orias are drought tolerant cultivars). It has been found out that drought-resistant cultivars are characterized by a relatively low content of proline in their leaves. It is supposed that this amino acid is involved in the protective reactions of apricot plants under water stress. The results of the photosynthetic apparatus studies in the presented cultivars demonstrated that in leaves, water loss less than 20% caused reversible changes in the parameters of CFI. An increase in the water deficit up to 25-30% caused the destruction of PS2 in weakly drought-resistant cultivars. The most stable photosynthetic apparatus activity was noticed in the cultivar Nagycorosi Orias. Deviations in photosynthesis processes were most pronounced during the period of water restoration in leaves.


1997 ◽  
Vol 34 (2) ◽  
pp. 155-159 ◽  
Author(s):  
Antonio Rescigno ◽  
Francesca Sollai ◽  
Andrea C Rinaldi ◽  
Giulia Soddu ◽  
Enrico Sanjust

Chlorophyll fluorescence induction (at 20 °C and 77 K) and quenching were analysed in relation to effects of environmental stresses imposed by chilling in high light and by freezing and thawing of spinach ( Spinacia oleracea L.) leaves. The data indicate that cold acclimation of spinach plants, which leads to increased frost tolerance of the leaves, results in decreased susceptibility to photoinhibition of photosynthesis at chilling temperatures. When plants acclimated to 18 °C and 260-300 µmol quanta m -2 s -1 were exposed to higher light (550 µmol quanta m -2 s -1 ) at 4 °C, they developed strong photoinhibition, as characterized by decreased quantum yield of O 2 evolution and decreased ratio of variable: maximum fluorescence (F V /F M ) of photosystem II. The decrease in F V /F M resulted from a decline in F V and an increase in F 0 . The F V /F M ratio was lowered to a significantly greater extent when induction was recorded at 20 °C, as compared with 77 K. The effects related to photoinhibition were fully reversible at 18 °C in dim light. Plants that had been cold-acclimated for 10 days exhibited slightly decreased quantum yield and lowered F V /F M ratio. However, they did not show further photoinhibition on exposure to 550 µmol quanta m -2 s -1 at 4 °C. The reversible photoinhibition is discussed as a protective pathway serving for thermal dissipation of excessive light energy. It is hypothesized that such a mechanism prevents destruction of the photosynthetic apparatus, until other means of protection become effective during long-term acclimation to high light. Inhibition of photosynthetic carbon assimilation caused by freezing and thawing of leaves in the dark was closely correlated with inhibition of photochemical fluorescence quenching (q Q ). As a sensitive response of the thylakoid membranes to freezing stress, the energy-dependent quenching, q E , was inhibited. Only more severe impact of freezing caused a significant decline in the F V /F M ratio. It is concluded that measurements of fluorescence induction signals ( F V /F M ratios) provide a sensitive tool with which to investigate photoinhibition, whereas freezing damage to the photosynthetic system can be detected more readily by the quenching coefficients q Q and q E than by F V /F M ratios.


1985 ◽  
Vol 104 (3) ◽  
pp. 501-504 ◽  
Author(s):  
M. Havaux ◽  
R. Lannoye

SummaryDisks of hard wheat (Triticum durum Desf.) leaves subjected to rapid desiccation over 4 h showed noticeable changes in the shape of the in vivo chlorophyll fluorescence induction curves. In drought-sensitive varieties (such as Claridoc), water stress resulted in a strong inhibition of the slow fluorescence induction transients. In particular, the fluorescence quenching rate was markedly decreased in water-stressed leaf disks. In contrast, leaves of drought-resistant varieties (such as Aouedj) showed only minor changes in chlorophyll fluorescence. The results of this investigation suggest that the slow transient of the in vivo chlorophyll fluorescence induction phenomenon may provide a simple method for selecting drought-tolerant wheats.


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