Azam Amiri; Bahram Baninasab
Abstract
Introduction: Salinity is a common abiotic stress that seriously affects crop production in some parts of the world, particularly in arid and semi-arid regions. The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, ...
Read More
Introduction: Salinity is a common abiotic stress that seriously affects crop production in some parts of the world, particularly in arid and semi-arid regions. The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, specific ion effect (salt stress), or a combination of these factors. Paclobutrazol (PBZ), a member of the triazole plant growth inhibitor group, is a broad-spectrum gibberellin biosynthesis inhibitor. Triazoles have both fungal toxicity and plant growth regulatory effects. They also increase tolerance of various plant species to biotic and abiotic stresses, including fungal pathogens, drought, air pollutants, and low- and high-temperature stress. According to our knowledge, there are no reports on the effects of exogenous PBZ enhancing vegetative peach- almond hybrid (GF 677) rootstock tolerance to salt stress. Therefore, the objective of this work was the possibility test of this idea that PBZ application would protect GF 677 rootstock from damaging effects of salinity.
Materials and Methods: One-year-old rooted cuttings of GF 677 were grown in in plastic pots in the research greenhouse of Agricultural College, Isfahan University of Technology of Iran. The minimum and maximum temperatures during the experiment period were 19 and 32˚C, respectively. After cutting establishment (3 months), the plants were sprayed twice (with a 7 days interval) with 0 (control), 20 and 40 mg l-1 PBZ to the point of run-off. One week after the second foliar application of PBZ, each plants was subjected to one of several salt stress treatments. The salt treatments (0, 25 and 50 mM NaCl) were applied to the pots intervals in 0.5 l of irrigation water. To avoid osmotic shock, the NaCl concentration was increased gradually. The layout was a 3×3 factorial experiment in a completely randomized design, with four replications. The experimental measurements were carried out 60 days after beginning the salt treatments.
Results and Discussion: The results showed that salt stress and application of PBZ significantly affected injury rating valve (IRV). The Injury rating value of plants was found to increase significantly as the salt concentration was raised. After exposure to salt stress those plants that did not receive PBZ exhibited higher symptoms of salt injury. There was a significant interaction between salinity and PBZ application. The lowest IRV in all NaCl concentrations observed when 20 mg l-1 PBZ was applied. Salinity caused significant decrease leaf parameters so that the lowest means of leaf number (12.5) and leaf fresh weight (6.52 g) were recorded at 50 mM NaCl treatment, showing a 55.80% and 41.78% decrease compared with the control, respectively. The application of PBZ significantly increased leaf number, with the largest increase when 40 mg l-1 PBZ was applied. The interaction between salinity and the application of PBZ showed that at 25 mM NaCl maximum valve of leaf number was observed in plants after spraying with 40 mg l-1 PBZ. Relative leaf chlorophyll (RLC) was not affected by salt stress. Application of PBZ significantly increased relative RLC value compared with the control, with the largest increase in RLC measured when 20 mg l-1 PBZ was applied. The interaction between salinity and the application of PBZ showed that at 50 mM NaCl maximum valve of RLC was observed in plants after spraying with 20 mg l-1 PBZ. The proline content of leaves was significantly influenced by the salt stress and PBZ application, but not their interaction. Salinity stress, increased proline content in the leaves of salt-treated plants. At 50 mM NaCl, proline content was maximum compared to those of the controls and other salt levels. PBZ treatment increased proline content in leaves. The highest proline content was obtained from leaves of the plants treated with 40 mg l-1 PBZ (55.62μmol g-1 FW), which was 39.18 % more than the control. Salt stress significantly reduced the relative water content (RWC) with maximum reduction observed in plants grown by 50 mM NaCl. Application of PBZ significantly increased RWC compared with the control, with the largest increasing in RWC at 20 mg l-1 PBZ application. Leaf electrolyte leakage was affected by both salt stress and PBZ application. Salt stress significantly increased leaf electrolyte leakage, with a maximum increase observed in plants grown by 50 mM NaCl. The application of PBZ significantly decreased electrolyte leakage in leaf discs, with the largest decreaseing in leaf electrolyte leakage measured at 20 mg l-1 PBZ application..There was a significant interaction between salinity × PBZ concentrations. However, the greatest decreasing in leaf electrolyte leakage occurred at 40 mg l-1 PBZ in non-saline condition. In this study, the correlation between vegetation and physiological parameters of GF677 plants subjected to salt stress was analyzed. These correlations suggested that salt injury symptoms was negatively correlated with number and fresh weight of a leaf, RWC, RLC, but positively correlated with proline content and leaf electrolyte leakage.
Conclusions: in overall, this investigation revealed that salt stress had an inhibitory effect on the vegetative growth of GF 677 plants. The responses of GF 677 plants to the PBZ treatments suggest that the application of PBZ could partially increase the survival capacity of GF 677 plants and protect the plants against injuries such salt stress.
Ali Momenpour; Ali Imani; Davoud Bakhshi; Hamed Rezaie
Abstract
Introduction: Almond (Prunus amygdalus B.) is one of the most important crops consumed as a dry fruit and it is mainly adaptable to arid and semi-arid regions mostly suffering from salinity stress (8). Soils with dry humidity regime are dominant in Iran and in the world at large and mostly include regions ...
Read More
Introduction: Almond (Prunus amygdalus B.) is one of the most important crops consumed as a dry fruit and it is mainly adaptable to arid and semi-arid regions mostly suffering from salinity stress (8). Soils with dry humidity regime are dominant in Iran and in the world at large and mostly include regions with more evaporation than precipitation. This in turn leads to increased salinity of the soil (9 and 10). Based on available reports, roughly 12.5% of land areas in Iran are saline, which overwhelmingly contain sodium, while more than 800 million hectares of land area on the earth (6% of overall global land area) are affected by salinity (9 and 10). Therefore, compound of rootstock and scion may be used as one of the influence factors in sensitivity or tolerance to salinity of planted fruit trees including almonds (8 and 11). In recent years, for various reasons including the uniformity of trees, instead of sexual rootstock, vegetative rootstock is used. Rootstock GF677 an inter-specific hybrid (Almond Peach) is propagated asexually as clone (8). It has been reported that rootstock GF677 is tolerant to salinity while rootstock nemagard (P. persica X P. davidiana) is sensitive to salinity (16). It has been reported that rootstock GF677 tolerated salinity (5.5 ds/m), (19) or 5.2 ds/m (17 and 14).However, as plant species and different cultivars within the same plant species vary considerably in their tolerance to salinity (10), properly selecting plants and/or cultivars that can be grown well under adverse conditions, created in the root zone by salinization, is the most efficient and environmentally friendly agricultural practice for a more permanent solution of the problem of salinity (10).
Despite the presence of information on the effect of salinity on concentration of nutrition elements of almond cultivars leaves and roots, tolerantscion/rootstock combinationshave not been introduced for this plant. Therefore, the aim of the present study is to evaluate the effects of salt stress on concentration of nutritional elements of selected almond genotypes leaves and roots, grafted on GF677 rootstock and introducing most tolerant genotypes to it.
Materials and Methods: In this research, the effects of salinity stress were investigated on nutrient of almond leaves and roots by a completely randomized design (CRD), with two factors, genotype (in the four levels) and irrigation water salinity (in the five levels) with tree replications in the research greenhouse of Seed and Plant Institute in the year 2013. Studied Genotypes included ‘Shokofeh’, ‘Sahand’ and ‘13-40’ budded on GF677 and ‘GF677’ (none budded as control) and irrigation water salinity included 0, 1.2, 2.4, 3.6 and 4.8 g/l of natural salt (whose electrical conductivity are equal to 0.5, 2.5, 4.9, 7.3 and 9.8 ds/m, respectively).Nutrition elements such as K+, Ca++, Mg++, P, Na+, Cl-, Zn++, Cu++, Fe++, Na+to K+ ratio, Na+ to Ca++ ratio, Na+ to Mg++ ratio, Na+ to P ratio, were investigated in selected almond genotypes leaves and roots. Then salinity stress was applied.
Results and Discussion:The results showed that type of scion and level of salinity had affected nutrient concentration of leaves and roots. Evaluation of nutrition elements concentration in leaves and roots showed that in the total studied genotypes, the highest percentage of Na+, Cl-, Na+to K+ ratio, Na+ to Ca++ ratio, Na+ to Mg++ ratio, Na+ to P ratio and the lowest percentage of Ca++, Mg++, P and concentration of Cu++ in leaves and roots and the lowest concentration of Zn++ in leaves were observed in treatment 9.8 ds/m. The result showed that the type of scion was effective in obstruction of Na+absorptionby therootsand their transportationtoleaves.Percentageof Na+, Cl-, Na+ to K+ ratio and Na+ to P ratio in levels of salinity 3.6 and 4.8 g/l and Na+ to Ca++ ratio, Na+ to Mg++ ratio in level of salinity 4.8 g/l in ‘Shokofeh’ cultivar were significantly lessthan other genotypes. Also, this cultivar could compare with control plants at levels of salinity 3.6 and 4.8 g/l by increasing the percentage of K+and concentration of Fe++ ,and it could tolerate the harmful effects of Na+ more than other genotypes.
Conclusion: Overall, the results showed that both rootstock and type of scion were effective in tolerance to salinity. GF677 rootstocks (non-budded) tolerated salinity of 2.4 g/l (4.9 ds/m), but withincreasingsalt concentration, plants were severely damaged. The results showed that the type of scion affected tolerance to salinity. In this research,at base concentration of nutritional elements,‘Shokofeh’ cultivar was the most tolerant cultivar against salinity stress. This cultivar could well tolerate salinity of 3.6 g/l (7.3 ds/m) and partly salinity 4.8 g/l (9.8 ds/m). In contrast, Sahand cultivar was the most sensitive cultivar to salinity stress. These cultivar as GF677 rootstocks (non-budded as control) only could tolerate salinity of 2.4 g/l.
Vahid Rouhi; Zahra Rafiei
Abstract
Almonds belong to Prunus genus, which is related to Rosaceae family. It has close relatives with different species of stoned fruits. One of the main reasons for the long period of seed germination in Prunus is compound dormancy, such as the external seed cover as physical dormancy and embryo dormancy ...
Read More
Almonds belong to Prunus genus, which is related to Rosaceae family. It has close relatives with different species of stoned fruits. One of the main reasons for the long period of seed germination in Prunus is compound dormancy, such as the external seed cover as physical dormancy and embryo dormancy causes physiological dormancy. Seed stratification and treatments with various hormones are used to eliminate the physiological dormancy in Prunus genus seeds. Ancillary methods such as removing the shell and scarification are used in order to eliminate physical dormancy. This research was carried out in order to study the effect of scarification (scarification or lack of scarification) and gibberellic acid (0, 150, 300 and 450 mg/lit) on percent and rate of germination in four species of almond (Three wild species; Prunus elaeagnifolia, P. scoparia and P. lycioides and one domestic species; P. dulcis) in factorial design based on completely randomized design with three replications. Removing the shell caused a significant increase in the percentage and rate of germination in all species. In general, treatment of seeds with 300 mg/lit gibberellic acid increased percentage and rate of germination than control significantly, but according to depth of seed dormancy, the response of the species to the concentrations of gibberellic acid was different. According to the results, the seed germination amount is different in different genotype.
Jalil Dejampour
Abstract
In fruit trees damage of frost and freezing is depended to time of chillhng and tree phonological stage. Almond (Prunus amygdalus B. (and apricot (P. armeniaca L.) cultivars are usually the first fruit trees to bloom and susceptible to damaging frosts in the early spring. A study was conducted on different ...
Read More
In fruit trees damage of frost and freezing is depended to time of chillhng and tree phonological stage. Almond (Prunus amygdalus B. (and apricot (P. armeniaca L.) cultivars are usually the first fruit trees to bloom and susceptible to damaging frosts in the early spring. A study was conducted on different types of almond and apricot cultivars in order to investigation the main factors related to frosting, irregular of productivity and low crop load of trees for 10 years. Six almond cultivars; Sahand, A200, Shkoofeh (very late bloom), Touno, Super nova (late bloom and self- compatibility), Managa (early bloom) and 6 apricot cultivars; Canino, Royal, Telton (self- compatibility), Ordbad, Nasiri and Asgarabad (self- Incompatibility) were evaluated for aspects of some biological and physiological characteristics that related to frost tolerance and fruit set. The results of 10 years evaluation showed that some cultivars despite were resistant to spring frost and usually their crop load was optimum. In addition of freezing damage, other factors like; undesirable climatic conditions in flowering time, direct or indirect influence on bearing and fruit set. Touno and Super nova as self compatibility and late blooming almond cultivars, Canino, Royal and Tilton as self- compatibility apricot cultivars were tolerant to cool and unfavorable climatic conditions in early spring. Therefore, they usually had higher and regular productivity. This differences were related to some phonological and physiological characteristics like; time of flowering, interior components of flower buds, time of niter and period of dormancy, temperature reaction of flower buds, effective pollination period, self – compatibility, frost resistance of pistils and flowers.
Mehdi Oraei; Seyyed Jalal Tabatabaie; Esmaeil Fallahi; Ali Imani; Leila S. Fatemy
Abstract
Boron (B) toxicity is an important disorder that can limit plant growth in arid and semi-arid environments. It has been proven that use of tolerant rootstocks impede B uptake or transport to the aerial portions of plants. This may alleviate B toxicity in the scion, consequently improves the tolerance ...
Read More
Boron (B) toxicity is an important disorder that can limit plant growth in arid and semi-arid environments. It has been proven that use of tolerant rootstocks impede B uptake or transport to the aerial portions of plants. This may alleviate B toxicity in the scion, consequently improves the tolerance to excess B in the root zone. An experiment was conducted to find the effects of B toxicity on vegetative growth, physiological characteristics and B distribution of almond tree (Prunus dulcis Mill.) cv. “Ferragnes” grown in the controlled environment. Three levels of B (0.25, 10, 20 mg/L) from H3BO3 and two almond rootstocks (GF677, Tuono) were factorially combined in a completely randomized design with four replications. The results showed that B toxicity had significant effects on vegetative growth, physiological characteristics and B distribution in almond tree. With increasing B levels in nutrient solution, vegetative characteristics including leaf production percentage and main shoot elongation was decreased significantly. However, Fr/Tuono was affected less than Fr/GF677. Also, physiological characteristics such as electrolyte leakage percentage, proline content and leaf necrosis percentage were increased significantly in two scion-rootstock combinations. On the basis of these results, GF677 because of an inability to restrict uptake and/ or transport of excess B from root system to aerial parts of scion, have a higher sensitivity to B toxicity. Instead, Tuono via mechanism of preferential distribution of B in roots inhibited the accumulation of high concentration of B either in young leaves or meristematic tissues partially and protected these susceptible organs against injury caused by B toxicity. In conclusion, it seem that under excess B conditions Tuono rootstock have higher tolerance than GF677.
