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- Author or Editor: Majid Rahemi x
The effects of NaCl stress on some growth parameters and ion accumulation in roots, shoots, and leaves of four fig genotypes (S × P, S × K, S × Sh, and S × D) were investigated. Eight-month-old fig plants growing in a mixture of sand, leaf mold, and clay (1:1:1) were irrigated with solutions containing NaCl at various levels: 0.6 (S0), 4 (S1), 6 (S2), and 8 (S3) dS·m−1. Salinity stress decreased growth parameters to a different extent in each genotype. Leaf water potential, stomatal conductance (g S), leaf number, shoot height, and root fresh weight were significantly decreased by salinity; and among the four fig genotypes studied, S × P and S × K were the most sensitive and the most tolerant genotypes, respectively. Furthermore, the highest reduction in shoot diameter and shoot fresh and dry weight were observed in S × Sh and the lowest reduction in S × K. Root dry weight decreased by increasing salinity, mainly in S × D. At S1 salinity treatment in both S × Sh and S × D genotypes, Na+ ion concentration was higher in leaves than in roots, but this pattern was not evident in S × P and S × K genotypes in NaCl treatments below S2 and S3, respectively. Chloride concentrations in all organs increased and were higher in roots than in both leaves and shoots, except in S × D genotype that accumulated more Cl− ion in leaves than in roots at S2 and S3 levels. These results indicate that the ability to sequester Na+ and Cl− ions in roots differs among the genotypes used in this study. Overall, results indicated that salinity tolerance in fig tree is strongly associated with Na+ and Cl− ions exclusion mechanism from shoots. Moreover, to our surprise, salinity stress considerably increased K+ ion concentration in leaves and shoots of salt-sensitive genotypes. Our proposed explanation is that the inability of salt-sensitive fig genotypes to prevent delivery of hazardous ions to shoot is compensated by tissue tolerance mechanism. Keeping high cytosolic K+ ion may lead to better sequestration of Na+ ion in vacuoles and, therefore, enable the genotypes with poor Na+ exclusion mechanism to handle large amounts of Na+ ion in leaves. Finally, S × K is the most salt-tolerant genotype due to efficient exclusion of Na+ and Cl− ions and lower reduction in growth factors.
The xenial and metaxenial effects of five different male sources on cross pollination of three pistachio cultivars, were studied in 1990 and 1991 in Rafsanjan/Iran. The pollen grains used were P. atlantica Desf., P. mutica F.& M., P. vera L. (Momtaz), P. vera L. (Soltani), and an open pollination. The female cultivars chosen were `Owhadi', `Kalleh-ghuchi', and `Momtaz', which occupy the largest cultivation area. Experiment was done in two successive years in a completely randomized design. Results of this study agreed with previous studies regarding the retardance of pistachio nut development by wild pollen species rather than P. vera L. The greatest change in various characteristics of nuts, e.g., kernel weight and shell splitting, occurred when P. mutica F.& M. pollen grains used followed by P. atlantica Desf. pollen grains. Thus, some manifestations of xenia and metaxenia could be inferred. In general, larger kernels and increased shell dehiscence resulted from the use of P. vera L. pollen grains. Greater kernel weight of `Kalleh-ghuchi', higher shell splitting of `Momtaz', and higher blank of `Owhadi' produced by pollination with P. vera L. in some extent could also be cultivar characteristics.
To study the cold-hardiness of Persian walnut cultivars and selections, three methods were compared: 1) thermal analysis; 2) evaluation of tissue health after controlled freezing; and 3) field observations after a severe midwinter freeze. Stem segments and buds were collected from eight Persian walnut genotypes (four commercial cultivars and four promising Iranian selections). Thermal analysis was conducted using thermoelectric modules (TEM) to measure the high (HTE) and low (LTE) temperature exotherms produced when water and tissues freeze. TEM signals were recorded as the temperature of the samples was decreased at a rate of 2 °C/h. Tissue injury under controlled temperatures was evaluated using pre-chilled stem segments cooled at 2 °C/h to set temperatures ranging from –5 to –30 °C and then held at these temperatures for 16 h. Frozen samples were thawed and visually evaluated for severity of injury. Cold damage under field conditions was evaluated after an unusually severe winter freeze. Twigs from affected trees were removed in mid-February and in April and visually rated for extent of injury and ability to recover. The occurrence of LTEs was correlated with death of the tissues as assessed by tissue browning. Both the capacity to supercool and the cold-hardiness of cultivars and selections tested increased with accumulated seasonal chilling and decreased as they approached spring budbreak. Thermal analysis showed a tendency for buds and stems to exhibit multiple LTEs at peak dormancy. The cultivars and selections were classified into three groups based on their cold-hardiness: sensitive (‘Z30’ and ‘Serr’), semihardy (‘Z53’ and ‘Z67’), and hardy (‘Lara’, ‘Hartley’, ‘Z63’, and ‘Pedro’).
Penicillium digitatum is one of the most important causes of postharvest decay of Mexican lime fruit. The first stage of this study dealt with examining the effect of savory (Satureja hortensis) essential oil on P. digitatum mycelial growth in vitro. Savory essential oil (SEO) applied at concentrations of 0, 200, 400, 600, 800, 1000, and 1200 μL·L−1 to potato dextrose agar (PDA) medium. The results revealed that the application of SEO at concentrations of 1000 and 1200 μL·L−1 completely prevented the growth of P. digitatum. Gas chromatography–mass spectrometry results indicated that the dominant components of SEO were carvacrol (55.67%) and γ-terpinene (31.98%). In the second phase of the experiment, in vivo assays were conducted to evaluate the efficiency of SEO (800 and 1000 μL·L−1), hot water (40 and 50 °C), and gum arabic coating (2.5% and 5%) in restricting the fungi activity on Mexican lime fruit. The Mexican lime fruit were immersed in the aqueous solutions of SEO and gum arabic or in the hot water for 5 minutes, and then stored at 8 °C for 30 days. Savory essential oil at the concentration of 800 μL·L−1 proved to be the most effective treatment in conserving bioactive compounds of the fruits such as total phenols. This treatment also optimally maintained antioxidant activity and suppressed the activity of polyphenol oxidase (PPO) in the fruit peel. Moreover, hot water at 40 °C caused the least physicochemical changes and the highest appearance quality during storage.
The objective of this work was to determine the chilling and heat requirements of Persian walnut cultivars and genotypes using excised twigs. The experiment was carried out from Nov. 2006 and 2007 to Mar. 2007 and 2008. One-year-old twigs were prepared from four cultivars and four domestic genotypes of Juglans regia L. After leaf fall, the twigs were taken and placed in plastic bags and kept at 4 ± 1 °C to stimulate 400 to 1500 chilling hours. After chilling, the excised twigs were transferred to the greenhouse with a natural photoperiod and a temperature from 18 to 27 °C. The evaluation of budbreak was made three times a week and the number of accumulated growing degree hours (°C) was determined until the buds reached the balloon or green tip stage. The chilling requirements were lowest (400 h) for catkins and highest (1000 h) for lateral buds. The Serr cultivar and ‘Z30’ genotype had the lowest chilling requirements (650 and 650 h). ‘Lara’, ‘Z63’, ‘Z53’, ‘Pedro’, and ‘Z67’ showed intermediate chilling requirements with values of 900, 900, 800, 750, and 750 h, respectively. Finally, ‘Hartley’ completed its dormancy after an accumulation of 1000 h, being the walnut cultivar with the highest chilling requirement in our study. As the final result, the cultivars and genotypes were classified into three groups based on their heat requirements: low requirement (‘Z30’ and ‘Serr’), medium requirement (‘Z53’, ‘Z67’, ‘Lara’, and ‘Pedro’), and high requirement (‘Hartley’ and ‘Z63’).