مجله علوم و فنون باغبانی ایران
سال بیست و یکم شماره 2 (تابستان 1399)

In order to evaluate the tolerance of carob seedlings to drought and salinity stresses based on growth and ecophysiological indices, a factorial experiment was conducted based on a completely randomized design with three replications. Factors included drought at 3 levels (5, 10 and 15 days irrigation intervals) and 3 salinity levels (0, 80 and 160 mM NaCl). The results showed that drought and salinity stresses reduced the vegetative indices of carob seedlings so that the lowest vegetative indices were observed in 15 days irrigation interval and 160 mM NaCl. The shoot fresh and dry weight decreased with increasing salinity and drought intensity. The highest shoot fresh and dry weight were recorded in control plants and the lowest shoot fresh and dry weight were recorded in plants treated with 160 mM NaCl and 15 days irrigation interval. The results of this study also showed that relative water content of leave decreased in plants treated with 10 days irrigation interval with increasing salinity levels while there was no significant difference between salinity levels in 15 irrigation intervals. The results also showed that the concentration of Na in root and shoot was increased with increasing salinity and drought stresses so that the highest concentrations of Na in shoots and roots were observed in plants treated with 15 days irrigation interval and 160 mM NaCl. According to the results of this study, it can be concluded that carob seedlings can tolerate 10 days of irrigation and 80 mM salinity.

This study was performed to screening of some hybrid apple rootstocks for drought stress using physiological and biochemical indices in leaf. The experiment was carried out in a CRBD design, in a factorial scheme 12×2 (12 types of apple and  2  irrigation regimes) with three replicates. The types of apple studied were 1 year old plants including genotypes AR1 to AR11 accompanied by MM111 as control (drought tolerant). Irrigation regimes applied in this study were 20 and 40 percent of FC Under drought stress, the apple rootstocks physiologically and biochemically exhibited different responses. Drought stress symptoms evaluated in this experiment were reduction of cell membrane stability, photosynthetic pigments, and chlorophyll fluorescence, increment of proline and malondialdehyde content.  In this experiment at least one of the aforementioned indicators were observed in the AR1, AR3, AR5, and AR7 being identified as sensitive rootstocks. In contrast, the rest of rootstocks with the most physiological stability and the least damage were considered drought stress tolerant and selected for subsequent studies.

Mentha longifolia L. is one of the most valuable perennial, rhizomatous, aromatic and herbaceous plants belonging to the Lamiaceae family. In this study, the effects of deficit irrigation stress on physiological traits and yield of 20 different wild mint populations were evaluated by a split-plot experiment based on a randomized complete block design with three replications. Soil moisture control was performed using irrigation treatments based on 100% (control) and 60% of field capacity. In the current study, physiological traits including chlorophyll a, b and total, carotenoids, proline, total carbohydrate, relative water content, ion leakage, stomatal conductivity, sodium and potassium elements, dry matter yield and essential oil yield were investigated. There were significant differences (P<0.01) between populations in two levels of water deficit treatment. The most tolerant populations had the highest essential oil yield (4.69%), relative water content (69.91%), total chlorophyll (0.32 mg/g) and proline (2.80 µmol/g) under water deficit stress. Results of correlation between dry matter yield and all traits except carotenoid content were significant. Finally, five populations of Hormozgan, Khuzestan, South Khorasan, Kerman-1 and Lorestan respectively were identified as the tolerable populations and introduced for future breeding programs.

In this study, the effects of deficit irrigation along with a foliar application of silicon on growth, yield, and quality of tomato (Lycopersicon esculentum L. cv BHN) were evaluated. This experiment was conducted as a factorial arrangement in a completely randomized design with three replications. Tomato plants were planted in pots containing coco-peat and perlite (80:20 v/v). The plants were treated with different irrigation levels (60, 80, and 100% full irrigation) and different levels of silicon (0, 100, and 200 mg L-1). Results showed that with an increase in irrigation levels vegetative growth and fruit quality was improved. The highest plant height and fruit number were found in 100% water requirement. Application of 200 mg L-1 silicon significantly increased fruit number and yield in 60% deficit irrigation. Deficit irrigation significantly increased catalase and peroxidase enzyme activity. The application of 100 mg L-1 silicon could increase TSS in 80% deficit irrigation. Overall, it seems that foliar application of silicon (200 mg L-1) could alleviate the negative effects of drought stress in tomato and improved growth, yield, and fruit quality under drought stress conditions.

Three experiments were carried out under in vivo and in vitro conditions to evaluate the effects of gibberellic acid (GA3) and freezing on germination and growth of Prunus scoparia (Badam Kohi) and Prunus elaeagnifolia (Arjan) species. In the first experiment, treatments were 4 concentrations of GA3 (0, 50, 100 and 150 mg/L) and two soaking duration time (12 and 24 h). In the second and third experiments, the effects of different temperatures (18 and -16 °C) on the germination and growth of different species in soil and on tissue culture MS (Murashig and Skoog) media were investigated. The results showed that both seed germination percentage and germination rate increased significantly using GA3 and freezing temperature. The highest shoot length (4.48 cm) and root length (20.5 cm) were obtained in P. scoparia in 150 mg L-1 GA3 and duration time of 24 and 12 h, respectively. In freezing conditions (-16 °C) and in soil medium, although the highest germination percentage (92%) was related to Badam Kohi, but it did not show any significant difference with other treatments in freezing and MS medium. Shoot length of both P. scoparia and P. elaeagnifolia species increased with freezing pretreatment, but this increase was not significant under in vitro condition. The results of this study make it possible to use freezing treatment in soil conditions to produce seedling rootstocks of P. scoparia and P. elaeagnifolia in the nursery with shorter duration time and lower cost than other methods.

Iranian almond germplasm is regarded as one of the most diverse and valuable genetic resources for almond improvement. In the present study, almond genotypes from Ghazvin province were evaluated during 2013 and 2014 to determine the overall degree of variation and to select superior trees. During the first year evaluation, 45 superior genotypes were selected and some phonological traits were recorded according to IPGRI descriptor for almond. Results of analysis of variance and mean comparison of traits showed that cultivars and genotypes were significantly different in all studied traits, indicating significant differences between genotypes and traits. Some traits such as fruit width and diameter, shell diameter, fruit and kernel weight, branch length, leaf width and the number of leaves showed higher coefficients of variation. Cluster analysis using UPGMA method and Euclidean distance detected four major clusters and showed a considerable diversity within the same germplasm population. Principal component analysis indicated that the first and second components explained 69.97% of all variance. The results of this study showed the high diversity of the almond genotypes based on their morphological traits. This variety is useful for almond breeding programs.

One of the major issues in date production and packaging are storage pests such as Oryzaephilus surinamensis which cause reduction in date postharvest quality. Present experiment was carried out to study mortality impacts of exposure of O. surinomensis larvae, pupa and adults in laboratory to extreme temperatures (45, 50, 55, 60 °C) in a factorial in completely random design with three replications. Peel separation from pulp, TSS, fruit humidity, pH and perishability percentage were measured.  Data were analyzed using MSTAT-C software and means were compared using the Duncan test at 1% and 5% probability levels. The results showed 100% mortality after 3h of exposure to 55 °C in the development stage (larvae, pupa, adult). High temperature treatments reduced fruit weight compared with control.  Heat treatments influenced fruit moisture content. However, the responses were not significantly different in comparison with control until 50 °C. Effect of temperature treatments on TSS, pH and perishability percentage was not significant compared with control. 0 and 60°C treatments reduced the rate of peel separation from pulp.

Efficiency of the pre-storage hot water dip to prolong storability and maintain the quantitative and qualitative traits of the cold-stored ‘Rabab-e-Neyriz’ pomegranate was evaluated. Fruits were stored at 2 ± 0.5 ºC and 90 ± 5% relative humidity for 90 days. The experiment was factorial based on a complete randomized design with 4 replicates in each treatment. Experimental factors included pre-storage heating for 4 min (at two levels: dip in water at 45 ºC, and distilled water at 25 ºC as control) and sampling time (day 0 followed by 30 days intervals). The weight loss and skin characteristics assessed remained unchanged for up to 1 month, which was related to the internal ability of the fruit skin to acclimate to chilling temperature conditions. Afterwards, significant increase in chilling injury indices was happened. After 90 days of storage, treated fruits had higher (63%) total phenol (as a non-enzymatic antioxidant index) and lower (42.53%) malondialdehyde (MDA) contents in their skin compared to controls. Furthermore, the treated fruits had a 23.63% lower weight loss and lower chilling injury symptoms, but their quality characteristics were the same as the control.