مجله علوم و فنون باغبانی ایران
سال بیست و سوم شماره 3 (پاییز 1401)

Recently, the use bioregulators to ameliorate the effects of environmental stresses on agricultural products has been considered. This split plot experiment was conducted as a randomized complete block design to investigate the moderating effect of some bioregulators on vegetative, biochemical and yield characteristics of greenhouse tomatoes under drought stress in the research greenhouse of University of Hormozgan. Experimental factors were three drought stress levels as the main factor, were include full irrigation as control, moderate and severe drought stress, respectively, irrigation of plants based on providing 100, 75 and 50% readily available water, and foliar application of 0.5 g per plant of biological compounds (the first time one day before applying drought stress and the second time before flowering begins) as a sub-factor including control (without the use of compounds), proline, chitosan and N-Succinyl and N, O dicarboxymethylate chitosan (NSC and NOC, respectively). Application of bioregulators at each water stress level increased the of proline content and catalase and peroxidase enzymes activity in comparison with the control, which in most cases the highest increase in enzyme activity related to NSC. Chitosan derivatives, on the other hand, were able to reduce the amount of malondialdehyde (MDA) and hydrogen peroxide in tomato leaves. Among the biological compounds, NSC and chitosan had the greatest improving effect on the fruit yield via increasing the number and diameter of fruit. So that foliar application with NSC increased fruit yield in control, moderate and severe water stress by 5.33, 17.91 and 33.24%, respectively. Therefore, according to these results, under deficit irrigation conditions, chitosan and its derivatives can reduce the effects of drought stress on tomatoes more efficiently than proline.

Citrus fruits are important sources of antioxidants including phenolic compounds, flavonoids, carotenoids and ascorbic acid, which can be changed by using mineral elements, especially potassium and calcium. This research was conducted factorial form in a completely randomized design. Foliar application of calcium nitrate (0, 2 and 4 g L-1) and potassium phosphite (0, 1.5 and 3 g L-1) before commercial maturation of blood orange fruits of Sanguine cultivar, and one week after treatment, fruit harvesting operation done. The fruits were stored for 3 months in normal storage. The antioxidant properties, elements and enzymes were evaluated at the time of harvest and during the storage period at intervals of one month. The results showed that the use of higher concentrations of calcium nitrate and potassium phosphite improved the characteristics measured on the day of harvest. Fruits treated with 4 g L-1 calcium nitrate and 3 g L-1 and 1.5 g L-1 potassium phosphate had the best effect on antioxidant properties and elements. Also, the amount of APX and SOD enzymes increased with these treatments during the storage period.

Ajowan (Trachyspermum ammi L) belongs to the Apiaceae family. Using plant tissue culture techniques, plant genetic diversity can be conserved in a controlled environment. The aim of the present study was to investigate the effect of different concentrations of ZnO and TiO2 nanoparticles and light qualities on somatic embryogenesis of ajowan and regeneration. The present experiment was framed in factorial (factors including ecotype, nanoparticles, optical spectrum) based on completely randomized design in three replicates. After the addition of nanoparticles to the MS medium, the explants were placed under red, blue, and light spectra and combined of them. The results showed that the use of ZnO and TiO2 nanoparticles reduced the percentage of fungal and bacterial contamination compared to the control treatment. With increasing the concentration of TiO2 nanoparticles under blue and red spectra, there was no contamination. Also, the highest rate of callogenesis, somatic embryogenesis and regeneration was obtained in Shiraz and Ardebil ecotypes with TiO2 nanoparticle under the combinational use of blue and red spectra. The blue light spectrum had the greatest effect on the control of contamination using ZnO nanoparticle. The formation of embryonic cells increased in TiO2 culture medium with a concentration of 10 mg L-1 under the combinational use of blue and red lights. With increasing nanoparticle concentration and light intensity, the accumulation of free radicals and activity of polyphenol oxidase were inhibited and the nutrient uptake by growing cells increased. In contrast, the regenerated control plants turned into white mass and causing the death of embryogenic calli, and seedlings. This study, using TiO2 and ZnO nanoparticles, it was possible to present an effective and useful protocol for induction of vegetative embryo and regeneration in the shortest time in the culture medium.

Referring to the alleviating role of antioxidant enzymes in various abiotic stresses, the impact of high temperature (heat) stress on the activity of some antioxidant enzymes as well as their gene expression patterns were evaluated in one-year-old olive cultivars “Zard” and “Direh”. For this, potted olive seedlings were transferred to the artificial growth chamber and exposed to three different temperature regimes including 32°C (before-stress), 45°C (during-stress) and 36°C (after-stress) through a completely randomized factorial design. Based on the results, cumulative shoot growth (%) in “Zard”, and proline accumulation in “Direh” were dominant in response to the heat stress. The activity of peroxidase (POD) and superoxide dismutase (SOD) enzymes increased by high temperature stress in both cultivars. In after-stress stage, the activity of ascorbate oxidase (APX) enzyme was soared just in “Zard” in comparison with during-stress stage. The patterns of expression of POD and SOD coding genes were in coordinate with their relevant enzymes activities, though the expression level in cultivar “Direh” was about two times more than in that of “Zard”. With compared to the before-stress stage, the expression of APX gene(s) was down regulated at both during-stress and after-stress stages. Generally, olive cultivars “Zard” showed fewer fluctuations in terms of the studied activities of the antioxidant enzymes and their relevant genes expression patterns. Also, cultivar “Zard” had relatively quick recovery ability from heat stress based on the analyzed traits.

The purpose of the present study was to improve the vegetative and reproductive growth of gerbera (Gerbera jamesonii ‘Bayadere’) using different light spectra and foliar application of calcium. Light spectra of red (100%), blue (100%), and red (70%) + blue (30%) were used in addition to natural light in greenhouse. Calcium chloride (CaCl2: 0, 0.5, 1, and 1.5 g L-1) was foliar sprayed. The highest number of leaves (20) was observed under combined (red + blue) LED lights + 0.5 g L-1 CaCl2, while the lowest number (8) was obtained under natural light conditions. Combined LED lights + 1 g L-1 CaCl2 produced the largest leaf area (117.90 cm2). Under the red light, the lowest leaf area (29.51 cm2) was observed. The highest diameter of flower stem, neck, and capitulum was obtained by application of combined LED lights and 1.5 g L-1 CaCl2. By separate application of combined LED lights or calcium chloride, fresh weight of flower stem and capitulum were significantly increased. The maximum (65.83 ̊) and the minimum (2.35 ̊) neck bent were observed under natural sunlight + 0  g L-1 CaCl2 and combined LED lights + 0 g L-1 CaCl2, respectively. Totally, application of combined (70% red + 30% blue) LED lights along with foliar spraying of 1-1.5 g L-1 CaCl2 is recommended to improve the flower quality of this cultivar of gerbera.

Several experiments were conducted to study the effects of bud position and plant growth regulators on the micropropagation of Rosa damascena. In the first experiment, the effects of bud localities (the proximal, middle, distal and shoot tip), BAP (2.5 and 5 mgL-1), TDZ (0.05 and 0.1mgL-1) and NAA (0.1 mgL-1) were studied on the regeneration of plant. The highest shoot length in the distal, middle and proximal bud locations was attained by 2.5 and 5 mgL-1 BAP + 0.1 mgL-1 NAA. For the proximal and shoot tips, the top data was related to 0.05 mgL-1 of TDZ + 0.1 mgL-1 NAA. In the second experiment, Kin and BAP (0, 1.5, 3 and 4.5 mgL-1) treatment combinations were tested on the regeneration potential without considering bud location. The highest shoot length belonged to 4.5 mgL-1 of BA and BAP. For the rooting stage; 0.1, 0.2 and 2 mgL-1 of NAA and IBA were examined and the highest rooting percentage and root length was recorded for 0.1 mgL-1 IBA. In conclusion, the in vitro regeneration response was controversy for the bud location. However, the growth regulators had promising effects on the regeneration of Rosa damascena.

In order to study the effects of direct seeding and transplanting methods on yield and agronomic characters as well as economic benefit in short day onion genotypes an experiment was conducted at Behbahan Agricultural Research Station located in the Southwestern part of Iran from 2014 to 2016. The experiment laid out as factorial based on randomized complete block design with six treatments and four replications. Factor (A) was onion genotypes: Ramhormoz landrace, improved population of Behbahan onion and Primavera cultivar. Factor (B) was planting methods (direct seeding and transplanting). In direct seeding, seeds were sown in field in mid-October. The seeds were sown in nursery bed in early October and the seedlings transplanted to field at two or three leaf stages. During the experiment characters: height and leaf number, Bolted plants percentage, total and marketable yield, doubling bulb percentage, bulb dry matter percentage, and total soluble solid were evaluated and recorded. The bolted plants and doubling bulb percentage in direct seeding were significantly higher as compared with transplanting method at 1% probability level. The effect of planting methods on total and marketable yield was not significant. Primaver cultivar produced the highest total and marketable yield. However no significant difference was recorded for total yield between Primavera and Ramhormoz landrace. The results of economic analysis indicated that direct seeding was more benefit than transplanting method. The highest cost and gross income were recorded for transplanting and direct seeding methods in Primavera cultivar respectively. The maximum benefit to cost ratio and net present value were found for direct seeding of improved population of Behbahan onion.

Identification of superior genotypes within the rich fruit trees germplasm in Iran is an important task. Eighty suitable genotypes were selected within the 600 genotypes that were grown in the Barzok, Kashan region, then 11 genotypes were considered as the superior genotypes. Besides recording the flowering periods of the 80 suitable genotypes, evaluation of the 11 superior genotypes was recorded during the 2017 and 2018 growing seasons. A 21 days difference at the beginning of flowering was recorded during two years of study. The high variability within the studied genotypes was observed in flower density. The genotype KB1045 with 158 flowers and genotype KB12939 with 60 flowers in 100 cm of shoot showed the biggest and lowest flower density, respectively. The highest fruit set record on 15 days after controlled self-pollination was recorded on genotype KB1045 (53.83 % fruit set) and the lowest was belong to genotype KB4541 (with 0 % fruit set). The microscopic examinations showed well germination of transferred pollens on the self-pollinated stigma. The microscopic fluorescence examination of pollen tube growth in the style at 48, 72, 96, and 120 h after self-pollination showed that very rare pollen tubes reached the ovary, so confirmed the incompatibility of the studied genotypes. Because the studied genotypes were superior in terms of many morphological traits, the obtained results can facilitate further apricot breeding programs on these genotypes.

Nannochloropsis salina is a promising species for lipid production, which is used in aquaculture and biofuel production. On the other hand, plant phytohormones also have different effects on the metabolism of protozoan algae. Therefore, an experiment was conducted with the aim of investigating the effect of abscisic acid (ABA) concentrations on growth and doubling time, chlorophyll, carotenoid, dry biomass, endogenous ABA and total lipid of N. salina microalgae in Gaillard (f/2) medium. The experimental treatments included 0 (control), 0.5, 10 and 20 mg L-1  ABA concentrations. This experiment was conducted in a completely randomized design (CRD) with three replications during 2019-2020. The analysis of variance showed that ABA treatment was significant on all studied characteristics at the 5% level. The treatment of 20 mg L-1 ‌‌ABA increased the growth rate, chlorophyll, endogenous ABA and total lipid in N.‌‌salina microalgae. The highest carotenoids and dry biomass were observed in 0.5 mg L-1 and control treatments, respectively. The findings of this study show that the concentration of 0.5 mg L-1 ABA is effective on lipid and carotenoid production of microalgae, but to increase total lipid production, the concentration of mg L-1 ABA is more suitable.

Bulblets require suitabale environmental conditions and particularly fertilization to obtain flower size. For this purpose, in a  CRD-based factorial experiment with four replications and 6 plants per replication, the effect of different concentrations of nitrogen, phosphorus and potassium on the growth of oriental lily bulbs of cultivar ‘Candy club’ was investigated. Treatments included different concentrations of nitrogen (100 and 160 mg L-1), phosphorus (40 and 80 mg L-1) and potassium (150, 225 and 300 mg L-1). Solutions containing elements with the desired concentrations were added to the hydroponic culture medium and after 10 months, growth indices were measured. The results showed that the highest number of leaves, shoot fresh weight, root fresh and dry weight, leaf potassium content and amount of soluble sugar and starch of bulbs were related to N: P: K treatment equal to 160: 80: 300. The highest leaf nitrogen content was observed in 160 mg L-1 treatment, the highest leaf phosphorus content in 80 mg L-1 phosphorus treatment and the highest leaf potassium content was observed in the interaction of nitrogen and phosphorus with concentrations of 160 and 80 mg L-1, respectively. The interaction of nitrogen and phosphorus with a ratio of 160: 80 also caused the highest leaf area, shoot dry weight, bulb fresh weight, bulb diameter, chlorophyll content of the leaf at the active growth stage and at harvest time (onset of dormancy symptoms). The highest bulb weight was observed in nitrogen and potassium treatments with concentrations of 160 and 300 and phosphorus and potassium with concentrations of 80 and 300 mg L-1, respectively. In general, the largest bulbs were produced at the highest levels of nitrogen, phosphorus and potassium used in the experiment.