وهب اسدی

Use of drought tolerant grapevine rootstocks and application of garden management practices, such as the use of plant growth regulators, can be effective in achieving drought control methods. For this purpose, a factorial experiment based on a completely randomized design was conducted with three replications in greenhouse conditions in 2018 in order to study the effect of triacontanol on the physiological characteristics of grafted plantlet of grapevine on two native rootstocks of Iran under drought conditions. The treatments consisted of two rootstocks (Khoshnav, Sorkhak Ghouchan) and Bidaneh sefid (no grafting), three levels of drought stress including soil water potential of -0.2 (control), -0.7 and -1.5 MPa, and three concentrations of triacontanol (0, 50 and 100 μM). The measured traits included ratio dry weight to leaf area (LMA), membrane cell stability (MSI), total chlorophyll, proline, glycinebetaine, relative water content (RWC), catalase (CAT) and peroxidase (POX) activity. Based on the results, drought stress reduced LMA (25%), MSI (5%), chlorophyll (20%) and RWC (5%) and triacontanol treatments increased LMA (20%), MSI (4.5%), chlorophyll (14%), RWC (2.5%), glycinebetaine (27%), proline (22%), and antioxidant activity of catalase (23%) and peroxidase (8%). plantlet with Khoshnav rootstock showed better results than the control plantlet, and triacontanol improves drought tolerance in plantlets.

Apple (Malus spp.) is one of the most economically important fruit crop worldwide. This crop is highly affected by various virus infections, leading its considerable devastation and eventually results in yield loss in the whole world. Among effective viruses, Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), and Apple chlorotic leaf spot virus (ACLSV) which have been firstly characterized in apple (Malus domestica), play important roles in altering the plant defense mechanism, leading a low performance. According to the references, heat treatments can reduce the movement of virus particles into the apical meristem through inhibiting viral RNA synthesis, so high temperature over a long period is an efficient method for virus elimination. In additions, meristem culture is also a common method to eradicate viruses from horticultural plants. This study was done to produce virus-free (ACLSV, ASPV, ASGV) apple (Malus pumila Mill.) plantlets.

The effect of different thermotherapy duration (0, 7, 14 and 21 days at 38 °C) and the sizes of apical meristems for meristem culture(less than 0.2 mm, between 0.2 and 0.7 mm and larger than 0.7 mm) was assessed on virus eradication. Our plant material was a genotype of red flesh apple belongs to Budagovsky Bud.9 (Malus+pumila) "Niedzwetzkyana" of Rosaceae family from Shahroud, that has high levels of important phytochemicals like antioxidants, flavonoids and anthocyanins in its cortex, which in addition to attractiveness, creating special healing properties in some disease. At first the presence of ACLSV, ASGV and ASPV were checked in mother samples by ELISA and RT-PCR methods. Then we performed the thermotherapy treatments and later meristems were cultivated and grown in vitro. Regenerated shoots from meristem were tested by ELISA and RT-PCR methods for all three viruses. Samples that were diagnosed virus-free by both techniques, were proliferated, rooted and transferred into the pots to be used for later propagation and establishment of the mother orchard. Results and Discussion ELISA results for the presence or absence of ACLSV, ASGV and ASPV were indeterminate; they were neither negative nor positive for each virus, indicating ELISA was not an accurate method to study virus infections in our samples. Therefore, careful examination of initial infection of samples was performed by RT-PCR. Examining mother samples by RT-PCR showed that all samples were infected by ASG, ASP and ACLS viruses. Results of RT-PCR testing suggested that the number of days in thermotherapy and the size of meristem had a significant effect (P<0.01) on the ACLSV, ASGV and ASPV elimination. Increasing in the duration of the thermotherapy decreased the survival rate of the explants and it was difficult to acquire virus-free explants after 21 days treatments, because all the explants were destroyed in this treatment. The relation between the size of meristem and its survival has been examined in different studies, whose results are consistent with the present research and confirms that increasing the size of the meristem and the number of leaf primordium, will increase the vitality. However, it should be noted that larger meristems are more susceptible to viral contamination. In the previous study, the percentage of ASGV and ACLSV elimination was significantly influenced by the size of the meristem and the duration of the thermotherapy. In the same study, ACLSV, ASGV and ASPV could not be detected in plants grown from meristems smaller than 1 mm after 35 days of thermotherapy. They also showed that virus eradication was happened after shorter period of thermotherapy if smaller meristems were cultured (0.7 mm). The results of our study were consistent with these observations; ACLSV, ASGV and ASPV appeared to be eliminated more frequently from the smallest meristem treatment (smaller than 0.2 mm) compared to the other treatments (0.2-0.7 mm and larger than 0.7 mm). Elimination rates of ACLSV, ASGV and ASPV were different in each case and ASPV-free frequency obtained in regenerated shoots treatment was higher than other viruses (ASGV and ACLSV). This observation was similar to the results of some previous studies. It could be due to differences in the morphology of the viruses and transmission factors in plant cells that affect viruses, which has been investigated and confirmed in previous studies. Meristem culture alone, without other treatments, had very low efficiency in virus elimination from explants. The best results of virus eradication from apple explants was obtained after 14 days of thermotherapy, that we had 44.44%, 11.11% and 88.89% of virus-free samples from ACLSV, ASGV and ASPV, respectively. Generally, our results showed that by increasing the thermotherapy duration, the elimination of all three types of viruses was increased. Many researchers also found that thermotherapy is a very effective treatment in virus eradication.

Results showed that increasing the duration of thermotherapy (14 days) and reducing the size of cultivated meristem (smaller than 0.2mm) increased the elimination rate of all three viruses (ACLSV، ASPV، ASGV) from apple explants.

Drought stress is one of the most important limiting factors for cultivation and production of grapes in the world and Iran. To study the effect of drought stress on some physiological traits of three cultivars, i.e. ‘Fakhri’, ‘Molaei’ and ‘Ghalati’, a factorial experiment in completely randomized design with three soil water potential treatments. i.e. -0.2 (control), -0.7 and -1.2 MPa was implemented in greenhouse conditions in 2016. In this study, non- grafted grape vines were placed in large 26-liter pots filled with a clay loam textured soil. According to the results of this study, both levels of stress had a significant effect on dry matter to leaf area ratio, cell membrane stability, chlorophyll, proline, and soluble carbohydrates concertation, leaf relative water content, catalase and peroxidase activities. Soluble carbohydrates concentration showed a significant increase of 47 percent compared to control (10.57 mg g-1 DM) in -1.2 MPa stress level. Drought stress decreased the RWC (2 Percent) and increased proline (9 Percent) and malondialdehyde (55 percent) concentration, the peroxidase (15 to 20 percent) and catalase activity (9 Percent). The highest and the lowest chlorophyll concentrations were observed in ‘Ghalati’ (1.63 mg g-1 FM) and ‘Fakhri’ (1.31 mg g-1 FM), respectively. In conclusion, ‘Ghalati’ cultivar had higher potential to withstand drought stress conditions than ‘Molaei’ and ‘Fakhri’ cultivars.

In most fruit trees, despite the fact that all the flowers are not converted to fruit, the amount of production is more than the tree's capacity, which reduces the quality of the crop and reduces the yield of the tree. While in many fruit trees, the conversion of 5 to 15 percent of the flowers into fruits leads to economic production. The size and quality of the fruit produced should be consistent with market conditions. The goal of horticultural Science is to achieve the desirable annual yield and produce throughout the life of the garden. This research was carried out to investigate the effect of a few mineral thinners and a biological regulator on the quantitative and qualitative characteristics of the nectarine "Shabrang" and its comparison with hand-thinning of flowers and fruits. The experiment was conducted in a commercial garden in Semirom in 2012-2014 as a randomized complete block design with 15 treatments and 5 replications. The treatments consisted of lime-sulfur (6, 8% and twice the application of 6%), ammonium thiosulfate (20, 25 ml per liter and twice the application of 20 ml per liter), urea (4, 8% and twice 4%) and Apogee (300, 450 mg / L and twice the use 300 mg / L) at flowering stage (spraying in single stage treatments in 70-80% of flowering and two-stage treatments first in 30-40% and then in 70-80% flowering), flower hand- thinning in the 70-80% flowering stage and then four weeks after the flowering stage were applied to selected trees. The results showed that all treatments had a significant effect on the traits of nectarine "Shabrang" at 1% level. The treatments reduced the fruit set, so that in the hand-thinning treatment of flowers, twice ATS 20 ml per liter and twice lime sulfur 6% reduced the fruit set by 50%. Flower hand-thinning were the best treatment in terms of size (11.33 cm3) and weight (151.34 gr) and the highest yield was related to control (90.42 kg per tree) and the least yield was related to fruit hand-thinning treatment (64.04 kg per tree). The yield efficiency in control treatment (3.32 )fruit/trunk cross-section area) was higher than other treatments and its least amount was for the twice lime sulfur 6% (1.99 fruit/trunk cross-section area) and twice apogee 300 mg / lit (2.01 fruit/trunk cross-section area). In terms of qualitative traits, the highest total soluble solids were recorded in flower (17.49%) and fruit (16.53%) hand-thinning respectively, after which the best results were obtained in the twice treatments of thinning compounds. The highest amount of total acid was recorded in lime sulfur 6% (4.88 mg / 100 ml juice) and flower hand-thinning (4.26 mg / 100 ml juice) had the highest index of ripening among all treatments. The highest of leaf area was in twice ATS 20 ml/L (70.42 cm2) and twice urea 4% (69.18 cm2) and the least of leaf area was recorded in control (55.81 cm2). Fruit color as one of the qualitative indices in flower hand-thinning (4.74) was higher than other treatments and the least amount of fruit color was related to lime sulfate 6% treatment (3/38). Flower hand-thinning created a more regular thinning, larger and more colorful fruits and with higher sugar. The results also showed that the flower hand-thinning was better than the fruit hand-thinning. In general, two-step treatments of the compounds produced more suitable effects on the quantitative and qualitative traits of nectarine. However lime sulfur in 8% and twice using 6% caused some leaf burning.

This study was aimed to production of healthy primary pear plants for propagation and establishment of a high health maternal orchard in 2014 at Agriculture Biotechnology Research Institute of Iran (ABRII). The experiments were conducted by evaluate the effectiveness of the chemotherapy treatments (Ribavirin (0, 20, 40 and 80 mg/l) and the sizes of apical meristems culturing (less than 0.2 mm, between 0.2 to 0.7 mm and larger than 0.7 mm) on virus eradicate (ACLSV, ASPV, ASGV) from seven pear cultivars ("Abate Fetal", "Beiruti", "Coscia", "Dargazi", "Louise Bonne", "Mellina" and "Spadona"). At first maternal samples were tested for ACLSV, ASGV and ASPV by RT-PCR and all explants had been infected with all three viruses except Fettel and Beirut that were free from ASPV. We performed the chemotherapy treatments then meristems were cultured and grown in vitro. Regenerated shoots from meristem were tested by RT-PCR for all three viruses. The results showed that increasing the concentration of ribavirin and reducing the size of cultivated meristem was effective on all the three viruses’ elimination from explants. Also the responses of studied cultivars and virus varieties were different in treatments of this research. Samples that were diagnosed virus free by using RT-PCR, were proliferated, rooted and transferred into the pots to be used for later propagation and establishment of maternal orchard.

Thinning operations is essential to produce quality products in peach cultivation. Inefficiencies due to the high cost of hand thinning and mechanical thinning increased tendency to chemical thinning. In order to study the effect of lime sulfur (6%, 8% and 6% twice), ammonium thiosulfate (20, 25, 20 mL/L twice) and Apogee regulator (300, 400 and 300 mg/L twice) as thinning agents on fruit quantitative and qualitative characteristics of peach ʻRed havenʼ, a research was carried out in a commercial orchard on selected uniform Six-year-old trees in Semirom, Isfahan, Iran in 2012-2013. Results showed that all of the treatments, but Apogee (300 and 450 mg/L) significantly thinned the fruits and reduced fruit set up to 65 percent. Treatments increased fruit weight, volume (45- 50 percent), total soluble solids (TSS) and color and also enhanced leaf area index (LAI). However, there was no significant differences among control and the treatments for total fruit acidity. Trees treated with ATS (20 ml/l twice) and lime sulfur (6% twice) showed relatively best of quantitative and qualitative characteristics.

In order to study the effects of mineral and biological compounds as thinning agents on fruit quantitative and qualitative characteristics of apple cv. Red Delicious and to compare them with flower and fruit-hand thinning, a research was carried out in a commercial orchard in Semirom, Iran. Treatments included lime-sulfur (6%, 8% and double application of 6% first at 30-40 and then 70-80 bolting percentage), ammonium thiosulfate (20, 25 and twice application of 20 mll-1 (in 30-40 and 70-80 bolting percentage) and prohexadione- calcium, Apogee® (300, 450 and twice application of 300 mgl-1 (first at 70-80 bolting percentage and then 2-3 weeks after FB), and hand-thinning of flowers (at full bloom) and fruits (at 4 week after FB),which were applied on selected trees. The results showed that all of the treatments except Apogee (300 and 450 mgl-1) significantly thinned the fruits and reduced fruit set (10 -50 %). The treatments increased fruit weight(51%), volume(48%), total soluble solids (23%), TSS/total acid ratio(38%) and color and enhanced leaf area index (30%). There were no significant difference between control and the total acidity of fruits. Twice application of 20 ml ammonium thiosulfate was the best economically treatment. In terms of yield and yield efficiency(TCSA), treatments were significantly different, so that the control and lime sulfur 8% had the highest and lowest yield, respectively.