مجله علوم و فنون باغبانی ایران
سال هجدهم شماره 3 (پاییز 1396)

In this research, three types of fig graft combinations (Sabz/Sabz, Sabz/Siah, Sabz/Torsh) and three ungrafted (Sabz, Siah, Torsh as control) fig rootstocks were subjected to 4 levels of irrigations (100%, 75%, 50% and 25% water requirement, WR) for a period of 12 weeks as a factorial experiment in a completely randomized design with 5 replications. The results showed that with increasing drought stress, vegetative growth and RWC were decreased and leaf proline content was increased. However, the responses were different according to type of rootstocks and graft combinations. In all levels of irrigation, ungrafted Siah rootstock showed the highest stem length compared to ungrafted Sabz rootstock and enhanced stem growth in Sabz scion. In addition, this rootstock produced the highest stem fresh and dry weights in Sabz scion compared to ungrafted Sabz rootstock. Sabz/Torsh graft combination showed the highest leaf mass per area (LAM) in all levels of irrigation. In 25% and 50% of WR, the graft combination of Sabz/Siah conserved the highest RWC. Generally, the grafted combination of Sabz/Siah can tolerate higher levels of drought stress than other graft combinations.

This research compares leaf gas exchange behavior and chlorophyll fluorescence parameters of Yaghooti grapevine cultivar under three conditions for two years including severe heat stress in greenhouse (45±1 ºC), greenhouse with normal conditions (28±1ºC), and severe heat stress in vineyards of Ghir-o-Karzin (a semi-warm region in Fars province). Leaf gas exchange parameters including photosynthesis rate (A), stomatal conductance (gs), sub-stomatal CO2 concentration (Ci), transpiration rate (E), and chlorophyll fluorescence (Fv/Fm) were measured. Moreover, transpiration efficiency (A/E), intrinsic transpiration efficiency (A/gs) and carboxylative efficiency (A/Ci) were estimated. Results showed significant differences among all treatments for all gas exchange and chlorophyll fluorescence parameters. The most photosynthesis rate (9.6 µmol CO2 m2s-1) was found for vines grown under normal greenhouse condition. In vines subjected to heat stress in both greenhouse and vineyard conditions, a sharp decrease in photosynthesis rate and Fv/Fm was observed. Photosynthesis rate (3.34 µmol CO2 m2s-1) in vines subjected to heat stress under vineyard conditions was significantly higher than that of potted vines (2.00 µmol CO2 m2s-1) subjected to heat stress in greenhouse conditions. These results revealed that gas exchange behavior of Yaghooti vines against heat stress under vineyard conditions was different from gas exchange behavior in potted vines grown under heat stress in greenhouse conditions. It seems that the photosynthetic heat response of Yaghooti grapevine cultivar was acclimated to heat stress conditions during different growth stages. In other word, Yaghooti have an ability to acquire tolerance to heat stress (acquired thermotolerance).

This research was carried out to evaluate the effects of indole-3- butyric acid on rooting of date palm (Kabkab cultivar) off-shoots with different weights. The experiment was performed as a completely randomized design consisted of four treatments and four replications on thirty-two date palm off-shoots with weight of 2-6 kg or 8-12 kg. The treatments included the application of indole butyric acid at the rate of 0 (control), 1000, 2000 and 4000 mg L-1. The results showed that 4000 mg L-1 indole butyric acid provided the highest number of main and lateral roots, total number of roots (main and lateral), length of main roots, diameter of main roots, weight of main and lateral roots, total weight of roots (main and lateral) and rooting percentage on the off-shoots with weight of 2- 6 kg and 8-12 kg which was significantly different with compared to control treatment at 5% probability level. Therefore, the highest rooting rate can be produced by the application of indole butyric acid in low weight of (2-6 kg) date palm off-shoots and their used effectively for propagation and expansion cultivated area.

The present study, aimed to investigate the effects of different concentrations of plant growth regulators such as auxin (IBA) and cytokinin (BAP, TDZ) on shoot proliferation from leaf explants of Petunia hybrida on MS medium. The experiment was conducted as a factorial with completely randomized design including two factors and 3 replications. In this experiment, 4 concentrations of BAP or TDZ (0, 4.44, 8.88 and 17.76 µM) and 3 concentrations of IBA (0, 0.55 and 1.1 µM) were used. The highest amount of regenerated shoots, fresh and dry weight of shoots and callus were obtained in medium containing 17.76 µM BAP and 0.55 µM IBA. Explants on media supplemented with TDZ, turned yellow with no regeneration. The longest shoots were observed in media containing 1.1 µM IBA in combination with 4.44 and 8.88 µM BAP and number of leaves and nodes were the highest in medium containing 8.88 µM BAP with 1.1 µM IBA. The results showed that on proliferation of leaf explants of Petunia hybrida Double Cascade series, BAP was more efficient than TDZ.

In order to study agro-meteorological indices at different phenological stages and growth analysis of new potato genotypes in autumn planting in Khuzestan province, an experiment was conducted for one year (2014-15) in farms of Behbahan region. This research was conducted in randomized complete block design including five genotypes (Sante, Khavaran and Javid cultivars and two advanced clones) with three replications. Tubers were planted at early October and harvested at late February. The results indicated that the duration of vegetative stage was short but tuber bulking stage was long, the maturation stage was not observed. Heliothermal unit requirements at sprout development, vegetative growth, tuber initiation and tuber bulking stages (depend on genotypes) were 2663.41 to 3332.03, 1581.32 to 1731.86, 1194.2 to 1218.1 and 3491.24 to 3602.58-degree day hr-1, respectively. Photo thermal unit requirement from planting to harvest was 15909.22-degree day hr-1. Tuber growth rate and crop growth rate increased during early growth stage, reached maximum value and afterward decreased. The maximum relative growth rate for all genotypes was observed during early growth stage. Due to the highest thermal use efficiency and heliothermal use efficiency, tuber and crop growth rate of Khavaran cultivar increased, so that this cultivar produced the highest yield.

Pecan is one of the most important nut fruits of subtropical regions that has very high commercial value. In this research, chilling and heating requirements of 16 pecan cultivars (GraTex, Peruque, Comanche 4M, 10J, Wichita 6J, Mohawk, Mahan, Stuart 2J, 3J, Stuart 4J, GraKing, Choctaw, Apache, 6M, Wichita 7J, and Comanche 5M) were carried out at the Saidabad Agricultural Research Center of Dezful during 2014–15. The Utah model and chilling treatments of cuttings were used to determine chilling requirement of cultivars. Heat requirements were determined by growth degree day (GDD) method.The experiment was a randomized design factorial with 16 cultivars and 11chilling treatments for 0, 150, 300, 450, 600, 750, 900, 1050.1200, 1500 and 1800 hours at 4°C±1 and three replications. To calculate the chilling requirement of pecan cultivars in natural conditions, meteorological data of Safiabad station were used. The results showed that chilling requirement was lower than 200­h for 'GraKing', 'Wichita 6J' and ‘Wichita 7J’ and higher than 800­h for 'Comanch 5M' and heat requirement were 416­GDD for 'Apache' and 625­GDD for 'Comanch 5M'. In all of cultivars, heat requirement varied inversely with chilling accumulation hours and they required at least 500­h with >18ºC heating for spring budbreak. Finally, results of this study showed that 'Wichita 6J', 'GraKing', ‘10J’ and ‘Apache’ were suitable for subtropical regions of Iran with 300­h chill units and 'Comanch 5M', ‘GraTex’ and ‘6M’ were suitable for regions with 400-600­h chill units.

In order to assess the effect of different rootstocks on reaction of scions of Persian lime genotypes against withces’ broom disease of lime (WBDL), an experiment was conducted as factorial arrangement in randomized complete block design with two factors including rootstock (Bakraei, Mexican lime, Volkamer lemon and Sour orange) and scion (IAC, Tahitian lime, Deperse lime and Persian lime) in Agricultural Research Station of Minab during 2014-2017. The grafted plants were produced via T-budding. Reactions of the grafted plants and seedlings was evaluated via graft inoculation with Mexican lime scion infected with WBDL phytoplasma. Based on PCR assays, detection of WBDL phytoplasma was the earliest (40 days post inoculation) in the scions on Mexican lime rootstock and the latest (116 days post inoculation) in the scions on Volkamer lemon rootstock. Symptoms of WBDL were observed in all seedlings except Volkamer lemon and during the course of this study it was not observed in the grafted plants. The time between graft inoculation and WBDL sypmtoms appearance was shortest in Mexican lime seedlings. Totally, Volkamer lemon rootstock is introduced as the best rootstock for Persian lime genotypes in the WBDL-infected areas.

An experiment carried out to study the effects of arbuscular mycorrhizal fungi on growth and physiological parameters ofthreecommercialapple clonalrootstocks during growing season in greenhouse. This investigation was conducted with two factors, rootstock (M9, M7 and, MM106) and species of arbuscular mycorrhizal fungi (Glomus versiforme, Rhizophagus intraradices, Claroideoglomus etunicatum and, control) in a completely randomized design. Growth (including plant height and diameter and shoot fresh weight) and physiological (including total chlorophyll, photosynthesis, and transpiration) parameters as well as root colonization were measured in 11, 15 and 19 weeks after transplanting. Results showed that mycorrhizal treatments and rootstoks had significant effects on all measured parameters comparing to the control. It was also shown that the fungus Glomus versiforme performed better than other fungi having the highest records for almost all of the measured parameters. Among the rootstocks, MM106 performed the highest shoot fresh weight (as well as plant height in the first and second measurements) but the final height of M7 was more than MM106. The highest and the lowest plant diameter were observed in MM106 and M7, respectively. The highest chlorophyll content, transpiration and photosynthesis rate was measured in M9 but the highest root colonization was recorded in M7. It seems that choosing proper rootstocks and treating them with suitable arbuscular mycorhizal fungi could reduce adverse conditions of calcareous soils for apple trees.