مجله علوم و فنون باغبانی ایران
سال پانزدهم شماره 4 (زمستان 1393)

To develop reproducible parameters for identification of drought tolerance of potato wild species or cultivars, response of tree wild species of potato Solanum bulbocastanum (intolerant), S. stoliniferum (semi- tolerant), S. acaule (tolerant) and a cultivar (S. tuberosum cv. ‘Agria’) (tolerant) to osmotic stress, using polyethylene glycol (PEG 15%) was studied using MS medium in vitro. Osmotic stress reduced shoot dry weight (SDW) and increased malondialdehyde, other aldehydes, ion leakage, hydrogen peroxides and the activity of lipoxygenases, superoxide dismutase, and catalase. Ascorbate peroxidase, glutathione reductase and guiacol peroxidase enzymes in potato species. However, the response of species was different to osmotic stress, such as accule showed the highest and bulbocastanum the lowest level of tolerance, in terms of SDW production. Correlation showed that ion leakage (r=-0.91**), catalase (r=-0.89**), malondialdehyde (r=-0.8**) and lypoxygeneses (r= 0.75**) were significantly correlated which may be used to screen potato genotypes to osmotic stress. The use of ion leakage parameter is recommended due to its low cast, precision and applicability.

Two field experiments were conducted to study the impact of two plant growth regulators on growth, fruit yield and quality of melon fruit in Kerman University. In first experiment, the plants of two cultivars (‘Semsuri’ and ‘Ananasi’) were sprayed with 0, 2, 40, 60 mg l-1 indole butric acid (IBA) at 6-7 leaf and fruit set stages. In second experiment, 400 mg l-1 GA3 was applied as seed soaking, 50 mg l-1as foliar spray in 6-7 leaf stage, after fruit set and their combinations in Semsuri. IBA increased all parameters recorded, but flesh firmness, relative to control. 20, 40 and 60 mg l-1 IBA increased fruit yield by 14%, 26% and 25%, respectively. GA3 significantly reduced fruit set and increased plant growth and fruit yield by 22%. The correlation coefficients between fruit yield and other parameters showed that both growth regulators increased fruit yield, shoot fresh weight, chlorophyll and relative water content with similar mechanism.

Salt stress is one of the factors limiting plant growth and development. Putrescine is a compound which can improve the tolerance mechanisms of plants against abiotic stresses. In order to investigate the effects of putrescine on some biochemical characteristics of pot marigold plants under salt stress condition, a factorial experiment was conducted compelitly randomized design with three replications using four levels of soil salinity (the electrical conductivity of 1:1 soil: water extract =1, 3, 6 and 9 dS m-1) and three levels of putrescine solutions including 0, 1 and 2 mMol. Prolin, protein, peroxidase and catalase concentrations in the leaves and malondialdhyde and H2O2 content in both leaves and roots were measured. Results showed that interaction effects of salinity and putrescine were significant on all plant parameters except leaves prolin content and malondealdehyde and H2O2 in root. Application of 1mMol of putrescine at highest level of salinity, decreased malondealdehyde of the leaves 55% compared to control. Application of 2 mMol of putrescine under highest level of salinity decreased leaves H2O2 to 57% while increased protein, catalase and peroxidase content at 132%, 97% and 20% respectively.

An experiment was conducted to study the effect of different salinity levels of irrigation water on leaf morphological changes, electrolytes leakage and pigments content in the presence of arbuscular mycorrhizal fungi. The experiment was a completely randomized design and a factorial combination of two mycorrhizal treatments (with and without mycorrhiza), four salinity levels of irrigation water (0.5, 5, 10 and 15 dS m-1) and three rootstocks (Sarakhs, Abareqi and Bane-Baqi). In this experiment, 150-days-old pistachio seedlings were exposed to different salinity levels for 75 days. Leaf indices in general and leaf area in specific were reduced as the effect of salt stress levels. Leaf abscission was increased with increase in salt stress severity. Chlorophyll concentration and electrolytes leakage were affected by salt stress in all rootstocks as it reduced chlorophyll content and increased electrolytes leakage. The results showed that colonization of pistachio seedling with mycorrhiza improved leaf indices (leaf number, dry weight, area, abscission and leaf area ratio) under salt stress in comparison with non-mycorrhizal seedlings. Chlorophyll contant of mycorrhizal seedlings were also higer than respected control. Mycorrhizal application reduced leaf electrolytes leakage over control. There were significant differences between rootstocks in case of mentioned parameters and Bane-Baqi and Sarakhs were superior over Abareqi (in case of leaf area, leaf area ratio, leaf abscission, specific leaf area and specific leaf weight) in response to salt stress.

GN15 (Garnem) is a vigorous rootstock, used for peach, nectarine and almond and is suitable for many areas of Iran. In this study, effect of 6-benzyladenine (BA) at 2, 4 and mg l-1 in combination with 1-naphthaleneacetic acid (NAA) at 0, 0.05 and 0.1 mg l-1 in WPM medium on shoot proliferation of GN15 rootstock were studied. The results showed the highest number of proliferated shoot per explant in 2 mg l-1 BA and 0.1 mg l-1 NAA. Maximum length of shoots was observed in treatment with 4 mg l-1 BA without NAA and number of nodes was increased in 2 mg l-1 BA and 0 mg l-1 NAA. Maximum length of internodes was obtained in medium containing 2 mg l-1 BA and 0.1 mg l-1 NAA. Increasing concentration of BA up to 8 mg l-1 without NAA increased vitrification and decreased shoot number per explants, shoot length, nodes number and internode length. Kinetin treatments had limited effect on proliferation. The influence of two basal medium, MS and 1/2MS with different concentrations of IBA and NAA were investigated on rhizogenesis. MS medium supplemented with 1 mg l-1 IBA was most effective for rooting percentage. Maximum number and length of roots per explants were seen in 1/2 MS medium supplemented with 1 mg l-1 NAA and 2 mg l-1 IBA, respectively.

Effect of ethephon foliar spray on berry anthocyanin contents and quality of grape (‘Beidaneh Ghermez) was studied, using a split plot design. Four ethephon levels [0 (control), 100, 200 and 300 ppm] were sprayed at two growth stages T1 (10-30% berry veraison) and T2 (50-70% berry ripening). Results showed that ethephon significantly increased berry anthocianin content, berry weight and total soluble solid (TSS). Meanwhile, there were not any significant differences among titrable acidity (TA), pH, test index (TSS: TA) and berry firmness compared with control treatment. Also, there was not any significant difference between applications of ethephon times on measured parameters. Ethephon spraying had more impact on increasing anthocianin in berry of ‘Beidaneh Ghermez’ and improved color. According on obtained results it can be said, 300 ppm concentration of ethephon in early ripening time (T1) had best effect. Also, ethephon spraying not only increased color and total soluble solid content also accelerated fruit maturity and ripening.

This study was conducted to quantify the effect of different irrigation levels on yield and physical properties of the olive fruit under subsurface drip irrigation in a gravel soil. Irrigation levels were included 20, 40, 60, 80 and 100% of crop evapotranspiration. The irrigation treatments arranged in a randomized complete block design with three replications. Physiological characteristics such as moisture of leaves and branches during the growing season, and yield and fruit physical characteristics at harvest date were measured.The effect of irrigation levels were significant (P<0.05) on juice content of fruits, arithmetic and geometric mean diameter, porosity of fruit and leaf water content. However, there was no significant difference for water branches. The maximum yield (12.03 kg tree-1) was occurred in the full irrigation level (ETc) and the lowest (4.95 kg tree- 1) was observed in the severe water stress treatment (0.2 ETc). Twenty percent reduction in applied water from full irrigation level caused 25.4 percent decrease in yield. The water content of leaves and branches was ranged between 38-50% for different irrigation levels. The overall conclusion of this study is that the subsurface drip irrigation system is a suitable method for irrigated olive trees in arid and semi arid region with gravel soil and the olive tree is perfect for green space.

Influences of pollination methods and plant growth regulators spraying; gibberllic acid (GA3) or naphthalene acetic acid (NAA) on some quantitative and qualitative parameters of date fruit (Phoenix dactylifera cv. ‘Kabkab’) was investigated in two years (2009 2010). The experiment was conducted based on randomized complete block design with eight treatments including embedded male inflorescence in spadix (EM), hand pollination (HP), hand duster (HD), motorized duster (MD), hand pollination + GA3 (100 mg l-1) (HP + GA100), hand pollination + GA3 (100 mg l-1) (HP + GA150), hand pollination NAA (150 mg l-1) (HP + NAA) and free strand (FS). Results showed that the highest fruit set percent, the lowest fruit abscission, the greatest fruit number per strand, the highest strand weight, the greatest fruit weight, the highest yield, the greatest fruit length, the greatest fruit diameter, the greatest fruit volume, the greatest pulp/seed ratio and the highest fruit growth rate were obtained by HP+GA150 treatment application. The highest fruit abscission and the lowest fruit number per strand were measured by MD treatment application. The lowest fruit weight was obtained in control (EM), HP and HD treatments. Control (EM), FS, HP, HD and MD treatments showed also the lowest yield. Treatment of HP+NAA150 had the lowest seed length and HP+GA100 treatment had the greatest seed length. The greatest and the lowest seed diameter were obtained by usage of HP+NAA150 and HP treatments, respectively. Seed weight was not influenced by exerting treatments. The highest and the lowest TSS were obtained by HP and HP+NAA150 treatments application, respectively. The highest pH was obtained by usage of HP+GA100. The lowest fruit moisture was observed in HP treated fruit and the highest moisture was observed in HP+NAA150 treated fruit. It can be concluded that application GA3 and NAA have a significant effect on yield increasing, quantitative and qualitative parameters of date fruit cv. Kabkab and HP+GA150 may be recommended.

Pomegranate is one of the most important horticultural crops in our country and one of the most important factors limiting development of its culture is the water shortage. Importance of amino acids in regulating plant growth and biosynthesis and anti-stress properties are well known to investigate drought stress on pomegranate and effect of amino acids application in reducing the damage caused by stress an experiment were performed as split-plot in a randomized complete block design. Irrigation in three levels (100% required water, 75% required water and 50% required water) and organic material treatment was in four levels (0, 2, 3 and 4 ml l-1). Some qualitative and quantitative traits of fruit were measured. The results revealed that drought stress significantly reduced yield. The use of amino acids could significantly enhance the yield efficiency and reduce the negative effects of stress, Also, with increasing levels of amino acid, ascorbic acid content significantly increased and by reducing irrigation levels the amount of ascorbic acid and anthocyanins significantly decreased. Therefore it was concluded that application of fertilizer containing amino acids increase the yield and fruit quality in pomegranate.

Plum (Prunus domestica L.) cultivation is mostly located in areas where flowering is injured by low temperatures, and so, retardants growth application such as cycocel and daminozide to bloom delay is suggested as a measure to avoid frost damage. This study was conducted to evaluate the effect of cycocel and daminozide on plum bloom delay. The layout was a factorial experiment in a randomized complete-block design with four replications. Treatment included daminozide at rates of 0, 500 or 750 mg l-1 and cycocel at rates of, 0, 1000 or 2000 mg l-1 and theirs combine together, during dormancy in three stages (Time1, 3rd February (80 days before blooming), Time 2, both stage, 3rd February (80 days before blooming) and 5th March (40 days before blooming) together and Time, 5th March (40 days before blooming) on bloom delay of plum, in 2011 and 2012. The results showed that effects of cycocel and daminozide on plum bloom delay were significant (P < 0.05). According results, 1000 mg L-1 cycocel delayed bloom by 3- 8 d and 750 mg l-1 daminozide, delayed bloom by 3d. The results of time factor on bloom delay showed, 3rd February (80 days before blooming) and 8th March (40 days before blooming) delayed bloom by 3d and 8 d, respectively. So, according these results, the best treatment was 1000 mg l-1 cycocel and the best spraying time was 40 days before blooming.

An experiment was conducted to evaluate the effects of exogenous salicylic acid application on physiological and biochemical indices of 'Dezfuli' tuberose (Polianthestuberose L.) under salt stress condition. A factorial experiment was conducted in a complete randomized design with 16 treatments; 4 salinity level (0.5, 3, 6 and 9 dSm-1) and 4 salicylic acid concentrations (0, 0.5, 1 and 1.5 mM) with 4 replications in the research greenhouse of the Department of Horticultural Science, College of Agriculture, Shiraz University. Results showed that salicylic acid alleviates the adverse effects of salinity stress and increased leaf area and shoot fresh and dry weights. Furthermore, increased proline and catalase and super oxide dismutase content, but reduced electrolyte leakage and prevented flowering delay. Positive effects of salicylic acid were not significant in some characteristics such as chlorophyll content and inflorescence length. Overall, salicylic acid can alleviate the adverse effects of salt stress on tuberose plants and its application can be recommended as an effective plant growth regulator to prevent the tuberose flower quality loss in the regions with low quality soil or irrigation water source.

Effects of foliar application of boron (B) and calcium (Ca) was investigated on fruit set and some quantity and quality characteristics of pistachio trees cv. ‘Owhadi’ in two consecutive seasons, 2011 and 2012. A factorial experiment was conducted in randomized complete block design whith nine treatments and three replicates at a pistachio orchard in Kusarriz region of Rafsanjan. Treatments include B as boric acid (0, 1000 and 2000 mg l 1) and Ca as calcium chlorid (0, 1 and 2%). Results of the first year showed that foliar application of 1000 mg l-l B increased the initial and final fruit set by 11 and 2l %, respectively, compared to controls. However, by application this level of B, some qualitative traits such as splitting rate, nut weight and rate of blankness significantly increased. In the second year, the highest rate of initial and final fruit set was obtained with application of 1000 mg l-1 boric acid. At the second year, concentration of Ca and B in the flower buds and leaves were increased by foliar spary of these elements, compared with controls. In general, the results of the present study showed that B application in concentration of 1000 mg l-1 after harvesting and swollen buds stages improved fruit set and some qualitative and quantitative characteristics of pistachio trees but foliar application of Ca reduced some of these parameters.