فصلنامه پژوهش های تولید گیاهی
سال هجدهم شماره 4 (زمستان 1390)

Bacterial canker and leaf spot are typical symptoms and of the most important diseases of stone fruit trees in world and in North your country. Significant management of plant disease is possible by identification and diagnosis plant pathogenic casual and associated agents. Various samples of canker and leaf spot tissues during 2007-2008 collected from different orchards of stone fruit trees of Golestan province and pathogenicity tests was demonstrated on peach young branches and leaf tissues by various bacterial isolates. Based on the morphological, nutritional, biochemical, physiological, total cellular protein pattern and PCR reaction with d21 and d22 primers Pseudomonas syringae pv. syringae (Pss), and Xanthomonas arboricola pv. pruni identified as casual agents of bacterial canker in this province. Pss was the major agent disease on the east regions such as Ali-Abad and Azad shahr but in west regions such as Kordkooy Xap was major agent. P.viridiflava isolated from gorgan areas only as associated agent with disease. This research is the first report on Xap, the casual agent of bacterial canker in stone fruit trees Golestan Province and also first report on P.viridiflava, as associated agent with bacterial canker stone fruit trees on the north regions Iran.

The effects of salinity on seed germination and tolerance of six medicinal plants were investigated. The experiment was factorial based on completely randomized designs with three replications. The first factor was salinity in five levels and second one was in six medicinal plants (Artichoke, Milk thistle, Fennel, Black cumin, Safflower and Flax). Salinity tolerance threshold for germination percentage in Artichoke, Milk thistle, Fennel and Black cumin was 4, 3.3, 10.6 and 16.5 ds m-1, respectively. But germination percentage in Safflower and Flax reduced very slowly and the amount of germination percentage was high (88 and 87 percent, respectively) under maximum salinity stress (22.22 dsm-1). Germination rate under salinity stress decreased linearly. Overall, dry weight and length of seedling reduced by the influence of salinity stress in seedling stage but salinity tolerance threshold and reduction ratio of these components were different in the plants. The results of cluster analysis showed that plants in stage of germination are categorized three groups: Safflower and Flax (tolerant to salinity), Fennel and Black cumin (moderately tolerant to salinity), Artichoke and Milk thistle (sensitive to salinity). The cluster analysis in the seedling stage showed that plants divided to four groups: Safflower (tolerant to salinity), Artichoke and Milk thistle (moderately tolerant to salinity), Fennel (moderately tolerant to salinity) and Black cumin and Flax (sensitive to salinity).

Salinity stress is regarded as one of the most important abiotic factors limiting plant growth and agricultural products, particularly in arid and semi-arid regions. This study was conducted to determine the effect of different salinity levels including 0.5 (control), 2.5, 5, 7.5 and 10 dS m-1 (a mixture of NaCl, KCl, CaCl2 and MgCl2 with weight proportional, respectively 2:1:1:1) in three replicates using a completely randomized design on growth indices (including plants height, stem diameter, leaf area, soot and root dry mass and shoot to root ratio), sodium, phosphorous and nitrogen concentrations and Na+/K+ ratio in Persian clover and wheat under greenhouse conditions. Results indicated that all the growth indices of clover and wheat decreased significantly (P<0.001) in response to salinity. Results also showed that salinity had a significant effect on nitrogen percentage in clover shoot (P<0.01), wheat shoot (P<0.001) and clover and wheat root (P<0.01). Salinity also induced significant increases (P<0.001) in sodium concentration and Na+/ K+ ratios in clover and wheat shoot. However, phosphorus concentrations in both plants were significantly (P<0.01) reduced by soil salinization. The results of the current study illustrated that wheat is capable of controlling the accumulation of sodium in its tissues, and can therefore decrease the sodium to potassium ratio when compared with Persian clover. Furthermore, the amount of decreases in phosphorus concentrations in wheat shoot in response to salinity was less than that in Persian clover. As a result, wheat is more tolerant to salinity than clover is.

In order to evaluate of genetic structure of an Iranian rice population using means analysis, P1, P2, F1, F2, BC1 and BC2 generations belong to Tarommahalli × Khazar cross planted as RCBD design with three replication in Gonbad High Education Center at 2008. Grain weight per plant, biomass, panicle lengh, plant height, flg leaf length, and width and branches number were recorded. Negative genetic parameter (F) was detected for grain number, panicle number, panicle exertion, flag leaf width. This showed that genes controlling of grain number, panicle number and flag leaf width are dominant in Tarommahalli and genes controlling of panicle exertion is dominant in Khazar. Gene action was over dominance for grain weight, days to heading, flag leaf width, branche number and biomass. Significant additive effects were recorded for biomass, days to heading, grain number, flag leaf length and width and branche number. In order to evaluation of molecular structure of agronomic traits in F2:4 population, linkage map was provided using 74 polymorphic microsatillate markers and 192 individuals. qWG-8 (grain weight), qHE-8 (plant height), qHD-10 (days to heading), qPL-1b, qPL-3 and qPL-4 (panicle leanght), qBR-8b and qBR-1b (branche number) were detected as major effects that explained 22.17, 26.25, 15.29, 25.73, 21.97, 22.23, 21.93, 20.56 and 22.94% of the total phenotypic variations. QTLs related to grain yield, days to heading and panicle exertion overlapped in RM1553-RM7424 interval. Two methods were showed that additive effect is important for controlling of days to heading and branche number, so, QTLs of these traits are useful for marker assisted selection.

Nowadays, pollination management problem has been over comed through introducing new self-compatible for almond genotypes. Therefore, producing self-compatible genotypes has high priority in almond breeding programs. So, evalution of self-compatible genotypes as compared to self-incompatible ones and study of thier pollen effect is considered to be important. The present studies, effects of self and open pollination on some quantitative and qualitative traits in 13 self-compatible genotypes were studied. To do so, four branches with enough flowers were selected in each tree at baloon stage. They placed inside bags and selfing was carried out by hand. Two branches also were selected for open pollination in each tree to compare self and open pollination effect on fruit set as well as fruit and kernel characteristics. Results showed that slfing had no negative effect on any of fruit and kernel characteristics, but it significantly reduced fruit set precantage. To slove this problem, it is recommended to plant two highly self compatible genotype together in the some orchard. Howerever, some of highly self compatible genotypes such as number 23 with high frut set (18.23%) can the planted as a monoculture.

Lemon verbena (Lippia citriodora) is a medicinal plant, belonging to Verbenaceae family and essential oil has accumulated in its vegetative and reproductive parts. This study was to evaluate the quantity and quality of seed essential oil of lemon verbena (Lippia citriodora). After preparing healthy cuttings and treatment of them for IBA, root cuttings were transferred to the greenhouse for culture and care. After flowering and fruit ripening, seeds were collected and the seed essential oil was obtained by hydro-distillation method (30 grams of seed) and was dehydrated using dry sodium sulfate. The essential oil was analyzed by GC and GC/MS. Results showed oil output in operation was 31%. Twelve major compositions containing 80.12% of the total oil were identified. The main compounds of this essential oil were Geranial (34.1%), Neral (26.01%) and Limonene (7.04%). The amount of these compounds had increased so significant in comparison with these values in essential oil from vegetative parts.

In order to measuring the leaf area index (LAI) of wheat canopy by AccuPAR at field condition, an experiment was conducted using seven wheat cultivars (Arya, Darya, Kuhdasht, Shiroudi, Tajan, Taro and Zagros) under irrigated and rainfed conditions during 2008-2009 at Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. This experiment was conducted as a Randomized Complete Block Design with four replications. LAI measuring was done by two methods, direct (destructive sampling) and non-destructive by AccuPAR from tillering stage to the canopy closure stage. The results showed that there was no significant difference between cultivars and the two conditions as aspect of equation coefficients, so one equation is usable for all cultivars under both conditions (LAI = 0.54 + 1.13 × LAI AccuPAR, R2=0.70). This equation can be used for estimation of actual LAI from calculated LAI by the AccuPAR.