فصلنامه پژوهش های تولید گیاهی
سال بیست و یکم شماره 3 (پاییز 1393)

Iran is among the world''s arid and semi-arid countries. Drought stress is one of the most important environmental stresses affecting fruit trees and considerably can cause yield reduction. Persian walnut (Juglans regia L.) with significant area harvest is one the most important nuts in Iran which require sufficient amounts of water for optimal growth and efficiency. In order to study the effect of different levels of water stress on some morphological and physiological parameters of Persian walnut and to determinate the tolerance of the seedlings to drought stress، the experiment has been carried out as factorial based on completely randomized design in a controlled greenhouse with nine treatments and 20 replications. In this study، stress levels including control (80% of field capacity)، moderate drought stress (50% field capacity) and severe drought stress (20% field capacity) were applied and measurements were carried out through three stages. The results of morphological، physiological and biochemical parameters showed that these parameters have been affected by the stress levels. It was found that the walnut seedlings could not able to tolerate the moderate drought stress even at 50% of field capacity. Therefore، the intolerance of walnut seedlings to moderate and severe levels of drought stress was accounted to the increased ion leakage، reduced leaf relative water content، chlorophyll degradation، decreasing the amount of reduced sugars، proteins and increase in proline and hydrogen peroxide as well as an inefficient antioxidant enzymes for stress tolerance.

It is essential to understand crop yield potentials and exploitable gaps to detect yield constraints of crops. Yield gap analysis is a method to evaluate our systems distance from actual capability of a region to produce a given crop which will direct researches and help for cropping patterns design and programming. Moreover، knowledge on a region capability could result in investigating on given crop. Thus، this research was aimed to quantify water-limited potential yield، comparison of actual and potential yield and yield gap analysis of chickpea production in Zanjan province. Also Geographical Information System (GIS) approach was used to produce agroecological zoning maps. Averaged water-limited potential yield in Zanjan province was assessed as 727 kg ha-1 (varied from 559-1075 kg ha-1) using a simple simulation model of chickpea. With considering averaged actual yield as 408 kg ha-1 (average of three years، from 2009-2011)، mean yield gap was evaluated as 43% (varied from 24-59%)، which its average value is equal to 320 kg ha-1 (varies from 157-475 kg ha-1). The most important finding was the possibility of considerable increasing of yield in studied province in comparison with current yield. Our results on yield gap revealed that with covering of 80% potential yield، it is possible to increase yield from 5 to 95% (48% in average). Improvement of sowing، protection and harvesting managements are the main and lowest-cost options to fill the chickpea yield gap in Zanjan Province.

Estimation of weed damage threshold is essensial in site-specific weed control programs. This experiment was conducted to determine the spatial distribution of weeds damage threshold in two wheat feilds. Data related to weed biomass and crop yield were collected from sampling at 120 and 135 points of the first and second fields respectively based on a 4×4 m grid at research field of agricultural college of Shahrood University، in 2012. The damage threshold based on 10% yield reduction estimsted by models was 2. 31 and 2. 77 gr. m-1 of total weed dry weight in the first and second fields respectively. The results also showed that the trained RBF neural network had high capability in prediction of weeds biomass spatial distribution based on damage threshold of 0 and 10% yield reduction (with 99 % output، 0. 99 coefficients and the average error of less than 1. 58 and 1. 3 respectively) in the first and second wheat fields. According to the experiment results، determination of saptial distribution of weed damage threshold using total weed s biomass can be used as an effective method in the mapping of weeds in site specific weed control programs.

In this research، the effects of pulsing application of preservative solutions containing salicylic acid (100 and 200 mg/L) and methyl jasmonate (25 and 50 mg/L) and long period application of preservative solutions containing thymol (75 and 125 mg/L)، menthol (75 and 125 mg/L) and eugenol (50 and 100 mg/L) on the maintain quality and extend vase-life of carnation cut flowers two tests were evaluated based on completely randomized design in four replication. Sucrose was added to all solutions at 4% and distilled water plus 4% sucrose used as control treatment. Meanwhile، the cut flowers were also kept at conditions of 25±2 ºC with air humidity (RH) of 50-55% and 3±1 ºC with RH of 80-85%. The results revealed that at the conditions of in 25±2 ºC the highest vase- life of 11 days and 10. 66 days was obtained with methyl jasmonate 50 and 25 mg/L، respectively. These treatments also increased flower diameter، absorption of preservative solution and delayed petal wilting. The result indicated that with 3±1 ºC In Comparison with control (62 days)، the highest vase- life of 70/03 days، 68/5 and 65/81 days were obtained in menthol 125،eugenol 100 and menthol 75 Mg/L، respectively. These treatments reduced petal wilting and increased total soluble solids، flower diameter and vase life compared to control and all other treatments.

This study was aimed to assess wheat-grown fields health in Gharessoo basin، Golestan province، Iran، using 79 fields in 8 villages in 2010. The samples were taken by Quadrates. The number and the type of weeds were recorded at genera and species levels. In parallel، management data were recorded by questionnaire. Species richness was defined as species number and Shannon-Wiener index، Simpson’s index of diversity and reverse Simpson index were used as weeds biodiversity assessment indices. Wheat fields map were detected by Landsat 5 satellite images by remote sensing techniques. Digital elevation model also was provided from 1:25000 digitized maps. Slope and aspect layers were provided by DEM and were reclassified. Climatic، biodiversity and yield interpolated layers also were provided using multiple regression models. All of these layers also were reclassified. The regions with higher yield than mean values and lower weed biodiversity indices were considered as healthy. Also، the fields with lower pesticide application than Golestan application mean (1. 45 lit. ha-1) were considered as healthy. A data mining method (CRT) was used to assess management options effect on weeds biodiversity indices and yield in studied fields. Our results revealed that just 44 percentage of cultivated lands (2064 ha) and just 11 percentage of studied fields (7 fields) were healthy in respect to yield، weeds biodiversity and pesticides application.

One of the important methods of plant propagation in large scale so as genetic manipulation and artificial seed production is somatic embryogenesis technique. The obtained results from this methods related to different factors including condition of culture medium. Therefore، the aim of this study conduction were determining the role of molybdenum during carrot petiole somatic embryogenesis. At the first، sections of carrot petiole were cultured in modified B5 medium as embryogenesis induction phase. In this study different treatments on carrot petiole somatic embryogenesis were investigated. So as B5 medium containing nitrate alone، B5 medium containing nitrate and ammonium that molybdenum was added in standard concentration (0. 99mg/L) from some of them and remove from others. After one month، the explants subcultured in realization medium with same condition of induction medium but without 2،4-D. After six weeks of realization، the number of roots and embryos were determined. The result shows، the most roots and globular embryos were formed in the medium containing only nitrate (with and without molybdenum). According to the statistical analysis، molybdenum affect root and globular embryos insignificantly in these media (P0. 05). But، the most total embryos were produced and developed in medium containing both nitrate and ammonium with molybdenum. In medium containing both nitrate and ammonium، the embryos were developed with thick hypocotyls. The results showed that plants materials in medium without molybdenum apparent green color were increased that shows positive effect of reduced nitrogen on synthesis of chlorophyll the same as cytokines increases.

Salinity is one of the important problems in the world''s agricultural land that each year millions tons of salt from the soil through crop irrigation arrive to arable lands. Wheat is one of the first and most important cereal crops in the world that provide staple food for more than a third of the world''s population. Using modern genetic methods such as sequencing provided quickly and accurately assess of genetic material at DNA and RNA levels. Therefore، in order to identify the allelic diversity of HKT gene used cultivated and wild samples from wheat. Seeds were planted in plastic pots and at two-to three-leaf stage DNA were extracted according Doyle et al (1998) and PCR was performed using specific primers and PCR products were purification and sequenced. Results display variation at nucleotide and amino acid levels among samples with bread wheat in NCBI. The results of the DNA sequencing indicated that Aegilops speltoides with 98. 9% have highest similarity and Ae. caudata and Ae. triuncialis with 93. 9% show least similarity with Triticum aestivum in NCBI respectively، whereas Hordeum spontaneum has only 36. 5 similarities with HKT sequence in NCBI. Phylogenetic construction using UPGMA method at DNA level confirm above results. Also، phylogenetic tree show that Ae. speltoides and bread wheat are located in the same sub-group، this means that HKT gene via introgression from Ae. speltoides transfer to bread wheat.

To find out the effect of sodium nitroprusside (SNP) in reducing oxidative damage induced by salinity stress in barley seedlings، a CRD based factorial experiment with three replications was conducted in Agronomy Laboratory of the Faculty of Agricultural Sciences، University of Guilan، in 2012. The experimental design consisted of two SNP levels (0. 1 and 0. 2 mM SNP; as nitric oxide (NO) donor) and two amount of NaCl (0 as control and 300 mM NaCl). Seven days after the onset of the experiment، Superoxide dismutase (SOD)، peroxidase (POD)، catalase (CAT)، ascorbate peroxidase (APX) and polyphenol oxidase (PPO) activities، lipid peroxidation (MDA) and oxidation of proteins content in leaves were measured. Results revealed that the highest POD (7. 07 μM g-1 FW. Min.) and CAT (17. 6 μM g-1 FW. Min.) activity was related to the treatment SNP0. 1 in saline condition. No significant effect of salinity stress was seen on APX enzyme activity; however، highest of the SOD and APX activity was attained in SNP0. 1. No significant effect of NO treatment was seen on PPO enzyme. Exogenous NO، as an antioxidant، also reduced peroxidation of membrane lipids (MDA) and delayed the oxidation of proteins. Overall، it seems that the concentration of 0. 1 mM NO is the best concentration for barley seedlings under saline conditions which could increase resistance seedlings through the reduction salinity stress adverse effects by influence on the plant antioxidant defense system.

Jujube (Ziziphus jujuba Mill.) is a native، economic Iranian plant mainly cultivated in Birjand. It is a deciduous shrub or tree with plain leaves with alternate placement pattern، androgynous flowers and hard fruits whose fruit and wood are used. Mycorrhiza is the most prevalent symbiosis between the fungi and vascular plants which has various types. Due to the beneficial effects of this symbiosis on growth، reaction to stress conditions، adaptation and propagation، the effect of irrigation period (water stress) on the degree of jujube’s colonization by mycorrhizae during a growth period was investigated based on randomized complete block design form of factorials with the factors being irrigation period، plant size، and time in the in farm conditions with two replications. Results from the investigation indicated that increasing irrigation period of trees which results in stronger water stresses increases mycorrhization. In addition، mycorrhization of the roots increases differently from May to August and there is a direct relationship between size of trees and quantity of mycorrhization. Considering the fact that jujube’s endomycorrhizal symbiosis facilitates its water and minerals absorption in environmental stressful conditions، using the technology of endomycorrhizal fungi development enables us to extend jujube cultivation lands to new environments in line with the principles of sustainable development.