Species and space: a combined gap analysis to guide management planning of conservation areas

Landscape Ecology - With accelerating global declines in biodiversity, establishment and expansion of conservation areas (CAs) have increasingly been advocated in recent decades. Gap analysis has...     

Characterization of Pectobacterium species from Iran using biochemical and molecular methods

Characteristics of forty strains from macerated potato tubers and water-soaked lesions of some ornamental plants were studied in north parts of Iran. The causal organisms isolated from infected tissues were identified as Pectobacterium spp. based on their physiological and biochemical assays and confirmed by species and subspecies specific PCR and RFLP analysis of 16S–23S intergenic transcribed spacer region. Artificial inoculation of isolates to their related hosts generated the same symptoms on potato and ornamental plants, from which the same bacteria were isolated and identified. We detected two groups of atypical isolates in this study. The first group from potato classified as Pectobacterium carotovorum subsp. carotovorum by phenotypic tests but was unable to elicit HR on tobacco leaves, to grow at 37°C and to amplify the pel gene relevant to this subspecies. The second one from ornamental plants which was again characterized as Pectobacterium carotovorum subsp. carotovorum in biochemical assays, produced a unique ITS-RFLP profile different from all of known Pectobacterium species and subspecies. Our findings based on phylogenetic analysis using concatenated partial sequences of housekeeping genes mdh and gapA, indicated the occurrence of P. wasabiae as a novel species in potato storage in Iran. Furthermore we detected a distinct clade of Pectobacterium spp. from some ornamental plants including Schlumbergera bridgesii, Syngonium podophyllum and Iris spp.     

Sand mining disturbances and their effects on the diversity of arbuscular mycorrhizal fungi in a riparian forest of Iran

The major objective of this study was to evaluate the effects of sand mining disturbances on the diversity of arbuscular mycorrhizal fungi(AMF). In addition, the proportional changes in the diversity of AMF to the distances from riverbanks were assessed. For this purpose, the riparian forest of the Maroon River, Iran was divided into three locations with a 200-meter wide zone in between. Thus, the locations studied were named Distance I(riverbank), Distance II(intermediate), and Distance III(farthest from riverbank). In each of these distances, 10 Tamarix arceuthoides and Populus euphratica of each species were randomly selected. At the same time, soil and root samples were collected from the rhizosphere of the tree species studied. Results indicated that totally 13 AMF species were observed in T. arceuthoides and 19 AMF species were recorded in P. euphratica rhizosphere belonging to 6 genera and 6 families. In these AMF species, Glomus segmentatum, G. geosporum, G. rubiforme, G. nanolumen, G. spinuliferum, Claroideoglomus drummondii, Gigaspora gigantea and Acaulospora paulinae appeared only in P. euphratica rhizosphere, while G. multiforum and Claroideoglomus claroideum were observed only in T. arceuthoides rhizosphere. Moreover, Distance II had the least AMF species both in T. arceuthoides and in P. euphratica rhizospheres, and also the least spore density and root colonization rate. Our results are important in that they provide a list of resistant AMF species that could be used in the conservation of biodiversity.     

Growth analysis of rhizomania infected and healthy sugar beet

Viral disease of rhizomania is one of the most important diseases of sugar beet all over the world. The disease significantly has reduced the yield and quality of sugar beet, and has imposed high economic loss to farmers. Long-term breeding programs to introduce tolerant cultivars are the only chance of avoiding further yield losses. This study tried to measure and analyze the growth of shoots and roots of rhizomania-tolerant and -susceptible sugar beet with the aim of providing information for modeling of the rhizomania effects on the growth of sugar beet. Growth indices were used for analyzing, quantification, and time-course of sugar beet growth under infested and non-infested soils conditions. A 2-year experiment was conducted using four sugar beet cultivars in 2010 and 2011 in Mashhad, Iran. The results of this study showed that under infested soils, root dry matter and leaf area index of the susceptible cultivars in comparison to tolerant cultivars were lower by 57 and 24%, respectively. In addition, crop growth rate and net assimilation rate of susceptible cultivars were affected by rhizomania and were lower than in tolerant cultivars. On non-infested soil, the difference between dry matter and growth indices of susceptible and tolerant sugar beet cultivars was not significant. Rhizomania decreased green area and photosynthesis capacity and led to lower growth rate and dry matter production. Our study quantified the growth of rhizomania-infested sugar beet plants in comparison with non-infested plants and provided information to be used for modeling of the rhizomania effects on the growth of sugar beet.     

Effect of thiamine injection on growth performance,hematology and germinal vesicle migration in sterlet sturgeon Acipenser ruthenus L.

The present study aimed to investigate the effect of thiamine on growth, hematological, egg thiamine content and oocyte nucleus migration indices in sterlet sturgeon (Acipenser ruthenus). A total of 45 female fish (698.6 ± 8.9 g) were distributed in nine fiberglass tanks with three treatments (each in three replicates). Experimental fish were fed once a day with practical diet supplemented with 1 g kg^?1 amprolium hydrochloride (as the antithiamine) for 5 months before spawning. Thiamine hydrochloride was injected to fish with one of three doses at 0, 5 and 50 mg kg^?1 body weight (BW) at three different stages. At the end of each month, fish were weighed and growth parameters such as weight gain, specific growth rate, feed efficiency and final weight were determined. At the end of the 5-month period, hematological parameters and egg thiamine content were measured. The results showed no significant differences in terms of growth performance. Hemoglobin, number of red blood cells and white blood cells were not significantly different among the treatments, but hematocrit was significantly higher in fish injected with 5 mg kg^?1 BW thiamine. The mean corpuscular volume and mean corpuscular hemoglobin were not significantly different, but lower value of mean corpuscular hemoglobin concentration was observed in fish injected with 5 mg thiamine. Percentage of lymphocytes, neutrophils, eosinophils and monocytes were not significantly different among treatments. The results of the germinal vesicle migration index at different stages showed no significant differences in different groups. Results showed that free thiamine, thiamine pyrophosphate and total thiamine in eggs significantly increased at 50 mg kg^?1 injection dose compared with the control, but no significant different was found in thiamine monophosphate. The results revealed that thiamine injection to sterlet broodstocks has positive accumulation in egg thiamine content and some hematological parameters but have no effect on growth and ovarian maturation. We conclude that thiamine can affect some physiological features of broodstock, which needs to be specified in further studies.     

Physiological and anatomical responses of calendula (Calendula officinalis L.) cultivars to heat-stress duration

It is necessary to identify the heat-tolerant cultivars of bedding plants in order to cope with the challenges of the global warming. The physiological and anatomical responses of four calendula cultivars (Candyman’, ‘Zen’, ‘Indian Prince’, and ‘Pacific Beauty’) to four duration levels (0, 7, 14 and 21 days) of heat stress (in a mean range of 35–42°C), were investigated after their establishment under greenhouse conditions. The results indicated that calendula cultivars displayed different responses to various heat duration levels in most parameters. Although the gas exchange of ‘Candyman’ was the highest in control treatment, it showed a considerable reduction in all levels of stress durations. In contrast, ‘Indian Prince’ maintained gas exchange and chlorophyll content and exhibited the most resistance to heat stress among others, especially for longer duration exposure, which might be resulted from the greater soluble sugar content, higher stomatal density, and thicker leaves. Experiment to assess cell membrane thermostability showed heat stress resulted in significant increase in electrolyte leakage percentage as the incubation temperature of all cultivars was increased. However, the least membrane stability was observed in ‘Zen’, indicating the higher sensitivity of this cultivar to heat-stress conditions in comparison to three other cultivars.     

Effects of drip irrigation regimes on potato tuber yield and quality

To evaluate the effects of drip irrigation regimes on potato (Solanum tuberosum L.) tuber yield and quality, an experiment was conducted in 2009 and 2010. Experimental factors were the irrigation regimes including: FI, providing 100% of the water requirement of potato; IR1, providing 70% of the water requirement of potato by reducing the applied irrigation water between planting and tuber initiation by 30%; and IR2, providing 70% of the water requirement of potato by reducing the applied irrigation water during the whole growing season by 30%; and three potato cultivars Agria, Almera and Sinora. The results indicated that cultivars Agria and Almera were much better than Sinora in terms of tuber yield under all irrigation regimes. For Agria and Almera, the experiments show that the full irrigation regime had the highest yield and water productivity. For Sinora, however, deficit irrigation yields higher water productivity than the full irrigation regime. Consequently, deficit irrigation IR1 and IR2 should be applied to Sinora, but not to Agria and Almera.     

Numerical modeling based on a finite element method for simulation of flow in furrow irrigation

In this study, a zero-inertia finite element model (ZIFEM) is developed and applied for simulating all phases of furrow irrigation based on Saint–Venant equations. The complexity and nonlinear behavior of the Saint–Venant equations are the major difficulty in developing a finite element model to simulate furrow irrigation. Therefore, through the Galerkin FEM approach, the model assesses the free surface flow on a variable cell length at each time step and determines the suitable element length for each individual cell and the model solves the equations by using an iterative method. Along with the free surface flow phase, the infiltration phase is estimated by the Kostiakov–Lewis equation. The ZIFEM model is verified using seven experimental data sets collected from the literature and observed data from the farm consisting of two free drainage furrows with a length of 72 m, a top width of 0.8 m, a depth of 0.25 m and a slope of 0.2%. The model accuracy is studied to simulate advance and recession trajectories and runoff by calculating the root-mean-square error (RMSE), relative error and percentage error. It is observed that in all irrigation events, the proposed model reasonably agreed with field measurements. An evaluation of the RMSE shows that in 81.25% irrigation events the ZIFEM is more accurate than the WinSRFR model. In overall, the results of the model suggest that the ZIFEM can be introduced as a potential numerical tool for analyzing and evaluating furrow irrigation.     

Comparative study on hormones and biochemistry indices in plasma,ovarian fluid and oocytes of LHRHa2‐induced female Stellate sturgeon (Acipenser stellatus)

Reproduction efficacy of sturgeon as donors of oocytes is regulated by hormones effects. It can influence the egg quality or larvae functions as rearing mediators for successful production. This study is conducted to evaluate the concentration of sex steroids, cortisol and thyroid hormones and distinguish the relationship of maternal hormones' correlation in Stellate sturgeon. The study followed the hormones fluctuations that could impress some egg quality information such as fertilization rate. Female breeders were injected with LHRH_a2 for controlled propagation. Samples from blood, ovarian fluid and oocytes were obtained for hormonal and biochemical analysis. Our results showed that the concentrations of estradiol 17‐β and testosterone were significantly higher and lower in oocyte and the plasma, respectively. The level of plasma cortisol was significantly higher than in ovarian fluid and oocytes. The results showed elevation of triiodothyronine and thyroxine concentrations in oocytes, which were significantly different with plasma and ovarian fluid. Thyroxine concentration of plasma and ovarian fluid revealed a significant negative correlation. The mentioned parameters showed negative correlation with fertilization rate. The biochemical parameters (calcium, glucose, cholesterol and triglyceride) revealed significant differences in blood, ovarian fluid and oocytes. These results showed direct relations of fertilization rate with hormones level. Therefore, fertilization rate as egg quality index could be recommended as a relevant indicator of maternal transferring of hormones from blood and ovarian fluid to oocyte.