Paddy Fields Of Iran Research Articles

Alborzia kermanshahica gen. nov., sp. nov. (Chroococcales, Cyanobacteria), isolated from paddy fields in Iran.

In Iran, polyphasic studies of unicellular cyanobacteria are still scarce, with more emphasis being placed on filamentous cyanobacteria in paddy fields and fresh water regions. In an effort to increase the knowledge of the diversity of unicellular cyanobacteria from paddy fields in Iran, we have isolated and characterized a new unicellular cyanobacterium strain. The strain was studied using a polyphasic approach based on morphological, ecological and phylogenetic analyses of the 16S-23S ITS rRNA gene region. Complementarily, we have searched for the presence of cyanotoxin genes and analysed the pigment content of the strain. Results showed that the strain was morphologically indistinguishable from the genus Chroococcus, but phylogenetic analyses based on the Bayesian inference and maximum-likelihood methods placed the strain in a separated monophyletic and highly supported (0.99/98, posterior probability/maximum-likelihood) genus-level cluster, distant from Chroococcus sensu stricto and with Chalicogloea cavernicola as sister taxa. The calculated p-distance for the 16S rRNA gene also reinforced the presence of a new genus, by showing 92 % similarity to C. cavernicola. The D1-D1', Box-B and V3 ITS secondary structures showed the uniqueness of this strain, as it shared no similar pattern with closest genera within the Chroococcales. For all these reasons, and in accordance with the International Code of Nomenclature for Algae, Fungi and Plants, we here proposed the description of a new genus with the name Alborzia gen. nov. along with the description of a new species, Alborzia kermanshahica sp. nov. (holotype: CCC1399-a; reference strains CCC1399-b; MCC 4116).

Life Cycle Assessment of Crop Rotation Systems on Rice Cultivars in Northern Iran

The release of environmental pollutants, which partly emanates from the application of chemical inputs, is a major global concern. Attempt to determine the methods to reduce environmental risk of rice cultivation are required. Selecting the best cover crop in rice rotation is necessary. The novelty of this research versus current knowledge is that life cycle assessment (LCA) has not been applied to assess the environmental impacts of crop rotation systems in paddy fields in Iran. Hence, the life cycle of rice cultivars in different crop rotations was assessed in Neka region, northern Iran from 2017 to 2018. All the management practices/inputs of local (‘Tarom Hashemi’) and improved (‘Shiroodi’) rice cultivars were monitored. After recording the data of 100 selected paddy fields for each cultivar, nine cover crop-rice rotations (fallow-rice, clover-rice, rape seed-rice, wheat-rice, barley-rice, faba bean-rice, garlic-rice, lettuce-rice and cabbage-rice) were identified. Functional unit of LCA was 1-ton rice yield. The results demonstrated that the maximum and minimum amount of nitrogen, phosphorus and potassium were applied in fallow-rice and clover-rice rotations, respectively. The highest paddy yield for local (4856 kg ha−1) and improved (7745 kg ha−1) cultivars was produced in clover-rice rotation. Fossil CO2 eq, biogenic CO2 eq, global warming potential (GWP) 100a, terrestrial acidification (TA) and fossil depletion (FD) of local cultivar were 11.79%, 34.76%, 13.35%, 15.48%, and 20.13% greater than improved cultivar. The most cumulative energy demand (CED) in both cultivars was obtained for fallow-rice rotation followed by rape seed-rice rotation. The highest emission of biogenic CO2 eq for both cultivar was observed in rape seed-rice and fallow-rice rotations. The lowest amount of GWP 100a was calculated in clover-rice rotation for local and improved cultivars (248.08 and 240.5 kg CO2 eq). In both cultivars, the most and lowest amount of TA, freshwater eutrophication (FEU), ozone depletion (OD) and FD was emitted in fallow-rice and clover-rice rotations. Among the crop rotations, clover-rice and fallow-rice had significantly lowest and most emission of heavy metals in the air, water and soil, respectively. As a matter of fact, the environmental emissions of the study is straightly linked to the application of inputs and field management practices. According to this, the lowest amount of environmental emissions for both cultivars was observed in clover-rice rotation. The emissions released from environmental pollutants are positively correlated with the application of inputs and field management practices for crop species in rotation system. In conclusion, clover-rice rotation showed the potential to save non-renewable energies (fuel, nitrogen, and etc.) with higher paddy yield which is considered to be environmentally friendly crop in rotation with respect to reduce emissions of GHG.

Inferring climatic controls of rice stem borers’ spatial distributions using maximum entropy modelling

AbstractAccurate assessment of pest potential distributions is needed to identify their establishment risks that play a key role in pest management in agricultural ecosystems. We used a correlative niche modelling method (Maxent) to predict and map the spatial distributions of two important rice stem borers, Chilo suppressalis and Sesamia cretica, in paddy fields of Iran. In total, 195 presence occurrence records (101 records for C. suppressalis and 94 records for S. cretica) were compiled. A set of environmental and topographic variables, with the highest effects on the species distributions and the lowest correlations among themselves, were used. The results showed that mainly the northern parts of Iran were the most suitable areas for C. suppressalis, and north, north‐east and south‐west of Iran as the most suitable areas for S. cretica. Both models performed well, with an area under the receiver operating characteristic curve (AUC) of 0.983 and 0.786 for C. suppressalis and S. cretica, respectively. The Maxent models showed higher accuracy for predicting the distribution of the specialist pest with the small range sizes compared to the generalist species. Assessing the importance of environmental variables, which were derived from the jackknife test, showed the precipitation as the variable with the highest contribution (66%) in explaining the spatial distribution of C. suppressalis compared to the other variables. The distribution of S. cretica was influenced by a set of variables derived from both the precipitation and temperature. The Maxent predictions were useful to map the geographical distributions of the risk for both rice stem borers that is needed to develop effective management strategies.

Optimization of cultivation conditions to maximize extracellular investments of two Nostoc strains

An investigation was undertaken on two Nostoc strains isolated from the paddy fi elds of Iran and having different morphologies of polysaccharide sheaths. Ex tracellular polysaccharides (EPS) presumably play a major (protective) role in cyanobacteria but there are no clear reports that link EPS production with (selected) abiotic stresses. The aim here is to investigate key factors enhancing EPS biosynthesis. The relationship between cell growth and the amount of EPS were compared under photoautotrophic, mixotrophic and heterotrophic growth conditions as well as under different salt concentrations, and under nitrogen-deplete and nitrogen-replete conditions Cell growth and EPS production are both highly dependent on culture conditions, but there is no correlation between cell growth and EPS production in cultures grown in different sources of nitrogen. In contrast, light inten si ty and cel l growth in cultures experiencing mixotrophic conditions at either 150 or 50 μmol photon m–2 s–1 have strong positive effect on EPS production. In salt-rich cult ures, in the ASN_S strain the outer cell layers p rotect the inner cells from NaCl s tress and hence its growth is maintained without inhibition under the NaCl stress. Each strain of Nostoc exhibits a different pattern of EPS synthesis, making it essential that the optimal culture conditions are determined for each species reading to the development of an effi cient technology for the maximum production of cyanobacterial EPS.

The Comparison of Farming Inputs Consumption in Traditional and Developed Paddy Fields in Iran

The most important of Land-consolidation programs is to decrease consumption of chemical inputs (fertilizer and toxins) in paddy fields, thus enhancing sustainability. This study compares the consumption of inputs in traditional and developed paddy fields in Iran, based on a case study of Gilan province. The research was conducted in the form of a sur- vey study. The data for this research was collected from 176 farmers who work traditional rice fields and 188 farmers who are part of a farm-development program in Gilan province, who were selected using a stratified random sampling procedure. Data was collected through a questionnaire. The reliability of questionnaire was determined by calculating the Cronbach's alpha coefficient (0.75) after conducting a pilot study. Analysis of the survey results showed that the average consumption of chemical fertilizer in developed paddy fields (363 kg of fertilizers per hectare) was greater than that in traditional paddy fields (308 kg/ha). In contrast, developed paddy fields used less toxins (6.4 kg/ha) than traditional paddy fields (8.3 kg/ha). The t-test showed that in two groups of farmers, the farmers of developed paddy lands used significantly more chemical toxins and manure, and significantly less chemical fertilizer, than farmers of traditional paddy lands.

Delineation of site specific nutrient management zones for a paddy cultivated area based on soil fertility using fuzzy clustering

Delineation of soil nutrient management provides basis for variable fertilization management in precision agriculture. The present fertilizer recommendations for paddy fields in Iran are typically uniform for large regions. This results in over-application of fertilizers in areas with high nutrient levels and under-application of those, in areas with low nutrient levels. A 24,000-ha paddy field was selected to define management zones (MZs) for more precise soil nutrient management. Soil samples were taken from 303 locations. Soil samples were analyzed for clay, pH, cation exchange capacity (CEC), organic carbon (OC), total nitrogen (TN), available phosphorous (AP), and available potassium (AK). After analyzing the spatial variability of these properties with geostatistical technique, they were used to delineate soil fertility management zones using principal component analysis (PCA), and fuzzy cluster algorithm. Results indicated that the optimum number of MZs for soil fertility was four. Analysis of variance indicated that there is heterogeneity in soil fertility status among different MZs. The mean values of soil nutrients in each zone can be used as a reference for variable-rate fertilization. Management zone 4 represents the most AK deficiency where soil K-supplying capacity was low. Furthermore, these results indicated that cluster analysis by reducing within-zone variability provided an opportunity for farmers to adopt site-specific nutrient management.

The Effect of Water Saving Irrigation and Nitrogen Fertilizer on Rice Production in Paddy Fields of Iran

Rice production in Iran needs to increase to feed a growing population whereas water for irrigation is getting scarce. There are 230000 ha paddy fields in Guilan province in north of Iran. About 73% of paddy fields irrigated by Sepeedrood dam. Shortage of water for rice production will be a problem in near future. In order to investigate the best irrigation regime and nitrogen level an experiment was conducted in split plot based on completely randomized block design with 3 replications at the rice research institute of Iran in 2008. Four levels of nitrogen (N1= 0, N2 = 90, N3 = 120 and N4 = 150 kg ha-1) w ere splited on 4 different irrigation managements (I1= con tinuous submergence (CS), I2 = 5, I3 = 8 and I4 = 11 days interval). The results clearly indicate that nitrogen levels and irrigation management in most of studied characteristics had very significant differences. Not only grain yield was statistically the same under CS and 8 days interval but also water consumption decreased 18%. Thus, concluded that water limited irrigation can lead to reduce water consumption in paddy fields and minimum 150 million m3 water of Sepeedrood dam saved annually.

New Records of Nostocalean Cyanobacteria from Rice Fields in the Golestan Province in North-East of Iran

The algal flora of five stations from paddy-fields of Golestan Province was investigated between October 2006 and September 2007. Eight filamentous heterocystous Nostocacean are recorded here for the first time from paddy fields of iran: Cylindrospermum licheniforme, Cylindrospermum stangnale, Cylindrospermopsis raciborskii, Calothrix ghosei, Gloeotrichia longiarticulata, Aulosira implexa var. crassa, Tolypothrix conglutionata var colorata, Scytonema multiramosum. Cylindrospermum stagnale, Aulosira implexa, Scytonema multiramosum, Tolypothrix conglutionata were dominant species in all stations and seasons, but Gloeotrichia longiarticulata and Cylindrospermopsis raciborskii were observed mainly during the spring and summer. Morphological characteristics of these species are described in detail and information about their ecological distribution is given.? 2011 Progress in Biological Sciences. Vol. 1, No. 2, 50-55.

Identification of new fungi isolated from Echinochloa spp., as potential biological control agents in paddy fields in Iran

Echinochloa spp. are the most important weeds of rice. Fungal pathogens can be exploited as biological agents for the management of agricultural weeds. Two pathogenic fungal species were isolated from naturally infected Echinochloaspecies and identified. In order to isolate the fungus from disease tissues, the obtained samples were cultured on potato dextrose agar medium. Isolates were cultured due to sporulation on water agar medium. Morphological characters of isolates were studied in order to identify the taxonomy. According to the results, isolates belonged to Bipolaris maydis (Nisikado and Miyake) Shoem., and Bipolaris australiensis (Tsuda and Ueyama) Alcorn. Pathogenicity test of isolates in species was done in desiccators, and revealed the pathogenicity of the species and their ability to cause leaf blight on Echinochloa spp.. Inoculation was done using a spore suspension consisting of 105 spore/ml distilled water and 1%Tween-20 at the 2 to 3 leaf stage. Results indicated that the disease rating caused by B. maydis and B. australiensis in Echinochloa spp. was higher than that observed in the studied rice cultivar. Hence B. maydis and B. australiensis can be considered as a probable mycoherbicide for controlling Echinochloa species. Key words: Echinochloa spp., fungi, biological control, Bipolaris spp.

Biotransformation of monoterpenes by immobilized microalgae

This paper reports the biotransformation of carvone, limonene, β-pinene, thymol, and linalool using whole-cell-immobilized microalgal strains isolated from paddy fields of Iran. The strains was recognized by morphological characterization and assigned according to amplified 16S/18S rRNA genes by PCR. Ten unialgal strains including Chlorella, Oocystis, Chlamydomonas, and Synechococcus were immobilized in calcium alginate beads. After a 24-h incubation with substrates, characterization and identification of biotransformation products were done by GC/MS. None of the isolated immobilized microalgae converted β-pinene. In contrast, most of these strains biotransformed carvone and limonene to the related compounds. Some strains only reduced the C = C double bond to yield the dihydrocarvone isomers while others reduced the ketone to give the dihydrocarveol. The transformation ratio showed that Oocystis sp. MCCS 033 and Synechococcus sp. MCCS 035 produced dihydrocarvone isomers with the highest efficiency. Furthermore, limonene was converted into a mixture of five corresponding products and the maximum yield was 52.1% for carvone, the bioconverted product. Only one strain, Synechococcus sp. MCCS 034, oxidized thymol, and the product obtained from thymol was thymoquinone. Also, linalooloxide isomers and dihydrolinalool were obtained from linalool, and finally dihydrolinalool was the main product. These results showed a novel conversion pathway of linalool-forming dihydrolinalool.

Cyanobacteria from paddy fields in Iran as a biofertilizer in rice plants

In this research cyanobacteria (Blue-Green Algae, BGA) were isolated, identified, multiplied and used as an inoculum in pot rice experiment. The pH, moisture and algal population were measured in four seasons. The highest and lowest pH (6.7, 6.2), moisture of soil (43%, 34%) and algal population (12, 20 Colony-Forming Units/50 ml on A and B medium and 4, 5 Colony-Forming Units/50 ml on A and B medium) were recorded in spring and winter, respectively. The only heterocystous cyanobacteria were found in soil samples identified as <I>Anabaena</I> with four species (<I>A. spiroides, A. variabilis, A. torulosa </I>and <I>A. osillarioides</I>). The germination of rice seeds treated with cyanobacteria was faster than control. The result of pot experiment were: increase of 53% in plant height; 66% in roots length; 58% in fresh leaf and stem weight; 80% in fresh root weight; 125% in dry leaf and stem weight; 150% in dry root weight; 20% in soil moisture; 28% in soil porosity and a decrease of 9.8% in soil bulk density and 4.8% in soil particle density. There were significant differences (<I>P</I> < 0.05) in pot treated with BGA as compared with control.

Antifungal and Antibacterial Activity of the Microalgae Collected from Paddy Fields of Iran: Characterization of Antimicrobial Activity of Chroococcus dispersus

Antifungal and antibacterial activity of the microalgae from paddy fields in the south of Iran were studied. Soil samples were collected from paddy fields of Fars province and were cultured in BG11 medium. Supernatants, methanolic and hexane extracts from biomass of 60 strains of microalgae were isolated and screened against six strains of bacteria and four strains of fungi. The culture supernatants of 21 strains of microalgae and methanolic extracts of 8 strains exhibited significant antibacterial effect and 17 strains showed antifungal effect. No antimicrobial activity was detected in the hexane extracts and no methanolic extracts inhibited the growth of fungi. In present screening, Chroococcus dispersus, Chlamydomonas reinhardtii and Chlorella vulgaris appeared to be the most promising strains and it was shown that they excreted a broad spectrum of antimicrobial substances in the culture medium. Among all of the species studied in this investigation for antibacterial and antifungal activity, Chroococcus dispersus PTCC 1677 indicated widespread spectrum of antimicrobial activities. Bioautography and Bioassay-guided fraction of culture medium of the Chroococcus dispersus exhibited a polar substance in the culture medium as well.