Growth Stages Of Rice Plants Research Articles

Effect of Different Zinc Sources and Application Methods on Content and Uptake of Micronutrients of Basmati Rice

Zinc (Zn) is an essential trace element for plants, animals and human’s health. Zn deficiency is widely spread in paddy soils of India and has negative impact on national rice production. Field experiment on rice crop was conducted in sandy loam soil at crop research center Chirodi of SVBP University of Agriculture and Technology, Meerut., during Kharif season of 2011 and 2012 toevaluate the “Effect of different sources and application methods of zinc on content and uptake of micronutrients in basmati rice crop in sandy loam soil. The experiment was laid out in randomized block design with three replications. The experiment comprised of twelve treatments viz.; T1 (control), T2 (recommended NPK @120:60:60 kg ha-1) T3 (5 kg Zn through ZnSO4.7H2O+RDF), T4(5 kg Zn through mono ZnSO4.7H2O),T5 (0.1% Zn spray through ZnSO4.7H2O+RDF ),T6 (0.1% Zn spray through ZnSO4.7H2O + RDF),T7 (0.012% Zn spray through chelated Zn at tillering + RDF),T8 (0.05% Zn spray through ZnSO4.7H2O at tillering +0.05% at panicle initiation+ RDF), T9 (0.05% Zn spray through mono ZnSO4.7H2O at tillering + 0.05% at panicle initiation +RDF),T10 (0.006% Zn spray through chelated Zn at tillering + 0.006% at panicle initiation+ RDF ), T11 (micronutrient mixture@ 25kg ha-1 + RDF), T12 (vermicompost @ 3tha-1+ RDF).The experimental soil was low in organic carbon and available nitrogen and medium in phosphorus and higher in potassium with slightly alkaline in pH. The status of DTPA extractable Zn 1.23 mg Kg-1,Fe 14.85 mg Kg-1 Cu 2.43 mg Kg-1 Mn 10.91 mg Kg-1 in the surface soil. Nutrient assimilation at different stages by the rice crop varied significantly due to application of different treatments in the study. Maximum zinc content 85.78 and 93.57 ppm and uptake 288.60 and 341.85 g/ha at 30 DAT during 2011 and 2012 found in T12 which was significantly higher than the rest of the treatments while minimum zinc content recorded in T1 was significantly lower than the rest of the treatments during both the years. Similar trends were also recorded at 60 DAT, grain and straw growth stages of rice plant. The zinc content of plant sample in T11 and T3 was also higher and statistically at par to the level of zinc content recorded in T12. The Cu, Fe, and Mn content and uptake at different growth stages of rice plant sample in T11 and T3 was also higher and like the level in T12. Among the method of Zn application, soil application resulted in higher biomass, micronutrient content and uptake in the grain and straw. Foliar application caused greater effect on zinc content and uptake and as well as content and uptake of Cu, Fe and Mn in rice plant at different growth stages during both the years. Among the sources of Zinc, ZnSO4.7H2O proved to be the most efficient source of Zn for rice production.

Optimizing window size and directional parameters of GLCM texture features for estimating rice AGB based on UAVs multispectral imagery.

Aboveground biomass (AGB) is a crucial physiological parameter for monitoring crop growth, assessing nutrient status, and predicting yield. Texture features (TFs) derived from remote sensing images have been proven to be crucial for estimating crops AGB, which can effectively address the issue of low accuracy in AGB estimation solely based on spectral information. TFs exhibit sensitivity to the size of the moving window and directional parameters, resulting in a substantial impact on AGB estimation. However, few studies systematically assessed the effects of moving window and directional parameters for TFs extraction on rice AGB estimation. To this end, this study used Unmanned aerial vehicles (UAVs) to acquire multispectral imagery during crucial growth stages of rice and evaluated the performance of TFs derived with different grey level co-occurrence matrix (GLCM) parameters by random forest (RF) regression model. Meanwhile, we analyzed the importance of TFs under the optimal parameter settings. The results indicated that: (1) the appropriate window size for extracting TFs varies with the growth stages of rice plant, wherein a small-scale window demonstrates advantages during the early growth stages, while the opposite holds during the later growth stages; (2) TFs derived from 45° direction represent the optimal choice for estimating rice AGB. During the four crucial growth stages, this selection improved performance in AGB estimation with R2 = 0.76 to 0.83 and rRMSE = 13.62% to 21.33%. Furthermore, the estimation accuracy for the entire growth season is R2 =0.84 and rRMSE =21.07%. However, there is no consensus regarding the selection of the worst TFs computation direction; (3) Correlation (Cor), Mean, and Homogeneity (Hom) from the first principal component image reflecting internal information of rice plant and Contrast (Con), Dissimilarity (Dis), and Second Moment (SM) from the second principal component image expressing edge texture are more important to estimate rice AGB among the whole growth stages; and (4) Considering the optimal parameters, the accuracy of texture-based AGB estimation slightly outperforms the estimation accuracy based on spectral reflectance alone. In summary, the present study can help researchers confident use of GLCM-based TFs to enhance the estimation accuracy of physiological and biochemical parameters of crops.

Triose phosphate utilization in leaves is modulated by whole-plant sink-source ratios and nitrogen budgets in rice.

Triose phosphate utilization (TPU) is a biochemical process indicating carbon sink-source (im)balance within leaves. When TPU limits leaf photosynthesis, photorespiration-associated amino acid exports probably provide an additional carbon outlet and increase leaf CO2 uptake. However, whether TPU is modulated by whole-plant sink-source relations and nitrogen (N) budgets remains unclear. We address this question by model analyses of gas-exchange data measured on leaves at three growth stages of rice plants grown at two N levels. Sink-source ratio was manipulated by panicle pruning, by using yellower-leaf variant genotypes, and by measuring photosynthesis on adaxial and abaxial leaf sides. Across all these treatments, higher leaf N content resulted in the occurrence of TPU limitation at lower intercellular CO2 concentrations. Photorespiration-associated amino acid export was greater in high-N leaves, but was smaller in yellower-leaf genotypes, panicle-pruned plants, and for abaxial measurement. The feedback inhibition of panicle pruning on rates of TPU was not always observed, presumably because panicle pruning blocked N remobilization from leaves to grains and the increased leaf N content masked feedback inhibition. The leaf-level TPU limitation was thus modulated by whole-plant sink-source relations and N budgets during rice grain filling, suggesting a close link between within-leaf and whole-plant sink limitations.

The early heading growth stage of rice plants in using the SRI method by giving liquid organic fertilizer of coconut husk and banana stems

Coconut husk and banana stem waste can be used as a source of organic material for plants which is utilized in the form of liquid organic fertilizer. This study aims to determine the interaction between types of liquid organic fertilizer and the concentration of liquid organic fertilizer. This research was carried out in Sungai Bangek, Balai Gadang Village, Koto Tangah District, Padang City from June until September 2022. The design used was a split plot in a randomized block design. The main plot is liquid organic fertilizer with 2 levels of coconut husk and banana stem while the subplot is liquid organic fertilizer concentration consisting of 7 levels (0, 50, 100, 150, 200, 250, 300 ml/liter). The data were analyzed through variance analysis using the F test and if significant, it was continued with Duncan New Multiple Range Test (DNMRT) with a significance level of 5%. The data is processed with Stat8 software. The observed variables consisted of plant height, the number of tillers, leaf area index, relative growth rate, and net assimilation rate. The results obtained on the growth variable have not shown significant results in every observed observation. There was a very strong correlation between the number of tillers and the leaf area index which had a unidirectional relationship. There was a fairly strong correlation between the leaf area index and net assimilation rate which has an opposite relationship.

STATUS AND PROSPECTS OF SPRING RICE IN NEPAL: A REVIEW

Spring rice as an alternative to the main season rice has been under major priority of Nepal Government for its huge potential in self-reliance in grain food production and food security in Nepal. Though having higher production and productivity, it was found that its production area had not been scaled up as anticipated. Sowing time is adjusted considering cold stress and pre-monsoon rainfall. Seedlings are generally raised in wet bed and dry bed nurseries based on availability of spring water and 30-40 days seedlings are transplanted in the Nepali month of Chaitra (Mar/Apr). Water being crucial during the growth stages of rice plant, water level of 2-5 cm is found to have better yield and performance. Whereas mainly 16 elements including both micro and macro elements have been required for proper growth and development of rice which were mainly supplied through FYM, compost, urea and DAP. Various cultural, mechanical and chemical methods are found for management of weeds. Similarly, IPM approach as well as modern approaches like gene manipulation, resistant varietal development have been evolving instead of solely pesticides application for better protection of spring rice crop in the present context.

A cumulative assessment of plant growth stages and selenium supplementation on arsenic and micronutrients accumulation in rice grains

Arsenic (As) accumulation in rice grain and subsequent transmission into the food chain is a major global concern. Numerous attempts to minimize As accumulation in rice have been researched till date. The current investigation evaluates the relative susceptibility of different growth stages of rice plant to As stress in terms of As accumulation in grain at maturity using sixty treatment combinations. Our findings suggest that supplementing with selenium (Se) resulted in minimizing As content significantly (at P < 0.001 level) in grain, irrespective of growth stages where As stress was introduced. The findings registered the following order of susceptibility to As stress: flowering > grain filling > maximum tillering. Our findings also showed that Se primed rice plants restricts majority of As accumulation in the root itself and minimizes As translocation to the above ground part. The results of this study shows that cultivation of Se primed seeds can be (i) an effective means to minimize As accumulation in rice, and (ii) potential mode of biofortification of rice grain with essential nutrient elements {iron (8.47–10.17 mg L-1), zinc (7.14–8.05 mg L-1), manganese (17.92–19.71 mg L-1) and copper (3.18–3.28 mg L-1)} improving the recommended dietary intake of micronutrients, an invaluable strategy especially for malnourished rice dependent populations. Using machine learning this study also predicts that the Se concentration of 0.862 mg L−1 could be the most effective input in minimizing As content and enhancing other micronutrient content, irrespective of As stress.

Effects of different water management and fertilizer methods on soil temperature, radiation and rice growth

In recent decades, the application of organic fertilizer to agricultural soils has attracted wide attention. However, few studies have carefully explored the effects of humic acid fertilizer on soil temperature, radiation, and the physiology of plant leaves, especially when coupled with different irrigation methods. To provide a better growing environment for crops and explore the best regulation method of humic acid fertilizer and irrigation in the farmland soil environment on the Songnen Plain, China, through field experiments, we selected rice as the test crop and applied humic acid fertilizer to the soil with different irrigation methods. The effects of different humic acid fertilizers and irrigation methods on the soil temperature and radiation changes during different growth stages were examined, and the subtle differences in agronomic and fluorescence characteristics in different growth stages of rice plants were compared. The results showed that the soil temperature was not significantly different among all the treatments. However, radiation interception was obviously different, and the best value was observed in the CT5 treatment. The fluorescence indices and leaf chlorophyll relative content (SPAD) differed with the change in humic acid fertilizer application and irrigation methods. At the jointing and heading stages, the Fv/Fm values of the CT5, FT5 and WT5 treatments were larger than those of the other treatments, and the best value was recorded in the CT5 treatment. The differences in NPQ at these two stages were significant, and the NPQ in the CT5 treatment was significantly higher than that in the other treatments (P < 0.05). In general, the QP under control irrigation was greater than that under flood and wet irrigation (P < 0.05). Moreover, there were no significant differences among the gradients under the different humic acid fertilizer application methods in terms of QP (P > 0.05). Additionally, SPAD values were higher under the CT5 and FT5 treatments.

Time‐course changes in the ionomic profiles of rice leaves and their application in growth stage prediction

AbstractIonomic profiling of plant tissues aims to understand the role of genetic factors and external conditions in mineral nutrient composition. However, little is known about the time‐course changes occurring in these profiles during plant growth. The influences of genotype, environment, and management factors are not well understood. To clarify the variation in time‐course data and to identify factors influencing these changes, we analyzed the ionomic leaf profiles of nine rice (Oryza sativa L.) cultivars, from transplantation to harvest, under different environmental conditions. An ANOVA was conducted separately for each element to elucidate the main effects of cultivar, fertilization, and growth stage, which were highly significant for all the elements observed except fertilization. The growth stage was the most significant for all elements except B. Conversely, the fertilization effect was not significant in half of the elements studied (Li, B, Na, Mg, P, S, K, Ca, and Cd). The elements during the growth stage were relatively stable across the environments and cultivars studied. To investigate the relationship between the changing pattern and the growth stage, we predicted the growth stage of rice based on the ionomic profile leaves using a machine learning model. Over 80% of the plants in this study were correctly classified into their growth stages with 10‐fold cross‐validation using the random forest model, with a highly significant contribution of the essential macronutrients P, Ca, S, Mg, and K as explanatory variables, indicating that they could be important indicators of the growth stage of rice plants.

Rice Growth Stages Mapping with Normalized Difference Vegetation Index (NDVI) Algorithm Using Sentinel-2 Time Series Satellite Imagery

Rice as one of the staple food commodities consumed by most of Indonesia's population. In terms of the rice consumption level, the trend always follows national population growth every year. In 2016, Bojonegoro Regency reached 1,050,000 tons of rice; hence, it obtained a surplus of 750,000 tons of rice from the production target. Considering this potency, it is necessary to monitor the stability of agricultural production regularly. This study monitored the rice growth stages by utilizing remote sensing data of Sentinel-2 optical satellite imagery. Analyzing the growth stages of rice plants can be done through the vegetation index algorithm. The algorithm used in this study is the Normalized Difference Vegetation Index (NDVI) in time series. From the analysis of NDVI time-series graphs, the correlation between NDVI values of Sentinel-2 images and the rice growth stages is 0.896 with a coefficient of determination of 0.803 or 80.34%. The seedling phase has an NDVI value <0.224. The vegetative phase has a range of values of NDVI 0.224 - 0.894. The generative phase has NDVI value range of 0.894 - 0.270. The fallow phase has a range of NDVI values <0.270. The results of the Sentinel-2 image classification obtained classification accuracy-test values for images on January 9, 2019 with a Kappa coefficient of 0.7824 and overall accuracy of 83.87%.

Proteomic analysis in different development stages on SP0 generation of rice seeds after space flight

The space biological effects of plants will drive the development of aerospace science and breeding science. The aim of this study is to reveal changes in the proteome of contemporary plants at different growth and development stages after space flight of rice seeds. We carried the rice seeds (DN416) through the SJ-10 returning satellite and returned to the ground for planting to the three-leaf stage (TLP) and tillering stage (TS) after a 12.5-day orbital flight. We found that the space flight caused the rice germination rate, the TLP plant height, and the number of tillers in the TS decreased by 11.64%, 9.75%, and 9.80%, respectively. In addition, the treatment group ROS and MDA level increased in the TLP and TS. The abundance patterns of proteins in these leaves identified 214 proteins in the TLP and 286 in the TS leaves that were markedly changed. Moreover, our study identified D14 proteins that control plant height and tiller. Our results show that the space environment may affect the downstream signaling mechanism by regulating the level of ROS in the body to achieve a response to the space environment. Meanwhile, the space environment may affect the plant height and tiller of rice by altering the expression of D14 protein and hormone-regulated proteins. Our results reveal changes in the proteome of different growth stages of rice plants, and also reveal the molecular mechanism of space environment regulation of rice plant height and tiller, which provides a new direction for further understanding of space biological effects and space mutation breeding.

Assessment of Flood Hazard and Agriculture Damage Under Climate Change in the Bagmati River Basin of Nepal

Assessment of flood hazard and damage is a prerequisite for flood risk management in the river basins. The mitigation plans for flood risk management are mostly evaluated in quantified terms as it is important in decision making process. Therefore, analysis of flood hazards and quantitative assessment of potential flood damage is very essential for mitigating and managing flood risk. This study focused on assessment of flood hazard and quantitative agricultural damage in the Bagmati River basin including Lal Bakaiya River basin of Nepal under climate change conditions. Flood hazards were simulated using Rainfall Runoff Inundation (RRI) model. MRI-AGCM3.2S precipitation outputs of present and future climate scenarios were used to simulate flood hazards, flood inundation depth, and duration. Flood damage was assessed in the agricultural sector, focusing on flood damage to rice crops. The flood damage assessment was conducted by defining flood damage to rice crops as a function of flood depth, duration, and growth stage of rice plants and using depth-duration-damage function curves for each growth stage of rice plants. The hazard simulation and damage assessment were conducted for 50- and 100-year return period cases. The results show that flood inundation area and agricultural damage area may increase in the future by 41.09 % and 39.05 % in the case of 50-year flood, while 44.98 % and 40.76 % in the case of 100-year flood. The sensitivity to changes in flood extent area and damage with the intensity of return period was also analyzed.

Assessing flood disaster impacts in agriculture under climate change in the river basins of Southeast Asia

This study focused on flood damage assessment for future floods under the impact of climate change. Four river basins of Southeast Asia were selected for the study. They included the Pampanga River Basin (PRB) in the Philippines, the Solo River Basin (SRB) in Indonesia, the Lower Mekong River Basin (LMRB) in Cambodia and Vietnam, and the Chao Phraya River Basin (CPRB) in Thailand. Flood damage to rice crops was assessed by flood damage functions considering flood depth and duration and the growth stage of rice plants. Flood characteristics such as flood depth, duration, and distribution were computed using the rainfall–runoff–inundation model to assess flood hazards under the present and future climatic conditions produced by MRI-AGCM3.2S. The damage assessment methodology for rice crops employed in this study was verified using data on past flood events. Then, flood damage assessment was conducted for both the present climate (1979–2003) and future climate (2075–2099) conditions, using MRI-AGCM3.2S precipitation datasets. Flood damage was assessed for worst cases chosen from each climate period and for floods of 50- and 100-year return periods with different rainfall patterns chosen from each climate scenario. The results of flood hazard and damage assessment show that the flood inundation area for a 100-year flood may increase in the future by 20% in PRB; by 66% in SRB; by 27% in LMRB; and by 27% in CPRB. The flood damage area of paddy fields for a 100-year flood may also increase in the future by 16% in PRB; by 55% in SRB; by 23% in LMRB; and by 13% in CPRB.

Dynamic influence of S fertilizer on Cu bioavailability in rice (Oryza sativa L.) rhizosphere soil during the whole life cycle of rice plants

Addition of S fertilizer influences the behavior of metals in soil, the mechanism of which has not been extensively studied to date. We explored the dynamic influence of S fertilizer (S0 and Na2SO4) applied in paddy soils on Cu bioavailability in rice rhizosphere soil during the life cycle of rice plants. Through a microcosm experiment, the speciation of Cu and S in rhizosphere soil was explored by traditional chemical extraction methods and advanced synchrotron-based X-ray absorption near-edge spectroscopy (XANES) techniques. In the vegetative stages of rice plants, sulfur fertilization increased the concentration of bioavailable Cu, as well as the dissolved organic carbon (DOC) concentration in rhizosphere soil. Meanwhile, a higher proportion of Cu-humic substances was found in soil treated with S than that in control soil. However, extended flooding conditions led to the reduction of S fertilizer to sulfide, which provided the substrate for Cu2S formation. Thus, in the reproductive stages of rice plants, a higher proportion of Cu2S formation from +S treatments led to a relatively lower concentration of bioavailable Cu in rice rhizosphere soil than in control soil. The influence of S fertilizer on Cu bioavailability depended on the growth stage of rice plants. Both the DOC and redox potential (Eh) were changed by S fertilization in paddy soils and are critical factors that control Cu speciation in rice rhizosphere soil.

Abundance of arthropod insect pests and natural enemies in rice field as influenced by rice growth stages and neighboring crops

Studies were conducted to record the abundance of arthropod insect pests and natural enemies in rice fields as influenced by rice growth stages and neighboring crops at the experimental farm of Patuakhali Science and Technology University (PSTU), Dumki, Patuakhali during 2012 in Boro rice season following randomized complete block design. Results indicated that rice-tree habitat showed the highest abundance of leafhoppers (100.75) followed by cricket (16.50), grasshoppers (15.25) and stink bugs (15.25). The lowest abundance of all insect pests was in rice-sesame habitat. No significant differences were found on the abundance of rice bug, rice hispa and stem borer populations. At seedling stage, the highest abundance of leafhopper (94.25) was recorded followed by grasshopper (47.00) and stink bug (26.50) while the lowest was stem borer (0.57) and rice hispa (6.00). At early tillering stage, maximum number of grasshopper (17.25) was recorded followed by cricket (7.00). At maximum tillering stage, the highest abundance of leafhoppers (122.5) was obtained followed by rice bug (62.00) and the lowest was the stink bug (7.00). At panical initiation stage, the highest abundance of rice bug (334.00) was recorded which was followed by leafhoppers (65.25) and the lowest was the cricket (15.75). No population of rice hispa and stem borer was recorded at maximum tillering and panical initiation stages. In case of natural enemies, the highest abundance of lady bird beetle (45.27) and damselfly (16.73) was found in rice-rice habitat. The highest abundance of ichneumonid wasp (57.53) was in rice-tree habitat and ground beetle (28.80) was in rice-sesame habitat. No significant differences were observed on the abundance of dragonfly, spider and dipteran fly among different habitats. Among different growth stages of rice plant, significantly the highest abundance of lady bird beetle was recorded at maximum tillering stage. The highest abundance of ichneumonid wasp and ground beetle was recorded at seedling stage. The highest abundance of damselfly, spider and dipteran fly was at early tillering stage. No significant difference was observed on the abundance of dragonfly among different rice growth stages.Bangladesh J. Agril. Res. 42(2): 309-319, June 2017

Arsenic mobility and bioavailability in paddy soil under iron compound amendments at different growth stages of rice

Iron (Fe)-based solids can reduce arsenic (As) mobility and bioavailability in soils, which has been well recognized. However, to our knowledge, there are few studies on As uptake at different growth stages of rice under Fe compound amendments. In addition, the formation of Fe plaques at different growth stages of rice has also been rarely reported. Therefore, the present study was undertaken to investigate As mobility and bioavailability in paddy soil under Fe compound amendments throughout the whole growth stage of rice plants. Amendments of poorly crystalline Fe oxides (PC-Fe), FeCl2+NaNO3 and FeCl2 reduced grain As by 54% ± 3.0%, 52% ± 3.0% and 46% ± 17%, respectively, compared with that of the non-amended control. The filling stage was suggested to be the key stage to take measures to reduce As uptake. At this stage, all soil amendments significantly reduced As accumulation in rice plants. At the maturation stage, PC-Fe amendment significantly reduced mobile pools and increased immobile pools of soil As. Besides, PC-Fe treatment promoted the transformation of Fe fractions from dissolved Fe to adsorbed, poorly crystalline and free Fe oxides. Moreover, significant positive correlations between soil Fe fractions and As fractions were found. Accordingly, we hypothesized that Fe compound amendments might affect the concentration distribution of Fe fractions first and then affect As fractionation in soil and its bioavailability to rice plants indirectly. The formation of Fe plaques varied with growth stages and different treatments. Significantly negative correlations between mobile pools of As and Fe or As in Fe plaques indicated that Fe plaques could immobilize mobile As in soils and thus affect As bioavailability. Overall, the effect of the soil amendments on reduction of As uptake varied with growth stages and different treatments, and further research on the key stage for reducing As uptake is still required.

Genetic variation and association of molecular markers for iron toxicity tolerance in rice

Iron toxicity in rice field can cause abnormality in plant growth leading to yield loss of 35–45%. This is caused by microbial reduction under flooded conditions of insoluble iron-III (Fe 3+) into soluble iron-II (Fe2+). The severity and symptoms of Fe toxicity depends on the growth stage of rice plant at which it is exposed to the stress. The plant developed various mechanisms to avoid/tolerate such stress which is a complex phenomenon governed by multiple genes/QTLs. Very few chromosomal loci are reported for Fe toxicity resistance in rice. But no locus has been fine mapped or cloned yet. Association mapping provides opportunity to have a greater coverage of genetic diversity in various germplasm lines so that large number of loci can be identified for Fe toxicity in rice. In the present investigation, 71 genotypes including landraces and released varieties were screened for their Fe toxicity resistance ability. Various agro-morphologic traits were observed to be affected by Fe stress. The genotypes Dhusura, Jalapaya, Gelei, Kendrajhali, Rasapanjari, Saluagaja and Asinasita were observed to be resistant under field stress condition and controlled condition in hydroponic culture. These genotypes can be used as donor lines for improvement of Fe tolerance in rice. The marker-trait association study could identify the markers namely RM243, RM234, RM248, RM501, RM594 and RM517 to be associated with leaf bronzing index which is considered to be indicator of Fe toxicity resistance. These markers individually showed phenotypic variance ranging from 6.0–10.5%. These markers can further be used for marker assisted breeding programs to incorporate the Fe resistance genes/QTLs into susceptible high yielding popular varieties.

Growth and Yield Under Low Solar Radiation During the Reproductive Growth Stages of Rice Plants

Growth and Yield Under Low Solar Radiation During the Reproductive Growth Stages of Rice Plants

Evaluación de tres promotores constitutivos para la expresión GUS en arroz (Oryza sativa L., cv. J-104)

&lt;p&gt;Se analizó la expresión constitutiva del gen reportero de la ß-Glucuronidasa (GUS) fusionado a tres promotores: el 35S del virus del mosaico de la coliflor (CaMV), el promotor quimérico A9 que contiene la actina-1 de arroz y el promotor ubiquitina-1 de maíz. La actividad de los promotores fue analizada cualitativa y cuantitativamente en diferentes tejidos y estadíos de crecimiento de plantas de arroz (variedad J-104) transformadas mediante biobalística. Se demostró la expresión constitutiva de GUS bajo los promotores estudiados, con distintos patrones de actividad relativa en hojas, tallos y raíces de plantas in vitro y ex vitro, y en plantas de la progenie T 1. Bajo el promotor quimérico A9 se lograron los mayores niveles de expresión GUS en todos los tejidos y fases de crecimiento de las plantas.&lt;/p&gt;

Response of leaf endophytic bacterial community to elevated CO2 at different growth stages of rice plant.

Plant endophytic bacteria play an important role in plant growth and health. In the context of climate change, the response of plant endophytic bacterial communities to elevated CO2 at different rice growing stages is poorly understood. Using 454 pyrosequencing, we investigated the response of leaf endophytic bacterial communities to elevated CO2 (eCO2) at the tillering, filling, and maturity stages of the rice plant under different nitrogen fertilization conditions [low nitrogen fertilization (LN) and high nitrogen fertilization (HN)]. The results revealed that the leaf endophytic bacterial community was dominated by Gammaproteobacteria-affiliated families, such as Enterobacteriaceae and Xanthomonadaceae, which represent 28.7–86.8% and 2.14–42.6% of the total sequence reads, respectively, at all tested growth stages. The difference in the bacterial community structure between the different growth stages was greater than the difference resulting from the CO2 and nitrogen fertilization treatments. The eCO2 effect on the bacterial communities differed greatly under different nitrogen application conditions and at different growth stages. Specifically, eCO2 revealed a significant effect on the community structure under both LN and HN levels at the tillering stage; however, the significant effect of eCO2 was only observed under HN, rather than under the LN condition at the filling stage; no significant effect of eCO2 on the community structure at both the LN and HN fertilization levels was found at the maturity stage. These results provide useful insights into the response of leaf endophytic bacterial communities to elevated CO2 across rice growth stages.

TerraSAR反射強度画像のスペックルノイズの低減効果の評価

In this study, the effect of speckle noise reduction was evaluated with high resolution satellite TerraSAR intensity data. Multi-temporal polarization imagery (HH & VV) was acquired on different growth stages of rice plant. Three kinds of filters, i.e. Lee, Frost, Gamma Map, were applied for speckle noise filtering with different window sizes. Six indices, i.e. Standard deviation, Equivalent number of looks, Speckle suppression index, Edge preservation index, Image sharpness, and Image detail preservation index, were used in order to compare and assess the effect of speckle noise reduction of different filters. Based on the evaluation results, the most appropriate window size was determined for speckle noise filtering of utilized data.