Growth Characteristics Of Rice Research Articles

Predicting rice productivity for ground data-sparse regions: A transferable framework and its application to North Korea

The use of observation-dependent methods for crop productivity and food security assessment is challenging in data-sparse regions. This study presents a transferable framework and applies it to North Korea (NK) to assess rice productivity based on climate similarity, transferable machine-learning techniques, and extendable multi-source data. We initially divided the primary phenological stages of rice in the study region and extracted dynamic rice distributions based on Moderate Resolution Imaging Spectroradiometer products and phenological observations. We compared the performances of four representative environmentally driven models (Linear Regression, back-propagation Neural Network, Support Vector Machine, and Random Forest) in simulating rice productivity using an extensive dataset that included multi-angle vegetation monitoring, climate variables, and planting distribution information. The framework integrated an optimal environmentally driven model with agricultural management practices for transferability to predict rice productivity in NK over multiple years. Additionally, two crop growth scenarios (whole growth period (WGP) and seeding–heading period (SHP)) were compared to assess pre-harvest forecasting capabilities and identify dominant factors. Finally, independent datasets from the Food and Agriculture Organization, World Food Program, and Global Gridded Crop Models were used to validate the magnitude and spatial distribution of the predicted results. The results showed that phenological identification based on remote sensing can accurately capture rice growth characteristics and map rice distribution. Random Forest outperformed other models in simulating rice productivity variation, with r-squares of 0.87 and 0.83 in the WGP and SHP, respectively. The solar-induced chlorophyll fluorescence, maximum temperature, and evapotranspiration collectively determined approximately 40 % of the variation in yield simulated using Random Forest. Conversely, planting areas contributed over 42 % of the variation in rice production. Compared to Food and Agriculture Organization statistics, the environmentally driven framework explained 78.72 % and 76.89 % of the production variation and 69.42 % and 71.15 % of the yield variation in NK under the WGP and SHP, respectively. Moreover, the environmental management-driven framework captured over 90 % of the yield variation. The predicted spatial pattern of rice productivity exhibited significant concordance with the World Food Program and Global Gridded Crop Model reports. In summary, the proposed transferable framework for crop productivity assessment contributes to early warnings of production reduction and has the potential for scalability across various crops and data-sparse regions.

Optimizing Nitrogen Fertilizer Management Enhances Rice Yield, Dry Matter, and Nitrogen Use Efficiency

Optimizing nitrogen fertilizer management can effectively improve soil ecology, promote agricultural production, and increase the income of farmers and workers. Nitrogen fertilizer is an important factor in the growth and development of rice, and it is important to find out the optimal amount and frequency of fertilizer application for the super-hybrid early rice ‘Zhu LiangYou 819’ in Hunan Province, to give full play to its high quality and high yield characteristics. Various N fertilizer application frequencies (P1, basal–tiller fertilizer = 5:5; P2, basal–tiller–spike fertilizer = 4:3:3; P3, basal–tiller–spike–grain fertilizer = 4:3:2:1) and N application amounts (N1, 90 kg ha−1; N2, 150 kg ha−1; N3, 210 kg ha−1) were applied to the hybrid rice ZLY819. The results show that, under the same frequency of N application, ZLY819 had the highest yield, agronomic efficiency, and physiological utilization rate of N fertilizer with the N2 treatment, averaging 7.53 t ha−1, 18.10 kg kg−1, and 34.34%, respectively, with the yield under N2 being 19.38% higher than that under N1. For the same amount of N application, the yield, agronomic efficiency, partial factor productivity of N (PFPN), N contribution to seed, and N use efficiency (NUE) increased with an increase in the frequency of N application, mainly in the order of P3 > P2 > P1, whereby the yield of P3 was 10.11% higher than that of P1. According to the regression equation, the yield is higher when the amount of nitrogen application is 202.15 kg ha−1 and the fertilization frequency is four times. Appropriate N fertilizer management (P3N2) improved the rice growth characteristics, dry matter accumulation, crop growth rate, dry matter transport rate, dry matter contribution rate, and NUE, thus promoting an increase in the rice yield and efficient use of nitrogen.

Effect of biochar on biochemical properties of saline soil and growth of rice

To amend physical properties of coastal saline soil for rice production, six biochar treatments (0, 0.5, 1, 2, 4 and 6 kg biochar per m2 soil) were set up as CK, T1, T2, T3, T4 and T5, respectively and their effect on the biochemical properties of coastal saline soil and rice growth characteristics were evaluated in a barrel planting experiment. The results showed that compared with CK (with no biochar added), the soil EC of T1 and T2-T5 was reduced by 11.5 %, but increased by 8.8–62.9 %, respectively. The available potassium and organic matter contents of T1-T5 increased ranging from 3.7-10.2 % to 8.0–46.8 %, respectively. With the increase of the biochar amount, the urease activity of soil in the 0–10 cm deep soil showed an increasing trend by 194.8–744.6 % with T1-T5, compared with that of the CK treatment. The activity of alkaline phosphatase in soil increased first and then decreased, and its increment with T1-T5 was between 28.2 and 64.8 % in comparison with that of CK. With more biochar added to soil, the leaf dry weight, root dry weight, total dry matter mass, total root length, single panicle quality and weight per 100 grains showed a trend of increase first and then decrease. The highest incremental values of all measurements were obtained with T1 by 21.8 %, 23.9 %, 13.8 %, 33.9 %, 30.8 % and 11.6 % respectively, compared with those with CK. However, adding biochar in soil demonstrated insignificant effect on the weight of single panicle, panicle length, stem thickness, tillers, setting rate, soil hydrolyzable nitrogen, available phosphorus content, rice protein, amylose, and taste quality among all treatments. In summary, the application of 0.5 kg m−2 biochar can improve the biochemical properties of saline soil and therefore increase rice yield.

Benefits of mechanical weeding for weed control, rice growth characteristics and yield in paddy fields

Benefits of mechanical weeding for weed control, rice growth characteristics and yield in paddy fields

Interplay Impact of Exogenous Application of Abscisic Acid (ABA) and Brassinosteroids (BRs) in Rice Growth, Physiology, and Resistance under Sodium Chloride Stress.

The hormonal imbalances, including abscisic acid (ABA) and brassinosteroid (BR) levels, caused by salinity constitute a key factor in hindering spikelet development in rice and in reducing rice yield. However, the effects of ABA and BRs on spikelet development in plants subjected to salinity stress have been explored to only a limited extent. In this research, the effect of ABA and BRs on rice growth characteristics and the development of spikelets under different salinity levels were investigated. The rice seedlings were subjected to three different salt stress levels: 0.0875 dS m-1 (Control, CK), low salt stress (1.878 dS m-1, LS), and heavy salt stress (4.09 dS m-1, HS). Additionally, independent (ABA or BR) and combined (ABA+BR) exogenous treatments of ABA (at 0 and 25 μM concentration) and BR (at 0 and 5 μM concentration) onto the rice seedlings were performed. The results showed that the exogenous application of ABA, BRs, and ABA+BRs triggered changes in physiological and agronomic characteristics, including photosynthesis rate (Pn), SPAD value, pollen viability, 1000-grain weight (g), and rice grain yield per plant. In addition, spikelet sterility under different salt stress levels (CK, LS, and HS) was decreased significantly through the use of both the single phytohormone and the cocktail, as compared to the controls. The outcome of this study reveals new insights about rice spikelet development in plants subjected to salt stress and the effects on this of ABA and BR. Additionally, it provides information on the use of plant hormones to improve rice yield under salt stress and on the enhancement of effective utilization of salt-affected soils.

Response of Physiological Growth Characteristics of Rice to Different Biodegradable Mulching and Irrigation Methods in Cold Region of Northeast China

Highlights The tested biodegradable mulch film can be rapidly degraded in rice fields in cold regions and has good applicability. The degradation rate of white mulch film is faster than that of black film before the induction period, and the degradation law after the induction period is opposite. The combination of mulching film and water-saving irrigation can effectively enhance the photosynthetic capacity and dry matter transport of rice in cold regions. Through comprehensive evaluation, we found that the combination of ridge irrigation and mulching FC plastic film has the best effect on environmental protection and rice growth. Abstract. To reveal the mechanism of influence of different types of biodegradable plastic film mulching and irrigation combinations on the physiological growth characteristics of rice in cold regions, eight types of film mulching irrigation methods were designed, which combined four types of plastic film mulching and two types of irrigation methods for a total of nine treatments. The study analyzed the degradation law of degradable plastic film in rice fields in cold regions, and the effects of film-mulching irrigation methods on rice photosynthetic characteristics, dry matter transport, and rice yield. The results showed that the three biodegradable plastic films were suitable for the rice fields in the northeast cold region. Except for the jointing stage, mulching irrigation treatments could increase the chlorophyll content and net photosynthetic rate of rice, and the improvement degree showed a downward trend with the growth of rice. The film mulching irrigation treatments improved rice stems and leaves dry matter transport and grain contribution. The comprehensive evaluation based on the comprehensive index method showed that the combination of ridge irrigation and thin black biodegradable mulch is the best combination of biodegradable plastic film mulching and irrigation in the study area. Keywords: Biodegradable mulching, Comprehensive index method, Dry matter transportation, Irrigation method, Photosynthetic character.

Expression levels of genes involved in metal homeostasis, physiological adaptation, and growth characteristics of rice (Oryza sativa L.) genotypes under Fe and/or Al toxicity.

Acid sulphate soil contains high amounts of iron (Fe) and aluminum (Al), and their contamination has been reported as major problems, especially in rainfed and irrigated lowland paddy fields. Rice is sensitive to Fe and Al grown in acid soil (pH < 5.5), leading to growth inhibition and grain yield loss. The objective of this study was to evaluate Fe and/or Al uptake, translocation, physiological adaptation, metal toxicity, and growth inhibition in rice genotypes grown in acid soil. Fe and Al in the root tissues of all rice genotypes were enriched depending on the exogenous application of either Fe or Al in the soil solution, leading to root growth inhibition, especially in the KDML105 genotype. Expression level of OsYSL1 in KDML105 was increased in relation to metal uptake into root tissues, whereas OsVIT2 was downregulated, leading to Fe (50.3 mg g-1 DW or 13.1 folds over the control) and Al (4.8 mg g-1 DW or 2.2 folds over the control) translocation to leaf tissues. Consequently, leaf greenness (SPAD), net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (E) in the leaf tissues of genotype KDML105 under Fe + Al toxicity significantly declined by 28.4%, 35.3%, 55.6%, and 51.6% over the control, respectively. In Azucena (AZU; Fe/Al tolerant), there was a rapid uptake of Fe and Al by OsYSL1 expression in the root tissues, but a limited secretion into vacuole organelles by OsVIT2, leading to a maintenance of low level of toxicity driven by an enhanced accumulation of glutathione together with downregulation of OsGR expression level. In addition, Fe and Al restrictions in the root tissues of genotype RD35 were evident; therefore, crop stress index (CSI) of Fe + Al-treated plants was the maximum, leading to an inhibition of gs (53.6% over the control) and E (49.0% over the control). Consequently, free proline, total phenolic compounds, and ascorbic acid in the leaf tissues of rice under Fe + Al toxicity significantly increased by 3.2, 1.2, and 1.5 folds over the control, respectively, indicating their functions in non-enzymatic antioxidant defense. Moreover, physiological parameters including leaf temperature (Tleaf) increment, high level of CSI (>0.6), SPAD reduction, photon yield of PSII (ΦPSII) diminution, Pn, gs, and E inhibition in rice genotype IR64 (Fe/Al-sensitive) under Fe + Al treatment were clearly demonstrated as good indicators of metal-induced toxicity. Our results on Fe- and/or Al-tolerant screening to find out the candidate genotypes will contribute to present screening and breeding efforts, which in turn help increase rice production in the Fe/Al-contaminated acid soil under lowland conditions.

The spatial data of paddy rice classification over Northeast Asia using COMS geostationary satellite

The Korea Aerospace Research Institute (KARI) estimated paddy rice classification maps over Northeast Asia using the Cheonian geostationary orbiting satellite (COMS: Communication, Ocean and Meteorological Satellite) data. In the case of classification map of rice paddy, it is not only used as input data for estimating rice yield, but also for various fields such as agriculture, weather, climate change, bio energy, and ecology. The spatial resolution of the classified rice map is 500 m, and the classification map was estimated yearly temporal resolution from 2011 to 2017. The spatial coverage of the classification map was the Northeast Asia with the latitude 25 ° N ~ 47 ° N and the longitude 115 ° E ~ 145 ° E as shown in Fig. 1 including Heilongjiang Sheng, Jilin Sheng, and Liaoning Sheng. In this classification map of paddy rice, it was calculated by applying geostationary orbiting satellites based on value-added products from Geostationary Ocean Color Imager (GOCI). In this study, we additionally used MODIS Land Surface Water Indices (LSWI) to support rice classification by considering the physical characteristics of rice cultivation area in the transplanting season. Basically, the radiance value of the top of atmosphere (TOP) observed in GOCI satellite was corrected to the surface reflectance at the top of the canopy through radiative transfer model. After that, NDVI, which can reflect the time series growth characteristics of rice, was estimated first. In addition, the MODIS LSWI index was used to determine the rice cultivation area with the NDVI in Northeast Asia by reflecting the water characteristics of the rice cultivation area during the transplanting period. More details of validation results for this algorithm can be found in previous studies.

Evaluation of orderly mechanical seedling-broadcasting on yield formation and growth characteristics of rice

<p indent=0mm>Orderly mechanical seedling-broadcasting refers to the rice establishment methods that throw-transplanted the rice seedlings to the field in rows and lines by seedling broadcasting machine. Which are suggested to prominently increase the uniformity and efficiency of rice crops compared with manual seedling broadcasting. The present study was carried out to compare the differences between orderly mechanical seedling-broadcasting, manual transplanting and manual seedling broadcasting regarding yield formation and growth characteristics of rice. The results suggested that the grain yield of rice under orderly mechanical seedling-broadcasting was increased compared with manual transplanting and manual seedling broadcasting by 22.4%–28.3% and 2.8%–8.9%, respectively. On the aspect of growth traits, the orderly mechanical seedling-broadcasting was characterized as good ventilation, better assimilation ability of dry matter at late growth stages, delayed leaf senescence and high grain filling percentage, which increased the panicle numbers per square meter by 20.9%–64.2% compared with that of manual transplanting and increased the seed setting rate as compared with manual seedling-broadcasting. However, in order to further develop the potential of high yield, the techniques and planting machines of orderly mechanical seedling-broadcasting still need to be improved. In addition, the process of seedling recovery, tiller development and root growth traits of rice under orderly mechanical seedling-broadcasting should be explored in future studies.

Association Analysis of Growth Characteristics, WUE, and RUE of Rice in Cold Region Under Different Irrigation Patterns

In order to clarify the relationship between growth characteristics of rice, WUE and RUE, the apriori algorithm was used to mine association rules for rice indicators data. In this study, the experiments set up control irrigation, wet irrigation and flood irrigation from May to September in 2017 and 2018, which were carried out in Qing’an Irrigation Experimental Center in the semi-humid area of Heilongjiang Province, China. Because of the difficulty in data collection and the long test period during the study, insufficient data could not be collected for data mining. Therefore, before using the apriori algorithm, the original data was augment by using the generative adversarial network. Correlation analysis of indicators data showed that the correlation among the indicators of rice under the three irrigation patterns was very close. Height, stem diameter and other indicators interacted with each other, which in turn affected the yield, water and radiation use efficiency of rice. Water use efficiency and dry matter got the highest value of correlation analysis under control irrigation was 0.97, yield and dry matter got the second highest value was − 0.95. Yield and height got the highest value of correlation analysis under wet irrigation was 0.94, dry matter and seed setting rate got the second highest value were 0.90, respectively. Yield and height got the highest value of correlation analysis under flood irrigation was − 0.90, stem diameter and dry matter got the second highest value of correlation analysis was 0.85. The results of association analysis combined with three irrigation patterns indicated that the association between seed setting rate, height, leaf area index, dry matter, yield and water use efficiency was the closest. The increase of height, stem diameter, dry matter and seed setting rate can promote rice yield and water use efficiency, while reducing leaf area index and 1000-grain weight will have a negative impact on yield.

Comparative Study of Rice straw bio char and Compost on Rice Growth and Yield under Saline Sodic Soil Conditions

Two field experiments were raised at Farm of El-Sirw Agriculture Research Station, Dammitta province, Egypt through 2018 and 2019 seasons. The present study was performed to compromise the influence of rice straw biochar and other two soil amendments of rice straw compost and gypsum on rice growth and yield of three contrasting rice varieties,Giza177 (salt sensitive variety), Giza 178 (salt tolerant variety) and Giza179 new (salt tolerant variety) under saline sodic soil. The field experiments were designed in spilt plot design with four replications. The three rice varieties were scattered in the main plot, whereas the amendment treatments; control, gypsum(G), rice straw compost (RS) and rice straw biochar (RSB) were put in the subplots. The tested rice varieties were significantly different in growth parameters, yield attributes and yields in both seasons. Giza 179 as a new salt tolerant variety provided the maximum values of rice growth characteristics and most of yield contributes and yields without significant difference with Giza178 were considering yields. Applying varying soil amendments greatly improved rice growth and yields in addition to yield attributes comparing to the control treatments. Rice straw biochar surpassed significantly other two amendments, particularly in the first season, meanwhile in the second seasonthe three soil amendments were equally in increasing grain yield. Thereby, rice straw biochar could be applied each two years but rice straw compost has to apply in two successive season to get its efficiency. Two field experiments were raised at Farm of El-Sirw Agriculture Research Station, Dammitta province, Egypt through 2018 and 2019 seasons. The present study was performed to compromise the influence of rice straw biochar and other two soil amendments of rice straw compost and gypsum on rice growth and yield of three contrasting rice varieties,Giza177 (salt sensitive variety), Giza 178 (salt tolerant variety) and Giza179 new (salt tolerant variety) under saline sodic soil. The field experiments were designed in spilt plot design with four replications. The three rice varieties were scattered in the main plot, whereas the amendment treatments; control, gypsum(G), rice straw compost (RS) and rice straw biochar (RSB) were put in the subplots. The tested rice varieties were significantly different in growth parameters, yield attributes and yields in both seasons. Giza 179 as a new salt tolerant variety provided the maximum values of rice growth characteristics and most of yield contributes and yields without significant difference with Giza178 were considering yields. Applying varying soil amendments greatly improved rice growth and yields in addition to yield attributes comparing to the control treatments. Rice straw biochar surpassed significantly other two amendments, particularly in the first season, meanwhile in the second seasonthe three soil amendments were equally in increasing grain yield. Thereby, rice straw biochar could be applied each two years but rice straw compost has to apply in two successive season to get its efficiency.

Mapping high temperature damaged area of paddy rice along the Yangtze River using Moderate Resolution Imaging Spectroradiometer data

ABSTRACT The subtropical high temperature anomaly of 2013 in China, adversely affected paddy rice physiology, especially at the heading, flowering and grain filling stages, and left untold damage and significant rice yield reductions in that year. Considering the importance of data on crop failure induced by abnormal meteorological events, in understanding the potential impacts of climate change on agriculture and food security, and in support of crop insurance policies, the current study employs satellite remote sensing data to map and estimate the areal extent of high-temperature-induced damage on paddy rice in 2013, along the Yangtze River, a major rice producing area in China. In this regard, the daily mean and maximum air temperatures were first estimated using the Moderate Resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) products, MODIS Vegetation Indices (VI) products, altitude information from a Digital Elevation Model (DEM), and air temperature measurements at meteorological stations located within the Yangtze River Basin from 2000 to 2016, to derive fully covered mean and maximum daily air temperatures. Paddy rice cultivated areas were then identified based on the seasonal profiles of MODIS Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) in 2013, and map errors at provincial scales were no more than 8.7%. Finally, paddy rice growth characteristics were combined with MODIS VI products to identify heading and flowering stages, and the time series of daily mean and maximum air temperatures, paddy rice phenology and cultivated area, were integrated to map and estimate the rice crop area damaged by the anomalous high temperature. Our results show that all provinces along the Yangtze River, this study investigated, recorded a substantial damaged rice crop area, following the 2013 subtropical temperature high, and Anhui Province was the hardest hit with a damaged rice area of 63.6%. For the entire study area, a damage extent of about 5,656,000 ha, accounting for 35.9% of total paddy rice planted area, was recorded. This indicates a significant agro-meteorological disaster, and in an era of increasing climate variability and weather extremes, studies of this nature would greatly benefit global food security planning and management policies.

Silicon Affects Rice Growth, Superoxide Dismutase Activity and Concentrations of Chlorophyll and Proline under Different Levels and Sources of Soil Salinity

Silicon (Si) application shows beneficial effects on growth and salt tolerance of plants; however, its effects on the rice (Oryza sativa L. var. Hashemi) growth, superoxide dismutase (SOD) activity and concentrations of chlorophyll and proline have not been fully understood under different levels and sources of soil salinity. In this research, the effects of four salinity levels (0.46, 2, 4, and 8 dS m−1), two salt compositions (NaCl and four-salt combination) and four Si rates (8, 100, 200 and 300 mg kg−1 soil) as silicic acid (H4SiO4) on rice growth characteristics and SOD activity were studied in a greenhouse. Salt composition included NaCl, Na2SO4, CaCl2 and MgSO4 at a molar ratio of 4:2:2:1. The experiment was arranged in a factorial framework in a completely randomized design with three replications. Increasing soil salinity level significantly decreased dry matter (about 40%), number of tillers (about 12%), leaf area (about 55%), concentrations of leaf chlorophyll (about 45%) and Si (about 40%), whereas caused a severe increase in proline concentration (more than 200%) and SOD enzyme activity (up to 65%). Deleterious effect of salinity on dry matter and leaf area as well as its stimulating influence on proline accumulation and SOD activity was more intense in NaCl-treated plants than those subjected to a combination of salts. Source of salinity had no significant effects on dry matter, number of tillers and chlorophyll concentration. Si treatment strongly enhanced these parameters, except for proline that declined in plants subjected to Si. The suppressing effect of salinity on the rice growth characteristics can be alleviated by soil Si fertilization. The stimulating effects of soil Si fertilization on dry matter as well as chlorophyll concentration became more pronounced at the higher salinity levels. Consequently, when rice plants are to be grown in salt-affected soils, it is recommended to supply them with adequate Si.

Assessing the Activity Concentration of Agricultural Products and the Public Ingestion Dose as Result of a Nuclear Accident

Background: A model to assess the activity concentration of agricultural products and the public ingestion dose as result of a nuclear accident is necessarily required to manage the contaminated agricultural systems by the accident, or to estimate the effects of chronic exposure due to food ingestion at a Level 3 PSA. Materials and Methods: A dynamic compartment model, which is composed of three submodules, namely, an agricultural plant contamination assessment model, an animal product contamination assessment model, and an ingestion dose assessment model has been developed based on Korean farming characteristics such as the growth characteristics of rice and stockbreeding. Results and Discussion: The application study showed that the present model can predict well the characteristics of the activity concentration for agricultural products and ingestion dose depending on the deposition date. Conclusion: The present model is very useful to predict the radioactivity concentration of agricultural foodstuffs and public ingestion dose as consequence of a nuclear accident. Consequently, it is expected to be used effectively as a module for the ingestion dose calculation of the Korean agricultural contamination management system as well as the Level 3 PSA code, which is currently being developed.

Sodium chloride stress during early growth stages altered physiological and growth characteristics of rice

The salt stress affects plant growth and physiological characteristics during early growth stages in rice (Oryza sativa L.) The objective of this study was to examine the influence of salt stress on rice growth during early stages and to find out their salt tolerance levels. A pot culture experiment was conducted in rice cropping season 2016, with completely randomized design (CRD) and three replicates. The treatments were two rice cultivars, 'Liangyoupeijiu' (LYP9) and 'Nipponbare' (NPBA) with four salt stress levels 0 (control, CK), 1.5 (low salt stress, LS), 4.5 (medium salt stress, MS), and 7.5 g (heavy salt stress, HS) NaCl kg-1 soil at different growth stages with six seedlings per pot. About 15 parameters were recorded and most of the treatments were significantly different (P < 0.05) from each other. The results showed that salt stress reduced seed emergence characteristics of the rice. It also decreased photosynthetic parameters, growth characteristics including DM, and seedling height reduction increased at early seedling and maximum tillering stage in both rice cultivars but this disaster is less in 'LYP9' than 'NPBA'. On the basis of DM reduction, 'LYP9' was categorized as moderately susceptible (MS) and susceptible (S) at HS during early growth stage, and 'NPBA' was categorized as sensitive to the HS stress level. The result suggested that 'LYP9' showed somehow resistance under salt stress than 'NPBA'. This study will help us to provide new ideas for improving the high yielding rice cultivar (LYP9) to salt tolerance by genetic modification and cultivation techniques.

Effects of 1-Methylcyclopropene on Rice Growth Characteristics and Superior and Inferior Spikelet Development Under Salt Stress

Salinity stress hampers rice growth and development due to its osmotic, ionic, and hormonal (ethylene) stresses. High ethylene production affects inferior and superior spikelet development in rice cultivars under salt stress. 1-Methylcyclopropene (1-MCP) is an excellent ethylene inhibitor in plants. However, the effects of 1-MCP on rice growth and spikelet development under salt stress have not been studied. In this experiment, two rice cultivars, Liangyoupeijiu (LYP9, indica) and Nipponbare (NPBA, japonica), were grown in a pot culture experiment with three levels of salt stress [control (CK), 1.5 g NaCl/kg dry soil (low salt stress, LS), and 4.5 g NaCl/kg dry soil (heavy salt stress, HS)] and two 1-MCP levels (no 1-MCP and 1-MCP applied at the rice booting stage) over ten sampling times. The results showed that the application of 1-MCP significantly inhibited ethylene production in inferior spikelets of both cultivars compared with superior spikelets under salt stress. 1-MCP is more effective in increasing grain-filling rate and grain weight for inferior spikelets than for superior spikelets in both cultivars. The application of 1-MCP improved the net photosynthesis rate (Pn), stomatal conductance (gs), transpiration rate (Tr), SPAD values, and the leaf area index (LAI) of flag leaves in both cultivars compared with no 1-MCP application. 1-MCP was more effective in increasing grain-filling rate and grain weight in the LYP9 cultivar than in the NPBA cultivar under all salt stress treatments. As compared to the treatment without 1-MCP at the same salt stress level, the grain yield per plant with 1-MCP treatment increased by 35.6, 37.6, and 35.3% for CK, LS, and HS treatments, respectively, for LYP9 plants. 1-MCP treatment increased the rice grain-filling rate, plant dry matter, and yield components, such as 1000-grain weight, grain formation rate, and harvest index, of both NPBA and LYP9. These findings demonstrate the beneficial role of 1-MCP under salt stress by increasing rice growth characteristics and the development of spikelets, particularly inferior spikelets.

Effect of asymmetric warming on rice (Oryza sativa) growth characteristics and yield components under a free air temperature increase apparatus

Climate warming shows great diurnal variations with higher warming rate at nighttime, and consequently causes significant impacts on rice growth and grain yield. The objective of this study was to determine the effects of asymmetric warming (all-day warming, AW; daytime warming from 7:00 to 19:00, DW; and nighttime warming from 19:00 to 7:00, NW; and a control, CK) on rice growth characteristics andyield. Two bucket warming experiments were performed in Nanjing in Jiangsu Province, China under Free Air Temperature Increases (FATI) in 2013 and 2014.&lt; The daily mean temperatures in the rice canopy in the AW, DW and NW plots were 2.0°C, 1.1°C and 1.3°C higher, respectively, than those in the CK plots. Asymmetric warming reduced the maximum tillers and effective tillers in the order CK&gt;DW&gt;NW&gt;AW. In the AW, DW and NW treatments, the effective tillers were decreased by18.57%-37.77% in both years. Asymmetric warming also decreased plant height, the Absolute Growth Rate (AGR), the Soil and Plant Analyzer Development (SPAD) value, the Leaf Area Index (LAI) and the Net Photosynthetic Rate (Pn). The order of the plant height and Pn values were also in the order CK&gt;DW&gt;NW&gt;AW. The warming treatments affect the length of rice growth. The length from the transplanting date to the heading date was shortened by 3.5 days, 2.5 days and 3.0 days on average in the AW, DW and NW plots, respectively, in both years, while the length from the heading date to the maturation date did not show obvious changes. The aboveground biomass in the maturation stage declined by 13.38%, 3.56% and 6.22%, and the grain yield was decreased by 10.07%, 5.06% and 7.89% on average in the AW, DW and NW plots, respectively, in both years. There was a decreasing trend in the panicle number, grain number per panicle and grain filling rate, whereas irregular changes in the 1000-grain weight were observed in the warmed plots. Our results suggested that under the predicted climate warming, rice productivity would be further declined in the Yangtze River Basin.

Different response of an elite Bt restorer line of hybrid rice (Oryza sativa L.) in adaptation to nitrogen deficiency

Transgenic Bacillus thuringiensis (Bt) rice have been reported to acquire effective resistance against the target pests; however, the insertion and expression of alien Bt genes may have some unintended effects on the growth characteristics of rice. A screen-house experiment was conducted and repeated twice to investigate the growth characteristics and Bt protein expressions in two Bt rice lines [MH63 (Cry2A*) and MH63 (Cry1Ab/Ac)], which had different Bt protein expression levels in leaves, under zero nitrogen (N0) and recommended nitrogen (NR) fertilizer applications. Compared to the counterpart MH63, MH63 (Cry2A*) under N0 experienced accelerated leaf senescence and a lower internal N use efficiency (IEN), resulting in a 23.2% decrease in grain yield and a lower accumulated biomass. These variations were revealed to be correlated to the higher ratio of the Bt protein content to the soluble protein content (BTC/SPC) with a maximum value of 4.3‰ in MH63 (Cry2A*) leaves in the late growth stage. Under NR, no differences in growth characteristics between MH63 (Cry2A*) and MH63 were found. The growth characteristics of MH63 (Cry1Ab/Ac), with a lower BTC/SPC in the late growth stage compared to MH63 (Cry2A*), were identical to those of MH63 under the two N applications. Results show that the transgenic Bt rice MH63 (Cry2A*), with a relatively higher Bt protein expression in the late growth stage, had an inferior adaptation to nitrogen deficiency compared to its non-Bt counterpart. And this inferior adaptation was found to be correlated with the higher BTC/SPC in MH63 (Cry2A*) leaves in the late growth stage.

SIMULATING DAMAGE OF LEAFMINER, HYDRELLIA PROSTERNALIS AND ITS EFFECT ON RICE GROWTH CHARACTERISTICS AND GRAIN YIELD

Rice a vital food crop, in Egypt, particularly with the shortage of wheat production. Rice plants are subjected to several insect infestations which impair the productivity, consequently the growers tend to use insecticides for pest control. Unfortunately, they use these chemical insecticides regardless of insect infestation level. The current investigation was carried out at the Experimental Farm of Rice Research and Training Center, Sakha Agricultural Research Station during 2013 and 2014 rice seasons. Six defoliation levels; 0, 20, 40, 60, 80 and 100% were applied one month after transplanting to find out the effect of leaf removal on rice growth characteristics and yield. The whole leaves, at certain levels, were cut by hand. Leaf chlorophyll content was not affected by any of simulation levels. Plant height, leaf area index and dry matter content were not reduced due to defoliation up to 40 or 60%. These characteristics displayed significant reduction at 80 or 100% defoliation. As for yield components, the panicle weight was not significantly reduced up to 40% defoliation, but at levels of 60, 80 or 100% defoliation, the panicle weight was significant negatively affected. Also, the 1000-grain weight was significantly reduced at higher levels of defoliation (80-100%) compared to lower ones (20-60%). The grain yield was reduced by 14-17%, 21 and 34% at 60, 80 and 100% defoliation, respectively. Thus, rice leafminer infestation up to 40% could be considered not alarming to the rice growers.

Multi-temporal radar backscattering measurements and modelling of rice fields using a multi-frequency (L, S, C, and X) scatterometer

This article presents the backscattering coefficients of rice fields obtained using an L-, S-, C-, and X-band scatterometer system during the growth period for a rice field. The system has full-polarizations (VV, VH, HV, and HH) and can view various incidence angles (0°~90°) and azimuth angles (0°~360°). The field measurements were performed in Qionglai County of Chengdu (China) during the 2009 rice-growing season. The rice parameters, including biomass, leaf area index (LAI), and canopy structure, were also measured experimentally in the field. The results indicate that the backscattering coefficients are sensitive to the biomass and LAI. Combined with the rice parameters, the scattering properties of rice growth are analysed using the Monte Carlo model, which relies on a realistic description of the rice, enhancing the backscattering and clustering effects of the scatterers. The model is also improved using more realistic growth characteristics of rice to obtain accurate statistics for the backscattering coefficients, including the random tilt angle of rice stems and the probability density function (PDF) of rice leaves. The modelling results agree quite well with the field measurements of rice backscattering.