Distribution and Transport of Heavy Metals in Rice Plants in the Jiujiang River Basin

Inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the distribution and migration of heavy metals in rice plants in the Jiujiang River Basin,to evaluate the distribution of heavy metals in rice plants and to analyze their migration.The results showed that the distribution of different heavy metal elements in various tissues of rice plants varied greatly.The heavy metal migration factor of rice plant stems and leaves was significantly higher than that of rice husk and brown rice.The distribution of heavy metal content in rice in the Jiujiang River can provide a certain theoretical basis and reference value for the safety and quality of rice in the Jiujiang River Basin.

Contribution of Rice Plants and Cover Crop Biomass Amended Soil on Methane Emission

Rice plant and soil are playing vital role for produce of methane (CH4) emission from flooded rice soil. Contribution of rice plants and cover crop biomass amended soil on methane emission has not been yet studied under different cover crop biomass incorporated in paddy fields. Closed-chamber method was used to estimate CH4 emission rates during rice cultivation under soil plus rice plants and soil alone condition. Soil plus rice plants chambers 62 × 62 × 112 cm3 and soil alone chambers 20 × 20 cm2 were placed at the same time during rice cultivation (0 days after rice transplanting). Therefore, to evaluate the contribution of soil plus rice plants and soil alone on methane (CH4) emission under different rates of cover crop biomass incorporated soil during rice cultivation. Methane emission from soil plus rice plants increased up to 53 days after transplanting (DAT) and then it’s decreased and continued till harvesting. It was found that ca. 47% - 52% CH4 was mediated by rice plants and ca. 48% - 53% through rice soil alone under 12 Mg·ha-1 cover crop biomass incorporated treated plots. Whereas, only ca. 9% - 10% CH4 emission was mediated by rice plants and ca. 90% - 91% by rice soil alone when 0 and 3 Mg·ha-1 cover crop biomass was incorporated. Therefore, it could be concluded that rice soil alone was more influenced for CH4 emission than rice plants in paddy fields.

Global characterization of OsPIP aquaporins reveals that the H_(2)O_(2)transporter OsPIP2;6 increases resistance to rice blast

Plasma membrane intrinsic proteins(PIPs)are conserved plant aquaporins that transport small molecules across the plasma membrane to trigger instant stress responses and maintain cellular homeostasis under biotic and abiotic stress.To elucidate their roles in plant immunity to pathogen attack,we characterized the expression patterns,subcellular localizations,and H_(2)O_(2)-transport ability of 11 OsPIPs in rice(Oryza sativa),and identified OsPIP2;6 as necessary for rice disease resistance.OsPIP2;6 resides on the plasma membrane and facilitates cytoplasmic import of the immune signaling molecule H_(2)O_(2).Knockout of OsPIP2;6 increases rice susceptibility to Magnaporthe oryzae,indicating a positive function in plant immunity.OsPIP2;6 interacts with OsPIP2;2,which has been reported to increase rice resistance to pathogens via H_(2)O_(2)transport.Our findings suggest that OsPIP2;6 cooperates with OsPIP2;2 as a defense signal transporter complex during plant–pathogen interaction.

Model for Methane Emission from Rice Fields and Its Application in Southern China

A process model has been developed. The model has been used to calculate the methane emission from rice fields. The influence of climate conditions, field water management, organic fertilizers and soil types on methane emission from rice fields are considered. There are three major segments which are highly interactive in nature in the model:rice growth, decomposition of soil organic matter and methane production, transport efficiency and methane emission rate. Explicit equations for modeling each segment mentioned above are given. The main results of the model are: 1. The seasonal variation of methane emission of the model output agrees with that of field experiments. The deviation of seasonal average methane emission rate between modeled value and experimental data is about 10%. 2. In the whole rice growing period, model output is similar to experimental data in the seasonal variation of transport ability of rice plant. 3. Soil organic matter content and soil physics and chemistry are major factors that determine the total season average emission rate, while soil temperature controls the temporal variation of methane emission from rice fields.

Methane emission in a rice field of Thailand

In this study, emission of methane have been measured in a Thai rice field. Clear patterns of diurnal variations of methane emission have been observed and were found to follow the diurnal variation of the soil temperature. A detailed explanation was given for explaining the occurrence of a methane emission peak at night.The effects of urea fertilization and field draining on methane emissions were discussed. Methane emission from Thai rice fields is estimated to be 3. 32 Tg CH_4(2. 49 Tg CH_4-C) each year , contributing about 3. 4% to global methane budget due to rice cultivation.

Methane production from rice straw carbon in five different methanogenic rice soils:rates,quantities and microbial communities

The input of organic substances(e.g.,rice straw)in rice field soils usually stimulates the production and emission of the greenhouse gas methane(CH4).However,the amount of CH4 derived from the applied rice straw,as well as the response of bacterial and archaeal communities during the methanogenic phase,are poorly understood for different rice field soils.In this study,samples of five different rice soils were amended with 13^C-labeled rice straw(RS)under methanogenic conditions.Immediately after RS addition,the RS-derived CH4 production rates were higher in soils(Uruguay,Fuyang)that possessed a stronger inherent CH4 production potential compared with other soils with lower inherent potentials(Changsha,the Philippines,Vercelli).However,soils with higher inherent potential did not necessarily produce higher amounts of CH4 from the RS applied,or vice versa.Quantitative PCR showed copy numbers of both bacteria and methanogens increased in straw-amended soils.High-throughput sequencing of 16 S rRNA genes showed distinct bacterial communities among the unamended soil samples,which also changed differently in response to RS addition.Nevertheless,RS addition generally resulted in all the rice field soils in a relative increase of primary fermenters belonging to Anaerolineaceae and Ruminococcaceae.Meanwhile,RS addition also generally resulted in a relative increase of Methanosarcinaceae and/or Methanocellaceae.Our results suggest that after RS addition the total amounts of RSderived CH4 are distinct in different rice field soils under methanogenic conditions.Meanwhile,there are potential core bacterial populations that are often involved in primary fermentation of RS under methanogenic conditions.

OsbZIP72 Is Involved in Transcriptional Gene-Regulation Pathway of Abscisic Acid Signal Transduction by Activating Rice High-Affinity Potassium Transporter OsHKT1;1

We created CRISPR-Cas9 knock-out and overexpressing OsbZIP72 transgenic rice plants to gain a better understanding of the role and molecular mechanism of OsbZIP72 gene in stress tolerance,which has remained largely elusive.OsbZIP72 was expressed and integrated into rice transgenic plant genomes,and the OsbZIP72 transcript in overexpression lines was elicited by salinity,abscisic acid(ABA)and drought stresses.OsbZIP72 overexpressing plants showed higher tolerance to drought and salinity stresses,while knock-out transgenic lines showed higher sensitivity to these stresses.The differentially expressed genes(DEGs)from RNA-sequencing data encompassed several abiotic stress genes,and the functional classification of these DEGs demonstrated the robust transcriptome diversity in OsbZIP72.Yeast one-hybrid,along with luciferase assay,indicated that OsbZIP72 acted as a transcriptional initiator.Remarkably,electrophoresis mobility assay revealed that OsbZIP72 bound directly to the ABAresponsive element in the OsHKT1;1 promoter region and activated its transcription.Overall,our findings revealed that OsbZIP72 can act as a transcriptional modulator with the ability to induce the expression of OsHKT1;1 in response to environmental stress through an ABA-dependent regulatory pathway,indicating that OsbZIP72 can play a crucial role in the ABA-mediated salt and drought tolerance pathway in rice.

Effect of different fertilizers on methane emission from a paddy field of Zhejiang, China

Methane emissions from Chinese paddy soil (Zhejiang Province) were measured over the rice growing seasons. Different fertilizers (organic and chemical) were applied, emissions of methane were high during two periods(5 days after peak tillering and 7 days after heading flowering stage) and significant effect of fertilizers was observed. Methanogenic activities in soils treated with organic manures were obviously higher than those with chemical fertilizers. Among the organic manured fields the maximum methane emission from green manure, biogas residue and beef manure treatment were 52, 20 and 19 times respectively of that given by control, and among chemical fertilizers it was NH\-4HCO\-3>CO(NH 2) 2>(NH 4) 2SO 4>NH 4Cl>NaNO 3 with 2\^4, 2, 1\^5,1\^3 and 0\^2 times respectively of that from control.

NUMERICAL SIMULATION OF METHANE EMISSIONS FROM RICE PADDY FIELDS IN THE YANGTZE DELTA OF CHINA

A numerical simulation model is presented in this paper,which comprises the processes of crop growth,soil organic carbon decomposition,and methane emissions in agroecosystems. Simulation results show that the model can simulate the main process of methane emissions well, and the correlation coefficient between the simulated values and observed data is 0.79 with 239 samples,which passed a significance test of 0.01.The average error of methane emission simulation in whole growth period is about 15%.Numerical analysis of the model indicates that the average temperature during rice growth period has much impacts on methane emissions,and the basic trend of interannual methane emissions is similar to that of average temperature.The amount of methane emissions reduces about 34.93%,when the fertilizer is used instead of manure in single rice paddy.

New insight into iron biogeochemical cycling in soil-rice plant system using iron isotope fractionation

Iron (Fe) migration in soil-plants is a critical part of Fe biogeochemical cycling in the earth surface system. Fe isotope fractionation analysis in the soil-rice system is promising for quantitatively assessing various pathways and clarifying Fe transformation processes. However, the mechanisms of Fe isotope fractionation in the soil-rice system are not well understood. In this study, the Fe isotopic compositions (δ^(56)Fe) of rhizosphere soils, pore water, Fe plaque, and rice plant tissues at the jointing and mature stages of the plants were determined. The rice plants were slightly enriched in heavier δ^(56)Fe by 0.3‰ relative to the soil, and the stele and cortex showed similar δ^(56)Fe values, indicating that the uptake of Fe by rice plants predominantly occurred via Fe(III)-phytosiderophores (Fe(III)-PS) chelation, but not Fe(III) reduction. Additionally, at both the jointing and mature stages, the rice plant tissues showed similar δ^(56)Fe values. However, the Fe isotope fractionation between the roots and stems (Δ56Feroot−stem) was 1.39 ± 0.13‰, which is similar to the previously Ab initio-calculated values between Fe(III)-citrate and Fe(III)- 2-deoxymugineic acid (DMA), indicating that both the phloem and xylem have similar δ^(56)Fe values, and the major Fe-chelating substances in the phloem of the rice plants are Fe(III)-DMA and Fe(II)- Nicotianamine (NA). Therefore, this study demonstrates that Fe isotope fractionation can be used as a signature for interpreting the Fe uptake and translocation mechanism in the soil-rice system.

Estimate of CH_4 Emissions from Year-Round Flooded Rice Fields During Rice Growing Season in China

A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4 emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China. The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66 Mha were estimated to be 2.44 Tg CH…

植保无人机喷施封闭除草剂对稻田杂草的防效研究

为探究植保无人机喷施除草剂对直播稻田杂草防效,采用50%丁草胺乳油、26%噁草酮悬浮剂、350 g/L异噁草松微囊悬浮剂、300 g/L丙草胺乳油4种封闭除草剂,在飞行高度2 m和3 m,用水量22.5、45.0 L/hm^(2)条件下设置不同处理,考察播前施药结合水层管理及播后干封对水稻安全性及对直播稻田不同种类杂草的防除效果。结果表明,26%噁草酮悬浮剂2个用水量处理的成苗率和苗高显著低于其余处理,播后30 d各处理水稻分蘖数均显著高于空白对照,各处理5株苗茎基宽与空白对照无差异。药后15 d,3种除草剂供试浓度下高用水量处理对稗草、千金子、多花水苋、异型莎草等杂草的防效均优于低用水量;播前水封与播后干封效果整体上差异不大。药后40 d,整体上各处理防效均降低,26%噁草酮悬浮剂、350 g/L异噁草松微囊悬浮剂在高用水量时对稗草的株数防效显著优于低用水量,3种药剂在高用水量时对千金子的株数防效均显著高于低用水量,鲜重防效与株数防效趋势基本一致。3种药剂不同飞防参数下对异型莎草和多花水苋的防效有差异,且效果较差。同一药剂在用水量45 L/hm^(2)和飞行高度3 m时对不同杂草的防效优于用水量22.5 L/hm^(2)和飞行高度2 m处理。不同除草剂对不同种类杂草的防效存在差异,高用水量播前施药结合水层管理对不同杂草的防效均优于播后干封处理。后期应适时进行茎叶处理,以提升施药对田间杂草的治理效果。

硝化抑制剂双氰胺施用对水稻产量和温室气体排放的影响

为探究施用硝化抑制剂双氰胺对水稻产量和温室气体排放的影响,以常规粳稻品种南粳9108为供试材料进行盆栽试验,设置常规氮肥(CK)和常规氮肥配施硝化抑制剂双氰胺(DCD)2个处理。采用静态箱-气相色谱法连续监测稻田温室气体排放动态变化。结果表明,与CK相比,DCD显著提高了水稻产量(15.1%)和地上部生物量(28.4%),并且显著降低了稻田甲烷(CH_(4))累积排放量(22.2%)、氧化亚氮(N_(2)O)累积排放量(56.0%)、综合温室效应(GWP)(24.4%)和温室气体排放强度(GHGI)(31.7%)。可见,常规氮肥配施硝化抑制剂双氰胺可以协同实现水稻丰产和稻田温室气体减排。

水分调控下绿肥种植和石灰施用对双季稻稻米镉含量的影响

[目的]农田镉(Cd)污染是当前我国水稻产业高质量发展面临的主要环境问题之一,严重影响稻米商品价值和人民健康。本研究采用田间大区试验,探究水分调控下绿肥种植、石灰施用对稻米Cd含量及水稻产量的影响,以期为水稻安全生产提供技术参考。[方法]试验用早、晚稻品种分别为湘早籼24号和华润2号,试验地在湖南省益阳市,设置常规栽培(CK)、水分调控(W)、绿肥+水分调控(GW)、石灰+水分调控(LW)、绿肥+石灰+水分调控(GLW)共5个处理。[结果]与CK处理相比,W、GW和LW处理早晚稻平均糙米镉含量分别显著降低34.5%、83.5%和83.3%,稻谷镉含量分别显著降低26.3%、82.5%和83.4%;GLW处理仅晚稻的糙米镉含量显著降低43.7%,稻谷镉含量显著降低40.8%。相比CK处理,GW和LW处理早晚稻平均稻壳镉含量分别显著降低71.3%和74.2%,茎叶镉含量显著下降85.3%和79.1%;GLW处理仅晚稻的稻壳镉含量显著降低38.5%,茎叶镉含量显著降低51.9%。相比CK处理,W、GW和LW处理早晚稻平均灌浆期土壤pH值分别显著提高6.2%、23.7%和20.0%,GW处理早晚稻灌浆期土壤有效镉含量显著降低20.0%~22.6%。相比CK处理,GW和LW处理可显著降低早稻稻壳中的Cd向糙米转运;除W处理早稻稻壳和晚稻茎叶较CK处理差异不显著外,其余各处理均可显著降低土壤中的Cd向茎叶、糙米和稻壳富集。各处理间水稻产量差异不显著。[结论]在水稻孕穗后淹水灌溉基础上,配套冬季豆科绿肥种植或春季石灰施用,可实现轻度镉污染稻田水稻安全生产,不影响水稻丰产。

水稻对林丹的吸收累积与代谢组学研究

以有机氯代污染物——林丹作为研究对象,研究其在我国典型农作物——水稻(Oryza sativa L.)体内的迁移转化和代谢情况。结果发现,在林丹胁迫条件下,水稻根和地上部的林丹含量与水培溶液中的林丹浓度具有正相关性,表明水稻具有吸收林丹的能力。在不同林丹水培浓度下,水稻根内的林丹累积浓度在第二天均达到峰值,第三天后急剧下降。水稻根系内的林丹可以径向运输至茎叶中,但转运因子仅为0.08~0.13。在亚细胞水平上,水稻根中林丹的含量从高到低依次为细胞器>细胞壁>细胞质,表明细胞器和细胞壁是水稻根部林丹累积的主要部位。代谢组学分析结果表明,林丹胁迫下,脂质类代谢物的变化最显著,有43种上调、42种下调。受林丹胁迫影响,水稻根中的异牡荆苷等代谢物的含量提高,而天冬酰胺等代谢物的含量降低,多条植物代谢通路被改变,其中,鞘脂代谢通路和苯丙氨酸代谢通路受到较大影响。

水稻种植田间管理与病虫害防治分析

为了研究水稻种植田间管理与病虫害防治的有效措施,该文以广西桂林市灌阳县地区的水稻种植为例,通过整理分析相关文献及结合广西桂林市灌阳县地区种植实践,对水稻种植田间管理对策进行了分析,探讨水稻种植过程的田间管理工作,以期推动水稻高产增收,保障水稻产量得到进一步提升。

山区单季机插秧杂交籼稻栽培技术

针对山区单季机插秧杂交籼稻栽培中的温室育秧、大田整田及栽插、大田水肥管理等问题开展实地研究,总结了一套切合山区实际、便于普及推广的栽培技术,具有省力、高效、高产等优势。

水稻种植技术及管理措施分析

水稻生产时,种植技术是否规范,管理措施是否完善,直接影响着水稻产量和品质。为实现水稻高产稳产的目标,做好水稻种植技术及田间管理工作颇为关键。以青阳县为例,着重对水稻种植技术要点及田间管理措施展开了深入分析。

农业文化遗产的地方性知识体系:以湘西“子腊贡米”为例

作为中国重要农业文化遗产的“子腊贡米”,有其独特的地方性知识,主要包括“铺树造田”技术系统、灌溉系统、育林蓄水、“稻鱼鸭鸟蛙”等知识体系。这些知识体系至今仍为遗产地的民众所利用,也是确保当地农耕收获及农业发展可持续的基础,其所蕴含的农业生产观念对构建现代农业技术体系有着重要的借鉴与参考作用。

Plant Nutrition for Human Nutrition:Hints from Rice Research and Future Perspectives

Both plants and humans require mineral elements for their healthy growth and development.Mineral elements in the soil are taken up by the plant roots and transported to the edible parts for human consumption through various different transporters.An ideal future crop for human health should be rich in essential mineral elements but with less toxic elements in the edible parts.However,due to the great difference in the numbers and amounts of mineral elements required between plants and humans,it is a challenge to balance plant growth and nutrient requirement for humans.In this article,we mainly focus on the transport system of mineral elements from soil to grain in rice,a staple food for half of the world's population,and discuss recent progress on the underlying genetic and physiological mechanisms.Examples are given for silicon,zinc,and iron essential/beneficial for both plants and humans,selenium and iodine only essential for humans,and toxic cadmium and arsenic for all organisms.Manipulation of some transporters for these elements,especially those localized in the node for allocation of mineral elements to the grain,has been successful in generating rice with higher density and bioavailability of essential elements but with less accumulation of toxic elements.We provide our perspectives toward breeding future crops for human health.