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10 May 2010, Volume 24 Issue 3 Previous Issue    Next Issue
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研究报告
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Genetic Analysis of Heading Date of Some Early Season Indica Rice Cultivars and Hybrid Rice Parents in China XU Jun-feng,WEI Xiang-jin,JIANG Ling,LU Guang-wen,WANG Hong-jun,ZHOU Zhen-ling,WAN Jian-min 2010, 24(3): 215-222 .  DOI: 10.3969/j.issn.1001-7216.2010.03.001 Abstract ( )   PDF (2078KB) ( )   Heading date is one of the most important traits for the adaptation of rice to different cultivation areas and cropping seasons. Early season indica rice cultivars play an important role in rice production in China. Heading dates of 19 early season indica rice cultivars and hybrid rice parental lines from the middlelower region of the Yangtze River Valley and South China were investigated and their sensitivities to photoperiod and temperature were analyzed. Among the 19 rice materials, 16 were sensitive to temperature， and all showed a weak photoperiod sensitivity. The basic vegetative growth of most of these early season indica materials were weak but differed. A regression analysis showed that heading date was significantly correlated with basic vegetative growth. Genetic analyses based on a set of heading date near isogenic lines revealed that all the early season indica cultivars or hybrid parents carried the recessive photoperiod insensitivity allele hd2, and most of these materials carried the dominant earlyheading gene Ef1. All these materials carried either one or no photoperiod sensitivitydetermining dominant allele at E1 and Se1. These results indicate that with weak photoperiod sensitivity and short basic vegetative growth phase, these early season indica cultivars are suitable to be grown in the middlelower region of the Yangtze River Valley and South China as early season cultivars. It could be useful for breeding new early season indica cultivars.

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Genetic Analysis and Mapping of a ThermoSensitive White Stripe Leaf Mutant at the Seedling Stage in Rice(Oryza sativa) LI Chao,LIN Dong-zhi,DONG Yan-jun,YE Sheng-hai,ZHANG Xiao-ming 2010, 24(3): 223-227 .  DOI: 10.3969/j.issn.1001-7216.2010.03.002 Abstract ( )   PDF (979KB) ( )   A thermosensitive white stripeleaf mutant (tws) was selected from the M2 progeny of a japonica rice variety, Jiahua 1, treated with 60Co γradiation. In comparison with the wild type parent (Jiahua 1), the mutant displayed a phenotype of white stripe on the 3rd and 4th leaves, but began to turn a normal green phenotype on the 5th leaf when grown at low temperatures (20℃, 24℃). And also the content of total chlorophyll showed an obvious decrease in the leaves with white stripe. These results suggest that the expression of the mutant trait was thermosensitive and correlated with the leaf age of seedlings. The genetic analysis indicated that the mutant trait was controlled by a single recessive nuclear gene, designated as tws (thermosensitive white stripeleaf). In addition, by using SSR markers and an F2 segregating population derived from the cross between the tws mutant and 9311, the tws gene was mapped between MM3907 and MM3928 with a physical distance of 86 kb on chromosome 4.

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Analysis of Genetic Model for Rice Stripe Disease Resistance in Rice Restorer Line C224 ZHENG Wen-jing,LIU Zhi-heng,ZHANG Yan-zhi,LIU Xin,WANG Chang-hua,ZHAO Jia-ming 2010, 24(3): 228-232 .  DOI: 10.3969/j.issn.1001-7216.2010.03.003 Abstract ( )   PDF (377KB) ( )   Resistance inheritance to rice stripe disease of C224 were analyzed by the mixed major gene plus polygene mixed genetic model of quantitative traits. Meanwhile, the resistances of seven crosses derived from C224 and seven maintainer lines were investigated. The results showed that rice stripe disease resistance of the rice restorer line C224 was controlled by two major genes with additivedominanceepistatic effects plus polygene with additivedominance effects(E1 model). These two major genes showed different additive effects and negative dominance effects. One major gene′s additive effect was about -12.47 and the other was -24.75. There were significant epistatic and interactive effects between the two major genes. The heritability of the two major genes was about 92.12%, while the heritability of polygene was about 2.74%. The resistance to rice stripe disease had a significant major gene effect in the seven crosses. Of the seven crosses five possessed high or medium rice stripe disease resistance.

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Detection of Quantitative Trait Loci for Cold Tolerance at the Bud Bursting Stage by Using Chromosome Segment Substitution Lines in Rice (Oryza sativa) LIN Jing,ZHU Wen-yin,ZHANG Ya-dong,ZHU Zhen,ZHAO Ling,CHEN Tao,ZHAO Qing-yong,ZHOU Li-hui,FANG Xian-wen,WANG Yan-ping,WANG Cai-lin* 2010, 24(3): 233-236 .  DOI: 10.3969/j.issn.1001-7216.2010.03.004 Abstract ( )   PDF (808KB) ( )   The cold tolerance at the bud bursting stage (CTB) were evaluated at 5℃ by using a set of 95 chromosome segment substitution lines (CSSLs) derived from indica rice 9311 and japonica rice Nipponbare. The results showed that six CSSLs had slightly stronger CTB than 9311. Total four quantitative trait loci (QTLs) for CTB were preliminary mapped on chromosomes 5 and 7 by substitution mapping. qCTB51, qCTB52 and qCTB53 were mapped in the region of RM267-RM1237,RM2422-RM6054 and RM3321-RM1054, which were 21.3 cM, 27.4 cM and 12.7 cM in genetic distance on rice chromosome 5, respectively. qCTB7 was mapped in the region of RM11-RM2752, which was 6.8 cM in genetic distance on rice chromosome 7.

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SSR-Based Analysis on Genetic Diversity of Rice Landraces from Guizhou Province, China MA Lin,YU Xian-quan*,ZHAO Fu-sheng 2010, 24(3): 237-243 .  DOI: 10.3969/j.issn.1001-7216.2010.03.005 Abstract ( )   PDF (1285KB) ( )   The genetic diversity of 74 rice landraces from Guizhou Province, China was analyzed with 21 SSR markers and six standard varieties representing typical indica and japonica ecotypes. Ninetytwo alleles were detected. The average number of alleles per locus was 4.381 with a range from 2 to 9. The Shannon′s information indices varied widely from 02793 to 1.8732 with an average value of 0.935. The expected heterozygosities ranged from 0.0988 to 0.8313 with an average value of 0.5145. Cluster analysis results showed that the similarity coefficients varied from 0.64 and 0.98 and UPGMA cluster analysis showed that the rice materials tested could be divided into four groups at a genetic similarity coefficient of 0.682. Most of the materials were scattered around typical japonica ecotypes and the genetic relationship among these landraces was not in accord with their geographical origins. The results of principal coordinates analysis and UPGMA cluster analysis revealed that the genetic structure was multiplex in the rice landraces. The rice landraces from Guizhou Province showed lower genetic diversity and most were japonica ecotypes according to SSR analysis.

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Development of STS Marker KC1 for Brown Planthopper Resistance Gene Bph18(t) and Marker Assisted Selection Efficiency LIANG Yun-tao,#,WANG Chun-lian,#, LAI Feng-xiang, LIU Pi-qing,WANG Jian,FU Qiang,ZHAO Kai-jun 2010, 24(3): 244-250 .  DOI: 10.3969/j.issn.1001-7216.2010.03.006 Abstract ( )   PDF (1426KB) ( )   To facilitate application of the elite brown planthopper(BPH) resistance gene Bph18(t) to rice breeding program by molecular assisted selection(MAS), a STS marker, KC1, for Bph18(t) gene was developed. To test the MAS efficiency of KC1 for Bph18(t), the F2 plants derived from the cross between Yangdao 6(i.e.9311)\[without Bph18(t), susceptible to BPH\] and C4064 \[harboring Bph18(t)\] were subjected to both bioassay of BPH resistance in the field and molecular identification with the STS marker KC1 in the laboratory. Among the F2 plants, 292 plants were resistant to BPH while the other 84 plants were susceptible, indicating a single gene \[Bph18(t)\] controlling the BPH resistance in the F2 population. The results of molecular identification showed that the MAS efficiency of KC1 for Bph18(t) was 82.6%, indicating that the STS marker KC1 could be useful to trail Bph18(t) gene in rice breeding program.

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Changes in Organ Biomass in Rice Cultivars Released by Jilin Province, China During FortySeven Years of Genetic Improvement DI Yu-ting,ZHAO Guo-chen,XU Ke-zhang,WU Zhi-hai,ZHANG Zhi-an,LING Feng-lou,JIANG Nan 2010, 24(3): 251-256 .  DOI: 10.3969/j.issn.1001-7216.2010.03.007 Abstract ( )   PDF (3025KB) ( )   In order to understand the changes in yield, harvest index (HI) and biomass of aboveground parts of rice, 33 japonica rice cultivars released from 1958 to 2005 were planted. During the 47 years, the grain yield increased from 9 11836 to 15 0601 kg/hm2 and HI from 046 to 055 in the genetic improvement of rice, with the average annual growth rates of 139% and 044%, respectively. In the genetic improvement, the total number of tillers per plant decreased, and the biomass per unit area slightly increased at the harvest stage. The increases of yield and HI resulted from increased biomass of effective tillers and single plant, and the increase of single plant biomass was related to increased biomass of different organs during the genetic improvement. The stem and sheath biomass at heading and the leaf biomass at 30 d after heading showed the biggest increase, up by 7517% and 4994%, respectively. The biomasses of leaves and stem sheath at 10 d after heading, and single plant biomass at 30 d after heading were obviously correlated with the yield. The results indicate that the genetic improvement has resulted in the increase of yield and HI. This increase is correlated with the decrease of total tiller number per plant, and increase of biomasses of effective tillers and single stem. The leaf biomass after heading and the stem and sheath biomass at 10 d after heading can be used as a selection criterion of high yield cultivars.

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Effects of Aerated Irrigation on Physiological Characteristics and Senescence at Late Growth Stage of Rice ZHU Lian-feng,LIU Xue,YU Sheng-miao,OUYANG You-nan,JIN Qian-yu* 2010, 24(3): 257-263 .  DOI: 0.3969/j.issn.1001-7216.2010.03.008 Abstract ( )   PDF (1846KB) ( )   With the inbred japonica rice variety Xiushui 09, indica hybrid rice combinations Guodao 6 and Liangyoupeijiu as materials, a field experiment was conducted to study the effects of aerated irrigation on physiological characteristics and senescence at late growth stage of rice in 2007 and 2008. The dissolved oxygen concentration of aerated water was higher than river water with a slower decrease rate. The soil oxidationreduction potential under the aerated irrigation treatment was significantly higher than that of the traditional irrigation treatment at 0.05 or 0.01 level, resulting in a significant increment in number of effective panicles, seead setting rate and grain yield. Further research showed that aerated irrigation increased photosynthetic rate by 4.13% in Xiushui 09 and 3.78% in Liangyoupeijiu. The contents of chlorophyll and soluble protein and stomatal conductance under the aerated irrigation were significantly increased, which were the main cause of the increased photosynthetic rate. Furthermore, the aerated irrigation improved root function, increased the activity of superoxide dismutase and decreased the content of malondialdehyde in leaves after flowering, postponed the leaf senescence effectively，thus prolonged leaf functional period and promoted grain filling.

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Dynamic Changes of Lodging Resistance and Chemical Component Contents in Culm and Sheaths of Japonica Rice During Grain Filling ZHANG Feng-zhuan,JIN Zheng-xun,MA Guo-hui,SHANG Wen-nan,LIU Hai-ying,XU Mei-lan ,LIU Yan 2010, 24(3): 264-270 .  DOI: 10.3969/j.issn.1001-7216.2010.03.009 Abstract ( )   PDF (391KB) ( )   The lodging resistance and chemical component contents in culm and leaf sheaths were analyzed by using japonica rice cultivars with different lodging resistance during grain filling. The results showed that there were significant differences in total amount of potassium (K), silicon (Si) and soluble sugars in culm and leaf sheaths, especially total amount of Si.The physical strength and maximum bearing capacity of culm gradually decreased during grain filling, and reached the minimum at the maturity stage, in particular, the physical strength at the dough stage decreased rapidly. The contents and total amount of K and Si in culm and the content of Si in leaf sheaths were increased gradually and presented precipitation phenomenon whereas the content and total amount of K and the total amount of Si in leaf sheaths were decreased gradually and assumed output sign. Except for the total amount of K in culm at the full heading stage, the physical strength was highly significantly and positively correlated with total amounts of K and Si in culm during grain filling, and significantly and positively correlated with the total amount of soluble sugars in culm at the full heading stage and milky stage, with the total amounts of Si and soluble sugars in leaf sheath at the full heading stage and with the total amount of K in leaf sheath at the full heading stage and milky stage. The physical strength was highly significantly and positively correlated with maximum bearing capacity during grain filling. It is suggested that increasing the amount of soluble sugars in plants at the early filling stage, and enhancing amount of Si in plants during grain filling by topdressing Si fertilizer at the early filling stage would be beneficial to improve the lodging resistance of japonica rice.

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Effects of Located Nitrogen Application and Nitrogen Application After Exhaustion on Rice Yield and Nitrogen Use Efficiency in the Taihu Lake Region, China LIN Zhong-cheng，#,YE Shi-chao,#, DAI Qi-gen,CHEN Jing-dou,GU Hai-yan,ZHAO Hong-xiang,ZHAO Xiao-hua, ZHANG Hong-cheng,HUO Zhong-yang,XU Ke, WEI Hai-yan 2010, 24(3): 271-277 .  DOI: 10.3969/j.issn.1001-7216.2010.03.010 Abstract ( )   PDF (416KB) ( )   通过在太湖地区持续施氮和土壤氮耗竭1年后再施氮的对比试验，研究了施氮量对水稻产量、干物质积累、植株吸氮量、氮肥利用效率和土壤氮素的影响。 经过3季（稻麦稻）不施氮处理，第3季作物水稻的产量显著下降，仅6673.42 kg/hm2；持续施氮和氮耗竭1年后施氮处理的产量均随着施氮量的增加而提高，但增产幅度逐渐减小，当施氮量为300 kg/hm2时，水稻产量最高，分别为10 514.95 kg/hm2和10 472.36 kg/hm2，施氮量继续增加时水稻都出现倒伏而减产；各施氮处理植株的干物质积累、总吸氮量和土壤全氮含量都随施氮量的增加而提高，而氮肥利用效率都随施氮量的增加而降低；氮耗竭1年后施氮处理与持续施氮处理之间的各项指标变化不明显，说明这些指标与氮耗竭1年后的土壤背景氮关系不密切，而与当季施氮量有关。

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Analysis on Microbial Diversity in the Rhizosphere of Rice by Phospholipid Fatty Acids Biomarkers LIU Bo, HU Gui-ping, ZHENG Xue-fang, ZHANG Jian-fu, XIE Hua-an 2010, 24(3): 278-288 .  DOI: 10.3969/j.issn.1001-7216.2010.03.011 Abstract ( )   PDF (1669KB) ( )   The microbial community structure in rice rhizosphere was analyzed using phospholipid fatty acids biomarkers(PLFAs) with seven hybrid rice combinations as materials under the same cultivation conditions. The PLFAs was detected by MIDI system to get the biomarkers and to calculate the microbial community diversity. Cluster analysis was introduced into the quantity statistic for the characteristics of rhizosphere microbial community in the rice materials. The results showed that 38 PLFAs biomarkers were detected, 23 of which were distributed in rhizosphere of the seven materials and 15 in the rhizosphere of some of the hybrid rice combinations. The quantities of PLFAs related to bacteria were higher than either those to fungi or to actinomycetes. The rhizosphere microbial community structure represented by PLFAs was closely related to the biology of rice materials.The PLFAs content was significantly and positively correlated with the number of effective panicles as well as the yield, whereas significantly and negatively correlated with the plant height of rice. Moreover, cluster analysis displayed that the PLFAs were associated with rice genetic characteristics. It is concluded that the microbial community structure represented by PLFAs in rice rhizosphere was rich, which sensitively reflected the relation between the PLFAs and the biological and genetic characteristics of rice variety.

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Responses of Seedling Growth and Antioxidase Activities of Different Zinc Efficient Rice Genotypes and Their F1 Hybrids to Zn2+ Activities MENG Jie,WANG Ren-min*,WAN Ji-li,FU Li-cheng 2010, 24(3): 289-296 .  DOI: 10.3969/j.issn.1001-7216.2010.03.012 Abstract ( )   PDF (425KB) ( )   Studying the physiological mechanism of genotypic difference in tolerance and the tolerance of F1 hybrids to low zinc stress in rice is one basic work to improve rice zinc efficiency as well as to solve the problem of rice zinc shortage. The Znefficient rice cultivars IR8192 and IR36, Zninefficient rice cultivars Ce64 and IR26, and their F1 hybrids of the crosses IR36×IR8192, IR36×IR26, and Ce64×IR26 were grown in chelatorbuffered nutrient solution at both low zinc level (pZn2+110) and normal zinc level (pZn2+9.7), respectively. The relative values of both parents and F1 rice seedlings under pZn2+110 to the ones under pZn2+9.7 in plant height, sheath height, shoot and root dry weights and zinc contents, chlorophyll content in leaves, and activities of SOD, CAT, POD, and MDA could be used as the screening index of Znefficient rice. At low zinc level, the four cultivars and their F1 hybrids showed similar trends in all the indices. However, IR8192, IR36, IR36×IR8192 had smaller decreases in chlorophyll content and activity of SOD, greater increases in activities of POD, CAT and APX, and a smaller increase in MDA content, suggesting that these rice genotypes had a stronger ability to resist low zinc stress. Under the low zinc stress, POD, CAT and APX were the main active oxygen scavenging system, while SOD protective enzyme system was firstly weakened. In the low zinc stress, except root length and APX activity, the relative values of the traits in IR36×IR8192 and IR36×IR26 showed overparent heterosis whereas Ce64×IR26 were close to midparent values, which indicates that lowzinctolerance was controlled by dominant effect and there existed duplicate effect of gene. Therefore, rice cultivars with stronger ability to resist low zinc stress could be obtained by hybridization of Znefficient parental rice.

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Development and Application of a Model and GISBased Decision Support System for Rice Production Management LIU Xiao-jun,CAO Jing,TANG Liang,CAO Wei-xing,ZHU Yan* 2010, 24(3): 297-302 .  DOI: 10.3969/j.issn.1001-7216.2010.03.013 Abstract ( )   PDF (1887KB) ( )   In order to realize the precise management for rice production, a model and GISbased decision support system for rice production and management (MGDSSRM) was developed, which was guided by the system engineering theory and software technology, using rice precision management knowledge model as intelligentized and digital decision support, with GIS as spatial data management platform. The system realized the functions as basic map handling, information management, cultural plan design, fertilizer and water management, pestdiseaseweed management, suitable dynamic indices design, realtime regulation based on growth status, expert consultation, and system help, etc. Case studies on the system in the rice field experiments in Jiangsu and Zhejiang Provinces, China indicated that the average yield under the precision management plan was 10 464.8 kg/hm2, 12.53% over that in the general plan (9 299.5 kg/hm2). Moreover, the amount of nitrogen fertilizer decreased by 31.5 kg/hm2, as comparing to the general plan. The present work has provided a modeling and systematized decision tool for the design of rice production management prescription, and a basal framework for developing other crop management decision support system.

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Comparison of Phasic Development Models in Rice SHI Chun-lin,FENG Hui-hui,JIN Zhi-qing, WANG Hua 2010, 24(3): 303-308 .  DOI: 10.3969/j.issn.1001-7216.2010.03.014 Abstract ( )   PDF (708KB) ( )   The difference in response patterns of development rate to temperature and daylength, the phase division and parameter setting, and the relationship among accumulated growth degree day(GDD), development rate(DVR) and development physiological day number(DPD) were discussed by comparing the phasic development models from CERESrice, ORYZA2000, RCSODS and RiceGrow. The four models showed a similar response pattern of development rate to temperature. The parameter setting in CERESrice, ORYZA2000 and RiceGrow was same in basic vegetative phase and grain filling phase, although different parameters were used in these models, such as GDD, DVR, and DPD. During photoperiodsensitive phase, three parameters, such as development rate, critical daylength and daylength effect factor were used in these models, but one parameter was fixed in CERESrice and RiceGrow. One new parameter was applied in ORYZA2000 to describe the development process in reproductive phase, but no new parameter was introduced to development models in CERESrice and RiceGrow. The response patterns of development rate to daylength in photoperiodsensitive phase in CERESrice, RCSODS and ORYZA2000 was similar, which was different to that in RiceGrow. The simple phase division in RCSODS led to fewer genetic parameters. The phasic development model in ORYZA2000 was the most common, but with maximum parameters, and which could not be obtained merely from cultivar data.

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Visually Modeling Spatial Shape of Rice Panicle Based on Calculation of Bending Deformation DING Wei-long,LIU Chang,ZHANG Yu-ping,ZHU De-feng,ZHANG Qian-yuan,GU Hui 2010, 24(3): 309-314 .  DOI: 10.3969/j.issn.1001-7216.2010.03.015 Abstract ( )   PDF (1363KB) ( )   Visually simulating the geometrical shape of rice panicle is a key step to build virtual rice growth model, which can help us to better understand crop growth process. Because of its complex shape, it is quite difficult to vividly model threedimensional architecture of rice panicle. To address this issue, a new visually modeling algorithm for rice panicle structure was proposed based on bending deformation model in mechanics of material and threedimensional form of rice panicle was visually simulated. First of all, the threedimensional morphological data and the weight of rice panicle at different growth stages were measured through field experiments. And then, according to the type of rachis branches and different distributions of gravity, the curved patterns of panicle axis and various types of rachis branch were simulated with the improved model of the bending deformation and the space coordinates. Finally, the whole threedimensional shape and the growth process of rice panicle were simulated successfully in accordance with its growth laws. The experimental results show that this algorithm provides an approach to realistically modeling the threedimensional architecture of rice panicle under natural conditions.

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Population Dynamics of Nilaparvata lugens and Its Two Sibling Species under Black Light Trap LUO Ju,FU Qiang,LU Zhi-jian,WU Cai-qian,LI Yi-bo,DUAN De-kang,LIU Yu-kun,ZHANG Zhi-tao 2010, 24(3): 315-319 .  DOI: 10.3969/j.issn.1001-7216.2010.03.016 Abstract ( )   PDF (2347KB) ( )   Population dynamics of brown planthopper, Nilaparvata lugens, and its two siblings under black light traps were investigated in five sites of four provinces, Guangxi, Hunan, Jiangxi and Zhejiang, China during 2008-2009 and the percentage of each species under various conditions was analysed. The annual percentages of N. lugens, N. muiri and N. bakeri from the five sites were 58.4%, 41.5% and 0.1% in 2008, 50.5%, 46.8% and 2.7% in 2009, respectively. In general the dominant species was N. muiri at early stage, but N. lugens at late stage. However, population development patterns among the five sites varied. The percentages of N. lugens in the two sites of Guangxi were 60.4% to 91.3%， but those of N. muiri in Linxiang, Hunan and Fuyang, Zhejiang were 59.3% to 80.7%. N. lugens started to appear under light trap in April, became dominant in June and showed two peaks at JuneJuly and October (or OctoberNovember) in the two sites of Guangxi, but started to appear under light trap in MayJune, became dominant in September, and showed only one peak at SeptemberOctober in the other three sites. Therefore, it is very important to identify specimens caught under light trap for improving brown planthopper forecasting.

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Stability of Eating Quality Traits of Japonica Soft Rice from Different Locations at Different Altitudes in Yunnan Province, China SU Zhen-xi*,ZHAO Guo-zhen,LIAO Xin-hua,SHI Rong,JIANG Cong,ZHU Zhen-hua,ZOU Qian 2010, 24(3): 320-324 .  DOI: 10.3969/j.issn.1001-7216.2010.03.017 Abstract ( )   PDF (663KB) ( )   Five japonica soft rice cultivars were cultivated at four different altitudes in Yunnan Province, China to evaluate the genetic stability of eating quality traits including amylose content, gel consistency, protein content based on AMMI model. The results showed that genotype ×environment interaction and difference in eating quality traits among genotypes and environments were significant at 5% or 1% level. The amylose content, gel consistency, and protein content were also significantly different in IPCA value. The order of stability of eating quality traits for the five cultivars was as follows: Yinguang > Yunjing 20 > Yunjingyou 4 > YH64 > H559. Environment factors affecting stability of eating quality traits were altitude and daily mean air temperature. In view of grain yield, eating quality and its stability, Yinguang and Yunjing 20 could be applied as parents to improve eating quality (especially in low amylose content breeding) and its stability.

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A Hotelling TransformBased Algorithm for Rice Grain Type Detection with Color Images LIU Ying-ying,DING Wei-min, CHEN Jian-wei,SHEN Ming-xia 2010, 24(3): 325-328 .  DOI: 10.3969/j.issn.1001-7216.2010.03.018 Abstract ( )   PDF (628KB) ( )   An algorithm for rice grain type detection using color image segmentation and the Hotelling transform was proposed. The rice grain images were segmented in I1 band(the average of red, green and blue color bands) chosen from seven color bands according to quantitative analysis of segmentation performance. The coordinate vector of segmented image edge was converted by the Hotelling transform. Grain size features were extracted in the new coordinate system using minimum enclosing rectangle. This algorithm was run in MATLAB 7.5.0 to count rice grain ratio. The relative error compared with manual measurement were 1.65% and 2.24%, and the running times were 0.323 s and 2.837 s per image, respectively, for this algorithm and algorithm using minimum enclosing rectangle.

综述与专论

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A Review on Arsenic in Rice WANG Yong-jie, ZHENG Xiang-min*,ZHOU Li-min 2010, 24(3): 329-334 .  DOI: 10.3969/j.issn.1001-7216.2010.03.019 Abstract ( )   PDF (670KB) ( )   Arsenic（As) is now regarded as one of the most serious contaminants as a typical noxious element，especially inorganic arsenic. Indeed, arsenic has a chronic poisoning effect in human body. Recent studies have shown that rice is much more efficient in assimilating arsenic into its straw and grains than other staple cereal crops, and consumption of rice constitutes a large proportion of dietary intake of arsenic. Therefore, scientists pay a high degree of attention to arsenic in rice. In rice total As content varies from 0.005 to 0.710 mg/kg. Arsenic speciation in rice grain is dominated by inorganic As(Ⅲ+V) and dimethylarsinic(DMA). The inorganic As content in rice varies from 10% to 90% of total As. Now, studies have shown that there are two types of arsenic contained rice, one with arsenic speciation dominated by DMA, and the other by inorganic arsenic. Both of them show an increasing trend in DMA/As(Ⅲ+V) content with rising total arsenic. The flooded conditions is one of the main reasons for enhanced arsenic accumulation in rice, and growing rice aerobically can dramatically decrease the arsenic transfer from soil to rice. Differing chemical states of arsenic, the mechanism of arsenic mobility in rhizosphere and mediated by microbial activity is need to be further researched in the near future. In addition, molecular approaches and functional genomics may also help understand the mechanisms of arsenic transportation and transform in rice.