Effect of Combined Application of Subsurface Drainage and Mineral Fertilization on Iron-Reducing Bacterial Populations’ Developments and Fe2+ Uptake by Two Rice Varieties in an Iron Toxic Paddy Soil of Burkina Faso (West Africa)

Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is related mainly to the activity of Iron Reducing Bacteria in the rice field’s ecosystems. In order to control the harmful effects of Iron Reducing Bacterial populations and to improve rice productivity, a pots experiment was conducted at the experimental site of the University Ouaga I Pr. Joseph KI-ZERBO. An iron toxic soil from Kou Valley (West of Burkina Faso) and two rice varieties, BOUAKE-189 and ROK-5, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were drained for 14 days (D2) and amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complexes). Control pots without drainage and fertilization (D0/NF) were prepared similarly. The kinetics of Iron Reducing Bacterial populations and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using a spectrometric method. Data obtained were analyzed in relation to drainage and fertilization mode, rice growth stage and rice yield using the Student’s t-test and XLSTAT 2014 statistical software. The experiment showed that the combined application of subsurface drainage and NPK + Urea + Ca + Mg + Zn fertilization, reduced significantly the number of IRB in the soil near rice roots for both rice varieties (p = 0.050 and p = 0.020) increased the leaf tissue tolerance to excess amounts of Fe, and rice yield.

Resistance Evaluation of Part of Leading Rice Varieties to Rice Blast in Guangxi Province

In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.

Study on Cadmium Tolerance of Seed Germination and Seedlings Growth of Different Rice Varieties

The research used bioassay method to explore seed tolerance of Cd in terms of seed germination and seedling growth. Specifically, 12 rice varieties of three types were investigated under Cd stress, covering germination rate, shooting index, vigor index, seedling and shoot lengths, and fresh weights. The results showed that as Cd concentration grew, seed germination and seedling growth kept increasingly inhibited; germination index, vigor index, root length, shoot length and fresh weights went down; inhibition effects on seed germination and seedling growth were conventional rice〉two-line hybrid rice〉three-line hybrid ,rice. Shanyou 9588, Tianyou 998, Chuanxiang 8, and Y Liangyou 1 performed ~rongly in Cd tolerance; C Liangyou 651, Nei 5 You 263, Xiangwanxian 16, Huanghuazhan, Xiangwanxian 13, and Zhunliangyou 527 performed poorly in Cd tolerance, and Cd tolerance of rest treatments were moderate.

Analysis of the Nationally Registered Rice Varieties in the Last Decade

The nationally registered rice varieties during 2006-2015 were analyzed and there were 49.4 varieties on average annually registered in the last decade. In terms of the structure of varieties, there was a decreasing trend for the proportion of three-line hybrid rice varieties but a rapid increase for that of two-line hybrid rice varieties. The percentage of rice varieties developed by scientific research institu- tions was decreasing but that developed by seed companies kept a rapid increase, indicating the commercial breeding conducted by seed companies has become a principal model in rice breeding. With regard to grain quality of varieties, the con- ventional rice varieties showed an increasing trend while the hybrid rice varieties had a decreasing trend in the proportion of high quality varieties, indicating hybrid rice needs improving more in grain quality in breeding programs.

Major Physiological Characters of Different Double Cropping Rice Varieties by Different Mechanical Transplanting Methods

The research selected 16 rice varieties（8 early and 8 late double-cropping rice） by mechanical transplanting modes as per equivalent row and wide-narrow row to explore yield and physiological traits in order to provide references for selection of rice variety suitable for mechanical transplanting. The results showed that yields of early and late rice improved by 2.90% and 2.73% by mechanical transplanting as per equivalent row and wide-narrow row respectively. Besides, leaf area index in the treatment as per wide-narrow row was higher compared with the treatment as per equivalent row, as well as average photosynthetic potential which grew by 0.92%,3.99% and 5.64% of early from tillering-peak stage to mature stage and 3.46%,7.09% and 6.79% of late rice. Furthermore, by mechanical transplanting as per wide-narrow row, SPAD value, and root activity performer higher, as well as the number of differentiated branch and glumous flowers, but degradation rate showed lower. In addition, with mechanical transplanting the same, early rice Zhuliangyou819 and late rice Fengyuanyou 299 took advantages in yield, which can be priorities for mechanical transplanting in double-cropping areas in Jiangxi Province.

Advances in Breeding of High-amylose Indica Hybrid Rice Combinations in Sichuan Province

During 2000-2013, totally ten high-amylose specific hybrid rice combinations approved and five combinations for production test were bred in Sichuan Province. In the paper, rice yield, economic traits, quality indicators and rice blast-resistance identification results of these 15 hybrid combinations were described and analyzed. Results show that Chuanxiangyou37 and Tianlongyou540 have relatively high amylose content, good yielding ability, high resistance and appropriate growth period, which are new hybrid rice varieties with organic combination of high amylase content, high gel consistency, high yield, stable yield and wide adaptability. Therefore, Chuanxiangyou37 and Tianlongyou540 are recommended as the main combination for rice production.

Evaluating Varieties and Test Sites in the 2017 Rice Regional Trials of Hubei Province by GGE Biplot Based on Genstat

为分析水稻区试参试品种的丰产性、稳产性、适应性以及区试地点的代表力和鉴别力,采用Gen Stat软件中的GGE双标图对湖北省2017年水稻区试A组12个参试品种和10个区试地点进行了分析。结果表明,深两优10号、亮两优1212、隆晶优4393、襄优5327产量较高,亮两优1212、隆晶优4393、聚两优639、深两优10号具有较好的稳产性,襄优5327稳产性较弱,但在生产上仍有推广利用的价值。区试地点沙洋县、黄冈市、孝南区的代表力和鉴别力较强。

Grain Yield,Biomass Accumulation,and Leaf Photosynthetic Characteristics of Rice under Combined Salinity-Drought Stress

Simultaneous stresses of salinity and drought often coincide during rice-growing seasons in saline lands,primarily due to insufficient water resources and inadequate irrigation facilities.Consequently,combined salinity-drought stress poses a major threat to rice production.In this study,two salinity levels(NS,non-salinity;HS,high salinity)along with three drought treatments(CC,control condition;DJ,drought stress imposed at jointing;DH,drought stress imposed at heading)were performed to investigate their combined influences on leaf photosynthetic characteristics,biomass accumulation,and rice yield formation.Salinity,drought,and their combination led to a shortened growth period from heading to maturity,resulting in a reduced overall growth duration.Grain yield was reduced under both salinity and drought stress,with a more substantial reduction under the combined salinity-drought stress.The combined stress imposed at heading caused greater yield losses in rice compared with the stress imposed at jointing.Additionally,the combined salinity-drought stress induced greater decreases in shoot biomass accumulation from heading to maturity,as well as in shoot biomass and nonstructural carbohydrate(NSC)content in the stem at heading and maturity.However,it increased the harvest index and NSC remobilization reserve.Salinity and drought reduced the leaf area index and SPAD value of flag leaves and weakened the leaf photosynthetic characteristics as indicated by lower photosynthetic rates,transpiration rates,and stomatal conductance.These reductions were more pronounced under the combined stress.Salinity,drought,and especially their combination,decreased the activities of ascorbate peroxidase,catalase,and superoxide dismutase,while increasing the contents of malondialdehyde,hydrogen peroxide,and superoxide radical.Our results indicated a more significant yield loss in rice when subjected to combined salinity-drought stress.The individual and combined stresses of salinity and drought diminished antioxidant enzyme activities,inhibited leaf photosynthetic functions,accelerated leaf senescence,and subsequently lowered assimilate accumulation and grain yield.

Conservation of Traditional Rice Varieties in a Globally Important Agricultural Heritage System (GIAHS):Rice-Fish Co-Culture

The traditional rice-fish farming system is selected as a ＂globally important agricultural heritage system＂ （GIAHS） by the Food and Agriculture Organization （FAO）,United Nations Development Programme （UNDP）,and Global Environment Facility （GEF）,etc.In Zhejiang Province of China,where the pilot site for this GIAHS farming system is located,we compared the use of traditional rice varieties in rice-fish co-culture and rice monoculture.Further,we determined how traditional rice varieties were performed in this rice-fish system.Only 19% of the farmers who practiced rice monoculture planted traditional varieties while 52% of farmers who practiced rice-fish co-culture planted traditional varieties.Traditional varieties represented 13% of the total land cultivated under rice in the rice-fish system but only 2% in the rice monoculture system.In the rice-fish system,yield was lower for traditional rice varieties than hybrid varieties but application of fertilizers and pesticides was also lower.In a field experiment in the rice-fish system without pesticides,rice planthopper numbers and sheath blight incidence were lower from three traditional varieties than one hybrid variety;yields were 8 to 32% lower from the traditional varieties than the hybrid.Our results showed that traditional rice varieties can be preserved through conserving GIAHS rice-fish co-culture.Our study also indicated that traditional rice varieties can survive in the rice-fish system because these varieties are helpful to the whole system and beneficial to the farmers.

Evaluation of Chinese rice varieties resistant to the root-knot nematode Meloidogyne graminicola

The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa （aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica）. Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly （r=0.87, P≤0.05） with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11 （aus）, Shenliangyou 1 （hybrid aus） and Cliangyou 4418 （hybrid indica） were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.

Factors Affecting Adoption of Improved Rice Varieties among Rural Farm Households in Central Nepal

The use of improved high yielding crop varieties is an important avenue for reducing hunger and food insecurity in developing countries. Using cross-sectional data obtained from a survey conducted during 2013 crop season, we performed a probit model （plot-level analysis） to determine the probability of adopting new improved rice varieties （NIRVs） by smallholder farmers particularly from two main agro-ecological regions （hills and tropical plain terai regions） of Central Nepal. The results revealed that education, extension services and seed access play significant roles in adoption decisions. Additionally, farm and field characteristic variables such as farm size, endowment of favorable land type （e.g. lowlands）, and animal power （e.g. oxen） are the key factors influencing the probability of adopting NIRVs. The results showed that technology specific variables （e.g. yield potential and acceptability） are significant for explaining adoption behavior, implying that it is important to take farmers＇ preferences to varietal characteristics into consideration in the design of a research and development program. Given the significant role played by extension and access related variables, increased emphasis on information dissemination, field demonstration, and farmers＇ participatory research and training programs to popularize new rice varieties and enhance their adoption rate are required. This also suggests that policy intervention should be made on improving the educational status of farming households, and developing programs on varietal package of rice seed which offer farmers a variety of choices among the appropriate pools of germplasm. Such programs ultimately help farmers develop more profit-oriented behavior which are necessary to enhance adoption rate, production and food security in the long run.

Characterization of QTL for unique agronomic traits of new-plant-type rice varieties using introgression lines of IR64

To enhance the yield potential of an elite indica rice cultivar,an introgression(BC_3-derived) line of IR64,YTH288,was developed using a new-plant-type cultivar,IR66215-44-2-3,as a donor parent.YTH288 has agronomically valuable characteristics such as large panicles,few unproductive tillers,and large leaves inherited from NPT.To identify the genetic basis of these traits,we used 167 F_2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits:days to heading(DTH),culm length(CL),flag leaf length(FLL),flag leaf width(FLW),and filled spikelet number per panicle(FSN).Six putative QTL were detected:four on chromosome4(for CL,FLL,FLW,and FSN) and two on chromosome 2(for DTH and FLL).All QTL with the IR66215-44-2-3 allele,except that for FLL on chromosome 2,had positive effects on each trait.To confirm the effects of these putative QTL,we developed NILs with the IR64 genetic background by marker-assisted selection.We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes2 and 4.Additionally,four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropic To enhance the yield potential of an elite indica rice cultivar, an introgression(BC3-derived) line of IR64, YTH288, was developed using a new-plant-type cultivar,IR66215-44-2-3, as a donor parent. YTH288 has agronomically valuable characteristics such as large panicles, few unproductive tillers, and large leaves inherited from NPT.To identify the genetic basis of these traits, we used 167 F2 plants derived from a cross between IR64 and YTH288 to conduct QTL analysis for five agronomic traits: days to heading(DTH), culm length(CL), flag leaf length(FLL), flag leaf width(FLW), and filled spikelet number per panicle(FSN). Six putative QTL were detected: four on chromosome4(for CL, FLL, FLW, and FSN) and two on chromosome 2(for DTH and FLL). All QTL with the IR66215-44-2-3 allele, except that for FLL on chromosome 2, had positive effects on each trait. To confirm the effects of these putative QTL, we developed NILs with the IR64 genetic background by marker-assisted selection. We observed significant differences in several agronomic traits between IR64 and NILs that carried these QTL on chromosomes2 and 4. Additionally, four IR64-NILs carrying chromosomal segments derived from different NPT varieties on the long arm of chromosome 4 exhibited similar pleiotropiceffects for unique agronomic traits. These NILs can be used as research materials for studying each trait and as breeding materials for yield improvement of indica rice cultivars.

A Comparative Study of SSR Diversity in Chinese Major Rice Varieties Planted in 1950s and in the Recent Ten Years(1995-2004)

Forty pairs of SSR markers were used to compare the genetic diversity changes in 151 Chinese major rice varieties planted in 1950s and in the recent ten years. Of 40 SSR loci, 39 were found to be polymorphic while one locus （RM479） monomorphic. A total of 213 alleles were identified from the 39 polymorphic loci. The average number of alleles per locus （Na） was of 5.5, ranging from 2 to 11. Nei＇s gene diversity index （He） varied drastically among loci from 0.309 at RM174 to 0.869 at RM418, with an average value of 0.649. There existed significant difference in SSR allelic diversity between indica and japonica subspecies, and indica had more variation than japonica both in Na and He. By comparison with the genetic changes in Na and He, it was revealed that the varieties planted in 1950s had more alleles and higher He than those in the recent ten years both for indica and japonica rices. The difference between two subspecies for Na was significant in a tendency over time （indica： z = 2.677, P = 0.007; japonica： z = 3.441, P = 0.001）, but not significant for He （indica： z = 1.471, P = 0.141; japonica： z = 1.932, P = 0.053）. Analysis of molecular variance （AMOVA） indicated that there existed significant difference （P 〈 0.05） in genetic variation between the two periods, of which more genetic variation was contributed by indica （Fst= 0.050） and japonica （Fst= 0.082） subsets. Using locus-by-locus AMOVA procedure, significant genetic differentiations were observed in 13 loci （RM21, RM128, RM147, RM169, RM190, RM221, RM231, RM251, RM253, RM317, RM341, RM418, and RM478） for indica varieties and 11 loci （RM101, RM135, RM152, RM159, RM169, RM190, RM251, RM253, RM311, RM418, and RM478） for japonica ones between the two periods. It was found some alleles had been lost in current major rice varieties as comparing with those in 1950s. Therefore, it should be necessary to exploit more alien elite genetic resources for extension of genetic background in current rice breeding program.

Comparison of yield performance between direct-seeded and transplanted double-season rice using ultrashort-duration varieties in central China

Labor scarcity requires double-season rice to be planted by direct seeding as an alternative to transplanting. Only ultrashort-duration varieties can be used in direct-seeded, double-season rice(DSD) in central China where thermal time is limited. Whether ultrashort-duration varieties grown in DSD can be as productive and efficient in nitrogen(N) use as transplanted double-season rice(TPD) remains unclear. Field experiments were conducted in Hubei province, central China with two establishment methods(DSD,TPD) and three N rates in the early and late seasons of 2017 and 2018. Nitrogen treatments included zero-N control(N0), total N rate of 60 kg N ha;with equal splits at basal, midtillering, and panicle initiation(N1), and weekly N application at 15 kg ha;from seeding/transplanting to heading(N2). Both early-and late-season rice under DSD matured within 95 days, on average 9 days shorter than rice under TPD. The grain yield of DSD was comparable to or higher than that of TDP in both seasons, although the daily yield was significantly higher under DSD than under TDP. Before heading, DSD had higher leaf area,stem number, intercepted radiation, and radiation use efficiency than TPD, which compensated for the negative effect of short growth duration on biomass production. Total dry weight and harvest index under DSD were comparable to or higher than those under TDP. In general, the recovery efficiency of fertilizer-N under DSD was higher than that under TPD, but the reverse was true for physiological N use efficiency. Thus, there was no significant difference in agronomic N use efficiency between DSD and TPD. These results suggested that DSD with ultrashort-duration varieties is a promising alternative to TPD in central China for maintaining high grain yield and N fertilizer use efficiency with less labor input.

Changes in starch quality of mid-season indica rice varieties in the lower reaches of the Yangtze River in last 80 years

Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance to improve rice quality. This study was designed to investigate the starch characteristics in the kernels and associated physiological traits of indica rice varieties in the lower reaches of the Yangtze River in China in last 80 years. Eight representative mid-season indica rice varieties were grown in the field. The results showed that the grain yield was significantly increased with the improvement of varieties and such an increase was mainly attributed to the increase in total number of spikelets. The tall varieties applied in the 1940s–1950s had higher protein content, relative crystallinity and infrared (IR) ratio of 1 045/1 022 cm^–1. The semi-dwarf varieties applied in the 1980s–1990s had higher gel consistency, amylopectin content, IR ratio of 1 022/995 cm^–1, and breakdown value. With the improvement of varieties, the amylose content, large-sized starch granule number and volume distribution, onset and peak of gelatinization temperature, gelatinization and retrogradation enthalpy, setback value, pasting temperature, viscosity of peak, hot and final, and 1-aminocycopropane-1-carboxylic acid (ACC) concentrations in panicles and root bleeding were gradually decreased, whereas the medium-sized starch granule number and volume distribution, activities of key enzymes in grains, and zeatin (Z)+zeatin riboside (ZR) contents in panicles and root bleeding at grain filling stage were gradually increased. Correlation analysis showed that starch thermodynamic characteristics were closely related to starch structure and components, key enzymes and hormones. The results suggest that starch quality was enhanced through the optimization of starch components, structure, thermodynamics, and the regulation of key enzymes in grains and hormones in panicles and root bleedings at grain filling stage during the improvement of mid-season indica rice.

Construction and Testing of a Primary Microsatellite Database of Major Rice Varieties in China

Sixty-three major inbred varieties and parental lines of major F1 hybrids used in the commercial rice production in China were assayed with rice microsatellites screened in a previous study and additional microsatellites on four chromosomes. A set of 24 markers was selected and proposed for its application in the variety identification of rice, which are distributed on all the 12 rice chromosomes with 2 markers on each chromosome. The 63 major varieties and parental lines, as well as 41 major F1 hybrids, were genotyped with the markers. Alleles detected in each line at each marker locus were verified. By matching marker genotypes of corresponding F1, maternal and paternal lines of hybrid rice, high reliability of the maternal lines was verified, data on the paternal lines were modified, and a false hybrid was removed. A database containing genotype data of 103 major rice vadeties and parental lines at the 24 marker loci was constructed and analyzed.

Response of Rice Varieties to Water Stress in Sokoto, Sudan Savannah, Nigeria

Pot experiment was conducted at the Botanical Garden of the Department of Biological Science, Usmanu Danfodiyo University, Sokoto Nigeria, during the 2013 dry season. The main objective of this research was to determine the effect of water stress and variety on productivity of rice (Oryza sativa) at Sokoto. The treatment consisted of water stress at three growth stages (Tillering, flowering, Grain filling) and unstress (control) and three rice varieties (FARO 44, NERICA 2 and FARO 15) laid out in a Completely Randomised Design (CRD) replicated three times. The result indicated that water stress significantly (P < 0.05) resulted to decreased in plant height, number of leaves per plant, total biomass, harvest index and grain yield. The results indicated significant (P < 0.05) differences among genotypes. Faro 44 differed significant from in plant height, number of leaves per plant, total biomass, harvest index and grain yield. FARO 44 differed significantly from NERICA 2 and FARO 15 at all the parameters under study. Water is very vital as far as rice production is concern should be applied at every stage of rice production. FARO 44 is recommended for the area for higher yield.

LociScan,a tool for screening genetic marker combinations for plant variety discrimination

To reduce the cost and increase the efficiency of plant genetic marker fingerprinting for variety discrimination,it is desirable to identify the optimal marker combinations.We describe a marker combination screening model based on the genetic algorithm(GA)and implemented in a software tool,Loci Scan.Ratio-based variety discrimination power provided the largest optimization space among multiple fitness functions.Among GA parameters,an increase in population size and generation number enlarged optimization depth but also calculation workload.Exhaustive algorithm afforded the same optimization depth as GA but vastly increased calculation time.In comparison with two other software tools,Loci Scan accommodated missing data,reduced calculation time,and offered more fitness functions.In large datasets,the sample size of training data exerted the strongest influence on calculation time,whereas the marker size of training data showed no effect,and target marker number had limited effect on analysis speed.

Relationship Between the First Base of the Donor Splice Site of Waxy Gene Intron 1 and Amylose Content in Yunnan Indigenous Rice Varieties

There exists a single nucleotide polymorphism, G or T, at the first base of the donor splice site of waxy gene intron 1 in rice. In order to study the relationship between the first base of the donor splice site of waxy gene intron 1 and amylose content in rice, the one-step PCR method was used to determine whether it is G or T in 220 Yunnan indigenous rice varieties from 14 districts, 55 towns/counties of Yunnan Province, and 101 varieties of which were validated by the PCR-Acc I method. According to the G/T polymorphism, 164 rice varieties showed GG-genotype, while the other 56 fell into TT- genotype, accounting for 74.5% and 25.5% of all the test varieties, respectively. When all the rice varieties were divided into indica and japonica subspecies, it was found that 80.5% of indica rice and 67.0% of japonica rice belonged to GG-genotype. The rice varieties with GG-genotype had significantly higher amylose content （18.95% on average） than those with TT- genotype （all below 16%）, but 33 rice varieties with GG-genotype still had low amylose content ranging from 3.91% to 15.93%, and most of them came from the Dai minority area in the Southwest of Yunnan Province. However, there was no significant difference in the mean amylose content of the same GG or TT genotypes between indica and japonica rice, suggesting that different genetic backgrounds, indica or japonica, had no effect on amylose content. The coefficient of correlation between the genotype and amylose content was 0.733 （P〈0.01）.

A New Combination and Two Varieties of Polystigmate Gomphonema (Gomphonemaceae Bacillariophyta) from Heilongjiang Province, China

The authors discribed a new polystigmate combination, Gomphonema turris Ehr. var. okamurae (Skv.) Fan et Bao.comb.nov., and two new varieties, Gomphonema turris Ehr. var. latum Fan et Wang. var. nov. and Gomphonema acuminatum var. obtusum Fan et Bao, var. nov., that were distinguished by frustule morphology under LM. The samples were collected from freshwater of Heilongjiang Province, China.