Archive

28 January 2015, Volume 22 Issue 1 Previous Issue    Next Issue
---
Orginal Article


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Orginal Article

Select

Genetic Diversity of Main Inbred Indica Rice Varieties Applied in Guangdong Province as Revealed by Molecular Marker Ming Huang, Ya-hui Wu, Xing-xing Tao, Yong-zhu Liu, Gui-li Yang, Zhi-qiang Chen 2015, 22(1): 1-8.  DOI: 10.1016/S1672-6308(14)60275-4 Abstract ( )   HTML ( )   PDF (67384KB) ( )   Genetic diversity of 299 inbred indica rice varieties, including 33 introduced varieties, applied in Guangdong Province of China were assessed using 20 ILP (intron length polymorphism) and 34 SSR (simple sequence repeat) markers. Totally, 154 loci were screened for the 299 varieties, with the average number of alleles (Na), rare alleles (Nr), and polymorphism information content (PIC) scored at 3.4, 0.7 and 0.32, respectively. The Nei’s genetic distance (GD) was estimated ranging from 0 to 0.7529 with an average of 0.4797. There was no significant difference of Na, Nr, PIC or GDs between the introduced and local varieties. Neighbor-joining (NJ) analysis showed that the 299 varieties failed into three main distinct groups, and the 33 introduced varieties were distributed over all the groups or subgroups. Model-based cluster analysis demonstrated that only 73 (24.4%) of the 299 varieties and 7 (21.2%) of the 33 introduced varieties could be distinctly classified into the three groups. Analysis of molecular variance showed that within the groups divided by NJ analysis, the genetic variations revealed by ILP, SSR and these two combined were 7.7%, 5.6% and 6.6%, and within the groups divided by region (Guangdong local and the introduced varieties), the genetic variables were 2.1%, 4.6%, 5.4%, respectively. These results suggested that the genetic diversity of the 299 inbred rice varieties in Guangdong Province was low, simultaneously relationship among varieties was poor and close in all kind of groups. Hence, it is very necessary to extend the genetic diversity during the breeding and selection practical procedure.

Select

Mapping of qTGW1.1, a Quantitative Trait Locus for 1000-Grain Weight in Rice (Oryza sativa L.) Hong-wei Zhang, Yu-yu Chen, Jun-yu Chen, Yu-jun Zhu, De-run Huang, Ye-yang Fan, Jie-yun Zhuang 2015, 22(1): 9-15.  DOI: 10.1016/S1672-6308(14)60279-1 Abstract ( )   HTML ( )   PDF (3860KB) ( )   1000-grain weight (TGW) is one of the three component traits of the grain yield in rice (Oryza sativa L). This study was conducted to validate and fine-map qTGW1.1, a minor QTL for TGW which was previously located in a 3.7-Mb region on the long arm of rice chromosome 1. Five sets of near isogenic lines (NILs) were developed from two BC2F4 populations of the indica rice cross Zhenshan 973/Milyang 46. The NIL sets consisted of two homozygous genotypic groups differing in the regions RM11448-RM11522, RM11448-RM11549, RM1232-RM11615, RM11543-RM11554 and RM11569-RM11621, respectively. Four traits, including TGW, grain length, grain width and heading date, were measured. Phenotypic difference between the two genotypic groups in each NIL population was analyzed using SAS procedure GLM. Significant QTL effects were detected on TGW with the Zhenshan 97 allele increasing grain weight by 0.12 g to 0.14 g and explaining 8.30% to 15.19% of the phenotypic variance. Significant effects were also observed for grain length and width, whereas no significant effect was found for heading date. Based on comparison among the five NILs on the segregating regions and the results of QTL analysis, qTGW1.1 was delimited to a 376.9-kb region flanked by DNA markers Wn28382 and RM11554. Our results indicate that the effects of minor QTLs could be steadily detected in a highly isogenic background and suggest that such QTLs could be utilized in the breeding of high-yielding rice varieties.

Select

Development of New Submergence Tolerant Rice Variety for Bangladesh Using Marker-Assisted Backcrossing Md Iftekharuddaula Khandakar, Uddin Ahmed Helal, Ghosal Sharmistha, Rahman Moni Zakiah, Amin Al, Shamsher Ali Md 2015, 22(1): 16-26.  DOI: 10.1016/S1672-6308(14)60277-8 Abstract ( )   HTML ( )   PDF (2398KB) ( )   Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC2F2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines (BRLs) was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under controlled submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.

Select

Elevation and Land Use Types Have Significant Impacts on Spatial Variability of Soil Organic Matter Content in Hani Terraced Field of Yuanyang County, China Feng-bo Li, Guang-de Lu, Xi-yue Zhou, Hui-xiang Ni, Chun-chun Xu, Chao Yue, Xiu-mei Yang, Jin-fei Feng, Fu-ping Fang 2015, 22(1): 27-34.  DOI: 10.1016/S1672-6308(14)60282-1 Abstract ( )   HTML ( )   PDF (950KB) ( )   Soil organic matter (SOM) content is one of the most important indicators of the sustainability of soil. To maintain sustainable soil utilization and management in fragile Hani terraced field, it is meaningful to investigate the effects of topography and land use type on SOM content. Descriptive statistics and geostatistics were used to analyze the data and the kriging method was applied to map the spatial patterns of SOM content. The results showed that the mean SOM content was 32.76 g/kg, with a variation coefficient of 40%. The SOM content was affected by elevation and land use type. As the increase of elevation, the SOM content in Hani terraced field also increased obviously. The SOM content in tea garden, which is almost at high elevation, was the highest in all six land use types, and the SOM content decreased in a following sequence: tea garden > paddy field > corn field > banana garden > cassava field > sugarcane field. In addition, at the same elevation, the paddy field had the highest SOM content compared with other land use types. All these results demonstrate that paddy field is the most efficient and suitable land use type for SOM conservation at high, middle or low elevations in the fragile Hani terraced field. In order to protect soil quality and maintain the sustainable agricultural development, it is necessary to maintain or even to enlarge the area of paddy field in Yuanyang county, Yunnan Province, China.

Select

Factors Affecting Adoption of Improved Rice Varieties among Rural Farm Households in Central Nepal Ghimire Raju, Wen-chi Huang, Shrestha RudraBahadur 2015, 22(1): 35-43.  DOI: 10.1016/S1672-6308(14)60278-X Abstract ( )   HTML ( )   PDF (752KB) ( )   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.

Select

RL3(t), Responsible for Leaf Shape Formation, Delimited to a 46-kb DNA Fragment in Rice Min Guo, Rong-de Li, Jian Yao, Juan Zhu, Xiang-yun Fan, Wei Wang, Shu-zhu Tang, Ming-hong Gu, Chang-jie Yan 2015, 22(1): 44-48.  DOI: 10.1016/S1672-6308(14)60276-6 Abstract ( )   HTML ( )   PDF (3280KB) ( )   Two mutants with rolled leaves, temporally designated as rl3(t)-1 and rl3(t)-2, were served for exploring the mechanism underlying the rolled leaf characteristic. Except for having typical rolled leaves, the plant heights and panicle lengths of rl3(t)-1 and rl3(t)-2 significantly decreased, and the seed-setting rate also decreased when compared with wild type 93-11. Cytological analysis suggested that the rolled leaf phenotype might be caused by the changes of number and size of bulliform cells. Genetic analysis indicated rl3(t)-1 is allelic to rl3(t)-2, and controlled by a recessive gene. Gene mapping result indicated that RL3(t) gene resided in a 46-kb long region governed by the sequence tag site markers S3-39 and S3-36 on rice chromosome 3. The result provides an important clue for further cloning the RL3(t) and understanding the mechanism of rice leaf development.

Select

New Temperature Sensitive Genic Male Sterile Lines with Better Outcrossing Ability for Production of Two-Line Hybrid Rice J. Arasakesary S., Manonmani S., Pushpam R., Robin S. 2015, 22(1): 49-52.  DOI: 10.1016/S1672-6308(14)60273-0 Abstract ( )   HTML ( )   PDF (720KB) ( )   An investigation was carried out with three newly developed temperature sensitive genic male sterile (TGMS) lines for their floral traits, seed production potential and outcrossing ability in ten cross combinations. In the TGMS lines, fertile pollens had an average diameter of 0.89 mm while the sterile pollens was with 0.02 mm diameter.TS-29-150GY produced the biggest fertile pollens with 0.92 mm and other two lines produced relatively smaller pollens with 0.91 and 0.85 mm. Pollen fertility during the fertility reversion period was an average of 60.7%. TS-29-150GY had the maximum of 66.9% spikelet fertility whereas other two lines (TNAU18S and TNAU60S) had relatively lower spikelet fertility of 27.8% and 26.7%, respectively. Average of 17.00 g of seed yield was obtained in the TGMS lines during the fertility reversion period. TS-29-150GY had the highest value of 21.20 g of seed yield while TNAU18S and TNAU60S produced 16.6 g and 13.2 g of seed yield, respectively. The low seed production ability of these three TGMS lines was attributed only to the environmental conditions prevailing during the period. All three TGMS lines had considerable outcrossing potential of 41.2%, 24.6% and 25.0%, respectively. The cross combinations viz. TNAU18S/IET21508 (36 g/plant), TNAU18S/IET21044 (13 g/plant), TNAU18S/IET21009 (26.5 g/plant), TNAU60S/CB-09-106 (26.2 g/plant), TNAU60S/IET21009 (14 g/plant) and TS29-150-GY/DRR 3306 (39.2 g/plant) showed perfect synchronization with acceptable hybrid seed yield, indicating suitability of TGMS system under Indian condition. Based on the outcrossing related traits viz. panicle exertion, angle of glume opening, stigma length and pollen size, TNAU18S was identified as the best, followed by TS-29-150GY.