Genetic analysis of blast resistance On rice cultivars with wide—spectrum resistance

In recent years,indirect selection based ontightly linked genetic markers has been sug-gested to pyramid the resistance genes.How-ever,resistance parents used in the linkagestudies were usually near isogenic lines possessing a single resistance gene derived fromthe original resistance donor.Little was knownon the interaction among the genes at differentloci.In the present study,the genetic controlof blast resistance in two wide—spectrum re-vistance rice cultivars was analyzed.A susceptible indica varieties Xianfenglwas used as the female parent,and the blastresistance cultivars Tetep and Hongjiaozhanwere used as the male parents.The threeparental lines were inoculated with each of 20races of Pyricularia oryzae Cav at tilleringstage.The race ZC_(13) was selected to inoculatethe 161 F_3 lines of Xianfeng1/Tetep and 175 F,lines of Xianfengl/Hongjiaozhan.Eighteen in-dividuals of each line were inoculated.In both populations,all the individualsdemonstrated extreme reaction to the blast dis-ease.In the F_3 po     

Genetic effects analysis for grain traits of indica rice

Genetic effects analysis of grain traits was conducted based on the additive-dominance genetic model (Zhu, 1992, 1993) for the quantitative traits. Incomplete diallel crosses from early season indica rice (Oryza sativa L. ) were made using eight parents with short grain shape (Guanglu'ai 4 et al. ) as females and five parents with long grain shape (Xiangzaoxian 3 et al. ) as males. F_1 seedlings and their parents were transplanted into the field at 15×15cm spacing, with three replications. Seeds from 10 plants in the middle of plot were used to measure the agronomic traits, including grain length, grain width, grain thickness, ratio of grain length to     

Identification of a major QTL for Hessian fly resistance in wheat cultivar ‘Chokwang’

The Hessian fly(HF, Mayetiola destructor) is one of the destructive pests of wheat(Triticum aestivum L.)worldwide. Resistant cultivars can effectively minimize wheat damage due to this insect pest. To identify new quantitative trait loci(QTL) for HF resistance, a population of recombinant inbred lines(RILs) was developed from a cross between the HF-resistant wheat cultivar ‘Chokwang’ and susceptible wheat‘Ning 7840’, and phenotyped for responses to HF attack. A linkage map was constructed using ...     

Genetic diversity of rice sheath blight isolates (Rhizoctonia solani AG-1 IA) from different rice cultivars

Rhizoctonia solani AG-1 IA, the non-specific, soil-borne, and plant casual a-gent of rice sheath blight, occurring world-widely in rice fields, has become a major disease to rice. In this study, relationships among R. solani AG-1 IA isolates, collected from different rice cultivars were reported.In 1999, the genetic diversity of 40 isolates of rice sheath blight collected from six rice varieties were analyzed by using random amplified polymorphic     

Improving the phenotypic expression of rice genotypes:Rethinking “intensification” for production systems and selection practices for rice breeding

Intensification in rice crop production is generally understood as requiring increased use of material inputs: water, inorganic fertilizers, and agrochemicals. However, this is not the only kind of intensification available. More productive crop phenotypes, with traits such as more resistance to biotic and abiotic stresses and shorter crop cycles, are possible through modifications in the management of rice plants, soil, water, and nutrients, reducing rather than increasing material inputs. Greater factor productivity can be achieved through the application of new knowledge and more skill, and(initially) more labor, as seen from the System of Rice Intensification(SRI), whose practices are used in various combinations by as many as 10 million farmers on about 4 million hectares in over 50 countries. The highest yields achieved with these management methods have come from hybrids and improved rice varieties, confirming the importance of making genetic improvements. However,unimproved varieties are also responsive to these changes, which induce better growth and functioning of rice root systems and more abundance, diversity, and activity of beneficial soil organisms. Some of these organisms as symbiotic endophytes can affect and enhance the expression of rice plants' genetic potential as well as their phenotypic resilience to multiple stresses, including those of climate change. SRI experience and data suggest that decades of plant breeding have been selecting for the best crop genetic endowments under suboptimal growing conditions, with crowding of plants that impedes their photosynthesis and growth, flooding of rice paddies that causes roots to degenerate and forgoes benefits derived from aerobic soil organisms, and overuse of agrochemicals that adversely affect these organisms as well as soil and human health. This review paper reports evidence from research in India and Indonesia that changes in crop and water management can improve the expression of rice plants' genetic potential, thereby creating more productive and robustphenotypes from given rice genotypes. Data indicate that increased plant density does not necessarily enhance crop yield potential, as classical breeding methods suggest. Developing cultivars that can achieve their higher productivity under a wide range of plant densities—breeding for density-neutral cultivars using alternative selection strategies—will enable more effective exploitation of available crop growth resources. Density-neutral cultivars that achieve high productivity under ample environmental growth resources can also achieve optimal productivity under limited resources, where lower densities can avert crop failure due to overcrowding. This will become more important to the extent that climatic and other factors become more adverse to crop production. Focusing more on which management practices can evoke the most productive and robust phenotypes from given genotypes is important for rice breeding and improvement programs since it is phenotypes that feed our human populations.     

Effect of phytate on the amylosynthetase activity and rice grain quality

Phytate of three concentrations was sprayed on the leaves of an indica rice Yuanfengzao in heading stage, full heading stage, filling stage and wax ripeness stage respectively. The effects of phytate on the enzyme activity in endosperm and rice grain quality were determinated. Plants sprayed with distilled water were used as control. It was showed that spraying solutions in full heading stage had the most manifest effect. The activity of amylosynthetase between the 100mg/kg and 150mg/kg phytate treatment was identical, which was 7.4% higher than that of 50mg/kg treatment. On the other hand, amylase activity on the 50mg/kg treatment was 12.5% and 8.7% lower than those     

Verification test on an innovated method for the studies on inheritance of resistance to rice sheath blight

Ｗｅｈａｖｅｒｅｃｅｎｔｌｙｄｅｖｅｌｏｐｅｄａｓｙｓｔｅｍａｔｉｃｍｅｔｈｏｄｆｏｒｔｈｅｓｔｕｄｙｏｎｔｈｅｉｎｈｅｒｉｔａｎｃｅｏｆｒｅｓｉｓｔａｎｃｅｔｏｓｈｅａｔｈｂｌｉｇｈｔ．Ｔｈｅｋｅｙｏｆｔｈｅｓｙｓｔｅｍｉｓａｎｉｎｎｏｖａｔｅｄｍｅｔｈｏｄｏｆｉｎｏｃｕｌａｔｉｏｎａｎｄｉｎｖｅｓｔｉｇａｔｉｏｎａｌｏｎｇ ｗｉｔｈｔｈｅｅｍｐｌｏｙｍｅｎｔｏｆｔｈｅｐｅｒｍａｎｅｎｔｐｏｐｕｌａｔｉｏｎ．Ｔｈｉｓｐａｐｅｒｒｅｐｏｒｔｅｄｔｈｅｐｒｏｃｅｄｕｒｅｏｆｔｈｅｓｙｓ ｔｅｍａｎｄ…     

Verification and evaluation of the ＂Three Optimums Theory＂ in rice breeding for maximum yield

Rice breeding for maximum yield is a hot topic today in the rice community of the world, and a hard out to crack into the bargain. For many years, we have been devoted to the subject. In 1987 we discussed the subject in publications at home and abroad,     

Verification and evaluation of the “Three Optimums Theory”in rice breeding for maximum yield

Rice breeding for maximum yield is a hot topic today in the rice community of the world, and a hard nut to crack into the bargain. For many years, we have been devoted to the subject. In 1987 we discussed the subject in publications at home and abroad, in which we first introduced the general strategy of combining ideal plant morphology with the use of vigor. Afterward, drawing on the wisdoms of other researchers, we experimented with test materials featuring "rather short stalks" and "rather big panicles", but the results were not very satisfactory. Then, we switched from the "two rathers" to the "three optimums" (plant height, panicle size, and tillering ability). Three years' (1991-1993) verification, especially the demonstra     

Preliminary studies on radiant spectrum of the leaves of the paddy and upland rice

To study the property of the radiant spectrum(RS),i.e.absorption,reflectance and trans-mission ratio.Four upland rice varieties i.e.Haogelao,Hongkuo—laoshuya,Chengjiang—ludao,and IRAT—109,and four paddy ricevarieties Xifeng,Akihikari,Zhongbai 4,andYuefu were sown at Beijing on dry land in themiddle May,1992 and 1993.The plants weretreated with drought stress during seedling,booting,heading and flowering stages.It wasrainy season or intermittent irrigation duringother period.The RS and the chlorophyll con-tent of the third leave of seedlings and that offlag leave at heading—flowering period weremeasured with UV—190 model spectrometer.The results are shown in Fig 1 and Fig 2.There were little difference of RS in 800-200 mn and chlorophyll content between theleaves of paddy and upland rice during seedlingstage (Fig 1).However,remarkable differ-     

Preliminary studies on microbiological mechanism of the dynamics of CH4 and N2O emission from rice field

Greenhouse gases, CH4 and N2O emitted from rice field, are the products of microbial metabolism. So the characteristics of CH4 and N2O production and emission in rice field can be understood through microbiological study. In this paper, the relationships between the dynamics of CH4 and N2O emission from rice field in northern China and the related soil bacteria groups were discussed.     

Relationship between the eating quality and the physico-chemical properties of high grain quality rice in China

Relationship between eating quality (EQ) andphysico-chemical properties of 78 high grainquality rice varieties, 45 indica and 33 japoni-ca, were studied in 1995. The samples werecollected from different rice growing regions in20 provinces. The physico-chemical proper-ties, including grain length (GL), length towidth ratio (L/W), chalky grain rate (CG),chalkiness (CH), translucency (TR), gela-tinization temperature (GT, measured by alka-li spreading value), gel consistency (GC),amylase content (AC), and protein content(PC) were measured according to the standard     

Insecticide-induced changes in the levels of resistance of rice cultivars to the whitebacked planthopper Sogatella furcifera (Horváth) (Homoptera: Delphacidae)

IR2035-117-3 (highly resistant), ARC 10239 (resistant), and TN1 (susceptible) rice plants received one application at 40 days after transplanting (DT) or three spray applications (20, 30, and 40DT) of monocrotophos, diazinon or deltamethrin. When these plants were exposed to S. furcifera adults, either 24 hours after the single application, or 15 days after the third of the spray applications, the deltamethrin-treated were most preferred. The percentage of S. furcifera that alighted on the three varieties decreased correspondingly with an increase in the level of varietal resistance. Differences in S. furcifera population growth, nymphal survival, nymphal duration, growth index and feeding rate between IR2035-117-3 and TN1 were significant. Foliar application of deltamethrin caused a significant increase in population growth on IR2035-117-3, ARC 10239, and TN1 and an increase in the nymphal survival and growth index on TN1.     

Influence of grain quality,heat, and processing time on the reduction of aflatoxin B1 levels in ‘tuwo’ and ‘ogi’: Two cereal-based products

During the production of tuwo from laboratory-contaminated corn (AFB₁:150 mcg/kg) and sorghum (AFB₁:87.5 mcg/kg) grains, reductions in the aflatoxin-B₁ levels of pastes boiled for 30 min and 60 min were found to be 68.0% and 80.8%, respectively. In the preparation of ogi from contaminated corn and sorghum grains, reductions of about 72.5% and 71.4%, respectively, were obtained after fermentation at ambient conditions. Reconstitution of ogi paste into a porridge (akamu) considerably reduced the AFB level.     

Studies on the relationship between the changes of the endogenous scavengers of active oxygen and resistance in hybrid rice under temperature stress

The seedlings of indica hybrid rice Weiyou 49 and Weiyou 28 were exposed to 1℃ and 40℃ .and the changes of activity (content) of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbic acid (ASA), glutathione (GSH),malondialdehyde (MDA) and leakage of electrolytes (%) were measured.     

RFLP tagging of a gene for giant embryo and the integration of chromosome 7 of rice

Lipid content of rice grain was lower than that of corn and other oil crops, but it was rich in the content of unsaturated lopacid. As all the lipid was stored in embryo, one of the promising way to raise its content is to increase the embryo size. Genetic etidies on giant embryo was therefore of great importance. In this experiment, Kinmaze, a japonica giant embryo mutant derived from Japan, and an indica variety Nanjing 11 were used as parents to construct a F_2 population of 58 plants. In combination with eight restriction enzymes (EcoR Ⅰ, EcoR Ⅴ, Dra Ⅰ, Xba Ⅰ, Hind Ⅲ, BamH Ⅰ, Bgl Ⅱ, andSca Ⅰ), 262 DNA clones were used to detect the RFLP's of the parents, of which 73.2% detected polymorphism between the two parents. Seventy-four polymorphism clones were used to analyze the RFLP's of 58 F_2 individuals. Linkage analysis was then performed with the computer package MAPMAKER (Lander et al, 1987). Twelve linkage groups were constructed, among which RFLP markers RG678 and RE395 on chromo     

Ultrasound-Assisted Extraction for the Recovery of Carotenoids from Guava’s Pulp and Waste Powders

Plant Foods for Human Nutrition - In this work, lycopene- and β-carotene-rich extracts were obtained from guava’s pulp and waste powders using maceration (ME), ultrasonic bath (BUAE,...