جستجوی مقالات مرتبط با کلیدواژه "gelatinization temperature" در نشریات گروه "زراعت"

The occurrence of water shortage and drought stress during plant growth, is caused yield loss as well as the grain quality of rice genotypes. Hence, this experiment was conducted to determine eefects of different irrigation methods on rice grain yield and several important grain quality traits such as amylose percentage, degree of milling and gelatinization temperature in Rice Research Institute of Iran (Mazandaran Branch, Amol) in 2017. Experiment carried out as split plots using randomized complete blocks design with main factor of irrigation methods in three levels of flooding irrigation, alternate wetting and drying method up to 10 (AWD10) and 20 (AWD20) cm below the soil surface and sub-factor with ten rice genotypes. The results showed that different irrigation treatments were statistically significant on garin lenghg before cooking, crash grain, amylose content and gelatinization temperature. Among the genotypes, Neda with average of 6901.7 kg.ha-1 had the highest grain yield, harvest index 44.2%, milling efficiency, degree of milling 72.3% and healthy garin 65.3%. The highest degree of milling (90%), grain length after cooking (13.2 mm), elongation ratio (2 mm) and Gelatinization temperature (5.6) belong to Vandana, IR74428-153-2-3, Firozan and IR70416-53-2-2 genotypes, respectively. In general, considering to the important quantities and qualities traits of genotypes in irrigation regime treatments were not different from flooding method, therefore, the studied genotypes are recommended for planting in areas with lack of irrigation water. It should be noted that Neda genotype is introduced as a superior genotype due to increase of sevral important quantities and qualities traits compared to other genotypes.

Rice provides food for more than half of the world's population. Unlike other cereals used in the form of processed, rice is mostly consumed directly with removal of paddy and brown husks. Therefore, considering rice grain quality is one of the main factors in product marketability and consumption. Rice grain quality can be considerd and evaluated by assessment of four properties: physical, chemical, sensory and nutritional value. Physical properties such as grain shape, chalky grains, transparency and uniformity of grains. Grain size, chalkiness and color are important features that affect consumer choice. Grain cooking properties (chemical factors) mainly include apparent amylose content, gelatinization temperature, and gel consistency. Also, the viscosity properties of starch grains are considered as an important secondary difference in cultivars with similar amylose content. Sensory characteristics include aroma, grain hardness after cooking, color and taste which are important and favorite characteristics for rice consumers in the world. Major nutrients in rice include; starch, protein, fats, and non-starch polysaccharides. The key period for the formation of grain quality characteristics of rice is early and mid-grain filling stages. In addition to genetic factors, the cooking quality of rice is strongly influenced by environmental conditions, as the rice garin quality may vary from year to year or even from field to field. Rice grain quality prediction requires the association of genetic information with grain quality phenotypes in different environments. Despite the negative relationship between quality properties and grain yield in rice, targeted cross-breeding to transfer the quality related traits of local rice cultivars to improved commercial cultivars with reasonable levels of tolerance to environmental stresses as well as optimum crop management practices, are among the promising strategies for improving the rice grain quality.

This experiment was carried out to determine the morphological and qualitative traits and yield adaptability of 8 genotypes with hill spacing of 25cm×25cm with experimental design randomized complete block with 4 replications in two locations of Mazandaran province (Amol and Tonekabon) during 2004-2006. The eighteen traits were measured based on standard evaluation system for rice. The simple and combined analysis of variance were done for grain yield and the effect of year, location and genotype, genotype × year, genotype × location, year × location and the three way interaction of year × location × genotypes were calculated. Simple and combined analysis of variances showed that there were significant different between genotypes. Results showed genotypes 7 and 4 were the most stable, respectively on using Lin and Binns method, because of having less variance within location and less coefficient of variance. Development and release of high quality rice cultivars is one of the major objectives in rice breeding programs in Iran. Amylose content (AC), gelatinization temperature (GT) and gel consistency (GC) are very important characteristics determining end-use and cooking quality in rice. Results also indicated that (25-30%), (6-7 class) and (40-70 mm) for AC, GT, and GC, respectively. Consequently, appropriate breeding schemes based on hybridization and selection for these traits may bring about an improvement of cooking quality in rice.

Rice cooking and eating quality are the most important factors for accepting a variety by consumers. To determine the accurate gelatinization properties of rice starch with Little and Differential Scanning Calorimeter (DSC) methods, this research was carried out on 10Iranian rice varieties. All varieties were similar in amylose content and gelatinization score with Little method. The starch properties such as gelatinization enthalpy (ΔH), onest temperature (T0), peak temperature (Tp), conclusion temperature (Tc) were measured by using of the curve derived from DSC. Analysis of variance showed significant differences between studied varieties for gelatinization parameters obtained from DSC method, but there weren’t the significant differences between varieties for gelatinization scores derived from Little’s method. The maximum and minimum enthalpy (ΔH) was observed in Domsorkh (11.48 j/g) and Hasssansaraee varieties (6.44 j/g), respectively, but Domsorkh and Hassansaraee varieties had similar scores for alkali spreading values from the Little’s method. In varieties with the same amylose content, lipid-amylose complex increase crystalline structure of starch so enthalpy for gelatinization will be increased. Data analysis showed that there was significant correlation between lipid content and enthalpy at 5% probability level. In mean comparisons between varieties, the minimum and maximum onest temperature (T0) were observed in Domsefid (64.82 oC) and Domsiah (67.7 oC) varieties, respectively. Also, there was the significant correlation between onest temperature and lipid content. Results from current research showed that the Little’s method is a rapid and economical method for selecting lines and varieties with suitable gelatinization properties (3-5 score), but DSC method can explain more details of cooking differences between varieties where Little’s method is unable to explain them.

In order to map the QTLs for cooking quality in rice، two populations of BC2F5 lines، derived from indica rice varieties IR64 and Teqing (TQ) as recurrent parents and an Iranian rice variety، Tarom molaeii (TM) as donor، studied in International Rice Research Institute. Traits amylose content (AMY)، gelatinization temperature (GT)، and gel consistency (GC) were used to evaluate cooking quality. Two-hundred thirty five SSR markers on all 12 rice linkage groups were tested on parents to identify polymorphic markers potentially linked to QTLs controlling studied traits. One-hundred fourteen markers showed polymorphism and assigned for genotyping of the populations. The map length in IR64/TM and TQ/TM populations were 1692. 6 cM and 1743. 3 cM، respectively with an average interval size of 16. 3 cM and 15. 3 cM.، respectively. Transgressive segregation observed for all traits in population IR64/TM while in population TQ/TM، it was onley observed for AMY. Seventeen QTLs were identified in the population IR64/TM، including one for AMY، 3 for GC، and 13 for GT. QTLs identified in the population Teqing/TM were twenty six as one for AMY، 15 for GC، and 10 for GT. However، of the 43 QTLs detected in both backgrounds، only one (2%) were common and mapped to the same genomic regions in both genetic backgrounds. Our results indicated that expression of QTLs involved in cooking quality are affected by different genetic backgrounds and should be specially considered in marker-aided breeding programms of cooking quality in rice.

Genetic components controlling some of cooking quality related traits in rice (Oryza sativa L.) were studied using a 7×7 complete diallel cross design in Rresearch Field Station, Rice Research Institute of Iran (RRII) in 2006 and 2007 growing seasons. Analysis of variance showed significant differences among genotypes for traits of inetest including; amylose content (AC), gel consistency (GC), gelatinization temperature (GT) and grain elongation (GE). Based on Hayman’s diallel method, both additive (D) and dominance components (H1 and H2) were significant for AC and GC. However, for the other traits, only additive variance was significant. The average degree of dominance showed partial dominance effects of genes in controlling all the studied traits. The H2/4H1 ratio indicated nearly symmetrical distribution of the genes for AC and GE. Results also indicated that increase in AC and GT and decrease in GC were controlled by genes with dominance effects while decrease of GEL was governed by recessive genes. The broad sense heritability estimates were high (0.97% and 90% and 83%, for AC, GT and GC, respectively) to moderate (0.66 for GE). The magnitude of additive gene effects and heritabilities for traits of interest demonstrated high response to selection, particularly for AC and GT. Consequently, appropriate breeding schemes based on hybridization and selection for these traits may bring about an improvement of cooking quality in rice. Some crosses such as Sepidrood × IRFAON-215, Neda × IRFAON-215 and Saleh × IRFAON-215 can be employed for improving AC, GT and GC traits, respectively.