Genotypic and Phenotypic Relationship among Yield Components in Rice under Tropical Conditions

Abstract

The associations among yield-related traits and the pattern of influence on rice grain yield were investigated. This evaluation is important to determine the direct and indirect effects of various traits on yield to determine selection criteria for higher grain yield. Fifteen rice genotypes were evaluated under tropical condition at five locations in two planting seasons. The experiment was laid out in a randomized complete block design with three replications across the locations. Data were collected on vegetative and yield components traits. The pooled data based on the analysis of variance revealed that there were significant differences (p < 0.001) among the fifteen genotypes for all the characters studied except for panicle length and 100-grain weight. Highly significant and positive correlations at phenotypic level were observed in grain weight per hill (0.796), filled grains per panicle (0.702), panicles per hill (0.632), and tillers per hill (0.712) with yield per hectare, while moderate positive correlations were observed in flag leaf length to width ratio (0.348), days to flowering (0.412), and days to maturity (0.544). By contrast, unfilled grains per panicle (-0.225) and plant height (-0.342) had a negative significant association with yield per hectare. Filled grains per panicle (0.491) exhibited the maximum positive direct effect on yield followed by grain weight per hill (0.449), while unfilled grain per panicle (-0.144) had a negative direct effect. The maximum indirect effect on yield per hectare was recorded by the tillers per hill through the panicles per hill. Therefore, tillers per hill, filled grains per panicle, and grain weight per hill could be used as selection criteria for improving grain yield in rice.

Marker-assisted introgression of multiple resistance genes confers broad spectrum resistance against bacterial leaf blight and blast diseases in Putra-1 rice variety

“…The genotypic data obtained from the DNA scoring were subjected to Chi-square analysis using the formular: 2 E Where: O and E are the observed and expected values. The χ 2 calculated was compared with the χ 2 tabulated at P=0.05 in order to determine whether the markers showed significant differences from the Mendelian segregation ratio of 1:1 between the observed and expected values obtained from the backcross population.…”

“…Rice production is a very important activity all around the world. Many African and Asian countries rely on rice as a source of income and daily calories [1,2,3]. Bacteria leaf blight (BLB) which is caused by the pathogen Xanthomonas oryzae pv.…”

Marker-assisted selection and gene pyramiding for resistance to bacterial leaf blight disease of rice (Oryza sativaL.)

“…Identification of plants that carry specific genes or QTLs is based on their genotype and this is done by determining the allele of the molecular (DNA-based) marker [54]. Marker-assisted selection is very promising in the development of rice varieties resistant to BLB disease [5,97]. The use of molecular marker information to identify and select specific genotypes also gives a clear understanding of the molecular marker.…”

“…A marker can either be located within the gene of interest or be linked to a gene determining a trait of interest, which is the most common case. Molecular markers can also be used in confirmation of true F 1 , testing the seeds for genetic purity, protecting the cultivar, establishment of breeding strategies, linkage map construction, gene mapping and also mapping of QTLs associated with biological processes [5]. The following considerations are necessary in applying DNA-based markers in marker-assisted selection [96]: i.…”

“…Marker assisted selection is a technique that helps to make conventional breeding more efficient but not a substitute for conventional breeding [1]. It offers genetic tools for selection of target genes from the existing germplasm that would be used in breeding activities but does not include genetic engineering which involves the transfer of isolated gene sequences [5,6].…”