Study on selection effect, genetic advance and genetic parameters in rice
By Asadollah Ahmadikhah
Knowledge of selection effect on positive or negative changes of a character under improvement is of paramount importance for the success of any plant breeding program, and helps the selection of a desirable breeding method. Heritability and genetic advance are important selection parameters, and selection success is a reflectance of selection response. To estimate selection effect, genetic advance, heritability and selection success in rice, a study was conducted on 4 generations, including 2 parents, BC1 and BC1S1 populations. After development of BC1 population, one plant (BC1-#4) was selected based on its desirable performance, particularly in heading date and seven other morphological traits. BC1 population compared to mid-parent performance showed advance for heading date, plant height, tiller number, hundred seed weight, weight of filled seeds per panicle and grain yield per plant, while mean performance of BC1S1 population compared to BC1 population showed advance only for heading date, plant height, tiller number and grain yield. Estimation of degree of dominance (d) revealed prevalence of additive genetic effects in controlling panicle weight, hundred seed weight, weight of filled seeds per panicle, plant height and heading date, and prevalence of non-additive effects in controlling grain yield. High general heritability was observed for most traits, while only heading date and plant height showed a considerable specific heritability (60.7% and 67.5%, respectively), and grain yield showed a relatively low specific heritability (37.0%). High expected genetic advance (?Ge) was obtained for tiller number (49.4%), followed by grain yield (43.5%) and plant height (35.5%), while the highest real genetic advance (?Gr) was obtained for heading date (-8.5%) and tiller number (5.4%). High selection success was obtained only for heading date (51.8%). Altogether, the obtained results gave promise for selection of progenies with early maturity and semi-dwarfism in early segregating generations, while they suggested preference of heterosis for improvement of grain yield.
Key words: Rice, selection, heritability, response
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