In a population of 100 inbred, genotypically identical rice plants, variance for grain yield is 4.67. What is the heritability for yield? Would you advise a rice breeder to improve yield in this strain of rice plants by selection?

Verified step by step guidance

1. <span>Step 1: Understand the concept of heritability. Heritability in the broad sense (H^2) is the proportion of the total phenotypic variance (V_P) that is due to genetic variance (V_G). It is calculated as H^2 = V_G / V_P.</span>
2. <span>Step 2: Recognize that in inbred, genotypically identical populations, the genetic variance (V_G) is essentially zero because all individuals have the same genotype. Therefore, any observed variance in the trait is due to environmental factors.</span>
3. <span>Step 3: Since V_G is zero, the heritability (H^2) for grain yield in this population is also zero. This means that none of the observed variance in grain yield is due to genetic differences among the plants.</span>
4. <span>Step 4: Consider the implications for breeding. Since heritability is zero, selection based on phenotypic differences will not lead to genetic improvement in yield because the differences are not genetically based.</span>
5. <span>Step 5: Advise the rice breeder. Given the zero heritability, it would not be effective to improve yield in this strain by selection. The breeder might consider introducing genetic variation through crossbreeding with other strains to create a population with genetic diversity.</span>

Key Concepts

Heritability

Heritability is a measure of how much of the variation in a trait, such as grain yield, can be attributed to genetic differences among individuals in a population. It is expressed as a ratio, ranging from 0 to 1, where a higher value indicates a greater genetic contribution to the observed variation. Understanding heritability helps breeders determine the potential effectiveness of selection for improving traits.

Variance

Variance is a statistical measure that represents the degree of variation or dispersion of a set of values. In the context of genetics, it quantifies how much individual traits, like grain yield, differ from the average trait value in a population. A higher variance indicates a wider range of trait expression, which can influence the potential for selection and breeding strategies.

Selection in Breeding

Selection in breeding refers to the process of choosing individuals with desirable traits to reproduce, thereby increasing the frequency of those traits in future generations. In the case of rice plants, if heritability is high, it suggests that selection could effectively improve grain yield. Conversely, if heritability is low, the impact of selection may be limited, making it less advisable to pursue this strategy.