What is heterosis? What role has it played in crop productivity?

Explanation

Heterosis (=Hybrid Vigour). Heterosis is the reverse of inbreeding depression. Heterosis or hybrid vigour is the phenotypic superiority of the hybrid over either of its parents hi one or more traits. In other words, when two unrelated individuals or lines are crossed, the performance of F, hybrid is often superior to both its parents.
It increases the dominant alleles of both the parents in a progeny Crosses between inbreeds from different heterotic groups results in vigorous F, hybrids with significantly more heterosis than `F_1` hybirds from inbreds within the same heterotic group.
Heterosis is used to increase yield, uniformity and vigour. Hybrid breeding methods are used in maize, sorghum, rice, sugarbeat, onion, spinach, sunflowers, broccoli.