Direct Selection Response for Flowering Traits in Four Tropical and Subtropical Maize Populations by Mass Selection Effects of Grid Mass Selection in ZZ3 Maize Population Effects of Phenotypic Recurrent Selection and Mass Selection on Improvement of Agronomic Traits in Wheat Populations The genetic variation revealed by SSR markers in crossbreeding groups of annual ryegrass after continuous mass selection Breeding and spreading of new vairety "Yu-Qing No.1" of Artemisia annua Effects of Population Improvement by Mass Selection on the Tropical Maize Population MW964