Increasing Maize Productivity in China by Planting Hybrids with Germplasm that Responds Favorably to Higher Planting Densities

Abstract

We compared yield, genetic gain, and morphology for two sets of maize {Zea mays L.) hybrids using yield test plots grown in China at different planting densities.

Is There a Role for Sink Size in Understanding Maize Population–Yield Relationships?

“…1) could not have occurred without an increase in source activity per unit area, which has both a rate (i.e., canopy photosynthesis, g CO 2 m –2 GA d –1 , where GA is ground area) and a time component (principally the duration of kernel filling; Egli, 2011). The importance of kernel number in the increase in yield (Carlone and Russell, 1987; Russell, 1991; Tollenaar et al, 1992; Echarte et al, 2000; Li et al, 2011) suggests that the rate component was more important than the time component (longer kernel filling period). Traits listed by Duvick et al (2004a) and Duvick (2005) that contributed to increased productivity included smaller tassels, erect leaves, increased stay‐green characteristics of the leaves during kernel filling, less lodging, and improved disease and insect resistance.…”

“…It is possible to genetically increase ear size and prolificacy. Breeding programs in China (Li et al, 2011; Wang et al, 2011) and Argentina (Echarte et al, 2000; Luque et al, 2006) increased ear size. Hallauer and Ross (2004) increased ear length by 36% after 27 cycles of mass selection.…”

“…Genetic modifications associated with this yield improvement were documented extensively in experiments comparing hybrids from different eras in the same environment (Russell, 1984; Tollenaar et al, 1992; Duvick et al, 2004a; Duvick, 2005; Li et al, 2011; Smith et al, 2014). Modifications included an increase in the stay‐green characteristics of the leaves during kernel filling, longer kernel‐filling periods, erect leaves, decreases in seed protein concentration, less stalk lodging, disease and insect resistance, and shorter anthesis‐to‐silking intervals.…”

“…Modifications included an increase in the stay‐green characteristics of the leaves during kernel filling, longer kernel‐filling periods, erect leaves, decreases in seed protein concentration, less stalk lodging, disease and insect resistance, and shorter anthesis‐to‐silking intervals. Most of the increase in yield was associated with more kernels per unit area (Carlone and Russell, 1987; Russell, 1991; Tollenaar et al, 1992; Echarte et al, 2000; Li et al, 2011), with kernel size (weight per kernel) making a smaller contribution (Russell, 1991; Barker et al, 2005).…”

UPA2 and ZmRAVL1: Promising targets of genetic improvement of maize plant architecture

“…A salient feature in plant morphological changes of improved hybrids and inbred lines is reduced leaf angle that helps to reduce shading and increase photosynthesis efficiency in a dense canopy. Thus leaf angle has been an important target for maize breeding (Pendleton et al 1968; Duncan 1971; Li et al 2011; Li et al 2013). Thus, deciphering the molecular genetic basis of leaf angle is important for genetic improvement of this trait.…”