A High Oil Pollinator Enhancement of Kernel Oil and Effects on Grain Yields of Maize Hybrids

Several attempts to develop high oil (HO) maize (Zea mays L.) hybrids that are competitive in yield have met with limited success, because of the negative association between oil levels and grain yields. Generally, HO hybrids have high oil kernels but with reduced starch levels, smaller endosperm, and reduced kernel size. The objective of the study was to determine if the use of a high oil maize pollinator could reduce the potential grain yield losses associated with high oil maize production. Nine different single-cross hybrids were grown for 3 yr and pollinated by two different pollinators. To produce maize hybrids with different kernel oil concentrations under open-pollinated conditions, the nine hybrids were pollinated by a high oil pollinator (HOP) and by normal oil po llinator (NOP). Tocontrol pol linations, all nine hybrids were detasseled. A split-plot design allowed for a comparisono f the effects of the two pollinators. The four normalo il (NO) hybrids producedo il concentrations in the 60 to 70 g kg-I range on a dry weight basis when pollinated by a HOP, with no reduction in grain yields. These same hybrids produced oil concentrations in the 47 to 55 g kg-~ range and similar yields when pollinated by a NOP. The four HO hybrids produced yields about 15% lower than the NO hybrids when pollinated by a HOP and about 12% lower yields when pollinated by a NOP. The normal fertile check hybrid produced yields differing by only 1% with the two pollinators, but the oil levels showed an increase of 17 g kg-1 for a HOP relative to a NOP. This increase in oil levels of the NO hybrids pollinated by a HOP is the result of a small increase in germ weight, an increase concentration of oil in the germ, and a reduction in the percentage of endosperm. The changes in kernel traits do not appear to reduce grain yields of the NO hybrids, hut do increase oil levels. The consequence of this procedure is to trick the sporophyte into producing greater amounts of oil in the germ.