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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 a normal oil pollinator (NOP). To control pollinations, all nine hybrids were detasseled. A split‐plot design allowed for a comparison of the effects of the two pollinators. The four normal oil (NO) hybrids produced oil concentrations in the 60 to 70 g kg−1 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−1 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, but do increase oil levels. The consequence of this procedure is to trick the sporophyte into producing greater amounts of oil in the germ.

Several experiments were conducted to evaluate the nutritional value of high oil corn for poultry relative to that of conventional (CONV) corn. The variety of high oil corn (HO1) evaluated in most trials contained 6.0% oil and 9.6% protein on a 10% moisture basis. The protein quality of HO1 and CONV corn was assessed with female crossbred chicks fed corn as the sole source of dietary protein. There was no difference in either protein efficiency ratio or in net protein ratio between the two types of corn. True metabolizable energy (TME) and nitrogen-corrected TME (TMEn) values of HO1 corn were determined using adult roosters. The TME and TMEn values of HO1 corn were approximately 4.5% higher than those of CONV corn. Two experiments were conducted to evaluate the use of high oil corn varieties, containing from 6 to 13% oil, in practical diets of commercial broiler chicks from 8 to 22 days posthatching. Weight gain, gain-to-feed ratio, and skin and plasma pigmentation were improved in chicks fed 24% protein diets containing high oil corns compared with those fed the same diet containing CONV corn; magnitude of response was highly correlated to oil content of the corn. The relative value of HO1 corn in practical laying hen diets was examined in a 15-wk experiment. Hens fed a 17% protein diet containing HO1 corn from 23 to 38 weeks of age had a better feed-to-egg ratio than those fed the same diet containing CONV corn when the corn sources were substituted on an isonitrogenous basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Responses and limits to selection are found to differ in various maize (Zea mays L.) populations and traits. Twenty‐four cycles of recurrent selection for high oil concentration have been completed in maize population Alexho Synthetic. The objectives of this study were to determine the response of oil concentration direct selection and correlated responses of fatty acid concentration, grain yield, and other agronomic traits. Cycles 0, 3, 5, 9, 11, 15, 18, 21, and 24 per se, the same cycles crossed to inbreds B73 and R802A, and hybrid check B73 ✕ Mo17, were evaluated in six environments at Yugoslavia and at Urbana, IL in 1985 and 1986. Selection was effective in increasing oil concentration. Total oil concentration increased by 118, 51, and 57 g kg−1 of dry matter in cycles per se B73 and R802A testcrosses, respectively. The rate of response in oil concentration was 4.9, 2.1, and 2.4 g kg−1 cycle−1 for the cycles per se for B73 and R802A testcrosses, respectively. The quadratic response was significant in testcrosses, but not in cycles per se. Thus, oil concentration has not yet shown evidence of plateauing. Oleic and linoleic acid concentration changed with selection for oil concentration in cycles per se −1.39 and 1.39 g kg−1 cycle−1, respectively. Total grain yield of the cycles per se decreased by 1718 kg ha−1, which corresponds to a response of −71.6 kg ha−1 cycle−1. Yield of the testcrosses to inbreds B73 and R802 decreased 19.7 and 15.2 kg ha−1 cycle−1, respectively. Plant height, ear height, 500 kernel weight, ear length, and lodging decreased, while grain moisture and ear row number increased with selection for oil concentration. No change was found in days to silk.