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

Abstract

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.

Biochemical and physical kernel properties of a standard maize hybrid in different TopCross™ Blends

“…Significant positive correlation between tryptophan and oil content was also found in Ignjatovic-Micic et al (2015). Lambert et al (1998) attributed increased lysine content in TC Blends to the larger embryo associated with high oil maize, as most essential amino acids are located in the kernel embryo. Significant increase in the germ size was noted only in TC-2 and TC-3, but their tryptophan content was at the level of the ZP341 selfed.…”

“…Protein content was significantly lower in all TCs. On the contrary, Cromwell (2000) found that high oil maize contains up to 10 g kg −1 more protein than standard maize, while in some other research studies protein levels were similar for TC Blends and check hybrids (Lambert et al, 1998;Strachan and Kaplan, 2001;Thomison et al, 2003). The deviations from the expected results could indicate the complexity of trait inheritance.…”

Densidade, teor de óleo e produtividade de grãos em híbridos de milho

“…Destacaram-se os híbridos DKB 350, A 2555, Fort, BRS 1001, CD 306, Strike, AG 7000, 30F90, Brava, BRS 1010 e 30F98 com maiores teores de óleo, os quais podem ser indicados preferencialmente para reduzir o custo energético das rações, pois é provável que, nesta faixa relativamente baixa de óleo, o teor de amido permaneça inalterado nos grãos (ALEXANDER e LAMBERT, 1968;LAMBERT et al, 1998 A massa de cem grãos apresentou correlação negativa com o teor de óleo apenas na análise conjunta, onde há influência tanto do ambiente como das cultivares, e positiva com peso volumétrico em Assis e na análise conjunta, todos com baixos índices de correlação. Logo, considerando que o germe e o endosperma possuem diferentes densidades, sendo o primeiro mais denso, espera-se que a proporção entre as frações germe e endosperma tenha variado muito pouco entre os grãos com diferentes teores de óleo.…”

“…Geralmente, existe uma relação estreita entre os teores de óleo da fração germe e o do próprio grão porque 81% a 87% do óleo do grão está no germe (EARLE et al, 1946). Redução do tamanho e massa dos grãos com o aumento de óleo, e redução dos teores de amido, têm sido observados apenas em programas de melhoramento que atingem teores de óleo maiores que 7 % (MILLER et al, 1981;LAMBERT et al, 1998). Isso tem sido atribuído à menor eficiência metabólica na transformação de açúcar em óleo do que em amido (MILLER et al, 1981).…”

Genetic analysis of kernel oil content in tropical maize with design III and QTL mapping

“…This procedure consists in sowing a mixture of seeds of a normal kernel oil content high-yielding male-sterile singlecross (&90%) and a high-oil (but low-yielding) male pollinator (&10%). Lambert et al (1998) reported that hybrids pollinated with high oil and normal oil content strains had comparable yield, but those hybrids pollinated with high oil strains yielded 19 g kg -1 more oil than those pollinated with the normal oil content strains. Also, Thomison et al (2003) reported that with the Top Cross TM procedure the kernel oil content was quite higher (72.12 g kg -1 ) than in the normal single-crosses crop (41.25 g kg -1 ), but a significant reduction on grain yield was reported (Thomison et al 2002).…”