DENT CORN INBRED LINES AVAILABLE AS GENETIC STOCKS
The following inbred lines are available at $50 per unit of 100 kernels, postage paid. Offering seed as a genetic stock indicates the seed will be available as long as the supply lasts. There will be no further increase or distribution of the seed. Genetic stocks are generally not considered to be agronomically acceptable for incorporation into hybrids without additional breeding.
B52
This inbred is highly resistant to infestation by second generation of European corn borer. It has a vigorous plant type, medium ear size and a very hard stalk, but sheds only a small amount of pollen. Its maturity is adapted to south central and southern Iowa. The source of the line is unknown.
B75
This inbred is a selection from Iowa Corn Borer Synthetic #3. It is highly resistant to leaf feeding by first-generation European corn borer, but is moderately susceptible to leafsheath and collar feeding by second generation. It has good field resistance to sorghum downy mildew, moderate resistance to southern corn leaf blight (race 0) and northern corn leaf blight, and low‑level resistance to maize dwarf mosaic and maize chlorotic dwarf. The tassel has only one or two lateral branches, but the pollen production is adequate. The date of silk emergence is 2‑3 days earlier than B14A. The seed is relatively large and yield is good. Several tests for 3 years in north‑central and south‑central Iowa have shown that B75 does not contribute high root strength to hybrids. Also, although it has good resistance to stalk rots, stalk strength in hybrids is only average. Although no dent corn seed offered for sale has been treated with a fungicide, it is recommended that this inbred especially should have that protection.
B85
Developed from Iowa Corn Borer Synthetic #6 (now BSCB6, formerly Pa. Early Synthetic C3) by selection and self-pollination in the ear‑to‑row system for more than 8 generations. The plant has an erect‑leaf orientation and is single‑eared. The date of silk emergence is 2 days earlier than A632. Pollen production and seed yield are satisfactory. The ear is relatively small and the seed is flinty. Inbred B85 is highly resistant to leaf feeding by first generation of the European corn borer. Single‑cross evaluations in northern Iowa for 3 years have shown that it has good combining ability for grain yield and stalk strength, but it does not have satisfactory root strength.
B86
Inbred B86, a maize inbred line, was developed from the single cross B52 x Oh43. Inbred Oh43 contributed resistance to leaf feeding by the first generation of European corn borer, and B52 contributed resistance to sheath and collar feeding after silk emergence by the second generation plus some resistance to the first generation. Beginning with the F 2 of B52 x Oh43 and continuing through the F 5 generation, the inbred line was developed by selection and self‑pollination in the ear‑to‑row system.
Artificial infestation of the corn borer was used in all generations. Evaluations of B86 in 2 seasons have shown that it is highly resistant to the first generation and almost as resistant asB52 to the second generation. It is the only public line of central U.S. Corn Belt maturity that is known to combine both types of resistance into one genotype. The plants have ears of intermediate size, and the seed is flinty. Pollen production and seed yield are satisfactory. Preliminary evaluations in single‑cross hybrids in central Iowa have shown above‑average yields but only average stalk and root strength. The stalk of the inbred plant may be brittle in the pre-silk stage of plant development. The primary use for B86 will be in breeding programs as a source of resistance to the European corn borer for the whole life of the plant. The maturity classification is AES800.
B87
This inbred line was selected from BS22, which is a synthetic that has a maturity similar to A619 x A632. The line has been developed by selection and self-pollination in the ear‑to‑row system for five generations. The date of silk emergence is 1 to 2 days earlier than the Iowa Agriculture Experiment Station strain of A632. With artificial infestation of first‑generation European corn borer, B87 has a rating of 3 (1 ‑ highly resistant, 9 = highly susceptible) for resistance to leaf feeding. Also, the plant shows good resistance to diseases in central Iowa. Plant height is similar to A632, but ear placement is slightly lower. Pollen production and seed yield are good. The plants will produce a high frequency of second ears when the plant density is less than 40,000 plants/ha. The ear is slender with a length similar to A632 and most ears have 12 kernel rows. The kernel has a smooth, shallow dent and intermediate yellow color. Inbred B87 seems to be a line that seed producers can use in single‑cross seed production, either as male or female, and is early enough that it can be used in northern Iowa.
B88
Inbred B88 was developed from synthetic BS6(RC)C2, which is an improved version of BS6 that was obtained by crossing BSSS(R)C5 and BSCB1(R)C5. Inbred B88 is similar to B73 for dates of pollen shed and silk emergence. Pollen production may be sparse and seed yield is frequently low, evidently because of slow or incomplete silk emergence. In crosses with either B73 or Mol7 the yield is similar to B73 x Mol7. Generally, crosses of B88 have given similar or better resistance to root and stalk lodging than have comparable crosses of B73. Also, studies with high plant densities have shown that B88 contributes to hybrids strong resistance to barrenness. It is unlikely that this line can be used in a hybrid seed production program, but it should be a useful stock in a pedigree breeding program.
B92
Inbred B92 was developed from the backcross population of (B70 x H99) B70. The line was obtained by self-pollination in an ear-to-row breeding system for several generations. The purpose of the program was to obtain a line similar in hybrid performance to B70 but with improved resistance to lodging. Tassel shed and silk emergence are 4 days earlier than B73. Pollen production is good. Plant and ear heights are 40 to 30 cm shorter, respectively, than B73. B92 is resistant to first-generation European corn borer, moderately susceptible to the second generation, and has good resistance to disease in Iowa conditions. Hybrid performance of B92 is best in a single cross with B73. Compared with B73 x Mo17, B92 x Mo17 yields 4 percent higher and has better root strength, released as a germplasm line, rather than a parental line, because it is unstable for plant growth. The cause of the genetic similar stalk strength, fewer dropped ears, and higher harvest grain moisture (probably because of slower drying). B92 is being instability has not been determined. The genetic instability causes slow growth thus giving a variable plant size and smaller tassels. With greatest expression, there is no ear development. Heat and drought stresses before tassel emergence cause the effects of the instability to be accentuated. The condition seems to be completely recessive because in F 1 crosses no abnormal plants are evident.
B101
B101 is a yellow dent inbred line developed by single-seed descent from Iowa Stiff Stalk Synthetic (BSSS) that was designated as BSSS-53. B101 was identified as having higher levels of methionine. Relative to total protein (whole kernel) of B101, 39.5 grams per kilogram was methionine. B101 should be considered as a germplasm source with higher levels of methionine. Maturity classification of B101 is late AES800.
C.I. 31A
Selected from the open‑pollinated variety Midland. It is highly resistant to leaf feeding by first generation of the European corn borer. Pollen shedding is usually good and seed production is good. The maturity is late AES800.
B96
B96 is an orange flint inbred line known originally as 41.2504B, which was originally collected in Argentina. B96 is highly resistant to feeding by the first-generation European corn borer. B96 should be used as a donor parent because it has poor roots, poor pollen shed, small ears with small flinty seeds, and it is difficult to maintain in most conditions.
B96 can be obtained from: North Central Regional Plant Introduction Station,
Iowa State University, Ames, IA 50011.