Inbred Corn Line Designated ZS1513

Generally the present invention relates to the field of plant breeding. In particular the present invention concerns the development of corn plants. More specifically, the present invention relates to the development of elite germplasm capable of forming high performance hybrids when crossed with another elite inbred.

The invention relates generally to corn breeding and, more specifically, to an inbred corn line designated ZS1513. Corn or maize (Zea mays L.), is an agronomic crop of great commercial significance both in the United States and in many countries of the world. Corn is used for caloric intake both for animals and humans and has a wide variety of industrial applications. At the commercial production level, the dominant form of corn is single cross hybrids or varieties. Homozygous inbred lines, although not grown as a commercial crop, are extremely important as the source material for the production of hybrid varieties. The cross-pollination of two distinct homozygous inbred lines produces a first generation hybrid variety that is heterozygous at most gene loci.

The goal of plant breeding is to combine in a single variety/hybrid various desirable agronomic traits. For field crops, these traits may include resistance to diseases and insects, reducing the time to crop maturity, greater yield, and better agronomic quality.

Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant.

Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two homozygous lines produce a uniform population of hybrid plants that may be heterozygous for many gene loci.

Corn plants (Zea mays L.) can be bred by both self-pollination and cross-pollination techniques. Corn has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in corn when wind blows pollen from the tassels to the silks that protrude from the tops of the incipient ears.

The development of corn hybrids requires the development of homozygous inbred lines, the crossing of these lines to make hybrids and the evaluation of the resulting hybrids. Pedigree breeding and recurrent selection breeding methods are used to develop inbred lines from breeding populations. Breeding programs combine the genetic backgrounds from two or more inbred lines or various other broad-based sources into breeding pools from which new inbred lines are developed by successive generations of inbreeding and selection of desired phenotypes. The new inbreds are crossed with other existing inbred lines and the single cross hybrids from these crosses are evaluated extensively in field performance trials to determine which of those have agronomically desirable potential.

New inbred lines are developed by plant breeders through cross pollination of breeding materials having complementary desirable characteristics which results in a breeding population genetically segregating for a number of important agronomic traits. After initial development of this breeding population, breeders perform a number of successive generations of inbreeding and selection. The objective of these inbreeding and selection generations is to identify and genetically fix a new inbred line which has improved agronomic characteristics. These improved characteristics may be per se traits such as seed yield, seed quality, or disease resistance. However, the primary objective of most breeding programs is to identify new inbred lines which produce improved hybrid plant characteristics such as grain yield and harvestability when the new lines are crossed to other existing inbred lines to produce hybrids.

The process of determining whether newly developed inbred lines provide improved characteristics in hybrids produced using the new line involves extensive field evaluation and testing of the hybrid product. Each newly developed inbred line provides potentially much different contributions to hybrid combinations than its progenitors. Each inbred corn line also is true breeding. In layman's terms this means that when an inbred corn line is planted in isolation and allowed to pollinate itself, the resulting progeny will produce corn plants essentially genetically and phenotypically indistinguishable from the parent inbred.

A single cross hybrid corn variety is the cross of two true breeding inbred lines, each of which has a genetic composition which complements the other. They hybrid progeny of the first generation cross between two parent lines is designated "F.sub.1 ". In the hybrid seed development process, the F.sub.1 hybrid seed is that which is sold to and planted by commercial growers. The preferred F.sub.1 hybrid seed source is that which produces the highest level of vigor, agronomic strength, and yield compared to other F.sub.1 hybrid alternatives.

Because the parents of an F.sub.1 hybrid are true breeding, the seed resulting from a cross between the two parents will all be genetically identical, and will thus yield a stable and predictable phenotype in the commercial grower's fields. Also, because these parents are true breeding, they can be individually reproduced continually by open pollination in an isolated environment. Thus, it follows that the F.sub.1 hybrid can be continuously reproduced from the parent lines.

A single cross hybrid is produced when two inbred lines are crossed to produce the F.sub.1 progeny. A double cross hybrid is produced from four inbred lines crossed in pairs (A.times.B and C.times.D) and then the two F.sub.1 hybrids are crossed again (A.times.B).times.(C.times.D). Much of the hybrid vigor exhibited by F.sub.1 hybrids is lost in the next generation F.sub.2. Consequently, seed from hybrid varieties is not used for planting stock.

Corn is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop high-yielding corn hybrids that are agronomically sound based on stable inbred lines. The reasons for this goal are obvious: to maximize the amount of grain produced with the inputs used and minimize susceptibility to environmental stresses. To accomplish this goal, the corn breeder must select and develop superior inbred parental lines for producing hybrids. This requires identification and selection of genetically unique individuals which in a segregating population occur as the result of a combination of genetic recombinations plus the independent assortment of specific combinations of alleles at many gene loci which results in specific genotypes. Based on the number of segregating genes, the frequency of occurrence of an individual with a specific genotype is less than 1 in 10,000. Thus even if the entire genotype of the parents has been characterized and the desired genotype is known, only a few if any individuals having the desired genotype may be found in a large segregating population. Typically, however, the genotype of neither the parents nor the desired genotype is known in any detail.

Because commercial corn production relies on the development of novel and improved inbred corn lines, considerable money and effort is devoted by commercial seed companies and plant breeders to the development of inbred lines with the combining ability to produce first generation hybrid corn with the characteristics of high yield, resistance to disease and pests, improved plant stability, uniform phenotypical characteristics to facilitate machine harvesting, and so on, all with the goal of maximizing the efficient use of land and other resources in the production of foodstuffs and raw agricultural materials.

An object of the present invention is to produce an inbred corn line that can be used to form a hybrid for use in the Northern Region of the U.S. corn belt or a region having similar environmental traits.

Another object of the present invention is to provided an inbred that has a generally broad based combining ability with other inbreds to produce high yields in hybrid combination.

Still another object of the present invention is to produce an inbred that provide excellent inbred female seed yield.

Broadly the present invention is an inbred corn line designated ZS1513 and the plant or plants and the pollen and seed or seeds. Additionally the invention includes inbred corn plants with the phenotypic, physiological and morphologic characteristics of inbred corn line designated ZS1513.

A method is also contemplated within the present invention. A method for producing a corn plant, comprising the step of using a first parent corn plant with a second parent corn plant wherein the first or second parent corn plant is the inbred corn plant having designation ZS1513. The method wherein the first and second parent corn plants are both from the inbred corn line designated ZS1513.

The invention also includes the first generation (F.sub.1) hybrid corn plant produced by crossing a first inbred female corn plant with a second inbred male corn plant, wherein the first or second parent corn plant is the inbred corn plant having the designation ZS1513. The hybrid corn plant wherein the inbred corn plant having the designation ZS1513 is the female parent. The hybrid corn plant wherein the inbred corn plant having the designation ZS1513 is the male parent. A method for producing first generation (F.sub.1) hybrid corn seed, comprising the step of crossing a first inbred parent corn plant with a second inbred parent corn plant, wherein the first or second parent corn plant is the inbred corn plant having the designation ZS1513. A first generation (F.sub.1) hybrid corn plant produced by growing the hybrid corn seed. A plant cell which, upon growth and differentiation, produces the plant designated ZS1513.

DEFINITIONS

In the description and examples which follow, a number of terms are used. In order to provide a clear and consistent understanding of the specifications and claims, including the scope to be given such terms, the following definitions are provided.

BL MOIST

The moisture percentage of the grain at black layer, i.e., when 50% of the plants per plot have reached physiological maturity.

COLD GERM

Cold Germ is a measurement of seed germination under cold soil conditions. Data is reported as percent of seed germinating.

EMERGE

The number of emerged plants per plot (planted at the same seedling rate) collected when plants have two fully developed leaves.

GI

GI=100+0.5(YLD)-0.9(%STALK LODGE)-0.9(%ROOT LODGE)-2.7(%DROPPED EAR)

This is a selection index which provides a single quantitative measure of the worth of a hybrid based on four traits. Yield is the primary trait contributing to index values.

GLS

Grey Leaf Spot (Cercospora zeae) disease rating. This is rated on a 1-9 scale with a "1" being very susceptible, and a "9" being very resistant.

GW

Goss' Wilt (Corynebacterium nebraskense). This is rated on a 1-9 scale with a "1" being very susceptible, and a "9" being very resistant.

HEATP10

The number of Growing Degree Units (GDU's) or heat units required for an inbred line or hybrid to have approximately 10 percent of the plants shedding pollen. This trait is measured from the time of planting. Growing Degree Units are calculated by the Barger Method where the GDU's for a 24 hour period are: ##EQU1## The highest maximum temperature used is 86.degree. F. and the lowest minimum temperature used is 50.degree. F. For each inbred or hybrid it takes a certain number of GDU's to reach various stages of plant development.

HEATBL

The number of GDU's after planting when approximately 50 percent of the inbred or hybrid plants in a plot have grain which has reached physiological maturity (black layer).

HEATPEEK

The number of GDU's after planting of an inbred when approximately 50 percent of the plants show visible tassel extension.

HEATP50

The number of GDU's required for an inbred or hybrid to have approximately 50 percent of the plants shedding pollen. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.

HEATP90

The number of GDU's accumulated from planting when the last 100 percent of plants in an inbred or hybrid are still shedding enough viable pollen for pollination to occur. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.

HEATS10

The number of GDU's required for an inbred or hybrid to have approximately 10 percent of the plants with silk emergence of at least 0.5 inches. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.

HEATS50

The number of GDU's required for an inbred or hybrid to have approximately 50 percent of the plants with silk emergence of at least 0.5 inches. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.

HEATS90

The number of GDU's required for an inbred or hybrid to have approximately 90 percent of the plants with silk emergence of at least 0.5 inches. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.

MDMV.sub.A

Maize Dwarf Mosaic Virus strain A. The corn is rated on a 1-9 scale with a "1" being very susceptible, and a "9" being very resistant.*

MDMV.sub.B

Maize Dwarf Mosaic Virus strain B. This is rated on a 1-9 scale with a "1" being very susceptible and a "9" being very resistant.*

MOISTURE

The average percentage grain moisture of an inbred or hybrid at harvest time.

NLB

Northern Leaf Blight (Exserohilum turcicum) disease rating. This is rated on a 1-9 scale with a "1" being very susceptible, and a "9" being very resistant.*

PCT TILLER

Percentage of plants in a plot which have tillers.

PLANT HEIGHT

The distance in centimeters from ground level to the base of the tassel peduncle.

RM

Predicted relative maturity based on the moisture percentage of the grain at harvest. This rating is based on known set of checks and utilizes standard linear regression analyses and is referred to as the Minnesota Relative Maturity Rating System.

SHED

The volume of pollen shed by the male flower rated on a 1-9 scale where a "1" is a very light pollen shedder, a "4.5" is a moderate shedder, and a "9" is a very heavy shedder.

SLB

Southern Leaf Blight (Bipolaris maydis) disease rating. This is rated on a 1-9 scale with a "1" being very susceptible, and a "9" being very resistant.*

TWT

The measure of the weight of grain in pounds for a one bushel volume adjusted for percent grain moisture.

VIGOR

Visual rating of 1 to 9 made 2-3 weeks post-emergence where a "1" indicates very poor early plant development, and a "9" indicates superior plant development.

WARM GERM

A measurement of seed germination under ideal (warm, moist) conditions. Data is reported as percent of seeds germinating.

YIELD

Actual yield of grain at harvest adjusted to 15.5% moisture. Measurements are reported in bushels per acre.

% DROPPED EARS

Percentage of plants in a plot which dropped their primary ear divided by the total number of plants per plot.

% LRG FLAT

Percentage by weight of shelled corn that passes through a 26/64 inch round screen and a 14/64 inch slot screen, but does not pass through a screen with 20.5/64 inch round openings.

% LRG ROUND

Percentage by weight of shelled corn that passes through a 26/64 inch round screen, but does not pass through a 14/64 inch slot screen or a screen with 20.5/64 inch round openings.

% MED FLAT

Percentage by weight of shelled corn that passes through a 20.5/64 inch round screen and a 13/64 inch slotted screen, but does not pass through a screen with 17/64 inch round openings.

% MED ROUND

Percentage by weight of shelled corn that passes through a 20.5/64 inch round screen, but does not pass through a 13/64 inch slot screen or a screen with 17/64 inch round openings.

% SML FLAT

Percentage by weight of shelled corn that passes through a 17/64 inch round screen and a 12/64 inch slotted screen, but does not pass through a screen with 15/64 inch round openings.

% SML ROUND

Percentage by weight of shelled corn that passes through a 17/64 inch round screen, but does not pass through a 12/64 inch slotted screen or a screen with 15/64 inch round openings.

% ROOT LODGE

Percentage of plants in a plot leaning more that 30 degrees from vertical divided by total plants per plot.

% STALK LODGE

Percentage of plants in a plot with the stalk broken below the primary ear node divided by the total plants per plot.

*Resistant-on a scale of 1-9 with 9 evidencing the trait most strongly: 1-2.9 ratings are susceptible, 3-5.9 ratings are intermediate, and 6-9 ratings are resistant.

The yellow dent corn inbred line ZS1513 is characterized by a distinctive wide wavy leaf. But more importantly, inbred line ZS1513 has unique and superior characteristics. Inbred corn line ZS1513 has proven to be acceptable as a female or a male line in producing F.sub.1 hybrids. ZS1513 is acceptable for use as a male parent because of its pollen shed rating which is 5 to 7 on a scale of 0=sterile and 9=heavy shedder. Inbred line ZS1513 is adapted for use in the Northern regions of the United States and in other regions of the world having similar environmental characteristics. This inbred can be used to produce hybrids from approximately 95-110 relative maturity based on the Minnesota Relative Maturing Rating System for harvest moisture of grain. ZS1513 is unique as a female parent because of its broad general combining ability with other inbreds, and high yield in hybrid combination. As a female, ZS1513 provides excellent yields of medium sized, high quality seed, and evidences excellent seedling vigor. Inbred ZS1513 is characterized by short plant height and low ear placement. ZS1513 performs well as an inbred under cold germ test conditions as well as good growing conditions. Corn plants that are used as females are detasseled. Corn plants that are used to pollinate detasseled corn plants are used as males.

The inbred has shown uniformity and stability within the limits of environmental influence for all the traits as described in the Variety Descriptors (Table 1) that follows. Most of the data in the Variety Descriptors were collected at Slater, Iowa. Numeric data was generated from means over all environments where the inbred was evaluated.

The inbred has been self-pollinated for approximately 6-8 generations. During plant selection in each generation the uniformity of plant type was selected to ensure homozygosity and phenotypic stability. The line has been increased in isolated farmland environments with data on uniformity and agronomic traits being observed to assure uniformity and stability. No variant traits have been observed or are expected in ZS1513.

The best method of producing the invention, ZS1513 which is substantially homozygous, is by planting the seed of ZS1513 which is substantially homozygous and self-pollinating or sib pollinating the resultant plant in an isolated environment, and harvesting the resultant seed or the resultant pollen.

The Munsell code is a reference book of color which is known and used in the industry and by persons with ordinary skill in the part of plant breeding. The purity and homozygosity of inbred ZS1513 is constantly being tracked using isozyme genotypes as shown in Table 2.

Isozyme data were generated for Table 2 according to the procedure in Stuber, C. W., Wendell, J. R., Goodman, M. M., And Smith, J. S. C. Techniques and Scoring Procedures for Starch Gel Electrophoresis of Isozymes from Maize (Zea mays L.). Tech. Bull. 286. North Carolina Agricultural Research Service, North Carolina State University, Raleigh, N.C., March, 1988.

This invention also is directed to methods for producing a corn plant by crossing a first parent corn plant with a second parent corn plant wherein the first or second parent corn plant is an inbred corn plant from the line ZS1513. Further, both first and second parent corn plants can come from the inbred corn line ZS1513. Thus, any methods using the inbred corn line ZS1513 are part of this invention. The methods include but are not limited to selling, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using inbred corn line ZS1513 as a parent are within the scope of this invention. Advantageously, the inbred corn line is used in crosses with other, different, corn inbreds to produce first generation (F.sub.1) corn hybrid seeds and plants with superior characteristics.

As used herein, the terms "plant and plant parts" include plant cells, plant protoplasts, plant cell tissue culture from which corn plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants, or parts of plants, such as embryos, pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk and the like. Corn tissue culture procedures are also described in Green and Rhodes, "Plant Regeneration in Tissue Culture of Maize", Maize for Biological Research (Plant Molecular Biology Association, Charlottesville, Va. 1982, at 36-372). Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce the inbred line ZS1513.

The utility of the dent inbred line ZS1513 extends to the production of plants which may be crosses made with other species. The inbred line may be crossed with sweet corn or popcorn or other dent corn. It may potentially be suitable for crosses with sorghum.

Corn is used for human consumption (in a variety of different forms), animal consumption, and as a ingredient in many commercial products. The production of corn for human consumption includes products of the dry and wet milling industries. The most commonly recognized uses of corn kernels are corn grits, corn meal, and corn flour. Additional processing can be employed and provide various corn sweeteners and corn starch. Likewise, a variety of snack foods and breakfast foods are made of corn such as corn chips, cornflakes, cornbread, and the like. Likewise, corn oil and various components of corn oil have been used in industry and in cooking foods for human consumption.

Additionally corn products can be used to make alcohol products. Alcohol products can be used for human consumption, but likewise, they can be used for industrial purposes. Alcohol products made from corn can be used in gasoline. Flour and starch from corn can be used for sizing, for paper, adhesives, and the like. The corn products have been used in building materials and laundry starches and a variety of other industrial applications. Other parts of the corn plant can also be used. The non-grain portion of the plant and the grain portion of the plant can be chopped and fed to animals. Additionally, corn cobs can be used for firewood and husks can be used creatively in the arts for the making of corn husk dolls.

The seed, plant and plant parts of the of the inbred corn line ZS1513 and the seed plant and plant parts of the hybrid made with ZS1513 as a parent can be used for various industrial purposes.

The following examples compare the traits of the present invention with inbreds and hybrids having similar regions of usage, and/or similar traits and/or characteristics. The data will of course vary depending on the inbred and hybrid employed for the comparison.

Information provided in Table 3 compares inbreds ZS1513 to MBS847. Data supplied was generated from means over only those environments where both inbreds were evaluated. Inbred MBS847 is a widely used commercially available line. Inbred MBS847 is an important line that would be used in similar regions and would cross well with some of the same inbred lines as ZS1513. The data presented in Table 3 has been collected in research trials over a period of at least 3 years (when possible).

Data presented in Table 3 demonstrate that inbreds ZS1513 and MBS847 differ significantly for certain traits. Inbred ZS1513 yields 54.8 bushels to the acre, compared to MBS847 which yields 43.7 bushels to the acre. Inbred yield is important because it relates directly to cost and efficiency of production. Less acres of land are required to produce the desired amount of seed. Data in Table 3 also demonstrates that ZS1513 flowers significantly earlier than MBS847 (HEATP10, HEATP50, HEATP90, HEATS10, HEATS50 and HEATS90 of 1312 versus 1347, 1353 versus 1386, 1403 versus 1444, 1345 versus 1370, 1364 versus 1399, and 1397 versus 1438, respectively). Earlier flowering inbreds are advantageous because they enable the inbred to be used as parents of shorter season hybrids shorter season environments. Additionally, the grain moisture at black layer (BL MOIST) for inbred ZS1513 is significantly lower than for MBS847 (32.1% versus 36.8%). Relatively lower grain moisture at black layer indicates an inbred can be safely harvested earlier in the fall and, consequently, is less susceptible to damage by frost.

Table 4 provides data comparing ZS1513 crossed to an inbred tester and MBS847 crossed to the same inbred tester. Data for two widely grown commercially available hybrids (designated H1 and H2) are also provided as checks in Table 4 to demonstrate the significant commercial superiority of a ZS1513 hybrid.

The data in Table 4 indicate that the ZS1513 hybrid yields significantly more grain than the MBS847 hybrid (139 versus 129 bushels per acre) and the grain is significantly dryer at harvest (17.0% versus 19.8% grain moisture). Higher yielding hybrids permit more grain to be produced per acre. Hybrids that have lower grain moistures at harvest enable the grower to harvest the crop earlier and thus have less risk of frost damage, and/or the grower needs to artificially dry the corn less and thus reduces input costs, and/or that the hybrid can be grown in shorter season environments. Regression of grain moisture at harvest on The Minnesota Relative Maturity System (RM in Table 4) indicates that the ZS1513 hybrid has a ten day earlier relative maturity than the MBS847 hybrid (98 days versus 108 days). Similarly, data provided in Table 4 for commercial checks H.sub.1 and H.sub.2, both widely used commercial hybrids in the regions where the ZS1513 hybrid is grown, indicates that the ZS1513 hybrid has superior performance. The ZS1513 hybrid yields significantly more per acre than the H.sub.1 hybrid (139 versus 126 bushels per acre) and grain moisture at harvest is significantly lower (17% versus 19.7%). Similarly, the ZS1513 hybrid yields 9 bushels more than the H.sub.2 hybrid (139 versus 130 bushels per acre) and grain at harvest is significantly drier (17.0% versus 18.1%).

Comparisons of inbred per se data for ZS1513 and a widely used commercially available inbred demonstrate that ZS1513 provides significant advantage for yield, flowering and grain moisture at black layer. Additionally, comparisons of hybrid data from test crosses of ZS1513 and a widely used commercially available inbred demonstrate that ZS1513 provides a significant advantage for yield and grain moisture at harvest in hybrid combination. Hybrid data for two widely grown commercial hybrids is also presented as checks to demonstrate the superior commercial performance of ZS1513 in hybrid combination.

Applicant, (from a deposit maintained prior to Feb. 14, 1994, by ICI Seeds, at Slater, Iowa,) has deposited with the American Type Culture Collection (ATCC), Rockville, Md. 20852, U.S.A. on Feb. 17, 1994, at least 2,500 seeds of Inbred Corn Line ZS1513. This deposit of ZS1513 has ATCC Accession No. 75679. This deposit of ZS1513 will be maintained in the depository for a period of 30 years, or 5 years after the most recent request, or the life of the potent, whichever is longer, and will be replaced, in this period, if it becomes nonviable. The seed has been tested by the depository as viable on Feb. 28, 1994. Applicant does not waive its rights under the patent law or PVP Act, but Applicant imposes no restriction on the availability of the deposited material from the ATCC.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be also understood that it is not to be so limited since changes and modifications can be made therein which are within the full intended scope of this invention as defined by the appended claims.