United States Patent r191
`Maughan
`
`[54]
`
`INBRED MAIZE LINE PHKW3
`
`[75]
`
`Inventor; Kory W. Maughan, Lincoln County,
`Nebr.
`
`[73] Assignee: Pioneer Hi-Bred International, Inc.,
`Des Moines, Iowa
`
`[21] Appl. No.: 381,172
`
`[22] Filed:
`
`[51]
`
`Int. Cl.6
`
`Jan. 31, 1995
`.......... , .................... AOlH 5/00; A0lH 4/00;
`A0lH 1/00; C12N 5/04
`[52] U.S. Cl . .................. 800/200; 800/250; 800/DIG. 56;
`435/240.4; 435/240.49; 435/240.5; 47/58;
`47/DIG. 1
`[58] Field of Search ..................................... 800/200, 250,
`800/205, DIG. 56; 47/58.03, 58.05; 438/240.4,
`240.45, 240.49, 240.5, 172.3
`
`I 1111111111111111 11111 111111111111111 IIIII IIIII IIIII IIIII IIIIII Ill lllll llll
`US005534661A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,534,661
`Jul. 9, 1996
`
`Phillips, et al. (1988) "Cell/fissue Culture and In Vitro
`Manipulation", Com & Com Improvement, 3rd Ed., ASA
`Publication, No. 18, pp. 345-387.
`Poehlman (1987) Breeding Field Crop, AVI Publication Co.,
`Westport, Ct., pp. 237-246.
`Rao, K. V., et al., (1986) "Somatic Embryogenesis in Glume
`Callus Cultures", Maize Genetics Cooperative Newsletter,
`No. 60, pp. 64-65.
`Sass, John F. (1977) "Morphology", Corn & Corn Improve(cid:173)
`ment, ASA Publication. Madison, Wisconsin, pp. 89-109.
`Songstad, D. D. et al.
`(1988) "Effect of ACC
`(1-aminocyclopropane-1-carboxyclic acid), Silver Nitrate
`& Norbonadiene on Plant Regeneration From Maize Callus
`Cultures", Plant Cell Reports, 7:262-265.
`Tomes, et al. (1985) 'Toe Effect of Parental Genotype on
`Initiation of Embryogenic Callus From Elite Maize (Zea
`mays L.) Germplasm", Theor. Appl. Genet., vol. 70, pp.
`505-509.
`Troyer, et al. (1985) "Selection for Early Flowering in Corn:
`10 Late Synthetics", Crop Science, vol. 25, pp. 695-697.
`Umbeck, et al. (1983) "Reversion of Male-Sterile T-Cyto(cid:173)
`plasm Maize to Male Fertility in Tissue Culture", Crop
`Science, vol. 23, pp. 584-588.
`Wright, Harold (1980) "Commercial Hybrid Seed Produc(cid:173)
`tion", Hybridization of Crop Plants, Ch. 8: 161-176.
`Wych, Robert D. (1988) ''Production of Hybrid Seed", Com
`and Corn Improvement, Ch. 9, pp. 565-607.
`Lee, Michael (1994) "Inbred Lines of Maize and Their
`Molecular Markers", The Maize Handbook Ch. 65:423-432.
`Boppenmaier, et al., (1991) "Comparsons Among Strains of
`Inbreds for RFLPs", Maize Genetics Cooperative Newslet(cid:173)
`ter, 65, p. 90.
`
`Primary Examiner-Gary Benzion
`Attorney, Agent, or Firm-Pioneer Hi-Bred International,
`Inc.
`
`[57]
`
`ABSTRACT
`
`An inbred maize line, designated PHKW3, the plants and
`seeds of inbred maize line PHKW3, methods for producing
`a maize plant produced by crossing the inbred line PHKW3
`with itself or with another maize plant, and hybrid maize
`seeds and plants produced by crossing the inbred line
`PHKW3 with another maize line or plant.
`
`13 Claims, No Drawings
`
`Inari Exhibit 1084
`Inari v. Pioneer
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3/1989 Segebart .
`4,812,599
`5,157,206 10/1992 Noble ...................................... 800/200
`
`FOREIGN PATENT DOCUMENTS
`
`160390 11/1985 European Pat. Off ..
`
`OTHER PUBLICATIONS
`
`Conger, B. V., et al. (1987) "Somatic Embryogenesis From
`Cultured Leaf Segments of Zea mays", Plant Cell Reports,
`6:345-347.
`Duncan, D. R., et al. (1985) 'Toe Production of Callus
`Capable of Plant Regeneration From Immature Embryos of
`Numerous Zea mays Genotypes", Planta, 165:322-332.
`Edallo, et al. (1981) "Chromosomal Variation and Fre(cid:173)
`quency of Spontaneous Mutation Associated with in Vitro
`Culture and Plant Regeneration in Maize", Maydica, XXVI:
`39-56.
`Green, et al., (1975) "Plant Regeneration From Tissue
`Cultures of Maize", Crop Science, vol. 15, pp. 417-421.
`Green, C. E., et al. (1982) "Plant Regeneration in Tissue
`Cultures of Maize" Maize for Biological Research, pp.
`367-372.
`Hallauer, A. R. et al. (1988) "Corn Breeding" Com and
`Com Improvement, No. 18, pp. 463-481.
`Meghji, M. R., et al. (1984). "Inbreeding Depression, Inbred
`& Hybrid Grain Yields, and Other Traits of Maize Geno(cid:173)
`types Representing Three Eras", Crop Science, vol. 24, pp.
`545-549.
`
`

`

`5,534,661
`
`1
`INBRED MAIZE LINE PHKW3
`
`FIELD OF THE INVENTION
`
`This invention is in the field of maize breeding, specifi(cid:173)
`cally relating to an inbred maize line designated PHKW3.
`
`BACKGROUND OF THE INVENTION
`
`The goal of plant breeding is to combine in a single
`variety or hybrid various desirable traits. For field crops,
`these traits may include resistance to diseases and insects,
`tolerance to heat and drought, reducing the time to crop
`maturity, greater yield, and better agronomic quality. With
`mechanical harvesting of many crops, uniformity of plant
`characteristics such as germination and stand establishment,
`growth rate, maturity, and plant and ear height, is important.
`Field crops are bred through techniques that take advan(cid:173)
`tage of the plant's method of pollination. A plant is self(cid:173)
`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 25
`for many generations become homozygous at almost all
`gene loci and produce a uniform population of true breeding
`progeny. A cross between two different homozygous lines
`produces a uniform population of hybrid plants that may be
`heterozygous for many gene loci. A cross of two plants each 30
`heterozygous at a number of gene loci will produce a
`population of hybrid plants that differ genetically and will
`not be uniform.
`Maize plants (Zea mays L.), often referred to as com in the
`United States, can be bred by both self-pollination and 35
`cross-pollination techniques. Maize has separate male and
`female flowers on the same plant, located on the tassel and
`the ear, respectively. Natural pollination occurs in maize
`when wind blows pollen from the tassels to the silks that
`protrude from the tops of the ears.
`A reliable method of controlling male fertility in plants
`offers the opportunity for improved plant breeding. This is
`especially true for development of maize hybrids, that relies
`upon some sort of male sterility system. There are several 45
`options for controlling male fertility available to breeders,
`such as: manual or mechanical emasculation (or detassel(cid:173)
`ing), cytoplasmic male sterility, genetic male sterility, game(cid:173)
`tocides and the like.
`Hybrid maize seed is typically produced by a male 50
`sterility system incorporating manual or mechanical detas(cid:173)
`seling. Alternate strips of two inbred varieties of maize are
`planted in a field, and the pollen-bearing tassels are removed
`from one of the inbreds (female). Providing that there is
`sufficient isolation from sources of foreign maize pollen, the 55
`ears of the dctasseled inbred will be fertilized only from the
`other inbred (male), and the resulting seed is therefore
`hybrid and will form hybrid plants.
`The laborious, and occasionally unreliable, detasseling
`process can be avoided by using cytoplasmic male-sterile 60
`(CMS) inbreds. Plants of a CMS inbred are male sterile as
`a result of factors resulting from the cytoplasmic, as opposed
`to the nuclear, genome. Thus, this characteristic is inherited
`exclusively through the female parent in maize plants, since
`only the female provides cytoplasm to the fertilized seed. 65
`CMS plants are fertilized with pollen from another inbred
`that is not male-sterile. Pollen from the second inbred may
`
`20
`
`2
`or may not contribute genes that make the hybrid plants
`male-fertile. Usually seed from detasseled fertile maize and
`CMS produced seed of the same hybrid are blended to insure
`that adequate pollen loads are available for fertilization
`5 when the hybrid plants are grown.
`There are several methods of conferring genetic male
`sterility available, such as multiple mutant genes at separate
`locations within the genome that confer male sterility, as
`disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar
`10 et al. and chromosomal translocations as described by
`Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. These
`and all patents referred to are incorporated herein by refer(cid:173)
`ence. In addition to these methods, Albertsen et al., of
`Pioneer Hi-Bred, U.S. patent application Ser. No. 07/848,
`15 433, have developed a system of nuclear male sterility that
`includes: identifying a gene that is critical to male fertility;
`silencing this native gene that is critical to male fertility;
`removing the native promoter from the essential male fer(cid:173)
`tility gene and replacing it with an inducible promoter;
`inserting this genetically engineered gene back into the
`plant; and thus creating a plant that is male sterile because
`the inducible promoter is not "on" resulting in the male
`fertility gene not being transcribed. Fertility is restored by
`inducing, or turning "on", the promoter, that in tum allows
`the gene that confers male fertility to be transcribed.
`There are many other methods of conferring genetic male
`sterility in the art, each with it's own benefits and draw(cid:173)
`backs. These methods use a variety of approaches such as
`delivering into the plant a gene encoding a cytotoxic sub(cid:173)
`stance associated with a male tissue specific promoter or an
`antisense system in which a gene critical to fertility is •
`identified and an antisense to that gene is inserted in the
`plant (see: Fabinjanski, et al. EPO 89/3010153.8 publication
`no. 329,308 and PCT application PCT/CA90/00037 pub(cid:173)
`lished as WO 90/08828).
`Another system useful in controlling male sterility makes
`use of gametocides. Gametocides are not a genetic system,
`but rather a topical application of chemicals. These chemi(cid:173)
`cals affect cells that are critical to male fertility. The appli(cid:173)
`cation of these chemicals affects fertility in the plants only
`for the growing season in which the gametocide is applied
`(see Carlson, Glenn R., U.S. Pat. No. 4,936,904). Applica(cid:173)
`tion of the gametocide, timing of the application and geno(cid:173)
`type specificity often limit the usefulness of the approach.
`The use of male sterile inbreds is but one factor in the
`development of maize hybrids. The development of maize
`hybrids requires, in general, the development of homozy(cid:173)
`gous inbred lines, the crossing of these lines, and the
`evaluation of the crosses. 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 selfing and selec(cid:173)
`tion of desired phenotypes. The new inbreds are crossed
`with other inbred lines and the hybrids from these crosses
`are evaluated to determine which of those have commercial
`potential.
`Pedigree breeding starts with the crossing of two geno(cid:173)
`types, each of that may have one or more desirable charac(cid:173)
`teristics that is lacking in the other or that complement the
`other. If the two original parents do not provide all the
`desired characteristics, other sources can be included in the
`breeding population. In the pedigree method, superior plants
`are selfed and selected in successive generations. In the
`succeeding generations the heterozygous condition gives
`
`40
`
`

`

`5,534,661
`
`5
`
`30
`
`3
`way to homogeneous lines as a result of self-pollination and
`selection. Typically in the pedigree method of breeding five
`or more generations of selfing and selection is practiced:
`F1 ➔ F 2
`; F3 ➔F4; F4➔F5 , etc.
`Recurrent selection breeding, backcrossing for example,
`can be used to improve an inbred line. Backcrossing can be
`used to transfer a specific desirable trait from one inbred or
`source to an inbred that lacks that trait. This can be accom(cid:173)
`plished, for example, by first crossing a superior inbred
`(recurrent parent) to a donor inbred (non-recurrent parent),
`that carries the appropriate gene(s) for the trait in question.
`The progeny of this cross is then mated back to the superior
`recurrent parent followed by selection in the resultant prog(cid:173)
`eny for the desired trait to be transferred from the non(cid:173)
`recurrent parent. After five or more backcross generations 15
`with selection for the desired trait, the progeny will be
`heterozygous for loci controlling the characteristic being
`transferred, but will be like the superior parent for most or
`almost all other genes. The last backcross generation would
`be selfed to give pure breeding progeny for the gene(s) being 20
`transferred.
`A single cross hybrid maize variety is the cross of two
`inbred lines, each of that has a genotype that complements
`the genotype of the other. The hybrid progeny of the first
`generation is designated F1. In the development of hybrids
`only the F1 hybrid plants are sought. Preferred F 1 hybrids are
`more vigorous than their inbred parents. This hybrid vigor,
`or heterosis, can be manifested in many polygenic traits,
`including increased vegetative growth and increased yield.
`The development of a hybrid maize variety involves three
`steps: (1) the selection of plants from various germplasm
`pools for initial breeding crosses; (2) the selfing of the
`selected plants from the breeding crosses for several gen(cid:173)
`erations to produce a series of inbred lines, that, although 35
`different from each other, breed true and are highly uniform;
`and (3) crossing the selected inbred lines with different
`inbred lines to produce the hybrid progeny (F1). During the
`inbreeding process in maize, the vigor of the lines decreases.
`Vigor is restored when two different inbred lines are crossed 40
`to produce the hybrid progeny (F1). An important conse(cid:173)
`quence of the homozygosity and homogeneity of the inbred
`lines is that the hybrid between any two inbreds will always
`be the same. Once the inbreds that give a superior hybrid
`have been identified, the hybrid seed can be reproduced 45
`indefinitely as long as the homogeneity of the inbred parents
`is maintained.
`A single cross hybrid is produced when two inbred lines
`are crossed to produce the F 1 progeny. A double cross hybrid
`is produced from four inbred lines crossed in pairs (AxB and 50
`CxD) and then the two F 1 hybrids are crossed again (AxB)x
`(CxD). Much of the hybrid vigor exhibited by F I hybrids is
`) . Consequently, seed from
`lost in the next generation (F 2
`hybrid varieties is not used for planting stock.
`Maize is an important and valuable field crop. Thus, a
`continuing goal of plant breeders is to develop high-yielding
`maize 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 of the crop to environmental
`stresses. To accomplish this goal, the maize breeder must
`select and develop superior inbred parental lines for pro(cid:173)
`ducing hybrids. This requires identification and selection of
`genetically unique individuals that occur in a segregating
`population. The segregating population is the result of a 65
`combination of crossover events plus the independent
`assortment of specific combinations of alleles at many gene
`
`4
`loci that results in specific genotypes. Based on the number
`of segregating genes, the frequency of occurrence of an
`individual with a 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
`population. Typically, however, the
`in a large F 2 or S
`10 genotype of neither the parents nor the desired genotype is
`known in any detail.
`In addition to the preceding problem, it is not known how
`the genotype will react with the environment. This genotype
`by environment interaction is an important, yet unpredict(cid:173)
`able, factor in plant breeding. A breeder of ordinary skill in
`the art cannot predict the genotype, how that genotype will
`interact with various environments or the resulting pheno(cid:173)
`types of the developing lines, except perhaps in a very broad
`and general fashion. A breeder of ordinary skill in the art
`would also be unable to recreate the same line twice from the
`very same original parents as the breeder is unable to direct
`how the genomes combine or how they will interact with the
`environmental conditions. This unpredictability results in
`the expenditure of large amounts of research resources in the
`25 development of a superior new maize inbred line.
`Pioneer research station staff propose about 400 to 500
`new inbreds each year from over 2,000,000 pollinations. Of
`those proposed new inbreds, less than 50 and more com(cid:173)
`monly less than 30 are actually selected for commercial use.
`
`0
`
`SUMMARY OF THE INVENTION
`
`According to the invention, there is provided a novel
`inbred maize line, designated PHKW3. This invention thus
`relates to the seeds of inbred maize line PHKW3, to the
`plants of inbred maize line PHKW3, and to methods for
`producing a maize plant produced by crossing the inbred
`line PHKW3 with itself or another maize line. This inven(cid:173)
`tion further relates to hybrid maize seeds and plants pro(cid:173)
`duced by crossing the inbred line PHKW3 with another
`maize line.
`
`DEFINITIONS
`
`55
`
`In the description and examples that follow, a number of
`terms are used herein. In order to provide a clear and
`consistent understanding of the specification and claims,
`including the scope to be given such terms, the following
`definitions are provided. NOTE: ABS is in absolute terms
`and %MN is percent of the mean for the experiments in
`which the inbred or hybrid was grown. These designators
`will follow the descriptors to denote how the values are to
`be interpreted. Below are the descriptors used in the data
`tables included herein.
`ANT ROT=ANTHRACNOSE STALK ROT (Colletotri(cid:173)
`chum graminicola). A 1 to 9 visual rating indicating the
`resistance to Anthracnose Stalk Rot. A higher score indicates
`60 a higher resistance.
`BAR PLT=BARREN PLANTS. The percent of plants per
`plot that were not barren (lack ears).
`BRT STK=BRITTLE STALKS. This is a measure of the
`stalk breakage near the time of pollination, and is an
`indication of whether a hybrid or inbred would snap or break
`near the time of flowering under severe winds. Data are
`presented as percentage of plants that did not snap.
`
`

`

`5,534,661
`
`6
`GDU=Growing Degree Units. Using the Barger Heat Unit
`Theory, that assumes that maize growth occurs in the
`temperature range 50° F.-86° F. and tbat temperatures
`outside this range slow down growth; the maximum daily
`heat unit accumulation is 36 and the minimum daily heat
`unit accumulation is 0. The seasonal accumulation of GDU
`is a major factor in determining maturity zones.
`GDU SHD=GDU TO SHED. The number of growing
`degree units (GDUs) or heat units required for an inbred line
`or hybrid to have approximately 50 percent of the plants
`shedding pollen and is measured from the time of planting.
`Growing degree units are calculated by the Barger Method,
`where the heat units for a 24-hour period are:
`
`GDU
`
`(Max. temp.+ Min. temp.)
`2
`
`50
`
`35
`
`5
`BU ACR=YIELD (BUSHELS/ACRE). Yield of the grain
`at harvest in bushels per acre adjusted to 15.5% moisture.
`CLN=CORN LETHAL NECROSIS (synergistic interac(cid:173)
`tion of maize chlorotic mottle virus (MCMV) in combina(cid:173)
`tion with either maize dwarf mosaic virus (MDMV-A or s
`MDMV-B) or wheat streak mosaic virus (WSMV)). A 1 to
`9 visual rating indicating the resistance to Com Lethal
`Necrosis. A higher score indicates a higher resistance.
`COM RST=COMMON RUST (Puccinia sorghi). A 1 to
`9 visual rating indicating the resistance to Common Rust. A 10
`higher score indicates a higher resistance.
`D/D=DRYDOWN. This represents the relative rate at
`which a hybrid will reach acceptable harvest moisture
`compared to other hybrids on a 1-9 rating scale. A high score
`indicates a hybrid that dries relatively fast while a low score 15
`indicates a hybrid that dries slowly.
`DIP ERS=DIPLODIA EAR MOLD SCORES (Diplodia
`maydis and Diplodia macrospora). A 1 to 9 visual rating
`indicating the resistance to Diplodia Ear Mold. A higher
`score indicates a higher resistance.
`DRP EAR=DROPPED EARS. A measure of the number
`of dropped ears per plot and represents the percentage of
`plants that did not drop ears prior to harvest.
`D/T=DROUGHT TOLERANCE. This represents a 1-9
`rating for drought tolerance, and is based on data obtained 25
`under stress conditions. A high score indicates good drought
`tolerance and a low score indicates poor drought tolerance.
`EAR HT=EAR HEIGHT. The ear height is a measure
`from the ground to the highest placed developed ear node
`attachment and is measured in inches.
`EAR MLD=General Ear Mold. Visual rating (1-9 score)
`where a "l" is very susceptible and a "9" is very resistant.
`This is based on overall rating for ear mold of mature ears
`without determining the specific mold organism, and may
`not be predictive for a specific ear mold.
`EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The
`higher the rating the larger the ear size.
`ECB lLF=EUROPEAN CORN BORER FIRST GEN(cid:173)
`ERATION LEAF FEEDING (Ostrinia nubilalis). A 1 to 9 40
`visual rating indicating the resistance to preflowering leaf
`feeding by first generation European Com Borer. A higher
`score indicates a higher resistance.
`ECB 2IT=EUROPEAN CORN BORER SECOND GEN(cid:173)
`ERATION INCHES OF TUNNELING (Ostrinia nubilalis). 45
`Average inches of tunneling per plant in the stalk.
`ECB 2SC=EUROPEAN CORN BORER SECOND
`GENERATION (Ostrinia nubilalis). A 1 to 9 visual rating
`indicating post flowering degree of stalk breakage and other
`evidence of feeding by European Com Borer, Second Gen- 50
`cration. A higher score indicates a higher resistance.
`ECB DPE=EUROPEAN CORN BORER DROPPED
`EARS (Ostrinia nubilalis). Dropped ears due to European
`Com Borer. Percentage of plants that did not drop ears under
`second generation com borer infestation.
`EST CNT=EARLY STAND COUNT. This is a measure
`of the stand establishment in the spring and represents the
`number of plants that emerge on per plot basis for tbe inbred
`or hybrid.
`EYE SPT=Eye Spot (Kabatiella zeae or Aureobasidium
`zeae). A 1 to 9 visual rating indicating the resistance to Eye
`Spot. A higher score indicates a higher resistance.
`FUS ERS=FUSARIUM EAR ROT SCORE (Fusarium
`moniliforme or Fusarium subglutinans). A 1 to 9 visual 65
`rating indicating tbe resistance to Fusarium ear rot. A higher
`score indicates a higher resistance.
`
`The highest maximum temperature used is 86° F. and the
`lowest minimum temperature used is 50° F. For each inbred
`20 or hybrid it takes a certain number of GD Us to reach various
`stages of plant development.
`GDU SLK=GDU TO SILK. The number of growing
`degree units required for an inbred line or hybrid to have
`approximately 50 percent of the plants with silk emergence
`from time of planting. Growing degree units are calculated
`by the Barger Method as given in GDU SHD definition.
`GIB ERS=GIBBERELLA EAR ROT (PINK MOLD)
`(Gibberella zeae). A 1 to 9 visual rating indicating the
`resistance to Gibberella Ear Rot. A higher score indicates a
`30 higher resistance.
`GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1
`to 9 visual rating indicating the resistance to Gray Leaf Spot.
`A higher score indicates a higher resistance.
`GOS WLT=Goss' Wilt (Corynebacterium nebraskense).
`A 1 to 9 visual rating indicating tbe resistance to Goss' Wilt.
`A higher score indicates a higher resistance.
`GRN APP=GRAIN APPEARANCE. This is a 1 to 9
`rating for the general appearance of the shelled grain as it is
`harvested based on such factors as the color of harvested
`grain, any mold on the grain, and any cracked grain. High
`scores indicate good grain quality.
`H/POP=YIELD AT HIGH DENSITY. Yield ability at
`relatively high plant densities on 1-9 relative rating system
`with a higher number indicating the hybrid responds well to
`high plant densities for yield relative to other hybrids. A 1,
`5, and 9 would represent very poor, average, and very good
`yield response, respectively, to increased plant density.
`HC BLT=HELMINTHOSPORIUM CARBONUM LEAF
`BLIGHT (Helminthosporium carbonum). A 1 to 9 visual
`rating indicating the resistance to Helminthosporium infec(cid:173)
`tion. A higher score indicates a higher resistance.
`HD SMT=HEAD SMUT (Sphacelotheca reiliana), This
`score indicates the percentage of plants not infected.
`INC D/A=GROSS INCOME (DOLLARS PER ACRE).
`Relative income per acre assuming drying costs of two cents
`per point above 15.5 percent harvest moisture and current
`market price per bushel.
`INCOME/ACRE, Income advantage of hybrid to be pat-
`ented over other hybrid on per acre basis.
`INC ADV=GROSS INCOME ADVANTAGE. GROSS
`INCOME advantage of variety #1 over variety #2.
`L/POP=YIELD AT LOW DENSITY. Yield ability at
`relatively low plant densities on a 1-9 relative system with
`a higher number indicating the hybrid responds well to low
`plant densities for yield relative to other hybrids. A 1, 5, and
`
`55
`
`60
`
`

`

`5,534,661
`
`7
`9 would represent very poor, average, and very good yield
`response, respectively, to low plant density.
`MDM CPX=MAIZE DWARF MOSAIC COMPLEX
`(MDMV=Maize Dwarf Mosaic Virus and MCDV=Maize
`Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating the 5
`resistance to Maize Dwarf Mosaic Complex. A higher score
`indicates a higher resistance.
`MST=HARVEST MOISTURE. The moisture is the actual
`percentage moisture of the grain at harvest.
`MST ADV=MOISTURE ADVANTAGE. The moisture 10
`advantage of variety #1 over variety #2 as calculated by:
`MOISTURE of variety #2 -MOISTURE of variety
`#!=MOISTURE ADVANTAGE of variety #1.
`NLF BLT=Northern Leaf Blight (Helmninthosporium
`turcicum or Exserohilum turcicum). A 1 to 9 visual rating
`indicating the resistance to Northern Leaf Blight. A higher
`score indicates a higher resistance.
`PLT HT=PLANT HEIGHT. This is a measure of the
`height of the plant from the ground to the tip of the tassel in 20
`inches.
`POL SC=POLLEN SCORE. A 1 to 9 visual rating indi(cid:173)
`cating the amount of pollen shed. The higher the score the
`more pollen shed.
`POL WT=POLLEN WEIGHT. This is calculated by dry
`weight of tassels collected as shedding commences minus
`dry weight from similar tassels harvested after shedding is
`complete.
`It should be understood that the inbred can, through
`routine manipulation of cytoplasmic or other factors, be
`produced in a male-sterile form.
`POP Kl A=PLANT POPULATIONS. Measured as 1000s
`per acre.
`POP ADV=PLANT POPULATION ADVANTAGE. The
`plant population advantage of variety #1 over variety #2 as
`calculated by PLANT POPULATION of variety #2
`-PLANT POPULATION of variety #!=PLANT POPULA(cid:173)
`TION ADVANTAGE of variety #1.
`PRM=PREDICTED Relative Maturity. This trait, pre- 40
`dieted relative maturity, is based on the harvest moisture of
`the grain. The relative maturity rating is based on a known
`set of checks and utilizes standard linear regression analyses
`and is referred to as the Comparative Relative Maturity
`Rating System that is similar to the Minnesota Relative
`Maturity Rating System.
`PRM SHD=A relative measure of the growing degree
`units (GDU) required to reach 50% pollen shed. Relative
`values are predicted values from the linear regression of
`observed GDU's on relative maturity of commercial checks.
`RT LDG=ROOT LODGING. Root lodging is the percent(cid:173)
`age of plants that do not root lodge; plants that lean from the
`vertical axis at an approximately 30° angle or greater would
`be counted as root lodged.
`RTL ADV=ROOT LODGING ADVANTAGE. The root 55
`lodging advantage of variety #1 over variety #2.
`SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating
`indicating the amount of scatter grain (lack of pollination or
`kernel abortion) on the ear. The higher the score the less 60
`scatter grain.
`SDG VGR=SEEDLING VIGOR. This is the visual rating
`(1 to 9) of the amount of vegetative growth after emergence
`at the seedling stage (approximately five leaves). A higher
`score indicates better vigor.
`SEL IND=SELECTION INDEX. The selection index
`gives a single measure of the hybrid's worth based on
`
`8
`information for up to five traits. A maize breeder may utilize
`his or her own set of traits for the selection index. One of the
`traits that is almost always included is yield. The selection
`index data presented in the tables represent the mean value
`averaged across testing stations.
`SLF BLT=SOUTHERN LEAF BLIGHT (Helminthospo(cid:173)
`rium maydis or Bipolaris maydis). A I to 9 visual rating
`indicating the resistance to Southern Leaf Blight. A higher
`score indicates a higher resistance.
`SOU RST=SOUTHERN RUST (Puccinia polysora). A 1
`to 9 visual rating indicating the resistance to Southern Rust.
`A higher score indicates a higher resistance.
`STA GRN=STAY GREEN. Stay green is the measure of
`plant health near the time of black layer formation (physi-
`15 ological maturity). A high score indicates better late-season
`plant health.
`STD ADV=STALK STANDING ADVANTAGE. The
`advantage of variety #1 over variety #2 for the trait STK
`CNT.
`STK CNT=NUMBER OF PLANTS. This is the final
`stand or number of plants per plot.
`STK LDG=STALK LODGING. This is the percentage of
`plants that did not stalk lodge (stalk breakage) as measured
`by either natural lodging or pushing the stalks and deter-
`25 mining the percentage of plants that break below the ear.
`STW WLT=Stewart's Wilt (Erwinia stewartii). A 1 to 9
`visual rating indicating the resistance to Stewart's Wilt. A
`higher score indicates a higher resistance.
`TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was
`used to measures the degree of blasting (necrosis due to heat
`stress) of the tassel at the time of flowering. A 1 would
`indicate a very high level of blasting at time of flowering,
`while a 9 would have no tassel blasting.
`TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used
`to indicate the relative size of the tassel. The higher the
`rating the larger the tassel.
`TAS VVT=TASSEL WEIGHT. This is the average weight
`of a tassel (grams) just prior to pollen shed.
`TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was
`used to indicate the relative hardness (smoothness of crown)
`of mature grain. A 1 would be very soft (extreme dent) while
`a 9 would be very hard (flinty or very smooth crown).
`TILLER=TILLERS. A count of the number of tillers per
`45 plot that could possibly shed pollen was taken. Data is given
`as a percentage of tillers: number of tillers per plot divided
`by number of plants per plot.
`TST WT=TEST WEIGHT (UNADJUSTED). The mea-
`50 sure of the weight of the grain in pounds for a given volume
`(bushel).
`TST WTA=TEST WEIGHT ADJUSTED. The measure of
`the weight of the grain in pounds for a given volume
`(bushel) adjusted for 15.5 percent moisture.
`TSW ADV=TEST WEIGHT ADVANTAGE. The test
`weight advantage of variety #1 over variety #2.
`WIN M%=PERCENT MOISTURE WINS.
`WIN Y%=PERCENT YIELD WINS.
`YLD=YIELD. It is the same as BU ACR ABS.
`YLD ADV=YIELD ADVANTAGE. The yield advantage
`of variety #1 over variety #2 as calculated by: YIELD of
`variety #1 - YIELD variety #2=yield advantage of variety
`#1.
`YLD SC=YIELD SCORE. A 1 to 9 visual rating was used
`to give a relative rating for yield based on plot ear piles. The
`higher the rating the greater visual yield appearance.
`
`65
`
`30
`
`35
`
`

`

`9
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`5,534,661
`
`10
`described in the Variety Description Information (Table 1)
`that follows. Most of the data in the Variety Description
`information was collected at Johnston, Iowa. The inbred has
`been self-pollinated and ear-rowed a sufficient number of
`5 generations with careful attention paid to uniformity of plant
`type to ensure the homozygousity and phenotypic stability
`necessary to use .in commercial production. The line has
`been increased both by hand and in isolated fields with
`continued observation for uniformity. No variant traits have
`10 been observed or are expected in PHKW3.
`Inbred maize line PHKW3, being substantially homozy(cid:173)
`gous, can be reproduced by