Abstract:
According to the invention, there is provided an inbred corn line, designated CG00685. This invention thus relates to the plants and seeds of inbred corn line CG00685 and to methods for producing a corn plant produced by crossing the inbred line CG00685 with itself or with another corn line. This invention further relates to hybrid corn seeds and plants produced by crossing the inbred line CG00685 with another corn line.

Description:
This application is a continuation, of application Ser. No. 08/393,517, filed Feb. 22, 1995, now abandoned, which is a continuation of Ser. No. 08/253,191, filed Jun. 2, 1994, now abandoned, which is a continuation of Ser. No. 08/018,676 filed, Feb. 17, 1993, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention is in the field of hybrid corn (Zea mays L.) plant breeding, specifically relating to an inbred corn line designated CG00685. 
     BACKGROUND OF THE INVENTION 
     Of all the crops produced by U.S. farmers, corn is the crop that has the most economic value. Corn is utilized as livestock feed, as a basis for human consumption, as raw material for industry and as raw material for the production of ethanol. The primary use of farmer produced field corn is for livestock feed. This includes feed for hogs, beef cattle, dairy cows and poultry. 
     Human consumption of corn includes direct consumption of sweet corn and as snacks after extruder cooking, ground corn eaten as grits, corn meal and corn flour. Corn oil is also used as a high grade cooking oil, salad oil or in margarine. Corn is used in the production of some starches and syrups. Another important use is in the production of sweeteners used in soft drinks. 
     The wet-milling and dry-milling processes also produce corn starch and corn flour that have applications in industry. Some of these uses include building materials, the paper industry, textiles and starches. 
     The seed of inbred corn line CG00685, the plant produced by the inbred seed, hybrid seed produced from the crossing of the inbred, the hybrid corn plant grown from said seed, and various parts of the inbred and hybrid corn plant can be utilized for human food, livestock feed, and as a raw material in the industry. 
     The major reasons for the economic importance of corn and the large acreages planted to the crop are the hybridization of the corn plant and the continued improvement, by researchers, of the genetic stock that is used to produce the seed grown by farmers. This process has been on-going since its beginning in the early part of the century. The average bushel per acre yield for the American farmer has gone from around 30 in the middle of the 1930&#39;s (before hybrids became dominant) to the present average of close to 120. While not all of this four-fold increase can be attributed to genetic improvement (availability of relatively cheap nitrogen and improvements in farming practices are two other components), a good share of it can. 
     Corn is easily hybridized because of the physical distance between the tassel (male part) and the ear (female part). The method of hybridization first involves the development of inbred lines. Inbred corn lines are considered to be homozygous, or, in essence, genetically the same from generation to generation. They are produced by taking the pollen from one plant and putting it only on the ear of that same plant. The resulting seed is grown, selections for uniformity and improved agronomic characteristics are made and the process is repeated until the seeds from the ears of the plants produce homozygous plants and the line is pure. A hybrid is then produced by crossing one inbred with another, genetically different, inbred. The crossing consists of taking the pollen from one inbred and putting it on the ear of the other inbred. 
     The seed from the crossing of two inbred lines is a first generation hybrid and is called an F 1 . The F 1  of commercially viable hybrids have better yields, and other important characteristics, than either of the parents. This process is called hybrid vigor or heterosis. In succeeding generations (F 2 , F 3 , etc.) this heterosis is markedly reduced, making it economically justifiable for the farmer to go back to the seed company and obtain F 1  seed each year. As a result, the hybrid corn seed industry benefits both farmers and producers of hybrid corn seed. 
     The invention of new inbred lines and of new hybrids is extremely important to the companies in the hybrid seed corn industry that have investments in research. Much effort is given to the research and development of these inbreds and hybrids. The breeding and selection of inbred lines to be used as both seed parents and/or pollen parents and which when crossed to other inbred lines produce F 1  hybrid seed, which when planted, will produce plants that have characteristics that a farmer desires is a highly specialized skill. It involves many years of inbreeding, skilled selection, correct statistical testing, and decision making. 
     SUMMARY OF THE INVENTION 
     According to the invention, there is provided a novel inbred corn line, designated CG00685. This invention thus relates to the seeds of inbred corn line CG00685, to the plants of inbred corn line CG00685 and to methods for producing a corn plant produced by crossing the inbred line CG00685 with itself or another corn line. This invention further relates to hybrid corn seeds and plants produced by crossing the inbred line CG00685 with another corn line. 
     DEFINITIONS 
     This section will outline the definitions of terms used herein. 
     Yield (Bushels/Acre). Yield in bushels/acre is the actual yield of the grain at harvest adjusted to 15.0% moisture. 
     Percent Moisture. The percent moisture is the actual percentage moisture of the grain at harvest. 
     Percent Erect. The percent erect, a measure of standability, is the percentage of plants that are not broken below the ear at harvest. 
     Harvest Roots. Harvest roots is a visual rating. It is based on the number of plants that are root-lodged, i.e.; leaning from the vertical axis at an approximate 30° angle or greater. The ratings range from 1 to 9. A rating of 1 equals no plants root-lodged and a rating of 9 equals all plants root-lodged. 
     Percent Dropped Ears. The percent dropped ears is the percentage of plants that dropped (lost) their ears before harvest. 
     Percent Barren Plants. The percent barren plants is the percentage of plants that were barren (lacking ears). 
     Intactness. Intactness is a visual rating. It is based on the percentage of leaf and stalk matter remaining above the top ear at harvest. The ratings range from 1 to 9. A rating of 1 equals all matter remaining (intact) and a rating of 9 equals all matter gone or the stalk broken over just above the ear. 
     Percent Green. The percent green is the percentage of the total ear, leaf and stalk matter still green at the time of data collection, approximately physiological maturity. 
     Standard Index. Standard index gives a single measure of a hybrid&#39;s worth based on a linear model utilizing important traits such as yield, percent moisture, standability, percent dropped ears and harvest roots. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Inbred corn line CG00685 is a yellow dent/flint corn with superior characteristics and provides a good parental line in crosses for producing first generation (F 1 ) hybrid corn. 
     Inbred corn line CG00685 was selected for uniformity and agronomic traits using standard pedigree ear-row selection at Washington Court House, Ohio. The inbred was evaluated further as a line and in numerous crosses by the Washington Court House Research Station and other research stations across the central corn belt. Thus the line was evaluated for general and specific combining ability. 
     The inbred is adapted to the central and southern Illinois, Indiana, Ohio and Pennsylvania. It can be used advantageously in producing hybrids that are from approximately 105 day relative maturity to 125 day relative maturity based on the Minnesota Relative Maturity Rating System for harvest moisture of the grain. The inbred is an acceptable female parent with good seed size distribution. The inbred does not shed a large amount of pollen but has been successfully used as a male parent in seed production. It drys down rapidly and has contributed this trait to all of the hybrid combinations in which it has been tested. 
     The inbred has shown relative uniformity and stability for all traits as described in the following variety description information. It has been self-pollinated and ear-rowed a sufficient number of generations with careful attention paid to uniformity of plant type to insure relative homozygosity and phenotypic stability. The line has been increased by hand and in isolated fields with continued observations for uniformity. No particular variant traits have been observed or are expected in CG00685. 
     The inbred CG00685 is a Ciba-Geigy Seed Division (CGSD) proprietary inbred. 
     Inbred corn line CG00685 can be compared to the public inbred B68. The characteristics of CG00685 versus B68 are summarized below (based primarily on data collected at Bloomington, Ill.): 
     
         ______________________________________           CG00685   B68______________________________________MATURITYDays from emergence to 50%             65          72of plants in silkHeat units from emergence to             1583        174750% of plants in silkDays from emergence to 50%             64          68of plants shedding pollenHeat units from emergence to             1553        164450% of plants shedding pollenPLANT CHARACTERISTICSPlant height to tassel tip (cm)             201         186Ear height to top ear node (cm)             78          77Length of top ear internode (cm)             9           9Ears per stalk    Slight two- Single             ear tendencyNumber of tillers None        Slight                         tendencyAnthocyanin in brace roots             Present     PresentCytoplasm type    Normal      NormalLEAFColor             Medium green                         Medium                         greenAngle from stalk (degrees)             30-45       45Sheath pubescence Light       MediumMarginal waves    Few         FewLongitudinal creases             Few         FewWidth of ear node leaf at             8           7widest point (cm)Length of ear node leaf (cm)             70          76Number of leaves above the ear             5           7nodeTASSELNumber of lateral branches             5           8Branch angle from central spike             30-40       &gt;40(degrees)Peduncle length (cm)             12          4Pollen shed       Medium      MediumAnther color      Purple      YellowGlume color       Green       GreenGlume bars        Absent      AbsentEAR (Husked Ear Data at 12.5%Kernel Moisture)Length (cm)       13          15Mid-point diameter (mm)             36          32Weight (gm)       60          48Kernel rows       12, distinct,                         12, distinct,             slightly curved                         straightSilk color        Pink        PinkHusk color (fresh)             Light green Light greenHusk color (dry)  Buff        BuffHusk extension    Long (8-10 cm                         Very long             beyond ear  (&gt;10 cm)             tip)Husk leaf         Short (&lt;8 cm)                         Short (&lt;8                         cm)Shank length (cm) 12          11Shank (no. of internodes)             5           5Position of shank (dry husks)             Pendent     UprightTaper             Slight      SlightKERNEL (at 12.5% Kernel Moisture)Size (kernels taken from ear             9 mm long   8 mm longmidpoint)         7 mm wide   6 mm wide             4 mm thick  3 mm thickShape grade (% rounds)             &gt;80         60-80Pericarp color    Colorless   Red and                         white                         VariegatedAleurone color    Homozygous, Homozygous,             white       whiteEndosperm color   Yellow      YellowEndosperm type    Normal starch                         Normal                         starchGram weight/100 seeds (unsized             27          25sample)Test weight (pounds)             63          52COB Diameter at midpoint (mm)             23          24Strength          Strong      WeakColor             White       Red______________________________________ 
    
     Disease reaction information for CG00685 are given below: 
     
         ______________________________________Common rust        Moderately ResistantCommon smut        ResistantMaize chlorotic dwarf              ResistantMaize dwarf mosaic A              Moderately SusceptibleMaize dwarf mosaic B              Moderately SusceptibleSouthern corn leaf blight              Moderately ResistantWheat streak mosaic              Resistant______________________________________ 
    
     Heat units calculations are derived by using the following formula: Heat Units equals  Daily Maximum Temperature (≦86° F.) plus Daily Minimum Temperature (≧50° F.)! divided by 2 minus 50° F. 
     Electrophoresis results for CG00685 and the public inbred B68 are shown in Table 1 below: 
     
                       TABLE 1______________________________________Electrophoresis results for CG00685 and B68Alleles PresentLocus           CG00685  B68______________________________________Acp1            4        3Adh1            4        4Cat3            9        9Got1            4        4Got2            4        4Got3            4        4Idh1            4        4Idh2            6        6Mdh1            6        6Mdh2            6        6Mdh3            16       16Mdh4            12       12Mdh5            12       12Mmm             M        MPgm1            9        9Pgm2            3        4Pdg1            3.8      2Pdg2            5        5Phi1            4        5No. plants      36       9______________________________________ 
    
     This invention is also 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 corn plant is the inbred corn plant from the line CG00685. Further both first and second parent corn plants may be from the inbred line CG00685. Thus, any methods using the inbred corn line CG00685 are part of the invention: backcrosses, hybrid breeding, and crosses to populations. Any plants produced using inbred corn line CG00685 as a parent are within the scope of this invention. Advantageously, the inbred corn line CG00685 is used in crosses with other corn varieties to produce first generation (F 1 ) corn hybrid seed and plants with superior characteristics. 
     As used herein, the term &#34;plant&#34; includes plant cells, plant protoplasts, plant cell of 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 pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, and the like. Thus another aspect of this invention is to provide for cells which upon growth and differentiation produce the inbred line CG00685. 
     The seed of inbred corn line CG00685, the plant produced from the inbred seed, the hybrid corn plant produced from the crossing of the inbred, hybrid seed, and various parts of the hybrid corn plant can be utilized for human food, livestock feed, and as a raw material in industry. 
     The results in Table 2 compare a CG00685 corn hybrid to Funk G® brand 4626. Both hybrids have a parent in common other than CG00685. Funk G® brand 4626 is currently being sold in the United States and is adapted to most of the same areas as the CG00685 hybrid. The data was averaged across all locations and replications and would include experiments grown by several CGSD corn research programs in 1990 and 1991. 
     
                       TABLE 2______________________________________CG00685 hybrid (#1) compared to 4626 (#2)______________________________________                                   Percent  Yield   Percent    Percent                           Harvest Dropped  (BU/A)  Moisture   Erect Roots   Ears______________________________________1      120     15.5       93.6  1.6     1.022      120     17.8       94.6  1.8     0.89Difference   0      2.3        1.0   0.2     0.13Locations  142     142        123   14      28______________________________________  Percent  Barren               Percent                             Standard  Plants  Intactness   Green Index______________________________________1      10.3    6.0          32.5  1792      13.2    6.4          27.4  174Difference  2.9     0.4          5.1    5Locations  11      143          92    180______________________________________ 
    
     The data show that although CG00685 is earlier than 4626 (percent moisture) both CG00685 and 4626 make hybrids of similar yield. In this and other hybrid combinations, CG00685 has shown outstanding yield performance relative to other commercially sold hybrids of similar maturity. 
     The results in Table 3 compare a CG00685 corn hybrid to Funk G® brand 4530. Both hybrids have closely related parents in common other than CG00685, Funk G® brand 4530 is currently being sold in the United States and is adapted to most of the same areas as the CG00685 hybrid. The data was averaged across all locations and replications and would include experiments grown by several CGSD corn research programs in 1990 and 1991. 
     
                       TABLE 3______________________________________CG00685 hybrid (#1) compared to 4530 (#2)______________________________________                                   Percent  Yield   Percent    Percent                           Harvest Dropped  (BU/A)  Moisture   Erect Roots   Ears______________________________________1      124     15.6       93.3  1.7     0.802      124     17.8       96.3  2.0     0.33Difference   0      2.2        3.0   0.3     0.47Locations  171     171        154   26      65______________________________________  Percent  Barren               Percent                             Standard  Plants  Intactness   Green Index______________________________________1      7.0     5.4          38.8  1712      11.5    6.0          24.4  168Difference  4.5     0.6          14.4   3Locations  19      166          116   232______________________________________ 
    
     The data show that although CG00685 is earlier than 4626 (percent moisture) both CG00685 and 4626 make hybrids of similar yield. In this and other hybrid combinations, CG00685 has shown outstanding yield performance relative to other commercially sold hybrids of similar maturity. 
     Inbred seeds of CG00685 have been placed on deposit at the American Type Culture Collection (ATCC), Rockville, Md., 20852, under deposit accession number 75384 on Dec. 16, 1992. 
     Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the invention, as limited only by the scope of the appended claims.