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Lee and Herbek, Grain Crops Extension © 20061 Corn Growth and Development Chad Lee Grain Crops Extension Specialist 859-257-3203 ●

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Presentation on theme: "Lee and Herbek, Grain Crops Extension © 20061 Corn Growth and Development Chad Lee Grain Crops Extension Specialist 859-257-3203 ●"— Presentation transcript:

1 Lee and Herbek, Grain Crops Extension © Corn Growth and Development Chad Lee Grain Crops Extension Specialist ●

2 Lee and Herbek, Grain Crops Extension © Goals for Today Growth and Development Key Management Issues Scouting Techniques Biotech Options

3 Lee and Herbek, Grain Crops Extension © Corn Growth Stages Vegetative (V) Reproductive (R) How a Corn Plant Develops, Special Report No. 48 Iowa State University

4 Lee and Herbek, Grain Crops Extension © Vegetative StagesReproductive Stages VE emergenceR1 silking V1 first leafR2 blister V2 second leafR3 milk V3 third leafR4 dough V(n) nth leafR5 dent VT tasselingR6 physiological maturity * When staging a field of corn, each specific V or R stage is defined only when 50 percent or more of the plants in the field are in or beyond that stage.

5 Lee and Herbek, Grain Crops Extension © “Spiking” Corn

6 Lee and Herbek, Grain Crops Extension © VE - Emergence

7 Lee and Herbek, Grain Crops Extension © V1 – One Visible Collar

8 Lee and Herbek, Grain Crops Extension © Corn Growth Stages: Vegetative V3 3 Collars V6 6 collars V12 12 collars V15 15 collars VT tassel

9 Lee and Herbek, Grain Crops Extension © Corn Growth Stages V3 3 Collars Nodal roots active. Growing point below ground. V6 6 collars Growing point above ground. Tassel and ear development starting. V12 12 collars Ear size, kernel size and kernel number being determined. Limits on water and/or nutrients will reduce yields.

10 Lee and Herbek, Grain Crops Extension © V3 – Three visible collars

11 Lee and Herbek, Grain Crops Extension © V3 Root hairs begin to form on Nodal Roots. Seminal Root growth has basically stopped. Growing point is below the soil surface. Frosts on the surface will not kill the plants. Freezing soil temps will kill the plant. Flooding can kill plants.

12 Lee and Herbek, Grain Crops Extension © V6 Tassel development has started. Ear shoot formation has also started.

13 Lee and Herbek, Grain Crops Extension © To be certain about V-stages beyond V6: Split the entire stalk (from the tip to the roots) in half with a knife. The first five nodes will be clustered near the bottom of the stalk and the 6 th node will be very close to the soil line. Count nodes above the 6 th node to determine how many nodes are present. The total number of nodes equals the V- stage of the plant. For example 7 nodes = V7 corn. V6 Leaves start to tear off the plant

14 Lee and Herbek, Grain Crops Extension © V6 Nodal Root System is the primary root system for nutrients and water. Growing point is above the ground. Ear shoot.

15 Lee and Herbek, Grain Crops Extension © V6 Premature Tassel

16 Lee and Herbek, Grain Crops Extension © V9

17 Lee and Herbek, Grain Crops Extension © V9 Growth rate rapidly increases. Greater demand for nutrients and water. Ear shoot. Growing point.

18 Lee and Herbek, Grain Crops Extension © V12 Both kernel size and kernel number are being determined. Any limits on water or nutrients at this phase will drastically impact yields. Earlier maturing hybrids will pass through this phase faster than later maturing hybrids.

19 Lee and Herbek, Grain Crops Extension © Corn Growth Stages V15 15 collars Rapid growth, about 10 to 12 days before silking. Most critical stage for yield determination. Most sensitive to stress. VT tassel Last tassel branch is visible but prior to silking. Complete leaf loss will cause nearly 100% yield loss.

20 Lee and Herbek, Grain Crops Extension © V15 About days from silking. Entering the most critical stage for yield determination. The plant is most sensitive to water and/or nutrient stress at this stage. Irrigation- the 4 weeks around silking are the most critical.

21 Lee and Herbek, Grain Crops Extension © V15 Ear shoots near the top of the plant are starting to out- grow ear shoots lower on the plant. Lower part of plantUpper part of plant

22 Lee and Herbek, Grain Crops Extension © V18

23 Lee and Herbek, Grain Crops Extension © V18 Lower part of plantUpper part of plant

24 Lee and Herbek, Grain Crops Extension © V18 Lower part of plantUpper part of plant

25 Lee and Herbek, Grain Crops Extension © VT

26 Lee and Herbek, Grain Crops Extension © VT - Tassel Occurs when last branch of tassel is visible but before silks emerge. Most susceptible to hail damage at this stage. Complete leaf loss at VT will result in little to no yield.

27 Lee and Herbek, Grain Crops Extension © Pollen shed

28 Lee and Herbek, Grain Crops Extension © Corn Growth Stages: Reproductive R1 Silking R2 Blister R4 Dough R5 Dent R6 Physiological Maturity

29 Lee and Herbek, Grain Crops Extension © Corn Growth Stages R1 Silking N and P uptake are rapid. About 50% of total N is taken up after R1. K uptake is nearly complete. Water needed for pollination. Pollination occurs. R2 Blister Ear size nearly complete. Silks begin to dry out. A miniature corn plant is being formed in each fertilized kernel.

30 Lee and Herbek, Grain Crops Extension © R1- Silking

31 Lee and Herbek, Grain Crops Extension © R1 - Silking Silks starting to emerge. N uptake is rapid. P uptake is rapid. K uptake is nearly complete. Watch for corn borer feeding. Moisture is needed for pollination.

32 Lee and Herbek, Grain Crops Extension © R1 - Silking Cob material Premature kernel Two to three days are required for all silks on an ear to be pollinated.

33 Lee and Herbek, Grain Crops Extension © R2 - Blister An miniature corn plant has started to develop within the premature kernel. Ear size is nearly complete. Fertilized silks are starting to dry out.

34 Lee and Herbek, Grain Crops Extension © R3 - Milk Kernels are becoming yellow on the outside. Silks are dry. Kernels are at 80% moisture. Stress becomes less of a factor as kernels start to dry down.

35 Lee and Herbek, Grain Crops Extension © Corn Growth Stages R4 Dough Kernels have accumulated ½ of total dry weight. Five leaves have formed in the kernel. R5 Dent Most kernels have dented and are near 55% moisture at start. Starch layer has formed and progresses down the kernel.

36 Lee and Herbek, Grain Crops Extension © R4 - Dough Fluid in the kernel is becoming a consistency similar to dough. (70% moisture) Almost ½ of the dry weight has been accumulated. Five embryonic leaves have formed in the kernel. These will be the first five leaves of a new plant as it emerges next year.

37 Lee and Herbek, Grain Crops Extension © R5 - Dent Most of the kernels have dented on the top. Most kernels are about 55% moisture at the start of R5. A starch layer has formed and begins to progress down the kernel. A frost will stop dry matter accumulation and reduce yields.

38 Lee and Herbek, Grain Crops Extension © Corn Growth Stages R6 Physiological Maturity Blacklayer has formed at bottom of kernel. Kernel is about 30 to 35% moisture. For safe storage, needs to dry to 13 to 15% moisture

39 Lee and Herbek, Grain Crops Extension © R6 – Physiological Maturity Kernel is about 30 – 35% moisture. Kernels need to be at 13 to 15 % moisture for safe storage.

40 Lee and Herbek, Grain Crops Extension © R6 – Physiological Maturity Blacklayer

41 Lee and Herbek, Grain Crops Extension © Corn Planting Dates in Kentucky Corn should be planted by: Far Western KYMay 1 Western-Central KYMay 10 Eastern KYMay 15 Plant an earlier-maturing hybrid if corn planting is delayed after: June 5 A 1% yield loss per day can be expected in corn planted after: May 10-15

42 Lee and Herbek, Grain Crops Extension © Corn: Seeding Rates Table 3. Recommended corn seeding rates for Kentucky. Seeding rate* (seeds/acre) Grain22, ,000 Silage24, ,000 Irrigated26, ,000 * Range depends on potential yield of soil ranging from less than 100 bu/ac for the low range to more than 200 bu/ac for the high range.

43 Lee and Herbek, Grain Crops Extension © Biotech Tools for Corn Insects Bt Corn –YieldGard Corn Borer (Cry1Ab) –YieldGard Rootworm (Cry3Bb1) –YieldGard Plus (Cry1Ab+Cry3Bb1) –Herculex I (Cry1F) –Herculex RW (Cry34Ab1/Cry35Ab1) –Herculex Xtra (Cry1F+Cry34Ab1/Cry35Ab1) –Agrisure CB (Cry1Ab) –Agrisure RW ? (Cry3A) –Agrisure CB/RW ?

44 Lee and Herbek, Grain Crops Extension © Biotech Tools for Corn Weeds Roundup Ready genes –GA21 – “Roundup Ready” Applications from VE to V8 or 30 inches, whichever occurs first, up to 1.0 lb ae glyphosate/acre, depending on herbicide label (2 pt/A of 3 lb ae/gal formulation – Roundup Original) –NK603 – “Roundup Ready 2” Applications from VE to V8 or 30 inches, whichever comes first, up to 1.12 lb ae glyphosate/acre, depending on herbicide label (3 pt/A of 3 lb ae/gal formulation – Roundup Original) Drop nozzles from 30 to 48 are allowed

45 Lee and Herbek, Grain Crops Extension © Biotech Tools for Corn Weeds Liberty Link –T25 - Corn (PAT, BAR) –Combined with Herculex (Cry1F) Used as a marker gene for the Cry1F event

46 Lee and Herbek, Grain Crops Extension © Narrow Row Corn

47 Lee and Herbek, Grain Crops Extension © Estimating Corn Yield (kernels per ear) x (ears per acre) / (kernels per bushel) = (bushels/acre)

48 Lee and Herbek, Grain Crops Extension © Estimating Corn Yields Simplest (least accurate method) –Count number of kernels –Multiply that number by Using assumes 1) 27,000 ears per acre 2) 90,000 kernels per bushel 1

49 Lee and Herbek, Grain Crops Extension © Estimating Corn Yields Ears/AcreLarge Kernel Size (70,000 kernels/bushel) Multiplier Medium Kernel Size (90,000 kernels/bushel) Multiplier Small Kernel Size (110,000 kernels/bushel) Multiplier 22, , , , , , , , , , AGR-187: Estimating Corn Yields Including ears/acre as a factor and kernel size as a factor.

50 Lee and Herbek, Grain Crops Extension © Estimating Corn Yield Row Width (inches) Feet of row needed to equal 1/1000th acre Multiplier to Equal One Acre 1534 feet 10 inches1, feet 2 inches1, feet 9 inches1, feet 5 inches1, feet 6 inches1, feet 9 inches1,000 Measuring 1/1,000 th Acre AGR-187: Estimating Corn Yields

51 Lee and Herbek, Grain Crops Extension © Estimating Corn Yield More accurate stand measurements. Row Width (inches) Measured Row Length (feet) Total Measured Area (ft 2 ) Number of Ears per Measured Area Number of Ears per Acre , , , , , , , , ,848 AGR-187: Estimating Corn Yields

52 Lee and Herbek, Grain Crops Extension © Estimating Early Season Stand Losses Table 2. Grain yields for various planting dates and population rates, expressed as a percent of optimum planting date and population rate (uniformly spaced within row). Planting date Plants per acre at harvest 12,00014,00016,00018,00020,00022,50025,000 (% of optimum yield) April April April May May May May May May May June June Data from National Corn Handbook

53 Lee and Herbek, Grain Crops Extension © Keys to High Yields 1.Good genetics 2.Maximize days suitable for growing 3.90 to 95% light interception at silking (R1) 4.Adequate nutrients and water to complete plant growth and seed fill

54 Lee and Herbek, Grain Crops Extension © Keys to High Yields Good genetics –Good yield potential –Good stress tolerance –Good defense genetics

55 Lee and Herbek, Grain Crops Extension © Keys to High Yields Maximize days –Maturity group –Stress tolerance –Planting date

56 Lee and Herbek, Grain Crops Extension © Keys to High Yields 90 to 95% light interception at silking (R1) –Row spacing and population –Planting date –Hybrid Maturity

57 Lee and Herbek, Grain Crops Extension © Keys to High Yields Adequate nutrients and water to complete growth and seed fill –Soil pH –Adequate N, P, K, Zn –Precipitation –Water infiltration –Water availability

58 Lee and Herbek, Grain Crops Extension © Slats on a Barrel Economics Weather TOTAL YIELD Soil Fertility Hybrid Genetics Planting Date, Seeding Rate Pest Management Timely Harvest Soil Structure TOTAL YIELD Soil Fertility Hybrid Genetics Planting Date, Seeding Rate Pest Management Timely Harvest Soil Structure Economics Weather

59 Lee and Herbek, Grain Crops Extension ©

60 Lee and Herbek, Grain Crops Extension © Corn Growing Degree Days Each day has a slightly different average temperature. Temperature affects corn growth rate. Attempt to relate temperature to corn growth rate. Corn Growing Degree Day Base 50 ° F Max 86 ° F Min 50 ° F

61 Lee and Herbek, Grain Crops Extension © Corn Growing Degree Days Corn Growing Degree Day Base 50 ° F Max 86 ° F Min 50 ° F Example 1: –74 ° F average daily temperature –74 – 50 = 24 GDD Example 2: –90 ° F average daily temperature –86 – 50 = 36 GDD

62 Lee and Herbek, Grain Crops Extension © Corn Growing Degree Days Corn Maturity (Days)GDD 85 to – to – to – 3200 Growth StageGDD V2200 V6475 V12870 VT1135 R11400 R62700 GDD Requirements of a 2700 GDD Hybrid From NCH-40 Growing Season Characteristics and Requirements in the Corn Belt. National Corn Handbook.

63 Lee and Herbek, Grain Crops Extension © Planting Date and GDD Planting Date GDD As of 06/26/05 Difference From First Planting April May May May June Hybrid: DKC67-91: 119 CRM, 3000 GDD to Black Layer From University of Kentucky Ag Weather Center: Growing Degree Day calculator:

64 Lee and Herbek, Grain Crops Extension © Planting Date and GDD Planting Date GDD As of 07/11/05 Differenc e from First Planting April May May May June Hybrid: DKC67-91: 119 CRM, 3000 GDD to Black Layer From University of Kentucky Ag Weather Center: Growing Degree Day calculator:

65 Lee and Herbek, Grain Crops Extension © Date of Planting – Corn and Grain Silage Lexington Date plantedRelativeYieldRatio 35%Ear:Forage April 20Full :44 May 6Full :41 May 21Full :40 May 31Full :40 June 10Full :43 June 10Early :40 June 29Early :52 May 20S :58

66 Lee and Herbek, Grain Crops Extension © Effect of Tillage and Planting Date on Corn Yield 4-avg. ( ) Planting Date ConventionalNo-TillAvg. Corn Yield (bu/A) Early May Mid-May Early June Avg Three-year avg. only data missing for Early May.

67 Lee and Herbek, Grain Crops Extension © Corn Planting Depth and Planting Date Planting Depth Planting Date April 13May 2 (inches)% Stand Days to Emerge % Stand Days to Emerge

68 Lee and Herbek, Grain Crops Extension © Germination Temperature for Corn 50 O F at a 2-inch depth for three or four days is excellent. Soil temperature at 50 O F at 7:00 am or 55 O F at 1:00 should ensure that temperatures are suitable for germination and growth.

69 Lee and Herbek, Grain Crops Extension © Population Effect on Corn Yields (Hardin County, Kentucky, ) PopulationCorn Yield (Bu/A) Plants/ANo-TillConventional 14-18, , , Average146120

70 Lee and Herbek, Grain Crops Extension © Effect of Row Width and Plant Population on Corn Yields (8 location average) Yield (bu/A) Row Width20 inch170 ab* 30 inch175 a 36 inch169 b Plant Population20, a 26, b 30, c *0.10 level for row width, 0.05 level for population.

71 Lee and Herbek, Grain Crops Extension © Row Width Effect on Corn Yields (Hardin County, Kentucky) Row WidthCorn Yield (Bu/A) (inches)No-TillConventional

72 Lee and Herbek, Grain Crops Extension © Corn Hybrid and Population Effect on Grain Yield Plants/AYield (bu/A) IrrigatedRainfedIrrigatedRainfed Pioneer 3160B73 x P A 91 20, , , DeKalb XL32AAA , , , Population resulting in highest yield varied across hybrids and water regimes.

73 Lee and Herbek, Grain Crops Extension © What determines crop row width? Fig. 2 The relationship between hybrid yield at different plant densities and year of release. Data were obtained from field experiments conducted at three locations in central Iowa in Duvick D.N., and K.G. Cassman Crop Science 39:

74 Lee and Herbek, Grain Crops Extension © Row Width Effect on Corn Grain Yield (Non-Irrigated) Yield (bu/A) 30 inch36 inchDifference Average

75 Lee and Herbek, Grain Crops Extension © Row Width Effect on Corn Grain Yield (Irrigated) Yield (bu/A) 30 inch36 inchDifference Average

76 Lee and Herbek, Grain Crops Extension © Corn Hybrid, Row Width and Plant Population Summary Across Years Hybrid Yield (bu/A) Row Width Yield (bu/A) Pioneer 33Y a20 inch148.4 a So. States SS b30 inch150.9 a Plant Population Yield (bu/A) 24, a 28, a 32, a

77 Lee and Herbek, Grain Crops Extension © Recommended Corn Seeding Rates (Greatest Limiting Factor to Corn Yield) Plants / Acre Rainfed Grain Corn (No-Till and Conventional) 22,000 – 30,000 Irrigated Grain (No-Till and Conventional) 26,000 – 32,000 Silage24, ,000 From ID-139: A Comprehensive Guide to Corn Management in Kentucky.

78 Lee and Herbek, Grain Crops Extension © Uneven Corn Stands Cost Money Good stands = 2 inch deviation –Example 26,000 seeds on 30 inch row –Equals 1 plant every 8 inches –Good stand is 6 to 10 inches apart 2.5 bushel lost for every 1 inch increase in deviation –3 inch deviation = 2.5 bushel loss –5 inch deviation = 7.5 bushel loss

79 Lee and Herbek, Grain Crops Extension © Effect of Emergence Delays on Corn Yield Uneven emergence of: –10 days = 6 – 9 % loss –21 days = 10 – 22% loss –7 days = 5.5% loss –14 days = 13.2% loss Primary Causes: –1. Soil Moisture –2. Poor soil-to-seed contact (Wisconsin and Illinois research) (Minnesota research)

80 Lee and Herbek, Grain Crops Extension © The major factor influencing vegetative development in grain crops is: TEMPERATURE Ideal Growing Temperatures for: Corn=77 to 88 ° F Soybean=65 to 84 ° F Wheat=62 to 73 ° F

81 Lee and Herbek, Grain Crops Extension © Second Year Corn vs. Rotated Corn (Soybeans) Corn Yield (Bu/A) (2002 – 2005) (4 yr. Avg.) Rotated Yield Advantage Corn HybridSecond Year Corn Corn After Soybeans Bu/A(%) Non-Bt (11%) Bt (11%) Avg (11%) Yearly Range (7-15%)

82 Lee and Herbek, Grain Crops Extension © Corn Ears: Good and Bad 1

83 Lee and Herbek, Grain Crops Extension © Corn Ears: Good and Bad 2 1

84 Lee and Herbek, Grain Crops Extension © Corn Ears: Good and Bad 1


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