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Flashcards in Crop Growth Deck (42):
1

Characteristic of 

Germination and Emergence

  • occur when
    • seed imbibes water
    • embryo develops
    • coleoptile (monocot) or hypocotyl (dicot) crosses soil atmosphere interface 

2

Characteristics of 

Vegetative Growth Stage

  • include development of roots, stems and leaves

3

Characteristics of 

Flowering stage

  • reproductive stage
    • blooms / flowers produced

4

Characteristics of 

Seed Development

  • includes development of seed embryo and surrounding seed coat

5

Physiological maturity

Characteristics of 

  • occurs at maximum seed dry weight

6

Temp and Moisture Effects

Germination and Emergence

  • Germination and Emergence Reduced when
    • soil moisture above field capacity / below permanent wilting %
    • soil temp not in optimum range
    • Soil oxygen levels small or zero

7

Temp and Moisture Effects

Vegetative and Early Reproductive growth

  • Above / below optimum temp range, growth and dev slow
  • high temps
    • protoplasm in cells is destroyed
    • sun burning
  • low temps
    • cell damage (ice forms in plant)
    • water moves from protoplasm to intercellular spaces
      • dehydration of protoplasm / death
  • Vernalization - low temp that starts reproductive growth

Water

  • water needs small (primarily transpirational needs)
  • excessive water limits oxygen - roots at surface
    • large aerenchyma cells can form in some plants for more O2
  • drought
    • leaf surfaces waxy and tough
      • reduces transpiration losses
    • more efficient root systems, stomata closure

8

Temp and Moisture Effects

Flowering, seed development, physiological maturity

Temp / moisture extremes

  • flowering seed development  can be negatively impacted
  • most common
    • drought plus high temps
      • decreases pollinaiton
      • seed set
      • seed development
      • physiological maturity delayed

9

Growing Day

  • Growth / dev of plants influenced by heat
    • units are degree days
      • used to calculate culmulative amount of heat exposure plant has since starting point
      • generally, base temp above which heat units accumulate as the difference between average daily vs base temp
        • example = base is 50 degrees, average temp is 87
          • 37 added to growing degree days
    • if growing days are less than base temp
      • no heat units accumulate

10

Use Growing Degree Days

  • Growing degree days used in
    • cropping systems
    • time management practices
    • to determine crop growth stages including maturity (harvest)
  • management practices initiated by growing degree days
    • application of fertilizers
    • pesticides to avoid crop injury and improve control
    • initiation of scouting pests
    • irrigation or cessation of irrigation

11

Day length and flowering

  • also known as photoperiodism
  • day length on flowering is actually the impact of a period of darkness
    • short day plants flower after a series of dark period or nights
    • long day plants flower after series of short dark periods
    • flowering of some (nuetral) not impacted by day / night length

12

What are the growing points in grasses and broadleaf plants

Broadleaf Plants (dicots)

  • end or APICAL MERISTEM of the shoot is primary growing point for broadleaf plants (Dicots)

Grasses (monocots)

  • intercalary meristem located at base of the internods is primary growing point for grasses
    • may be located underground
      • protects grass from temp / injuries

13

Affect on canopy closure

  • as row spacing narrows, canopy closes earlier
  • plant pop increases, canopy closes earlier
  • plant growth habit impacts closure
    • upright / less bushy delays canopy closure

14

Summer Annual

  • Growing seasons = 1
  • Life Cycle
    • seeds germinate in spring
    • plants produce seed / die in fall

15

Winter annual

  • Growing seasons - 1
  • Life cycle
    • seeds germinate in fall
    • plants produce seed in spring and die in summer

16

Biennial

  • Growing seasons 2
  • life cycle
    • seeds germinate in year 1
    • after over wintering , vernalization plants produce seed in summer of year two and die that fall

17

Perennial 

  • growing seasons >2
  • life cycle
    • have vegetative structures that allow them to live more than two years

18

How the soil factor impacts crop root growth

pH

  • pH extremes can reduce root growth
  • roots of some crops not very tolerant of acid soils
    • aluminum toxicity might occur
  • roots of others may not grow in alkaline soils due to nutrient deficiencies 

19

How the soil factor impacts crop root growth

Moisture

  • if moisture is lacking, root growth will decline due to moisture stress
  • if moisture excessive
    • root growth may decline due to lack of oxygen 
      • adventitious roots may develop

20

How the soil factor impacts crop root growth

Texture / structure

  • determine size and distribution of pores in soil
    • in turn, determines moisture and oxygen status
      • needed for good root growth

21

Nutrient status

How the soil factor impacts crop root growth

  • controls root growth because nutrients that are deficient will limit root growth

22

How the soil factor impacts crop root growth

Fertilizer placement 

  • placement near actively growing roots will increase nutrient uptake and root growth 
  • too much fertilizer near root can cause root damage (salts)

23

How the soil factor impacts crop root growth

Soil borne dieseases / insects

  • can damage a root system,
    • but less likely to cause sufficient damage to decrease crop yields if root system healthy and active

24

How the soil factor impacts crop root growth

Compaction 

  • increases bulk density of soil 
  • physical barrier to root extension
  • potential for suboptimum moisture and oxygen for root growth / dev

25

How the soil factor impacts crop root growth

Salinity 

  • can reduce growth by
    • inhibiting water absorption (osmotic effect)
    • containing ions toxic to root system (specific ion effects)
    • or changing soil pH (nutrient avail changes)

26

How the soil factor impacts crop root growth

Soil Organic Matter

Soil Organic Matter

  • improves soil tilth,
  • decomposes releasing N and P
  • reduces leaching of K, Ca, Mg and cationic micronutrients

27

Tap or Fibrous Root systems

Nutrient Uptake

  • nutrient uptake occurs through diffusion, mass flow, root interception
    • requires root system to be at or near the nutrient in the soil 
      • especially diffusion and root interception
  • fibrous vs taproot root systems
    • tend to concentrate nutrient uptake nearer to soil surface than plants with taporoot systems

28

Tap or Fibrous Root systems

Water uptake

  • occurs where root system location at a depth where there is water
  • water uptake / transpiration function of
    • atmospheric properties (temp, relative humidity, wind)
    • location of avail water
    • location of root system

29

Tap or Fibrous Root systems

Erosion Control

  • increases when soil surface protected 
    • fibrous more effective of protecting from erosion

30

Tap or Fibrous Root systems

Soil Structure (aggregation)

  • can increase where root exudates occur
    • when roots decompose releasing binding substances
    • Aggregation highest with fibrous roots

31

Tap or Fibrous Root systems

Ability to penetrate compacted layers

  • occurs for both types
    • nature of pores created different
    • taproots create larger but fewer pores

32

Economics of Replanting

original planting date

  • more feasible if original planting date was early

33

Economics of Replanting

Expected date of replanting 

  • determines the potential yield and income of replanted crop

34

Economics of Replanting

Population of surviving plants

  • can be used to determine potential yield / income of the existing crop

35

Economics of Replanting

Pesticides

  • may impact subsequent crop
  • cost already incurred

36

Economics of Replanting

Stand uniformity

  • determines whether all or part of the field should be replanted

37

Economics of Replanting

Pest Pressure

  • changes throughout growing season 
  • may be different for the replanted crop
    • changes in pest management / costs

38

Economics of Replanting

Nutrients Applied

  • may or may not be avail to replanted crop 
    • changes in nutrient management / costs

39

Crop Insurance

Economics of Replanting

  • for lost crop may be more profitable than replanting

40

Seed Company Replant Policy

  • may alter profitability of replanting

41

Economics of Replanting

Weather

  • could be more feasible if weather suggests goof germination / stand

42

Diagnose Cropping Problem

 

  • pattern / history of field
  • Others to evaluate
    • cropping history
    • field prep
      • no till vs till
    • weather
    • management
      • planting date
    • equipment 
    • traits and seed treatments
      • seed sensitivity
    • pesticide history
      • carryover, overlapping sprays
    • soil characteristics
      • (pH, pans, salinity, compaction)