Crop Growth and Flowering Flashcards

1
Q

What are growing degree days (GDD)

A

GDD: a measure of accumulated thermal units during the growing season that is correlated with plant development

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2
Q

GDD calculation

A

Heat units= (max. temp + min. temp) / 2- base

*Min temp less than 50 are set at 50. Max temp higher than 86 are set at 86.

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3
Q

Why is it important to know crop growth statges? How are GDD related to growth stages?

A

To describe crop development.
To use as a guide to when to apply management treatments.
(ex. when to apply fertilizers or herbicides, when to irrigate)

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4
Q

photoperiodism

A

actual response in nyctoperiodism.
Plants will flower not according to a certain length of photoperiod but based on whether or not the photoperiod is longer or shorter than a certain length required by the species

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5
Q

Short Day Plants

A

flowering stimulated by day lengths shorter than a critical max.
Can be modified by temp. ex. soybeans, corn, sorghum

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6
Q

Long Day Plants (LDP)

A

flowering stimulated by day lengths longer than a critical max.
ex. winter annuals (wheat, barley, etc. ) biennials

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7
Q

Short-Long day Plants

A

flowering in response to a period of short days followed by long days.
Ex. many temperate perennial grasses; orchard grass; tall fescue

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8
Q

Long- short day plants

A

flowering in response to a sequence of long days followed by short days
ex. night jasmine

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9
Q

day neutral plants

A

flowering is insensitive to photoperiod

ex. dandelion, tomato

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10
Q

P far red (Pfr)

A

Absorbs light at 720-750 nm
Inhibits flowering in SNP
Promotes flowering in LDP
Inhibits growth of mesocotyl in some cereal species

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11
Q

Pred (Pr)

A

Absorbs light at 600-680nm
Promotes flowering in SDP
Inhibits flowering in LDP
More stable and biologically active form

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12
Q

Floral induction

A

production of a flowering stimulus (Chemical change) by cold or day length

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13
Q

Flower initiation

A

Transformation of vegetative growing points (meristems) into floral primordia in response to temp and photoperiod

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14
Q

Vernalization

A

The requirement of a cold treatment to stimulate flowering

Generally 2-6 weeks below a critical temp (approx. 45 degrees F)

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15
Q

Indeterminate

A

vegetative growth on main stem continues after flowering has initiated
- traditionally represented by northern maturity groups of soybean

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16
Q

Determinate

A

Vegetative growth on main stem stops when reproductive growth starts
- traditionally represented by southern maturity groups of soybean