Benefits and Liabilities
Associated with Early Maturity
and Determinacy in Cotton
What is Early Maturity and
Determinacy?
Physiologically, determinacy might be
defined as the degree to which a plant
segregates vegetative growth from
reproductive growth. A plant that
ceases all vegetative growth at the
onset of fruiting is completely
determinate.
What is Early Maturity and
Determinacy?
Physiologically, earliness might be
defined by the time required by the
plant to reach a reproductive growth
stage, and by the rate and duration of
fruiting.
What is Early Maturity and
Determinacy?
Agronomically, earliness is defined as
the time required to mature a
satisfactory crop and determinacy is
defined as the plant’s ability to
maintain vegetative growth and fruit
form production after the onset of
fruiting.
Characteristics and Components
of Early Maturity
•
•
•
•
•
Early fruit initiation (low fruiting node)
Accelerated rate of fruiting bud development
Accelerated rate of flowering
Compressed fruiting interval
Reduced rate of vegetative growth
Characteristics and Components
of Early Maturity
• Early and sharply defined cessation of
vegetative and reproductive growth (cutout)
• Shorter boll maturation period
• Shorter plant stature
High fruit retention rates
Accelerated Flowering and Cutout
Early maturity traits:
• Early fruit initiation
• Increased plant
determinacy reflected
by plant heights
High fruit retention
rates
Advantages of Early Maturity
• Shorter growing season
– Insect pest evasion and management
– Avoidance of environmental adversities:
• Cool planting temperatures
• Heat stress
• Cool temperatures during boll maturation
• Inclement weather during harvest
Escape from an
environmental
adversity (heat
stress) due to early
maturity in Pima
S-7.
Management Advantages
– Reduced insecticide applications
– Reduced numbers of irrigations
– Increased flexibility in the development
of management strategies
Uses or Proposed Uses of Early
Maturing Cultivars
• Late planting to create a suicidal emergence
of Pink Bollworm (Arizona).
• Late planting following the failure of a
medium or full season cultivar due to weather
(general, U.S.).
• Early or normal planting to avoid cool
temperatures during boll maturation and
resulting poor fiber quality (high plains,
Texas).
Uses or Proposed Uses of Early
Maturing Cultivars
• Early or normal planting to avoid rain and
fog conditions at harvest (northern San
Joaquin Valley, California).
• Use in multiple cropping schemes, allowing
production of food and cash crops in a
single year (China, north Africa, general).
Historically, insect pests have been the
predominant motivation for the development of
early maturing cultivars in the U.S.
• Pre-1890 – Use of early maturing cultivars in northern
cotton states due to short growing season.
• 1900’s – Severe boll weevil pressure led to movement
of early maturing cultivars into mid-south and the
development of new early maturing cultivars.
• 1970’s – Severe bollworm/budworm problems in midsouth renewed breeding efforts for earlier maturing
cultivars.
Reduction in growing season,
1960-1987
Season Reduction
Years
(planting – harvest)
1966-1987
28 days
Location
College Station,
Texas
Florence,
1968-1987
South Carolina
Mississippi Delta, 1960-1987
Mississippi
33 days
38 days
Cultivar Maturity Groups
3 Weeks
300 HU (30/13 C)
Medium
Short
Full
Pima S-6
SG 501
Pima S-7
DPL 20
DPL 5415
DPL 90
Short –Season Management for Pink
Bollworm Control in the Imperial Valley
of California, 1990-1994
• Primary Goal: Reduce pink bollworm
populations area-wide through increasing
time in which fields are free of the cotton
host.
• Secondary Goal: Cotton host avoidance of
damaging late season insect populations.
Management Program for Pink
Bollworm in the Imperial Valley
• Early termination of cotton crop with
chemical defoliants.
• Early mandatory destruction of plant
residue in fields.
• Switch from a full season to a medium
season cotton variety (from DPL 90 to
DPL5415), an unintended component.
Boll set, standard cultivar
Mandated
termination
Boll set, early maturing cultivar
Pink bollworm population
May
June
July
Aug
Sept
Short-Season Management for Pink Bollworm
Control, Imperial Valley, CA
PreLate Season program Program Years
(August)
1989 1990 1991 1992 1993 1994
Moths/trap/
night
Larvae/100
bolls
Lint yield
(Kg/ha)
3.1
4.4
1.4
1.8
0.1
0.0
89
15
3
12.5
--
--
1242
1177
1069 1133 1460 1503
Disadvantages of Early Maturity
and Increased Determinacy
•
•
•
•
Limitations on yield potential
Inflexibility in response to injury
Increased management oversight
Increased susceptibility to:
– Smog (ozone) damage
– Foliar leaf spot diseases, nutrient
deficiencies, and premature senescence
– Verticillium wilt
Cumulative Yield (lbs./acre)
Sequential harvests of an early maturing (8709)
and later maturing (91-311) cultivar
1700
1500
1300
1100
8709
91-311
900
700
500
300
155
166
176
Days after planting
201
Cumulative percent yield of an early maturing
(8709) and later maturing (91-311) cultivar
100
90
80
70
60
8709
91-311
50
40
30
20
155
166
176
Days after planting
201
Early Foliar Decline, a Maturity
Related Disorder of Pima Cotton
Correlation of early foliar decline severity with
plant growth traits, foliar potassium, and yield
in 60 populations at Tulare, CA, in 2000.
Early foliar
Traits
Decline rating
Nodes above open bloom
-0.64
Plant height
-0.67
Foliar potassium
-0.56
Lint yield
-0.72
• In cotton, Maturity and Determinacy
vary along along a continuous scale.
• Benefits and liabilities also change
on a scale.
• Environment, management, and
economics determine the appropriate
level of earliness and determinacy for
your situation.