1. Benefits and Liabilities Associated with Early Maturity and Determinacy in Cotton

2. 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.

3. 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.

4. 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.

5. 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

6. 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

7. Accelerated Flowering and Cutout

8. Early maturity traits:
Early fruit initiation
Increased plant determinacy reflected by plant heights
High fruit retention rates

9. 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

10. Escape from an environmental adversity (heat stress) due to early maturity in Pima S-7.

11. Management Advantages
Reduced insecticide applications
Reduced numbers of irrigations
Increased flexibility in the development of management strategies

12. 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).

13. 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).

14. 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 mid-south renewed breeding efforts for earlier maturing cultivars.

15. Reduction in growing season, 1960-1987
Location
Years
Season Reduction
(planting – harvest)
College Station,
Texas
28 days
Florence,
South Carolina
33 days
Mississippi Delta,
Mississippi
38 days

16. Cultivar Maturity Groups
3 Weeks
300 HU (30/13 C)
Short
Medium
Full
Pima S-6
SG 501
Pima S-7
DPL 20
DPL 5415
DPL 90

17. 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.

18. 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.

19. Mandated termination
Boll set, standard cultivar
Boll set, early maturing cultivar
Pink bollworm population
May
June
July
Aug
Sept

20. Short-Season Management for Pink Bollworm Control, Imperial Valley, CA
Late Season
(August)
Pre-program
Program Years
1989
1990
1991
1992
1993
1994
Moths/trap/
night
3.1
4.4
1.4
1.8
0.1
0.0
Larvae/100 bolls 89 15 3
12.5 --
Lint yield (Kg/ha)
1242
1177
1069
1133
1460
1503

21. 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

22. Sequential harvests of an early maturing (8709) and later maturing (91-311) cultivar
Cumulative Yield (lbs./acre)
8709
91-311
Days after planting

23. Cumulative percent yield of an early maturing (8709) and later maturing (91-311) cultivar
Days after planting

24. Early Foliar Decline, a Maturity Related Disorder of Pima Cotton

25. Correlation of early foliar decline severity with plant growth traits, foliar potassium, and yield in 60 populations at Tulare, CA, in 2000.
Traits
Early foliar
Decline rating
Nodes above open bloom
-0.64
Plant height
-0.67
Foliar potassium
-0.56
Lint yield
-0.72

26. 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.