Lu Feng Plant and Soil Science Department Texas Tech University Lubbock, TX Effects of irrigation and plant density on yield, quality and within-boll yield components for different cotton varieties

Background  Cotton (Gossypium spp.) is one of the most important economic crops in the world.  Improving the fiber quality on the premise of maximizing yield is necessary to maximize the profitability.  Therefore, cotton yield and fiber quality improvements become eternal targets for both cotton researchers and producers.

Yield is composed of boll number per unit area, seed number per boll, fiber number per seed and the weight per fiber (Bowman, 2001). The number of fibers and lint weight per seed surface area are the most basic within-boll yield components (Coyle and Smith,1997). Background

 Fiber quality is determined by fiber cell developmental process. The most important parameters for quality are fiber length, fineness, and maturity.  Differences in fiber properties can be traced to variations among the shapes and maturities of fibers on a single seed and, consequently, within a given boll.

Background Yield and fiber quality are variable Variety Environment soil and climate management practices within plant within boll within locule

Background  Plant density and irrigation are most common crop management practices.

Background Dr. Bednarz et al.(2006) found that boll size, boll number and within-boll yield components are greatly influenced by plant density.

Objective Document the effects of irrigation and plant density on boll distribution, yield components, and fiber quality for different cotton varieties.

Materials and Methods  Field experiment: Lamesa, Texas, 2006  Treatments : 1) Irrigation rate (High 6.33mm/day Low 4.32mm/day) 2) Plant density (32K, 52K, 80K/Acre) 3) Cultivar (FM9063B2RF, ST4554B2RF)  Experimental design: sub-sub split plot Replications: 3

Materials and Methods Harvest plants for each plot Box mapping Locule mapping Ginning SeedLint Delint WeightSurface area Weight AFIS Plant number Boll number Seed number Loc number Mote number

Materials and Methods  Plant mapping Plants were mapped according to node and fruiting position in each plot. Mapped cotton bolls for each plot were collected separately as samples. Mapping data were analyzed for yield determination.

Materials and Methods  Locule mapping  First position bolls from the 9th and 14th nodes on main- stem were employed for within-boll analysis for each plot.  Locules in each sample were spread apart by hand, and seeds in a locule were numbered by position.

Materials and Methods  Fiber quality analysis Advanced Fiber Information System (AFIS)Small Blender

Materials and Methods  Seed surface area analysis Seeds were scanned with Epson Perfection V700 PHOTO, and analyzed with WIN SEEDLETM 2007C software (Regent Instruments Inc.).

Preliminary Results Within-plant boll distribution Variations of fiber quality associated with node and seed position motes fiber length fineness maturity

Boll Distribution

Effects of Irrigation Fig 1. Boll distribution response to irrigation Fruiting position 1 Fruiting position 2

Effects of Plant Density Fig 2. Boll distribution as affected by plant density

Effects of Variety Fig 3. Boll distribution of two varieties position 1 position 2

Fiber Quality

Effects of Irrigation on Mote Number Fig 4. Number of motes affected by irrigation

Irrigation Effects Fig 5. Irrigation effects on fiber length

Node and Seed Position Phenomena Fig 6. Fiber length changed with node and seed position

Irrigation Effects Fig 7. Irrigation effects on fiber fineness

Density and Variety Effects Fig 8. Plant density and variety effects on fiber fineness a a a a b b

Seed Position Phenomenon Fig 9. Fiber fineness in different seed position

Irrigation Effects on Fiber Maturity Figure 10.Fiber maturity affected by irrigation

Maturity Affected by Plant Density Figure11. Response of fiber maturity to plant density

Response of Fiber Maturity to Variety Figure 12. Fiber maturity influenced by variety

Conclusion Irrigation improved boll distribution both vertically and horizontally on plants, and also improved fiber length and fineness. Modifications of plant density changed within-plant boll distribution. Changes in plant density may also change fiber fineness, but it is dependable on variety. Two different varieties used in this experiment show differences in both boll distribution and fiber quality.

Future Work Finish the data analyses for 2006 Repeat the experiment in 2007 and combine two years data.

Literatures cited Bednarz, C. W., R. L. Nichols, and S. M. Brown Plant density modifications of cotton within-boll yield components. Crop Science. 46: Bowman, D. T., G. A. Van Esbroeck, J. Van’t Hof, and G. M. Jividen Ovule fiber cell numbers in modern upland cottons. The Journal of Cotton Sciences. 5: Cramer, L. M A better understanding of the number of fibers per seed in cotton. a thesis in crop science. Texas Tech University, Lubbock, Texas. Coyle, G. G. and C. W. Smith Combining ability for within-boll yield components in cotton, Gossypium hirsutum L. Crop Science. 37:

Acknowledgement Texas Tech University International cotton research center Dr. Craig Bednarz Dr. Eric Hequet Dr. Hezhong Dong Cory Mills Heath Stoerner