To maximize profitability, cotton (Gossypium hirsutum L.) producand As. Elms et al. (1997) reported that yield in an ers must attempt to control the quality of the crop while maximizing irrigated cotton field in Texas displayed spatial correlayield. The objective of this research was to measure the intrinsic variability present in cotton fiber yield and quality. The 0.5-ha experi-tion. These authors also noted that production of fruitmental site was located in a producer's field (Norfolk-Coxville soil ing sites and fruit retention was spatially correlated. association) in Florence, SC, for 2 yr (1996 and 1997). Soil (0-20 cm) Micronaire exhibited a moderate degree of spatial variand fiber samples (1-m row) were collected from a regular grid (129.2 ability, and strength showed the lowest degree of variby 45.6 m, 7.6-m interval). Soil properties determined included soil ability.

Volatile emissions from residues of the winter cover legumes, Berseem clover (Trifolium alexandrinum L.), hairy vetch [Vicia hirsuta (L.) S.F. Gray], and crimson clover (Trifolium incarnatum L.), inhibited germination and seedling development of onion, carrot, and tomato. Using GC-MS, 31 C2-C10 hydrocarbons, alcohols, aldehydes, ketones, esters, furans, and monoterpenes were identified in these residue emission mixtures. Mixtures of similar compounds were found in the volatiles released by herbicide-treated aerial and root residues of purple nutsedge (Cyperus rotundus L.) and the late-season woody stems and roots of cotton (Gossypium hirsutum L.). Vapor-phase onion, carrot, and tomato seed germination bioassays were used to determine the time- and concentration-dependent inhibition potential of 33 compounds that were either identified in the plant residue emissions or were structurally similar to identified compounds. Cumulative results of the bioassays showed that (E)-2-hexenal was the most inhibitory volatile tested, followed by nonanal, 3-methylbutanal, and ethyl 2-methylbutyrate. All the volatile mixtures examined contained at least one compound that greatly inhibited seed germination.

the southeast USA, Porter et al. (1996) reported higher fiber strength, greater elongation, and lower micronaire Normal-and late-planted cotton (Gossypium hirsutum L.) often for late-planted cotton. They found no effect of planting differ in fiber properties, especially those properties related to fiber date on fiber length. Cathey and Meredith (1988) found secondary wall characteristics. This field study was conducted to (i) determine the effect of planting date on fiber properties of bolls at that late planting reduced micronaire but did not affect two flowering times, and (ii) determine the relationship between fiber fiber length, strength, or elongation. Bauer et al. (1998) properties and canopy photosynthesis during development of those found that cotton planted in late May had fiber with bolls. Cotton ('Stoneville 453') was planted on 3 May and 3 June in higher yarn strength, greater elongation, and greater 1995 and 3 May and 31 May in 1996. Canopy photosynthesis was fiber length, but lower micronaire and fiber maturity measured 10 to 12 times on sunny days from initial flowering through than fiber produced from cotton planted in late April. the end of the season. Fiber properties were determined on first Recent evidence suggests that carbohydrate supply sympodial position bolls that bloomed during the first and fourthcan affect fiber properties of cotton. Pettigrew (1995) week of flowering (WOF). Maximum canopy photosynthesis was 21% evaluated the effects of irradiance on cotton fiber prophigher in 1996 than in 1995 and lint yield was 22% greater in 1996 erties. He found that higher irradiance, which would than in 1995. Within each year, average maximum canopy photosynthesis did not differ between planting dates, although yield was approx-increase carbohydrate supply through higher photosynimately 30% lower for the late planting date each year. Bolls from thetic rates, increased micronaire and fiber strength. the first WOF generally had lower lint percent, higher short fiber Jones et al. (1996) indirectly measured carbohydratecontent, lower elongation, and lower whiteness index than bolls from supply effect on fiber properties by removing flowers, the fourth WOF. Micronaire, immature fiber fraction, and fiber crosswhich reduced competition for carbohydrate among the sectional area were linearly related to the amount of canopy photosynremaining developing bolls. Flower removal resulted in thesis that occurred from 15 to 45 d after flowering. Our results are higher boll weight and micronaire of the remaining bolls consistent with the hypothesis that assimilate supply influences cotton in that study. fiber properties associated with secondary wall characteristics.Canopy photosynthesis of cotton increases until 80 to 90 d after planting as plants develop leaf area, then decreases as leaves in the canopy age (

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