Cotton Response to Seasonal Patterns of Flower Removal: I. Yield and Fiber Quality

Abstract

Cotton (Gossypium hirsutum L.) yield and quality can be affected by altered fruiting patterns related to the abscission of fruiting forms. This field study quantified the effects of flower removal during various stages of reproductive development on subsequent yield development, boll development, and fiber properties. Effects of early‐, mid‐, and late‐season flower loss on cotton reproductive development was determined. Various flower removal treatments were imposed on two cultivars at Clayton, NC, during 1991 and 1992. Early flower removal treatments (3rd week and earlier) delayed boll development, but no significant reduction in yield was found at season's end. Later flower removals (4th week and later) significantly reduced total fiber yields (13–33%) compared with early‐season removals (1st, 2nd, and through 3rd week) and no removal. Boll weight was positively correlated with fiber properties and was related to the amount of competition among developing bolls. The largest bolls resulted from treatments that had the largest negative effect on yield. Micronaire was the only fiber variable affected by flower removal, with increased values associated with later removal. Data indicate that late‐season flower losses (4th week and later) are the most injurious to yield, with significant yield reductions occurring from even the least severe, late‐season removal treatment of 6th week and later flowers. Early loss (3rd week and earlier) of fruit can be tolerated if the season allows sufficient time for compensatory reproductive growth and if further losses due to plant stress or insect damage are controlled.

Recovery from Terminal and Fruit Damage by Dry Season Cotton Crops in Tropical Australia

“…In contrast, a similar level and timing of damage imposed on crops grown in Narrabri resulted in recovery in yield not signiÞcantly different to (but ranked lower) than the control (Sadras 1996a). Similarly, removal of large squares during early fruiting by Ungar et al (1987) in Israel and Jones et al (1996a) in North Carolina resulted in yield recovery equal to the control. We therefore conclude that cotton crops grown during tropical winter of northern Australia should be more tolerant of early fruit loss than those grown during temperate summer.…”

Field Evaluation of a <I>Helicoverpa zea</I> (Lepidoptera: Noctuidae) Damage Simulation Model: Effects of Irrigation, <I>H. zea</I> Density, and Time of Damage on Cotton Yield

“…Kletter and Wallach (1982) removed small squares (four per plant), large squares (four per plant), and bolls (two per plant) during three time periods with no effect on lint yield. Similarly, Jones et al (1996) found that removing all ßowers at the fourth week of ßowering or later decreased lint yields. Fife (2000) found yield decreases when 100% of squares were removed during the Þrst 4 wk of ßowering, but that lesser (up to 75%) removal levels did not affect lint yield.…”

“…Ungar et al (1987) found little yield response to square removal or to the removal of small bolls, but decreased yields when large bolls were removed. Retention of bolls that would have been abscised under normal conditions can make up for other bolls lost within a few days of ßowering (Jones et al 1996). Bolls that have developed for 15Ð18 d after ßower opening generally will not abscise from the plant although yield losses may still occur because of feeding by H. zea (Guinn 1982, Gore et al 2000a.…”

Adoption of Bt Cotton: Threats and Challenges

“…Removing fruiting forms usually enhances vegetative growth and development, such as increased plant height, total dry weight, leaf area index (LAI), and lengthening of anthesis (Ungar et al, 1987;Jones et al, 1996). Removing early-season flower buds increased root growth, while removing fruiting branches alters spatial yield distribution (Sadras, 1995;Bednarz and Roberts, 2001;Dumka et al, 2004).…”