Condensed tannins reportedly act as feeding deterrents to bollwonn [Helicoverpa zea (Boddie)], tobacco budworm [Heliothis virescens (F.)], and two spotted spider mite [Tetranychus urticae (Koch)] in cotton [Gossypium hirsutum L.]. This study was conducted to determine the effects of planting date, plant density, growth stage, and leaf age on the condensed tannin concentration of six cotton genotypes planted at College Station, TX, in 1988 and 1989. Planting commenced on 25 April in both years and consisted of three plantings at approximately 2‐wk intervals. The topmost unfolded leaf from the terminal and the fourth mainstem leaf from the terminal were sampled at five growth stages from plants spaced 8 and 30 cm, within rows spaced at 102 cm. Genotypes included two commercial checks and four high‐tannin breeding lines developed in a spider mite resistance program. Condensed tannin concentration, expressed as a percentage of fresh weight, was determined spectrophotometrically following extraction with HC1‐butanol. The younger leaf tissue had significantly higher levels of condensed tannins than the more mature leaf tissue. Condensed tannin concentration increased with plant age through the first‐bloom growth stage. The condensed tannin concentration of plants sown on Planting Dates 1, 2, and 3 did not differ in 1988, but in 1989, plants from Planting Date 2 had higher condensed tannin concentrations than those from Planting Dates 1 or 3. Plant density did not significantly affect condensed tannin concentration. Many interactions of other factors with genotypes suggest that breeding for high tannin levels would require close attention to leaf age, growth stage, and environment.
Condensed tannins are feeding deterrents to cotton bollworm [Helicoverpa zea (Boddie); syn. Heliothis zea], tobacco budworm [Helicoverpa virescens (F.); syn. Heliothis virescens], and spider mite (Tetranychus urticae Koch) in cotton (Gossypium hirsutum L.). This study was conducted to determine the effects of planting date and plant density on the condensed tannin concentrations of six plant parts of cotton sampled at two growth stages at College Station, TX, in 1988 and 1989. Cotton was sown every 2 wk to provide three planting dates beginning on 25 April in both years. Genotypes evaluated were ‘Tamcot CD3H’, ‘Arkot 518’, and four high‐tannin lines (TAM 86III24, TAM 86E3, TAM 86E8, and 86CC2) selected for spider mite resistance. The topmost unfolded leaf, a fourth mainstem leaf from the terminal, a 6‐d‐old bract, a 10‐d‐old sepal, and a bract and a sepal from a white bloom were sampled at first bloom and at 2 wk post first bloom from plants spaced 8 and 30 cm within rows spaced 1.02 m apart. Younger tissue consistently had a higher condensed tannin concentration than mature tissue. Condensed tannin concentrations were highest in TAM 86III24 and lowest in the two commercial cultivars, Arkot 518 and Tamcot CD3H. TAM 86E8, TAM 86E3, and 86CC2 were intermediate in tannins. Breeding cotton for high tannin concentration would require consideration of the tissue sampled because of the interaction of genotype with this factor.
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