Effects of Okra‐Leaf, Frego‐Bract, and Smooth‐Leaf Mutants on Pink Bollworm Damage and Agronomic Properties of Cotton¹

Abstract

Eight isolines of cotton, Gossypium hirsutum L., which carried all possible combinations of Okra leaf (L°2), frego bract (fg), and Smooth leaf (Sm2) vs. their normal‐leaf and normal‐bract equivalents in the La 71‐7 (a Stoneville) background, were grown in replicated experiments for 3 years in Arizona in insecticide‐free environments. Percentage of seed damage caused by pink bollworm (PBW), Pectinophora gossypiella (Saunders), and 11 agronomic properties were studied.Mean seed damage in the Okra‐leaf isolines was 82% of that in the corresponding normal‐leaf lines, a significant reduction. The Okra‐leaf isolines were comparable to the normal‐leaf types in agronomic properties. Their only negative effect was an 8% lower lint yield (which was significant). Okra leaf interacted with frego bract only for boll size and with Smooth leaf only for seed index. Okra leaf interacted with years for seed damage because the Okra‐leaf isolines had 76% as much damage as the normal‐leaf stocks in 1979, but 85% as much in 1978 and 88% as much in 1980. Seed damage in the frego‐bract isolines was not significantly different from that in its normal‐bract counterparts. Frego bract interacted significantly with Smooth leaf for lint percent and with years for seed damage, total lint yield, bolls/plant, boll size, lint percent, and plant height. When closely examined, the interaction for seed damage suggested that frego bract afforded a slight advantage during the years when seed damage was relatively high. However, deficiencies in numerous agronomic properties (including a 24% lint yield reduction) and the five year ✕ agronomic property interactions offset any advantages in reduced seed damage afforded by frego bracts. Smooth‐leaf isolines unexpectedly displayed more seed damage than the hirsute‐leaf lines. Smooth‐leaf isollnes were also inferior to the hirsute‐leaf types in all agronomic properties except seed index and displayed significant interactions between years and percent lint yield at second and third harvest, total lint yield, bolls/plant, and date of first flower. For PBW resistance and agronomic performance, Okra leaf appears to have value, frego bract does not, and Smooth leaf must be reevaluated.

Okra Leaf Cotton, its Commercial Utilization in Sindh

“…The yield performance and boll rot disease resistance of okra leaf strains against normal leaf checks NIAB-78 and CRIS-9 was evaluated during 1997-98 season in randomized complete block design trial replicated four times. The trial received recommended agronomic practices without Increased egg/larval mortality Wilson and George (1982) and Wilson (1986) insecticide applications. The yield, quality characters and boll rot disease incidence data are presented in Table 2.…”

“…Okra leaf confers resistance to banded wing whitefly Jones et al (1975). Wilson and George (1982) indicated that okra leaf has considerable value against pink bollworms. Wilson (1986) showed that okra leaf breeding stocks in certain backgrounds have a modest level of resistance to pink bollworm and yield as much or more lint than do normal leaf cultivars.…”

Effect of cotton cultivars on the oviposition preference of pink bollworm (Lepidoptera: Gelechiidae)

“…Pubescent cottons were found to impede movement of larvae, causing exhaustion and disorientation, and additionally extending exposure of neonates to detrimental biotic (predators and parasites), and abiotic (high temperatures) conditions in the field (Smith et al 1975). Lower seed damage caused by pink bollworms was observed in okra leaf cotton isolines when compared with the normal leaf type (Wilson et al 1977(Wilson et al , 1979Wilson and George 1982;Wilson 1986). The earliness of the okra leaf varieties, the rapidity of flowering and boll development, the physical (thicker carpel wall) or chemical changes in the carpel wall, and the inability of larvae to penetrate the carpel wall were reported as the possible reasons for the reduced seed damage caused by pink bollworm (Wilson et al 1979.…”

Ação gênica, heterose e depressão endogâmica de caracteres de produção em linhagens mutantes de algodoeiro herbáceo

“…Plantas de algodoeiro herbáceo com características morfológicas alternativas, tais como folha okra, bráctea frego e cor vermelha da planta, oferecem vantagens relacionadas à redução das lesões provocadas por inseto-praga (Jones, 1972;Wilson & George, 1982). Além disso, algodoeiros com folha okra ainda apresentam maior precocidade, maior produção de flores, melhor penetração de inseticidas, e reduzida incidência de maçãs apodrecidas, em comparação com algodoeiros de folha normal (Jones et al, 1980;Jones, 1982;Heitholt, 1993;Silva et al, 1996;Heitholt & Meredith Junior, 1998).…”