Cotton Strains Research Articles

Gossypol content of cotton leaves during the growing season, and growth suppression of Spodoptera littoralis (Boisduval) larvae on some high‐gossypol (HG) cotton strains1

AbstractThe dynamics of the gossypol contents of the cotyledons and true leaves of 12 high‐gossypol (HG) cotton strains, the commercial Acala SJ1 strain, and the glandless strain Acala 63–74, were compared at different growing periods. The gossypol level was the highest in strains HG‐6–1–1–144, HG‐247–1 and HG‐U‐2–1 at all stages of development; it was much lower in Acala SJ1 and especially in the glandless strain. In all strains tested the highest gossypol concentration was found in the cotyledons. Another maximum in concentration occurred during the flowering period. The weight gain of 10–20‐mg Spodoptera littoralis larvae after a 5‐day feeding on cotyledons was the highest on the glandless strain and the lowest on HG‐U‐2–1, HG‐247–1 and HG‐6–1–1–144.ZusammenfassungDer Gossypolgehalt von Baumwollblättern während des Anbaus und die Unterdrückung des Wachstums von Spodoptera littoralis (Boisduval)‐Larven auf einigen “high‐gossypol” (HG) BaumwollrassenDie Dynamik des Gossypolgehalts der Keimblätter und echten Blätter von 12 “high‐gossypol” (HG) Baumwollrassen, der Handelssorte Acala SJ, und des drüsenfreien Stammes Acala 63–74 wurde während verschiedener Anbauperiodeh verglichen. Der Gossypolpegel war in allen Entwicklungsstadien am höchsten in den Stämmen HG‐6–1–1–144, HG‐247–1 und HG‐U‐2–1; in Acala SJ1 und in dem drüsenlosen Stamm lag er wesentlich tiefer. In allen getesteten Stämmen wurde die höchste Gossypol‐Konzentration in den Keimblättern, ein zweiter Höchstwert während der Blütezeit festgestellt.Die Gewichtszunahme von 10–20 mg schweren Spodoptera littoralis‐Larwen, die fünf Tage lang auf Baumwollkeimpflanzen gehalten wurden, war am stärksten bei dem drüsenlosen Stamm und am tiefsten bei den Stämmen HG‐U‐2–1, HG‐247–1 und HG‐6–1–1–144.

Influence of Gossypol Content of Leaves of Different Cotton Strains on the Development of Spodoptera littoralis Larvae12

The effect of the gossypol contents of leaves of different cotton strains on larval growth, pupation rate, and pupal weight of Spodoptera littoralis (Boisduval) was investigated. Larvae weighing 90–110 and 170–190 mg were raised on the leaves of 5 cotton strains of different gossypol content. Larval weight after 2 days was lower, the length of time required for pupation was longer, and pupal weight was reduced in the larvae fed on the strain HG6-1-1-144, which had a mean content of 1.23% gossypol in the dry leaf powder; on strains with intermediate gossypol content, larval development was much less affected. The inhibition of larval growth and the reduction of pupation rate and pupal weight in neonates raised on leaves or cotyledons of HG6-1-1-144 was even more pronounced.

Synergistic and Antagonistic Effects of Gossypol for Phosfolan in Spodoptera littoralis Larvae on Cotton Leaves12

The effect of gossypol acetate on the toxicity of phosfolan (2-(diethoxyphosphinylimino)-1,3-dithiolane was investigated by topical application or by offering treated cotton leaves to larvae of Spodoptera littoralis Boisduval. When leaves were treated with phosfolan, larval mortality on the high-gossypol content cotton strain HG6-1-1-144 was consistently lower than on the glandless strain Acala 63-74. There also was a clear antagonistic effect of gossypol acetate on the toxicity of phosfolan when a mixture of the 2 was applied topically to the larvae; but when phosfolan and gossypol acetate were applied separately to 2 different larval abdominal segments, no antagonism occurred at any of the concentrations tested. A synergistic effect was obtained on leaves of the glandless strain with mixtures of a phosfolan EC and gossypol formulated in 0.1% NH4OH.

Effect of the Nectariless Trait on Cottonseed Protein and Amino Acid Composition1

Nectariless cottons (Gossypium hirsutum L.) are potentially useful agronomic strains of cotton. This experiment was conducted to compare the percent N of seed from nectariless cottons with that of seed from their nectaried recurrent parents. Two nectariless lines (‘DES DK he’ and ‘DES SL ne’) compared in 1969 and 1970 had higher seed percent N than their normal counterparts and one (‘DES 7A ne’) did not. In another experiment where eight BC5F4 ectariless lines were compared with their nectaried recurrent parents in 1974‐75, there was no effect of the nectariless trait on seed percent N. There was, however, a significant cultivar by location interaction, indicating considerable influence of the environment on seed percent N. Aspartic acid, threonine, serine, glycine, and alanine contents were significantly higher in the seed from nectariless cotton lines than in seed from normal cotton. The increases in absolute percentage values were, respectively, 0.10, 0.04, 0.03, 0.05, and 0.04. While these values were statistically significant, they would be of little consequence in affecting the quality of protein in seed from nectariless cotton plants.

Effects of Nectariless Cotton on Caged Populations of Campoletis sonorensis 12

Comparison of the longevity of adults of Campoletis sonorensis (Cameron) on one nectaried and 2 nectariless strains of cotton showed a reduced longevity due to lack of extrafloral nectaries. However, the effect was considerably less when floral nectaries were available (plants in bloom stage). Male longevity was less than female longevity on both nectaried and nectariless strains, and the effect of the nectariless character was greater on males than females. Releases of C. sonorensis against populations of tobacco budworm, Heliothis virescens (F.), on cotton in field cages showed that parasitism was lower on a nectariless strain than on a nectaried strain. However, rates of parasitism on both strains of cotton were relatively high, and parasites were able to maintain a generation cycle on nectariless cotton. Therefore, nectariless cotton appears to have only a slight effect on the impact of caged C. sonorensis as a parasite of the tobacco budworm.

Fiber production in vitro from a conditional fiberless mutant of cotton

A single-gene temperature-sensitive mutation regulates fiber development from ovular epidermal cells of a cotton strain derived from Gossypium arboreum L. Fiber development is permitted when unfertilized ovules are cultured at 30°C (and below) in nutrient medium containing indoleacetic acid and gibberellic acid, but it is restricted in identical medium at 32°C (and above).

Effects of Cottons Differing in Pubescence and Other Characters on Pink Bollworms in Arizona123

Strains of cotton, Gossypium hirsutum L., that ranged from glabrous to densely pubescent, and also differed in other characteristics, were evaluated in field cages and in the field for relative damage caused by Pectinophora gossypiella (Saunders). Damage was lower in TM-1 (H2), a densly pubescent strain carrying the pilose allele H2, than in most other strains tested, but levels of pubescence below that of TM-1 (H2) did not insure resistance. A glabrous strain in ‘Stoneville 7A’ background, carrying the Sm2 allele, had less pink bollworm damage than its normally pubescent counterpart. Two other strains that had no more damage than TM-1 (H2) in 1975 were 1 × 6–56 and AET-5 × (108 × Br-2)-7-69, The former was significantly earlier than the other strains tested and thus probably escaped some damage. The latter, however, is a promising strain because it had a significantly lower amount of damage than the controls ‘Deltapine 16’ and Stoneville 7A but was only moderately pubescent and slightly earlier and seemed to possess the high yielding capacity of the cultivars.

Phagodeterrency Induced by Pure Gossypol and Leaf Extracts of a Cotton Strain with High Gossypol Content in the Larva of Spodoptera littoralis12

The effect of pure gossypol or of extracts of a high gossypol cotton strain on the feeding rate of larvae of Spodoptera littoralis Boisduval was investigated by the ‘Styropor method.’ Styropor (foamed polystyrene) lamellae were painted on one side with 5% sucrose and on the other side with a solution of 1, 0.5, 0.25, and 0.1% pure gossypol. One percent gossypol strongly suppressed feeding, and a negative correlation was found between the feeding rate on the lamellae and the concentration of gossypol. Larvae fed about half as much on lamellae painted with the leaf extract of a high-gossypol-content cotton strain (HG6-11-144) as on those painted with an exract of the glandless strain Acala 63-74.

Interrelationships Among Gland Density, Gossypol Content, and Lint and Seed Characters in Cotton1

We crossed a heavily glanded, agronomically inferior strain of cotton, (Gossypium hirsutum L.), to a normally glanded, agronomically acceptable strain. The former has a high percentage of gossypol (2.63%) in flower buds (squares) whereas the latter has a much lower percentage (0.95%). In the F2, none of the five visual methods selection for high gossypol content that we used were particularly efficient, but some were significantly correlated with gossypol content. Probably the most useful one in this population was a rating of the number and size of glands on the calyx lobes. Stigma glands/mm identified as many plants with a high gossypol content, but was not as practical because glands had to be counted. Boll glands/cm2 was uncorrelated with gossypol content. The two other visual methods that we used, distribution of glands on the style, and rugose, heavily glanded bolls, were impractical in this population because too many F2 plants were saved. Even though gossypol content was significantly negatively correlated with boll size and lint percentage, correlations were low and should not constitute formidable barriers to improvement.

Nectariless and Glabrous Cottons: Effect on Pink Bollworm in Arizona12

Two nectariless strains of cotton, Gossypium hirsutum L., that were field tested for resistance to Pectinophora gossypiella (Saunders) supported significantly fewer insects and sustained less seed damage than their nectaried counterparts. A glabrous strain also had fewer insects and less seed damage than a hirsute cultivar. The nectariless and glabrous characters combined in a single strain reduced seed damage cumulatively.

Influence of Lint Percentage on Yield, Boll, and Fiber Characteristic in Acala strains of Upland Cotton1

Yield, boll, and fiber characteristics were studied in low, intermediate, and high lint percentage groups of Acala strains of upland cotton (Gossypium hirsutum L.). Three genotypes were used to represent each group. The three groups did not differ significantly in yield of seed cotton or seed, but the high lint percentage group produced significantly more lint yield, lint/plant, lint/boll, lint/seed (lint index), and fiber elongation than did the low lint percentage group. The high lint percentage group produced significantly less seed/boll, seed cotton/boll, and five‐lock bolls and smaller seed (seed index) than the low lint percentage group. Seed, lint, and seed cotton yield were highly correlated as were those three characters with bolls/m2.

Differential Response to Hail Damage among Pima Cotton Strains1

Large differences in vegetative regrowth among nine cultivars were noted in an American Pima cotton (Gossypium barbadense L.) regional test after severe hail damage on 22 July 1974. These differences were correlated negatively with the lint yield of the same cultivars in a nearby, undamaged, Pima cotton regional test. Correlations of number of new leaves and dry weight of new leaves 5 weeks after hail with lint yield on the undamaged test were −0.84 and −0.91, respectively. Theories on transport and utilization of photosynthate in cotton were used to explain differences in recovery among cultivars.

Effects of Pilose, Pubescent, and Smooth Cottons on the Cotton Leafperforator1

Strains of cotton (Gossypium hirsutum L.) deviating in both directions from the degree of pubescence typical of upland cotton, were more resistant than the latter to cotton leafperforator (Bucculatrix thurberlella Busck). Two densely hairy lines, TM‐I(H2) and SA 166, harbored significantly fewer insects than any of the other lines tested. Nonpreference for oviposition is probably the main mechanism of resistance involved. A no‐choice greenhouse feeding technique was devised that should be useful in screening cottons for resistance to cotton leaf perforator.

Fruiting Behavior of Insect‐resistant Cotton Strains in an Insect‐free Environment1

AbstractNectariless and frego bract strains of cotton (Gossypium hirsutum L.) were compared with background‐related strains or cultivars Bayou Sm 1, ‘Deltapine 16,’ and ‘Stoneville 7A’ on the basis of productivity and maturity in an insect‐free greenhouse environment. The nectariless strain of Deltapine 16 was similar to its parent cultivar, whereas nectariless Bayou D2Sm and Stoneville 7A were more productive from late flowers than their background‐related nectaried counterparts. La Frego 2 was similar to its Stoneville 7A parent, whereas La Frego 3159 was more productive from midseason flowers, and La Rak Frego 3161 yielded less and was earlier than Stoneville 7A. Neither trait differed consistently in fruiting behavior compared to that of its background‐related nectaried and normal bract counterparts. Thus, the observed differences may be due to heritable factors not associated with the trait per se, or to selection during the backcross program.

Herbicide, Leaf Type, and Row Spacing Response in Cotton

Near isogenic strains of okra, super okra and normal leaf cotton (Gossypium hirsutum L.) were grown in rows spaced 25, 50, and 100 cm apart and were sprayed with various combinations of trifluralin (α,α,α,trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and fluometuron [1,1-dimethyl-3-(α,α,α,-trifluoro-m-tolyl)urea]. Neither row spacing nor leaf type had any effect on early season weed control. Late season control was better with normal and okra leaf types than with the super okra leaf type. Weed control was significantly better with additional postemergence application of herbicides than with only preplant and preemergence applications. Although the cotton varied in opening date with herbicide programs there was no difference in total yield.

Histological Studies on Five Male‐Sterile Strains of Upland Cotton1

Microsporogenesis and pollen development in one cytoplasmic male‐sterile and four genetic male‐sterile strains of Upland cotton (Gossypium hirsutum L.) were studied in comparison with a male‐fertile variety.In the cytoplasmically male‐sterile Upland cotton with the G. harknessii cytoplasm, there was disorganization of tapetal cells and coalescence of pollen mother cells (PMC's) during the premeiotic stages.In the Ms4 dominant genetic male‐sterile anthers, degeneration of microsporocytes was observed before or shortly after the initiation of prophase I. The tapetal cells were reduced in size in some of the anthers.In another dominant genetic male‐sterile, Ms7, meiosis appeared normal in the majority of the PMC's. The abortion of microspores was noticed during formation of the pollen wall. There was no observable malfunctioning of the tapetum.In the double recessive ms5ms6 male‐sterile anthers, vacuolation of developing microspores led to their degeneration. Nutrient deficiency of several kinds might have been the cause of vacuolation and abortion of pollen.In Rhyne's double recessive male‐sterile unthers, premature degeneration of the tapetum caused the abortion of pollen in most locules. In a few locules viable pollen was produced but the anthers were nondehiscent. Seeds were produced when pollen from the indehiscent anthers was released by crushing and dusted on other male‐sterile plants.

Selecting for productivity within a strain of cotton, Gossypium hirsutum L., in three environments

The effectiveness of selecting cotton (Gossypium hirsutum L.) plants solely for productivity was examined in three climatic zones of the San Joaquin Valley. Individual plant selections (F7) were made from the breeding line 12302 (later released as Acala SJ-1 cultivar) in 1965 at locations in the northern, western, and southern zones of the valley. Increased production of seed cotton was shown for selections in each zone when compared with the parental check in replicated trial in 1968.Selecting at the northern zone resulted in a higher proportion of high yielding lines than was attained by selections at other zones. Observations indicated productivity in the northern zone of the valley may be closely associated with early maturity.Fiber quality was also affected to a greater extent for the northern selections, with the more productive selections showing a greater reduction in fiber length.These findings suggest that selecting plants or progenies in a marginal environment can aid in identifying variation due to cryptic variability that remains following pure line breeding in a favorable environment.

Mortality Factors Affecting Cotton Insects: I. Resistance of Smooth and Nectariless Characters in Acala Cottons to Heliothis zea, Pectinophora gossypiella, and Trichoplusia ni

AbstractHost plant resistance to insects has become a major breeding objective in cotton (Gossypium hirsutum L.), since significant increases in resistance may result simultaneously in yield increases and reduced usage of insecticides. Nectariless ‘Acala’ cotton strains with reduced pubescence are being developed in an attempt to gain significant host plant resistance against harmful Lepidoptera. Extensive studies were undertaken to evaluate the first‐order effects that the nectariless and reduced pubescence plant modifications would have upon oviposition behavior of three key insects. Cage trials with pink bollworms (Pectinophora gossypiella) have been difficult to manage and results are inconclusive. It was found that cabbage loopers (Trichoplusia ni) showed a slight increase in oviposition on nectariless cottons with reduced pubescence. The increase was so small as to be of doubtful economic importance. Paired isolation cage studies conducted over a 4‐year period showed that similar numbers of Heliothis zea moths laid only 45% as many eggs on nectariless Acala strains as on their normally hairy, nectaried companion lines. There was a disturbing reversal in form in certain tests, due to variables not yet clearly understood. However, there was a clear trend indicating that the suppression of oviposition is greatest when environmental conditions are most favorable for a bollworm epidemic. This large reduction of egg numbers at peak oviposition is the strongest confirmation of the value of developing nectariless cottons to minimize Heliothis damage.

The Role of a Boll Weevil Resistant Cotton in Pest Management Research

AbstractThe role of the boll weevil (Anthonomus grandis Boh.) resistant cotton (Gossypium hirsutum L.) strain, frego bract, in the management of cotton pests was investigated in 22 fields in Yalobusha County, Mississippi in 1971. The objectives were (i) to measure boll weevil population suppression when frego bract cotton was used with and without a reproduction‐diapause program the previous year, and (ii) to determine if the resistant cotton strain could materially aid in removing the boll weevil as the key pest in cotton fields. If so, one could potentially use integrated control for other cotton pests and also conduct research on pest management systems. The use of the frego cotton suppressed the boll weevil population 69% and 79%. respectively, with and without a diapause program. In addition, the beginning of weekly applications of insecticides for boll weevils was delayed 4 weeks longer in the frego fields than in nonfrego fields. We were able to go through the period of peak activity of the bollworm complex (Heliothis spp.) before we needed boll weevil insecticides in the frego. However, in the nonfrego fields we were applying boll weevil insecticides before and during this time. Thus, frego can be used in research on pest management systems while it continues to be tested for use as a resistance character for commercial varieties.

Analysis of Several Types of Gene Action Controlling Resistance to Bacterial Blight of Cotton by Means of a Generalized Computer Model1

A computer program has been written having the capability to fit three‐ or four‐gene models to F2 segregation data divided into ten or fewer phenotypic classes. The various types of gene action analyzed are known to occur in the determination of bacterial blight resistance in cotton. The genes in any specific model may be independent or dependent, unequal in effect, and either dominant, partially dominant, additive, or recessive. Successive increments of gene values were limited to integers. Linkage was in five increments from 0 to 50% recombination inclusive, coupling or repulsion, and restricted to two genes in any particular model. The X2 criterion was used to select those models printed out as possible solutions. Exact data based on hypothetical three‐gene models were solved satisfactorily by the computer program. To provide a “live” test, a strain of cotton (Gossypium hirsutum, L.) resistant to the bacterial blight pathogen (Xanthomonas malvacearum [(E. F. Smith) Dowson], was crossed to susceptible strain. Data from the segregating progenies were analyzed by the program, and feasible models for the gene action accounting for resistance were proposed. Classification into eight grades of resistance‐susceptibility were shown to be statistically satisfactory for resistant and susceptible parents and for a segregating progeny in a specified environmental range of temperature and humidity. Conclusions regarding gene action are restricted to the specified environmental range. The program is best adapted for analysis of samples of 200 to 350 individuals.