Response to Pix of cotton varieties in Greece

ABSTRACT
The climatic conditions in Greece, especially in the north of the country, limit crop duration. Maturing the crop early is frequently needed to avoid the risk of rain and cool temperature at the time of harvest. In these conditions it is important to secure the bottom and the first position bolls on the plants. The studies conducted in Greece during the last three years indicate that among the different techniques inducing earliness, the split use of a plant growth regulator (PGR) namely Pix, not only limits plant height but also induces early fruit set, better bottom boll production and earliness. The plant mapping technique is of great interest to ensure precise field follow up from early plant development to harvest. Preharvest mapping has given a clear indication of the plant production structure with different Pix application regimes. The best results were obtained either with three applications starting at pinhead square, i.e. 60 days after planting (DAP), then first flower (70 DAP) and 7 to 10 days later at the rate of 250, 250, 500 ml per hectare, respectively, or two applications 70 and 80 DAP at the rate of 500, 500 ml per hectare. Higher average yield (25%) and earlier maturity (one week) were obtained on two sites.

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Effect of Salinity on Botanical Characters and Fiber Maturity of Three Egyptian Cotton Cultivars

ABSTRACT
The objective of this study was to investigate to extent salinity affects the growth and other characters of three Egyptian cotton cultivars: Giza 77, Giza 75 and Giza 80. The salinity levels were 0, 2000, 4000 and 6000 ppm of either NaCl + CaCl2 or NaCl + KCl. Germination speed and capacity were lower as the concentration of various were salts increased. Salinity reduced plant height and the number of the main stem internodes. Salinity reduced cotton lint yield by up to 50%; specific weight of seeds by up to 18%; fiber maturity ratio by up to 8.9%; ovule width by up to 35% and fiber ribbon width by up to 4.9% where 6000 ppm of NaCl alone was applied. The effects of NaCl were greater than the effects of NaCl + CaCl2 or NaCl + KCl. The relationship between fiber maturity and ovule width at two days post anthesis with some other characters are investigated

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Production of High Gossypol Cotton Plants with Low Gossypol Seed from Trispecies Hybrids Including G. sturtianum Willis

ABSTRACT
Two tri-species hybrids that include G. hirsutum L. (2n=4X=52 (AD genome)) were created to develop upland cotton plants with low gossypol seed and high gossypol aerial parts. G. sturtianum Wil. was used as the donor parent (2n=2x=26, genome C1) and a wild American diploid cotton, G. thurberi Tor. (2n=2x=26, genome D1) or G. raimondii Ulb. (2n=2x=26 genome D5) as bridge species. Both tri-species hybrids were backcrossed to different G. hirsutum varieties, originating from Central and West Africa to produce BC1, BC2, selfed BC2 and BC3 seeds. Growth regulators applications at flowering, in vitro culture of the mature seed embryos and grafting of the more perturbed hybrids on vigorous G. hirsutum seedlings were necessary to obtain a large number of viable hybrid material. A drastic reduction of the gossypol gland density was expressed by at least 25% of the seeds of each backcross generation while the aerial parts of the resulting plants were normally glanded. Mortality rates of germinating seed and young plantlets were very high (76%) for BC1 material but decreased markedly in following generations. Cytogenetic observations confirmed the soundness of the introgression strategy. Both tri-species hybrids and several BC1 and BC2 genotypes issued from nearly totally glandless seeds were fertile and showed high frequencies of multivalent and chiasma formations at metaphase I, indicating important genetic material exchanges.

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Male sterility- New Frontiers in Cotton Breeding

ABSTRACT
Conventional hybrid cottonseed production is expensive and this has paved the way for intensification of research into male sterility systems in cotton. Histological, morphological differences, yield and fiber properties and changed restorer background were studied to establish facts on male sterility systems. Post meiotic obstruction in pollen development in GMS and pre-meiotic abnormalities in CGMS caused sterility in cotton. Morphologically fertile and sterile counterparts looked alike except for flower traits where significant reductions in ovary size, staminal column, style and anther filament length and anther number in CGMS. This was not apparent with GMS. Despite reports of reduction in yield with CGMS based hybrids compared to conventional hybrids of the same parents, some entirely new combinations of CGMS hybrids proved economically worthwhile. A comparison between two restorer lines, one based on G. hirsutum and the other on G. harknessii backgrounds, the latter proved superior for stable restoration. Among 64 lines converted, eight had a GOT above 40%, 33 had a seed index of 10 g or more and 11 had a halo length above 30 mm. A halo length of 28 mm, seed index up to 12 g and GOT up to 40% was observed in R lines. Hybrids of selected 12 lines and eight R lines exhibited heterosis for yield and boll features compared to the conventional checks. This emphasizes better performance of diversified A and R lines for hybrid production. The possibility of good CGMS lines in G aridum background is predicted.

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Heterosis Component Studies in Upland Cotton

ABSTRACT
Heterosis is by far the most important and effective tool in the hand of crop breeders for effecting rapid improvement in the yield and others economic attributes. Study of heterosis and inbreeding depression has a direct bearing on the breeding methodology to be employed for genetic improvement. In the present study, four diverse parents present of American Upland Cotton, g Bikaneri Narma, Model, Ganganagar Ageti and DP-16 were crossed to make hybrids. Data were recorded for seed cotton yield per plant and on its contributing traits. From the weighted least square estimates of components of generation means, components of heterosis were calculated. Heterosis in the F1 could be obtained if no mutual cancellation of components of heterosis occur. Over the over dominance as the predominant assignable cause of the heterosis was ruled out by observation of a higher magnitude of dominance (h) and its interaction components than of the additive (d) component.

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Cotton Hybrids and their Role in Indian Economy

ABSTRACT
India is the pioneer country in the world for cultivating hybrid cotton on a commercial scale. The world’s first intra-hirsutum hybrid i.e. H4 was released in 1970 from Surat (Gujarat) and the world’s first interspecific tetraploid hybrid i.e. “Varalaxmi” was released from Dharwad (Karnataka). Later on, several high yielding hybrids in tetraploid cottons and a few in diploid cottons were released especially for central and southern zones. Recently, some hybrids have been released for north zone also. Hybrid cottons now cover about 40% of the total cotton area and contribute about 50% to the national cotton production. Hybrid cottons have helped India in achieving self sufficiency in cotton production and also in providing employment opportunities to millions of rural people. Now India earns about 420 thousand million rupees of foreign exchange per annum by way of cotton export in the form of lint, yarn and fabrics, half of which comes through hybrids. Besides yield remarkable improvement has been achieved in fiber quality. Various aspects of hybrid cotton such as area under cultivation, types of hybrids, hybrid research centres, practical achievements, hybrid seed production, role of hybrids, limitations and future outlook are discussed.

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Host Suitability and Yield Response of Three Cotton Varieties to Meloidogyne incognita

ABSTRACT
One susceptible (Deltapine 90) and two resistant (LA 887 and NemX) cultivars were evaluated in field microplots for host suitability and yield loss to an isolate of Meloidogyne incognita. Five replications of seven initial population densities (Pi) of M. incognita (0, 0.5, 1, 10, 50, 100, 500 eggs/500 cm3soil) were established for each cultivar in the 1997 growing season in South Carolina. Deltapine 90 was an excellent host for M. incognita. Severity of galling (G) and reproduction, as measured by the final larvae population density of juveniles in the soil (Pf), responded in a positive linear manner to Pi as predicted by the models G = 1.28 log 10 (Pi + 1) – 0.278, (r 2 = 0.82) and Pf = 822.5 log 10 (Pi + 1) – 253.3, (r 2 = 0.61). NemX and LA 887 were both poor hosts. Severity of galling and Pf for these two varieties responded in a positive linear manner to Pi and could be predicted by the following models: G = 0.239 log 10 (Pi + 1) – 0.013, (r 2 = 0.27) and Pf = 111.78 log 10 (Pi + 1) – 4.80, (r 2 = 0.05) for NemX; G = 0.34 log 10 (Pi + 1) – 0.186, ( r 2 = 0.39) and Pf = 42.62 log 10 (Pi + 1) – 3.51, (r 2 = 0.25) for LA 887. Yield response of the cultivars to Pi did not fit a linear model. In a similar experiment utilizing the same Pi’s, greater yield suppression of DP 90 was observed. The negative linear relationship between Pi and yield fit the model y = – 9.30 log 10 (Pi + 1) + 60.05, (r 2 = 0.13). Generally, LA 887 yielded the highest across Pi’s and had smaller Pf’s at harvest.

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Comparative Evaluation of Intraspecific Isohybrids in Gossypium hirsutum L.

ABSTRACT
Isohybrids of Cotton Ankur 651 were tested at the research farm of the company under rainfed conditions during 1997-98 to study the effect of different plant characters on the economic parameters. New lines of the male parent Ca/H-128 that were isogenic for the character okra leaf shape, pigmented plant body and pigmented anther filament were developed by back-crossing. The combinations showed non-significant differences for days to flowering, number of monopodia, number of sympodia, plant height, ginning outturn, 2.5% span length, uniformity ratio, micronaire, fiber maturity and 1/8” gauge tenacity. Semi okra F1 gave the highest seed cotton yield followed by entire leaf F1, F1 with pigmented plant body and F1 with pigmented anther filament. Entire leaf F1 exhibited the highest average growth rate followed by F1 with pigmented anther filament, semi okra F1 and F1 with pigmented plant body. Semi okra F1 proved efficient for economic characters.

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Research and Development Efforts on Hybrids of Diploid Cotton in Mahyco, India

ABSTRACT
India is an important cotton growing country with the largest area under cotton in the world. India is also considered the birth place of the two diploid cotton species G. arboreum and G. herbaceum, known as Desi cottons. Since these species are highly resistant to pests and diseases, tolerant to drought, fit for rainfed cultivation in low rainfall and poor soil areas and possess high structural uniformity of the fiber, the advantage of exploiting the diploid inter and intra specific heterosis was considered .The present paper deals with the R & D efforts carried out in Mahyco to augment the yields in diploid cottons coupled with improvement in fiber properties and production technology.

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Brown Cotton – Home Coming

ABSTRACT
Pakistan had a well-developed cottage industry that perished under modernisation. Recently Fox Fibers revived the use of natural coloured organic cotton. Brown cotton seed samples were collected from a local ginnery. It had short staple (14-15 mm), and low yield. This material also had poor resistance against cotton leaf curl virus and insects. Eight shades in brown colour have been differentiated ranging from darkest (Pink) to lightest. In order to improve the yield, fiber quality, and resistance to disease and insects, hybridization work was undertaken. Rough and okra leaf characters have been incorporated to lend comparative tolerance to insects. The hybrid material is in F3. Green colour seed was collected from a local grower. The green colour is not stable but efforts are being made to stabilize it. D’Jura green an introduction from USA and local green were crossed producing dark colours between deep green and dark blue. It will be sown in F3 this year

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