Higher Seed Cotton Yield Research Articles

Impact of Harvest-aid Defoliants on Yield of American Cotton and Their Monetary Evaluation

Field experiments were conducted during Kharif 2012 and 2013 to determine the effect of two harvest-aid defoliants i.e Dropp ultra® and Ethrel, their application rates and time of application on three American cotton cultivars. Pooled data revealed significantly higher seed cotton yield for Bt hybrids MRC7361BGII (3055.2kg/ha) and MRC7017BGII (2913.0 kg/ha) as compared to non Bt variety F1861 (2346.0 kg/ha). Among tested defoliants, Dropp ultra® @200ml/ha resulted in better SCY, lint and seed yield. This yield enhancement in case of Dropp ultra® @ 200 ml/ha further lead to significantly better net returns (? 85373/ha) and B: C ratio (2.31) over other treatments. Application of defoliants at 150DAS resulted in significantly improved net returns (? 79288/ha) as compared to earlier application (? 73632/ha) at 140 DAS. Improved water productivity and fertilizer use efficiency coupled with better B: C ratio for Dropp ultra® @ 200 ml/ha at 150 DAS clearly indicated its superiority among all treatments. Therefore Bt hybrids seems to be superior over the non Bt varieties and application of ethrel@2000ppm or dropp ultra® @ 200 ml/ha at 150 DAS should be adopted as useful production practice for enhancing cotton yield under semi-arid conditions of north-western India.

Performance and behaviour of Bt cotton hybrids under sub-optimal rainfall situation

Growth behaviour and yield performance of Bt cotton hybrids under sub-optimal rainfall situation is of practical significance, because more than 60% of the cotton area is under rainfed condition in India. A field trial conducted in a sandy clay loam soil during the seasons 2006–2007, 2007–2008, and 2008–2009 to study the growth behaviour and yield performance under scanty rainfall situation revealed that growth in both Bt and non-Bt cotton hybrids significantly differed under these parameters. The crop experienced moisture stress at the early stages of growth and again during boll development phase in 2006–2007 and 2008–2009. However, Bt hybrids (1691 kg ha−1) produced higher seed cotton yield than non-Bt hybrids (1092 kg ha−1), while the controlled variety (LRA 5166) performed the average of these two (1399 kg ha−1). Similar trend was evident in respect of bolls per plant (at 90 DAP) and the final harvested bolls in both Bt and non-Bt cotton. Because of Bt gene, the early formed bolls were protected from the boll worms which led to less damage and higher yield with Bt hybrids. Amongst the hybrids, RCHB 708 Bt (1917 kg ha−1) performed better over the others.

Estado nutricional e produtividade de algodoeiro em função de diferentes espaçamentos e aplicação de regulador de crescimento

Strategies of cotton growth as row spacing and use of growth regulator are efficient when the knowledge of crop production potential as well as the amounts of nutrients content. The objective of this study was to evaluate the nutritional status of cotton DeltaOpal cultivar through leaf analysis of macronutrient, chlorophyll index and yield in relation to plant arrangement and managements of the growth regulator. The treatments consisted of plant arrangement: arrangement 1: 88,900 plant ha-1 and row spacing at 0.9m, arrangement 2: 114,300 plant ha-1 and row spacing at 0.7m, arrangement 3: 178,000 plant ha-1 and row spacing at 0.45m; management of growth regulator (mepiquat chloride) at 1.0 L ha-1 dose, concentration was50g L-1: a- no regulator application; b- single application at 70 days after emergency (d.a.e.); c- split application into four stages (35, 45, 55, and 65 d.a.e.). The reading reviews SPAD chlorophyll, leaf analysis of macronutrients and cotton yield were conducted in three agricultural years 2006/07, 2007/08 and 2008/09, under the experimental design of completely randomized blocks, in a 3x3 factorial scheme totaling up nine treatments with four replications. The reduction of row spacing and increasing plant density gives less absorption of potassium and sulfur by cotton crop. A single application of mepiquat chloride increase calcium leaf content. The split application of mepiquat chloride provides increased SPAD reading index, higher foliar magnesium concentration and highest seed cotton yield.

Identification of Resistance to Insect Pests Infestations in Cotton (Gossypium hirsutum L.) Varieties Evaluated in the Field Experiment

Resistance against insect pests is a crucial trait for the stability and sustainability of cotton production. A field trial was conducted to quantify relative tolerance and sensitivity varying in 10 released (new and existing) cotton varieties of Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan, against sucking and bollworm insect pest complexes. In general, it was observed that none of the cultivars were found completely resistant to pests although these originated as least susceptible, moderately susceptible and highly susceptible. Of them, N-777 was rated as more tolerant to white fly attack in comparison to N-Karishma that appeared susceptible. Variety N-9811 and Sitara-10 M carried maximum, and N-Karishma carried minimum jassid load for considering the best source for pest resistance. On the basis of mean bollworms damage values, the varieties N-Karishma, N-846 and N-852 carried less pest pressure than IR-824, Sitara-10 M and N-26 which were the most susceptible. Percent of seedling emergence was variable in most of the test genotypes. The variety N-9811 gave 99% emergence, while N-846 and N-777 conferred 95% emergence. Variety N-852 gave the poorest percent of emergence (72.99%) and the other six varieties conferred an emergence range of 94.05-83.76%. Differences in seed cotton yield were also observed, indicating that minimal and maximal pest injury on cotton influenced the crop yield. The varieties N- Karishma, N-852 and N-846 performed well in respect of higher seed cotton yield. The results suggest that tolerant cotton genotypes might be commercially cultivated extensively in this agro-climatic area and Scientists involving in development of host plant resistant cultivars are encouraged to utilize resistance sources as donar against key pest species.

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  The aim of this study was to determine seed cotton yield, yield components and fiber technological properties of four mutant cotton varieties from Azerbaijan (Agdas-3, Agdas-6, Agdas-7 and Agdas-17) and three local standard varieties (Maras-92, Sayar-314 and Stoneville-453) belonging to Gossypium hirsutum L. The study was carried out at the experimental field of Koruklu Agricultural Research Station in Sanliurfa Province (Akcakale-Harran Plain) in the South-east Anatolian Region of Turkey. The trial was established in randomized block design with four replications in four years (2001 to 2004 ). In the study, plant height, monopodia, number of sympodia and boll, weight of seed cotton per boll, ginning outturn, 100 seed weight, seed cotton yield, earliness ratio, fiber length, fiber fineness, strength and uniformity  were investigated. According to the results of four years' trials, the varieties, in all investigated characters except fiber fineness, strength and uniformity and year x variety interactions for plant height, number of bolls per plant, seed cotton yield and first harvest ratio, were found to be significant. The highest sympodial number was taken from Agdas-3 variety (13.79), the highest number of boll per plant was taken from Agdas-17 (15.41) and the highest seed cotton weight per boll was taken from Agdas-7 (5.54 g).   All Agdas varieties had less ginning outturn than local standard varieties. The highest seed cotton yield was obtained from Agdas-17 (3654.2 kg ha-1), followed by Agdas-3 (3593.8 kg ha-1). All Agdas varieties had more seed cotton yield than standards except Agdas-7. Among Azerbaijan varieties, Agdas-3 was the earliest maturing variety with 81.3% of first harvest ratio. All investigated varieties were similar to each other in fiber technological properties. In conclusion, it can be said that among Azerbaijan varieties, Agdas-17 and Agdas-3 had higher seed cotton yield than local standard varieties, and they are the most hopeful varieties for Southeast Anatolian Region.   Key words: Cotton, Gossypium hirsutum L., seed cotton yield and fiber technological properties.

Effect of Insecticide Rotation and Mixtures Use for Resistance Management on Cotton Aphid, Aphis gossypii Glover (Hemiptera, Aphididae) in Middle Awash Areas of Ethiopia

A field experiment was conducted at Werer Agricultural Research Center, Afar region, Ethiopia, to determine the best insecticide rotation sequence and use of compatible mixtures in the Insecticide Resistance Management strategy for cotton aphid, Aphis gossypii. Randomized Complete Block design having eight treatment combinations and four replications were used. The parameter assessed were aphid population at pre and post insecticide application; and seed cotton yield. In this experiment, four round of spray application was made by using insecticides from different chemical class and their mixtures. Using the modified Abbott’s formula, the percent efficacy was computed. A highly significant difference (P< 0.001) was observed among the treatments for post spray counts. In most of the treatments made during the first round spray, the aphid population didn’t show a response to the insecticides applied. But starting the second round, the insecticides were able to express their potential in reducing aphid population. In most cases sole treatments were better than mixtures. However, the mixtures like endosulfan + carbosulfan and endosulfan + furathiocarb gave better control of aphid. As the effect of insecticide rotation, treatment 2 (Carbosulfan, Diafenthiuron, Furathiocarb and Deltamethrin), 3 (Dimethoate, Carbosulfan, Deltamethrin and Diafenthiuron) and 5 (Endosulfan, Endosulfan + Carbosulfan, Deltamethrin and Dimethoate) were the best alternative combinations of insecticide groups to be used in IRM strategy. Seed cotton yield was significantly different (P< 0.0001) among treatments. The highest seed cotton yield (29.84 q/ha) was recorded from treatment 5 (Endosulfan, Endosulfan* Carbosulfan, Deltamethrin and Dimethoate), followed by treatment 1(Endosulfan, Carbosulfan, Deltamethrin and Furathiocarb) and 7 (Furathiocarb Endosulfan * Furathiocarb, Deltamethrin and Dimethoate) and yielding 26.29 and 20.47 q/ha, respectively. These findings point to the fact that, alternative use of insecticides from different class and using insecticide mititures is the best option to manage insecticides resistance in cotton aphid.

Evaluation of Commercial Cotton Harvesting Systems in the Southern High Plains

<abstract><title><italic>Abstract. </italic></title> Cotton production practices have changed in the Southern High Plains of the United States over the last decade resulting in increased yields and improved fiber quality. Moreover, the majority of U.S. cotton now competes in a global fiber market that demands higher quality fiber for ring spun yarn than the former domestic open-end market. The brush-roll stripper harvester is the predominate machine used to harvest the Southern High Plains cotton crop, but interest in spindle pickers has increased recently in efforts to better preserve fiber quality, enhance profitability, and maintain the market share of U.S. cotton in the global fiber market. This work was conducted to compare yields, fiber quality, and agronomic parameters between picker and stripper-based harvest systems under commercial production and ginning conditions. Large-scale harvest system comparison tests were conducted at seven sub-surface drip irrigated sites across the Texas High Plains during the 2008-2010 crop years using brush-roll strippers with field cleaners and spindle pickers. Four cotton modules harvested from each site under each harvest method were ginned by a commercial gin. Compared to picker-harvested cotton, stripper-harvested cotton had 1096 kg ha^-1 higher seed cotton yield which increased ginning charges by $72.40 ha^-1. Seed and lint yields were 217 and 108 kg ha^-1 higher, respectively, for stripper-harvested cotton resulting in $88.78 ha^-1 higher total production revenue. Notwithstanding higher lint yield for the stripper system, custom harvesting was $51.38 ha^-1 more expensive for the picker system due to the custom harvesting rates used (picking: $0.22 per lint kg; stripping: $0.18 per lint kg). Except for strength and reflectance that showed no difference by harvest method, all High Volume Instrument (HVI) fiber quality parameters were improved for picker-harvested cotton. Due to improved HVI fiber quality and a substantial decrease in the number of bark contaminated bales, lint value was higher for picker-harvested cotton. However, increased lint value was offset by decreased yield such that net revenue was $66.76 ha^-1 higher for stripper-harvested cotton across all sites.

Response of American Cotton (Gossypium hirsutumL.) Genotypes to Varying Plant Densities and Graded Levels of Fertilizers

A field experiment was conducted at research farm of Cotton Section, Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana during kharif 2011 to work out the optimum plant density and fertilizers level for hirsutum cotton genotypes LH 2107, LH 2108, F 2164 and LH 2076. Among the hirsutum cotton genotypes, LH 2107 (2397.9 kg/ha) and LH 2108 (2244.1 kg/ha) were statistically at par with each other but proved significantly superior over F 2164 (1967.2 kg/ha) and LH 2076 (1905.4 kg/ha). Higher plant density at plant geometry of 67.5 x 60 cm (2195.0 kg/ha) was found to be significantly superior over lower plant density at plant geometry of 67.5 x 75 cm (2062.3 kg/ha). Application of 100% RDF (2220.0 kg/ha) was statistically at par with 125% RDF (2189.6 kg/ha) and both these treatments registered significantly higher seed cotton yield than 75% RDF (1976.3 kg/ha).

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indicated that there were some positive correlations. These data indicated that photosynthetic yield, fluorescence, chlorophyll content (SPAD value), cell membrane thermostability (CMT), plant height and number of bolls per plant can be used for improving seed cotton yield. However, among these measurements CMT, SPAD value and fluorescence were more practical in large breeding trials. The results showed that AGC 375 and AGC 208 cotton varieties had lower relative cell injury level (higher cell membrane thermostability) and higher seed cotton yield and photosynthetic yield than other investigated varieties.

PHYSIOLOGICAL EFFECTS OF POTASSIUM FORMS AND METHODS OF APPLICATION ON COTTON VARIETY GIZA 80

Two field experiments were carried out at Sids Agricultural Research station, Beni-Suef Governorate in 2009 and 2010 seasons, to study the effect of the potassium sulfate and potassium humate on Egyptian cotton cultivar, Giza 80 (G. barbadense L.). The aim was to investigate the effect of two concentrations of soil potassium humate (80 %) with rate of 4 and 6 kg / fed. and foliar application of potassium humate with 2 and 3 g / L. sprayed at pinhead square, start of flowering and peak of flowering stages, on growth, leaf nutrient contents, earliness, seed cotton yield and yield components. The obtained results could be summarized as follows: Foliar application of potassium humate produced the highest values of leaf N, K, Ca, Fe, Zn, Mn and Cu ppm, contents as compared with the other treatments. All treatments led to significant increase of leaf macro and micronutrients contents compared with the control treatment, but values of leaf P % and Mg % content were not significantly increased. All treatments significant increase of leaves content of chlorophyll a, b, (a + b) and carotenoids. The highest seed cotton yield / fed. and yield components showed significant increase in the application of soil potassium humate (4 kg / fed. + spraying cotton plants potassium humate 2 g / L.). The application of potassium humate significantly increased number of fruiting branches, number of open bolls/plant, boll weight, seed cotton yield / fed., oil % and protein % in seeds of cotton as compared with the control treatment in both seasons. Various treatments had insignificant effects on lint %, earliness % and fiber quality in both seasons. Key words: potassium sulfate, potassium humate, Growth, leaf nutrient, yield and yield components, oil, protein.

Effects of different water levels on cotton growth and water use through drip irrigation in an arid region with saline ground water of Northwest China

Due to the mismanagement of water and fertilizer application, cotton cultivation in Xinjiang Northwest China is faced with the problems of soil deterioration and groundwater table ascension. This study was conducted to evaluate the effects of different levels of water applied through drip irrigation on cotton yield and water use in an arid region of Northwest China. The experiment included five water treatments in which the soil matric potential (SMP) at a depth of 20cm was controlled higher than −10kPa (S1), −20kPa (S2), −30kPa (S3), −40kPa (S4), and −50kPa (S5) after cotton was established. The results revealed that the highest cotton evapotranspiration (ETc) was achieved under S1 (−10kPa) treatment and the ETc, deep percolation and the ratio of deep percolation with irrigation water all increased with increasing SMP threshold. After three years experiment, no salt accumulation in surface soil layer was found under our irrigation schedule. The highest seed cotton yield was obtained when the SMP threshold was controlled above −30kPa in 2008, and −20kPa in 2009 and 2010. Moreover, the highest yield obtained after 3 years was 42% higher than the average yield achieved by local farmers in the area. Additionally, the water use value (WUE and IWUE) tended to increase as the SMP threshold decreased in 2009 and 2010. Considering the cotton yield and the impact of irrigation on the underground water table, an SMP higher than −20kPa at 20cm can be used as an indicator for cotton drip irrigation scheduling and agronomic practices in this area to help alleviate the dangerous increase in the water table while increasing the cotton seed yield.

CRSM-38, a new high yielding coupled with CLCuV tolerance cotton (Gossypium hirsutum L.) variety

CRSM-38 is a high yielding and leaf curl virus tolerant cotton variety, developed in Pakistan. Hybridization and subsequent pedigree method’s selection work was carried out under natural field conditions at Cotton Research Station, Multan during the year 2001 and 2002 by using a virus tolerant strain (583-85/99) and a variety (FH-900). The new variety exhibited an average of 77.9% higher degree of tolerance against cotton leaf curl virus (CLCuV) over respective checks, and attained an average of 46.52 % higher seed cotton yield than that of CIM-496 under various climatic conditions revealing its wider adaptability. It possesses harmonious combination of fiber traits, that is, 39.94% ginning out turn (GOT), 29.07 mm fiber staple length, 4.38 ig/inch fiber micronaire and 31.38 g/tex fiber strength. Significant differences among genotypes showed higher degree of genetic variability, heritability (78 to 90%) and genetic advance (38 to 63.90%) in seed cotton yield suggesting that these genetic components were under the control of additive genetic effects, whereas tolerance to CLCuV could be improved through selection for high seed cotton yield. On the basis of the aforementioned features, CRSM-38 was recommended for general cultivation by Punjab Seed Council during the year 2009. Key words : Gossypium hirsutum L ., CRSM-38, seed cotton yield, cotton leaf curl virus (CLCuV), heritability, additive genetic effect, genetic advance.

Response of cotton genotypes to planting date and plant spacing

Cotton growers face a problem of low cotton yield in late planting (after sunflower and maize). The objective of our study was to determine the effects of planting date, plant spacing (plant density), and genotypes on seed cotton yield and its components, ginning outturn (GOT%), and fiber quality traits (fiber length and fiber fineness). Five planting dates (May 1, May 15, May 30, June 15, and June 30), three plant spacings (15, 30, and 45 cm), and three cotton genotypes (CRS-6070, CRS-738, and CIM-496) were evaluated for seed cotton yield with its components and fiber quality traits. The results showed that monopodial branches/plant, sympodial branches/plant, number of bolls/plant, and seed cotton yield differed significantly among different planting dates, plant spacing, and genotypes. While the boll weight was significantly different among genotypes only. GOT%, fiber length, and fiber fineness were different significantly among planting time and cotton genotypes, which were not significantly affected by plant spacing. Cotton grown in early planting dates had higher seed cotton yield (4874 and 4653 kg/hm2) at the highest plant spacing (45 cm). While late sown cotton (June 15 onward) gave higher seed cotton yields (2068 and 1889 kg/hm2) at the lowest plant spacing (15 cm). GOT%, fiber length, and fiber fineness improved significantly in late planting and not affected from plant spacing. From our present study, it is concluded that high seed cotton yield can be achieved at high plant spacing in early planting while at low plant spacing in late planting.

Comparative performance of Bt cotton with some elite conventional cotton cultivars under arid to semi-arid conditions

oN, longitude 72.36 o E and altitude 157.65 m. The results revealed that plant growth parameters like plant height, number of bolls plant -1 and seed cotton weight boll1 , were differed significantly (P < 0.05) among Bt and non-Bt cotton cultivars. Seed cotton yield and fiber quality parameters such as maturity percentage, micronaire value, staple length, fiber strength and virus infection percentage were also significantly (P < 0.05) different among different cultivars. Bt -1 21 had maximum value for seed cotton weight boll-1 and maturity percentage and produced 26% higher seed cotton yield than all other cultivars. Furthermore, it also showed 58% less cotton leaf curl virus infection compared to other cultivars. BH-162 produced fiber with maximum length and fineness but it appeared most vulnerable to virus attack. It was concluded that Bt -1 21 performed best in most of the studied traits than other cultivars and may be recommended for cultivation in areas having arid to semi-arid climatic conditions.

Influence of Potassium Salt based Glyphosate on Weed Control Efficacy and Yield in Winter Irrigated Cotton

A field investigation was carried out at Tamil Nadu Agricultural University, during winter 2011- 12 to evaluate the new formulation of potassium salt based glyphosate (Roundup Crop Shield 460 SL) on weed control in winter irrigated cotton. Experimental results revealed that, post- emergence application of glyphosate at 1800 g a.e. ha-1 at 35 and 70 days after sowing + Intercultural operation as earthing up at 45 and 55 days after sowing resulted in lower weed density, weed dry weight and higher weed control efficiency. With respect to the relative weed density, broad-leaved weeds were higher at initial stages and grassy weeds were predominant at later stages of cotton. Higher seed cotton yield was obtained with POE glyphosate at 1800 g a.e. ha-1 at 35 and 70 DAS with + Intercultural operation at 45 and 55 DAS (2930 kg ha-1), which was comparable with PE pendimethalin at 750 g a.i. ha-1 + Intercultural operation at 45 and 55 DAS (2710 kg ha-1). Compared treatments without intercultural operation, intercultural operation carried out treatments performed better and recorded more seed cotton yield.

Enhancing Productivity of Summer Irrigated Cotton Through Plant Growth Regulator and Foliar Nutrition 248

A field experiment was conducted at Agricultural College and Research Institute, Madurai to study the influence of plant growth regulator (NAA 40 ppm) and foliar nutrition (DAP 2%, KCl 1%) on summer irrigated cotton for enhancing the productivity along with recommended dose of fertilizers 60:30:30 Kg N,P 2 O 5 ,K 2 O ha -1 . The growth characters of cotton such as plant height, leaf area index and plant dry matter production at various stages crop growth (60,90 and 120 DAS) were greatly influenced by application of RDF NPK with NAA 40 ppm and DAP 2% foliar spray either at peak flowering and boll development stages or at squaring peak flowering stages. Yield attributes of cotton viz., number of symbodial branches plant-1 , fruiting points plant -1 , bolls plant -1 and boll weight were increased in the alone promising treatments as compared to control and other treatments. As a result, higher seed cotton yield (19.29 q ha-1 ) was obtained in cotton receiving RDF and sprayed with NAA 40 ppm and DAP 2% either at square formation and peak flowering or peak flowering and boll development stage. Quality characters of cotton like seed index, lint index, ginning percentage, Bartlett's index, bundle strength and fibre finess were not influenced.

Assessment of yield and water use efficiency of drip-irrigated cotton (Gossypium hirsutum L.) as affected by deficit irrigation

A field experiment was conducted for 2 consecutive years to evaluate the response of cotton crop to deficit irrigation under drip irrigation conditions. Water use efficiency (WUE), seed cotton yield, and fiber quality parameters were assessed at various irrigation levels. The experiment was set up to apply water at 4 different application rates: 50%, 65%, 80%, and 100% of the soil water depletion. These were abbreviated as DI50, DI65, DI80, and FI, respectively. The total amounts of irrigation water applied were 408 and 773 mm and the average seed cotton yields were 2909 and 5090 kg ha^{-1} for the DI50 and FI treatments, respectively. The highest seed cotton yield was obtained with full irrigation treatment in both years. Values of WUE were 0.65 and 0.70 kg m^{-3} for the FI and DI80 treatments, respectively, in the 2007 season. In the 2008 season, WUE values were 0.65 and 0.72 kg m^{-3} for the FI and DI80 treatments, respectively. The highest values of WUE and irrigation water use efficiency (IWUE) were observed in DI80 (0.71 and 0.75 kg m^{-3}, respectively), and the lowest IWUE in both years was seen with the FI treatment (0.66 kg m^{-3}). The yield response factor (ky) was 1.00 during the entire growing season, based on averages of the 2 years. No significant differences in fiber length, strength, uniformity, elongation, or fineness were observed between the FI and DI80 treatments in the 2008 season. The DI80 treatment showed significant benefits in terms of irrigation water savings and better WUE, indicating an attainable advantage of deficit irrigation employment under water shortage conditions.

Relationship between Yield, Fiber Length and other Fiber-Related Traits in Advanced Cotton Strains

The objective of this study was to determine the relationship between yield, fiber length and other fiber related traits in advanced cotton strains, derived from a cotton breeding program. The experiments were conducted in the Southeastern Anatolia Agricultural Research Institute’s experimental area according to randomized complete block design (RCBD) with four replications during 2007 and 2008 cotton growing season. In the study, 9 advanced cotton strains and 2 check varieties (‘GW-Teks’ and ‘Stoneville 468’) were used as plant materials. The results of the statistical analysis indicated that the advanced cotton strains had significant differences in terms of the investigated characteristics when compared to the check varieties. The highest seed cotton yield (4087.0 kg ha-1) and fiber yield (1632.2 kg ha-1) were obtained from ‘SET-34’ cotton strain which had acceptable fiber quality properties. However, the highest fiber length (32.33 mm) was obtained from ‘ERA-85’. The correlation analysis indicated that there were significant negative correlations between fiber length and seed cotton yield, lint yield and ginning percentage, while there were positive and significant correlations between fiber length and fiber strength.

Assessment of Tolerance Level of some Cotton (Gossypium hirsutum L.) Varieties against Verticillium wilt (Verticillium dahliae Kleb.) Disease

The objective of this study was to assess the tolerance level of some cotton varieties against Verticillium wilt (Verticillium dahliae Kleb.) disease. Verticillium wilt is one of the major constraint diseases of cotton production worldwide and also in Turkey. The study was carried out at the Southeastern Anatolia Agricultural Research Institute’s naturally infected experimental area during 2004-2006. In this study, 10 different commercial cotton varieties were used as plant material. The experimental design was a randomized complete-block with four replications. During the cotton growing season, foliar disease index (FDI), vascular disease index (VDI) and vascular disease rate (VDR) were observed in addition to seed cotton yield and some fiber quality characteristics. According to the results, it was determined that with regards to FDI, VDI and VDR, the most tolerant varieties were ‘GW-Teks’, ‘GW-Golda’ and ‘Carmen’, while the most sensitive varieties were ‘Maras 92’, ‘Sayar 314’ and ‘Stoneville 453’. The other varieties had moderate tolerance levels. The highest seed cotton yield and lint yield were obtained from ‘DP-Deltaopal’ and ‘Stoneville 453’. These results showed that some sensitive varieties had high yield; the reason for this situation may be related with early or late occurrence of the disease. The result of this study indicated that ‘GW-Teks’, ‘GW-Golda’ and ‘Carmen’ varieties must be preferred for infected areas; on the other hand, ‘DP-Deltaopal’ and ‘Stoneville 453’ can be recommended and grown in uninfected areas. Additionally, ‘Carmen’, ‘GW-Teks’ and ‘GW-Golda’ varieties can be used as material for improving disease resistance in cotton breeding programs.

Deficit irrigation and nitrogen effects on seed cotton yield, water productivity and yield response factor in shallow soils of semi-arid environment

Abstract A field experiment was conducted for 2 years to investigate the effects of deficit irrigation, nitrogen and plant growth minerals on seed cotton yield, water productivity and yield response factor. The treatment comprises six levels of deficit irrigation (Etc 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5) and four levels of nitrogen (80, 120, 160 and 200 kg N ha−1). These were treatments superimposed with and without plant growth mineral spray. Furrow irrigation treatments were also kept. Cotton variety Ankur-651 Bt was grown during 2006 and 2007 cotton season. Drip irrigation at 1.0 Etc saved 26.9% water and produced 43.1% higher seed cotton yield over conventional furrow irrigation (1.0 Etc). Imposing irrigation deficit of 0.8 Etc caused significant reduction in seed cotton yield to the tune of 9.3% of the maximum yield. Further increase in deficit irrigation from 0.7 Etc to 0.5 Etc significantly decreased seed cotton yield over its subsequent higher irrigation level. Decline in the yield under deficit irrigation was associated with reduction in number of bolls plant−1 and boll weight. Nitrogen at 200 kg ha−1 significantly increased mean seed cotton yield by 36.3% over 80 kg N ha−1. Seed cotton yield tended to increase linearly up to 200 kg N ha−1 with drip Etc 0.8 to drip Etc 1.0. With drip Etc 0.6–0.5, N up to 160 kg ha−1 provided the highest yield, thereafter it had declined. Foliar spray of plant growth mineral (PGM) brought about significant improvement in seed cotton yield by 14.1% over control. The water productivity ranged from 0.331 to 0.491 kg m−3 at different irrigation and N levels. On pooled basis, crop yield response factor of 0.87 was calculated at 20% irrigation deficit.