Agronomical management of double crop Cotton

In recent year, extention of Cotton planting as double crope is important due to planting of compentitative crops such as Wheat and Canola. Late planting of Cotton (Gossypium hirsutum L.) is resulted in flowering delay and so boll development at lower temperature. For this reason, an experiment was conducted as 8 research project to identify suitable earliness cultivars for planting after Wheat and Canola harvesting. In this Research, with respect to genotypes comparison, Agronomical management of Cotton double crop was studied based on Irrigation planting layout, diseases, pests, and tillage. In this research, 20 earliness cotton genotypes were studied. In HashemAbad cotton research station, Gokorova, Tabladila and NO:200 in view of yield and B557, Bolgar 539, 4-S-4, Mehr and NO:200 with respect to earliness were in first class, respectively. In Karkandeh station, cotton genotypes had no significant difference in view of earliness but Bolgar 539 and NO:200 were in first class for seed cotton production. In Mogan station, Tabladila and NO:200 for yield and Opal, Bolgar539 and Gokorova for earliness were in first class, respectively. In the best suitable planting pattern and plant density Projects, the best planting pattern and variety was Mutajeneze early variety and 60Χ10 cm plant spacing (166000 plant per hectar). In hashemabad and Karkandeh Cotton Research Station ، the best plant pattern was 43259 'S genotype and 60Χ20 cm plant spacing (83000 plant hectar). In tillage projects, Siokra had good response to strip plowing + no tillage + two discs, but Syndose8o in plowing + disc and Mutagens earliness in chisel plowing +disc were better than other treatments. In projects of Crop residual management, the highest total yield was obtained by interaction effect of tillage + disk, remove crop residue and 20 kg/ha nitrogen fertilizer over recommended doses. In yield function project, maximum Cotton seed yield of Sahel, 43259 and 43347 were obtained with water consumptions of 1739,1832 and 1593 m3/ha, respectively. In order to determination of ferequency and irrigation water depth, the best treatment could be irrigation after 105 mm evaporation of pan with 80 % water requirement and 43347 cultivar. The results showed that various row spacing has affected yield and index of verticillum wilt. The best plant pattern and earliness variety was mutajeneze and 60Χ10 cm plant spacing (166000 plants per hectare). There was significant difference among pest's population. Number of Aphis gossypii (Glove.), Asymmetrasca decdens (Dlabo.), Bemisia tabaci (G.) and Thrips tabaci (L.) populations on B-557 and 43259 were less than Sahel. Number of cotton bollworm Helicoverpa armigera(Hub.) was no significant difference among varieties. Therefore, with respect to lesser pollution to cotton diseases the varieties of 43259 and B-557 are recommended to be grown as double crops (cotton after rapeseed) in Golestan provience.