Effect of kinetin concentration and methods of application on seed germination, yield components, yield and fiber properties of the Egyptian cotton (Gossypium barbadense)

Two field experiments in 1993 and 1994 as well as a laboratory germination experiment were conducted on the Egyptian cotton cultivar Giza 75 (Gossypha n burbadense) to determine the effect of six concentrations of kinetin (6-f urfurylaminopurine) ranging from 0 to 10.0 mg l(-1) and three different met hods of application: (A) seeds were soaked for 24 h before germination (lab oratory experiment) or sowing (field experiment) in solutions of different kinetin concentration, (B) cotton plants were sprayed twice with different kinetin concentrations at 60 and 75 days after sowing (DAS) during the squa re initiation and the beginning of belling stages, at volume solution of 48 0 l ha(-1). (C) Seeds were soaked in kinetin solutions before sowing as met hod A. In addition cotton plants were sprayed twice as method B with the sa me kinetin concentrations. Kinetin application improved seed viability and seedling vigour as shown by lengths of the hypocotyl, radicle and the entir e seedling, as well as seedling fresh weight. Moreover, significant increas es were recorded in the number of open bolls/plant, boil weight, lint and s eed indices, seed cotton yield/plant, and seed cotton and lint yields/plot. The highest means were obtained at 5 mg kinetin l(-1) concentration and un der method C of application. Treatments generally, had no significant effec ts on lint percentage, yield earliness and fiber properties. These results show that, the use of kinetin at 5 mg l(-1) for pre-soaking seeds before pl anting and spraying cotton plants at 60 and 75 DAS with the same concentrat ion could improve cotton germination, seed cotton and lint yields. (C) 2000 Elsevier Science B.V. All rights reserved.