Differential potassium influx influences growth of two cotton varieties in hydroponics

Potassium uptake rate of two cotton (gossypium hirsutum l.) varieties viz.,nibge-2 and mnh-786 was investigated in nutrient solution culture having deficient k @ 0.3 mm and deficient k+ na @ 0.3 +2.7 mm. depletion of k from solution was monitored over a period of 24 h at regular time intervals after 0,0.5,1.0,1.5,2,3,4,5,6,8,10,12 and 24 h to estimate k uptake kinetics of the roots i.e. maximum influx,imax and the michaelis-menten constant,km. nibge-2 had about 2-fold higher (2.0 mg g rdw-1 hr-1) imax value for k uptake rate at deficient k+na than that (1.207 mg g rdw-1 hr-1) for mnh-786. higher,michaelis-menten constant,km (12.82 ppm) for k uptake rate was observed in both cultivars nibge-2 and mnh-786 at deficient k+na than that at deficient k. main effects of treatments and varieties had significant (p< 0.05) effect on shoot dry matter,root dry matter,total dry matter and leaf area per plant. maximum k influx in nibge-2 at deficient k and deficient k +na was attributed to enhanced growth response as compared to that in mnh-786.