Growth, nitrate uptake and respiration rate in bean roots under phosphate deficiency

The decrease in inorganic phosphate concentration in bean (Phaseolus vulgaris L. cv. Złota Saxa) roots induced decrease in respiration rate. The decrease observed in ATP pool in phosphate deficient (-P) roots was greater than it would result from the decline in respiration and possible involvement of alternative pathway, suggesting an increased energy utilization for growth and ion uptake. Indeed, relative growth rate was higher in -P plants until 12 d of culture and later dropped to the rate similar to the control. Net nitrate uptake rate was higher in -P plants than in +P plants at the beginning of phosphate starvation, then during the prolonged culture it decreased rapidly in -P plants and after 19 d it was 8 times lower than that in the control. The decline in ATP production during prolonged phosphate starvation influenced NO₃ ^- uptake more than root growth. This revised version was published online in July 2006 with corrections to the Cover Date.