In order to establish the critical level of phosphorus in annual varieties IAC-20, IAC-19, IAC-17, CNPA 78/SME-4 and in perennial varieties CNPA 2M and CNPA 3M young cotton plants were grown in nutrient solutions containing the following phosphorus concentrations: 0.38ppm, 1.14ppm, 3.42ppm, 10.26ppm and 30.78ppm. The solutions were replaced every seven days. From plants at the age of 44 days, 59 days and 74 days, the 5th leaf from the apex of the plants were collected and separated into petioles and leave blades and the phosphorus content was determined. The authors concluded: - The petioles or leave blades are adequate for the determination of the critical level of phosphorus.
cotton; varieties; critical level; phosphorus