Critical level of phosphorus in cotton varieties: III. concentration of phosphorus in the leaves and petioles correlated with time of sampling

Abstract

In order to establish the time of sampling of leaves and petioles for the varieties IAC-17, IAC-19, IAC-20, CNPA 78/SME4 (annual) CNPA 2M and CNPA 3M (perennial) cotton plants were grown in nutrient solutions containing the following phosphorus concentrations: 0.38ppm, 1.14ppm, 3.42ppm, 10.26ppm and 30.78ppm. From plants 44 days, 59 days and 74 days old the 5th leaves from the apice of the plants were collected and their leaf blades separated from the petioles. Phosphorus content of these separate leaf parts were determined. The authors concluded that the most adequate time of sampling for the annual varieties is around 44 days whereas 59 days is adequate for the perennial varieties.