EFFECT OF PHOSPHORUS ON PHYSIOLOGICAL AND AGRONOMIC PARAMETERS OF SUGARCANE CULTIVARS IN THAILAND

摘要

The effects of phosphorus (P) fertiliser on yield and quality of three sugarcane cultivars was evaluated in the upper northeastern region of Thailand. The study was conducted on a Roi Et series (fine-loamy, mixed, isohyperthermic Aeric Paleaquults) soil with three cultivars (K 90-112, K 86-161 and Phil 66-07) and four P levels (0, 72, 101 and 129 kg P_2O_5/ha). Application of P increased growth in terms of dry weight, crop growth rate, leaf area index, and height compared with the control (0 kg P_2O_5/ha). Phil 66-07 had the highest dry matter and crop growth rate in response to P application, followed by K 86-161. The rate of applied P did not influence nitrogen (N) and potassium (K) contents in various parts of the plant. Phosphorus content in the third leaf, green leaf, leaf sheath and phosphate in juice was higher when P was applied than in the control. At harvest, the higher P application increased both cane yield and stalk weight. Phil 66-07, at 129 kg P_2O_5/ha, produced the maximum growth, yield and quality. Yield and yield components of cane and sugar were lower in the control for all cultivars. Varietal differences did occur with the application of P fertiliser with Phil 66-07 being the most responsive. However, the application of 72 kg P_2O_5/ha was the optimum rate at which all cultivars gave superior response in terms of growth, yield and quality.