Photosynthetic Parameters, Productivity and Plant Macronutrient Acquisition in Sugarcane as Affected by Potassium Salt of Active Phosphorus (PSAP) Under North Central and Eastern Zones of India

Among the macronutrients, potassium (K) and phosphorus (P) are also very important nutrients that improved the cane productivity and nutrient acquisition in sugarcane plants. The research experiment was carried out at RPCAU-Kalyanpur farm, Samastipur, Bihar, India, to know the effect of potassium salt of active phosphorus (PSAP) on photosynthetic parameters, productivity and plant macronutrient acquisition in sugarcane during the spring season under North Central and Eastern zones of India during 2021–22 and 2022–23. The results of the findings revealed that leaf surface temperature, transpiration and photosynthetic rate was significantly affected by the application of recommended dose of fertilizer + sett soaking with 0.80% PSAP solution along with PSAP at the rate of 0.40, 0.65, 1.10 and 1.10% in 4 times foliar spray (60, 80, 100 and 120 DAP). It was increased by 7.9, 38.6 and 36.9% over the recommended dose of fertilizer. Growth attributes such as tillers, cane length and millable canes did not significantly influenced by the different treatments. Significantly maximum single cane weight (1340 g) was found in the plots receiving RDF along with sett soaking at the rate of 0.8% PSAP solution and PSAP in 3 times foliar spray at the rate of 0.4, 0.65 and 1.10% (60, 90 and 120 DAP). While highest cane yield (106.8 t ha −1 ), gross (336.4 × 10 3 Rs ha −1 ) and net returns (146.1 × 10 3 Rs ha −1 ) were recorded in the plots applied with recommended dose of fertilizer + sett soaking with 0.80% PSAP solution along with PSAP at the rate of 0.40, 0.65, 1.10 and 1.10% in 4 times foliar spray (60, 80, 100 and 120 DAP). Although maximum value of benefit: cost ratio (1.91) was observed in recommended dose of fertilizer + sett soaking with 0.8% PSAP solution. Significant improvement in plant macronutrient (NPK) acquisition was registered under the application of recommended dose of fertilizer + sett soaking with 0.80% PSAP solution along with PSAP at the rate of 0.40, 0.65, 1.10 and 1.10% in 4 times foliar spray (60, 80, 100 and 120 DAP) and it was increased by 27.6, 37.9 and 29.2% in N, P and K compared to recommended dose of NPK (recommended dose of fertilizer). However, soil macronutrient availability and juice quality did not significantly influence by the different treatments except sugar yield. Results of the study suggests that recommended fertilizer dose + sett soaking with 0.80% PSAP solution along with PSAP at the rate of 0.40, 0.65, 1.10 and 1.10% in 4 tim