Potassium Influencing Physiological Parameters, Photosynthesis and Sugarcane Yield in Subtropical India

Potassium plays an important role in the metabolism of plants, growth, development and yields. Worldwide, KCl is commonly used as source of K fertilizer in agricultural crops. The present experiment was taken up to assess the response of various sources of K on physiological attributes, yield and quality parameters of sugarcane. Treatments were no K application, potassium ammonium sulphate (H 4 KNO 4 S-9:0:30:20, NPKS ratio), slow release K fertilizer (0:0:45:0), sulphate of potash/potassium sulphate (K 2 SO 4 -0:0:50:17.5), muriate of potash (KCl-0:0:50:0) and muriate of potash (KCl) + elemental S @ 40 kg ha −1 . Application of K 2 SO 4 recorded 15.8% improvement in tiller population (during peak tillering stage) and 22.2% improvement in dry matter accumulation (at the harvest stage) over the KCl. About 12.33–24.16% increments in crop growth rate and the highest net photosynthetic rate (19.91 µmol m −2 s −1 ) were also recorded with application of K 2 SO 4 . Application of K fertilizers improved the availability of potassium in soil by 8.17% (254.2 kg ha −1 ). Potassium uptake in sugarcane crop ranged from 245 to 347 kg ha −1 . The highest individual cane length (311 cm) was measured with application of K 2 SO 4 . Application of K 2 SO 4 brings forth about 23.8% increments in millable canes, 14% in cane weight and 33.8% in cane yield over no K. Application of K also increased mean sucrose content in juice by 0.58 unit (17.0 pol per cent juice) over no use of K. Overall effect of K application on increasing sugarcane yield and sucrose content simultaneously brought forth improvement in commercial cane sugar (CCS) by 29.43% (10.50 t/ha) over no use of K. However, application of K 2 SO 4 also improved CCS by 25.89% (11.67 t/ha) over the application of KCl.