Plant growth, Leaf Nutrient status, fruit yield and quality of Nagpur mandarin (Citrus reticulate Blanco) as influenced by potassium (K) fertigation with four potash fertilizer sources

To investigate the effect of different potassium (K) fertilizers applied through fertigation system during three different seasons on yield and quality behaviors of 14-16 years Nagpur mandarin an experiment was conducted at National Research Centre for Citrus, Nagpur during 2009-2012. The Nagpur mandarin plants requires potassium which, when applied in different amounts during the flower bud initiation to before fruit maturity can affect the yield and quality of fruit as well. The treatments in experiment consisted of; T1 - fertigation with potassium chloride [KCL], T2- fertigation with potassium nitrate [KNO3], T3- fertigation with potassium sulphate [K2SO4] and T4- fertigation with mono potassium phosphate [KH2PO4] @ 150 g K2O/plant. The recommended fertigation dose was 500:150:150 (N:P:K) and given through these treatments along with various fertilizers combination of urea of phosphate, urea, and P2O5 acid. Nitrogen elemnet was given from October to January month and N, P and K all were given from February to June month. Each fertigation treatment was given at 15 days interval and fruit yield and quality were measured at harvest. Results showed the highest response of the fruit yield (31.13 t/ha) with treatment mono potassium phosphate followed by in fertigation with potassium nitrate (29.4 t/ha). The total soluble solids was highest (10.49 0Brix) in K fertigation with mono potassium phosphate followed by fertigation with potassium sulphate (10.48 0Brix). Highest juice content (38.76 %) and low acidity (0.77 %) was found in K fertigation with mono potassium phosphate. The highest TSS to acidity ratio (sweetness indicator) was observed in Mono potassium Phosphate (13.6) followed by Potassium sulphate (13.1).