Effect of controlled-release fertilizers on growth, yield and fruit quality of guava cv. Sardar in Ustochrepts

Three levels (200, 400 and 600 g/plant) each of urea, urea supergranule and neem-coated urea were applied on 3-year-old plants of guava cv. Sardar in two equal split doses (i.e. in March and September). Correlation matrix between all possible pairs of vegetative growth characters were worked out. Significant increase in vegetative growth was recorded with 600 g neem-coated urea. As regards yield, 102 fruits in the first year and 125 fruits in the second year, weighing 28.3 kg and 31.9 kg/plant respectively and yield per hectare calculated 7.8 t and 8.8 t/ha, was recorded highest with 600 g neem-coated urea which was significantly higher than with all the other treatments and the control (no fertilizer). Fruit quality was also improved with application of slow-releasing fertilizers. Total soluble solids at 14.8°Brix and 4.5% reducing sugars were recorded with 600 g neem-coated urea. Maximum ascorbic acid content (326.7 mg/100 g fruit with 600 g urea in the first year and 339.9 mg/100 g fruit) with 600 g neem-coated urea in the second year were observed with 600 g neem-coated urea compared with 258.9 and 237.1 mg/100 fruit in the control. Acidity in fruits was not affected by the different levels and sources of nitrogen. Leaf N increased to 2.11% from 1.77%, and the P and K contents also increased after the application of treatments and fixed doses of P and K.