Nitrogen Management in Grapes as a Function of Rate and Time of Application

Background/Objectives: Nutrient management plays a key role in growth and yield of grapes. Among the macronutrients, nitrogen is very important because its deficiency and sufficiency both affect yield and quality. Since, this study was aimed to evaluate nitrogen rates and time on yield and nutrient accumulation of grapevines. Methods: The experiment was designed in Randomized Complete Block Design (RCBD) in factorial arrangement consisted of N rates as factor (A) i.e. 0.0, 50, 80 and 110 kg N ha^-1 and time of N application as factor (B) i.e. bud break, at flowering and fruit set. Findings: The results showed higher bunch weight on 80 kg N ha^-1 applied one week before flowering which was 232.66 g for small, 456.77 g for medium and 795.67 g for large bunch along with greater fruit yield of 41.32 t ha^-1. However, the increasing N rate (110 kg N ha^-1) reduced yield by 15.5% over 80 kg N ha^-1 applied at bud break. In case of petiole nutrient concentration, higher N concentration (1.95%) was noted at 110 kg N ha^-1 but maximum P (0.45%) and K concentration (2.70%) were found at 80 kg N ha^-1. The established correlation study indicated that yield was positively and significantly correlated with petiole N (r = 0.87), P (r = 0.92) and K concentration (r = 0.83) indicating yield dependence on nutrient supply. Applications/Improvements: From this study, it is suggested that 80 kg N ha^-1 must be applied one week before flowering but this rate and time might be varied for other soil type.