Price instability, seasonal index and modelling for major vegetables in India

Abstract: Vegetable production plays a pivotal role in the horticulture industry, yet the availability of vegetable crops remains unpredictable. Seasonal volatility contributes to unclear supply, resulting in price fluctuations. This study aimed to assess the seasonal indices and price instability of key vegetables in India using the Cuddy-Della Instability Index and the Ratio to Moving Average approach. Monthly price series spanning January 2010 to December 2021 were collected from the AGMARKNET website. Seasonality in the price series was examined using the Kruskal-Wallis test. The results indicated that potatoes exhibited moderate instability, while onions and tomatoes displayed high instability. The onion price series demonstrated the highest seasonal indices in October, November, and December. Wholesale and retail prices were lowest in April, May, and June. October and November marked the peak wholesale and retail prices for potatoes, with the lowest prices recorded in February and March. July and August were the months with the highest wholesale and retail tomato prices, while February and March saw the lowest prices. The ARIMA model, applied to de-seasonalized price series, estimated factors excluding the seasonal component. Recognizing these price patterns enables farmers, policymakers, and government sectors to take necessary precautions against sudden price changes.