Growth and Instability in Blackgram Production in Karnataka and India: Trends in Area, Production and Productivity

Blackgram (Vigna mungo (L.) Hepper) is an important pulse crop in India, but its long-term production patterns differ between geographical regions. The present study analyses the growth and instability of area, production and productivity of blackgram (Vigna mungo) in India and Karnataka over a 25-year period from 1999–2000 to 2023–2024, using the compound annual growth rate (CAGR) and the Cuddy–Della Valle Index (CDVI). At the national level, blackgram showed positive trends in all three parameters. Area increased from 2.94 to 3.54 million hectares (CAGR 1.77%; CDVI 15.39%, medium instability). Production rose from 1.33 to 2.32 million tonnes (CAGR 3.59%; CDVI 19.07%), while productivity improved from 453 to 656 kg/ha (CAGR 1.79%; CDVI 11.08%, low instability). The pattern in Karnataka was contrasting. Area declined sharply from 131 thousand hectares in 1999–2000 to 48 thousand hectares in 2023–2024, a statistically significant negative CAGR of −3.53% (CDVI 17.20%). Productivity increased from 346 to 458 kg/ha (CAGR 3.61%, significant), whereas production showed no significant trend (CAGR 0.11%) and high instability (CDVI 40.62%). Linear, cubic and exponential trend models were compared to justify the use of the compound growth model. These findings indicate that national growth in blackgram has been supported by both area expansion and yield gains, whereas Karnataka faces a significant decline in area despite productivity gains and unstable production. Policy attention to area retention, irrigation access and the promotion of blackgram in pulse-based cropping systems is therefore warranted.