Assessment of crop coefficients for tomato in temperate region of Kashmir

Tomato crop coefficients in Kashmir

Abstract

A field experiment was conducted at SKUAST-K, Shalimar using a drainage-type lysimeter to determine the water requirement and crop coefficients (single and dual) for tomato (Solanum lycopersicum L.) under temperate conditions. Reference evapotranspiration (ET₀) during different crop growth stages was estimated using four empirical models and compared to actual crop evapotranspiration (ETc) measured via the lysimeter. Model performance was assessed using statistical indicators including Nash–Sutcliffe Efficiency (NSE), root mean square error (RMSE), and correlation coefficient (r). Results indicated a "Satisfactory" to "Very Good" agreement between computed and observed ETc values. A Z-test revealed no statistically significant differences at the 5% level between lysimeter-measured ETc and values estimated by the four models, affirming their applicability. Among these, the FAO Penman-Monteith model showed the closest agreement with lysimeter data, with R² values of 0.88, 0.93, 0.91, and 0.92 across initial, development, mid, and late stages, respectively. The single crop coefficient (Kc) values determined were 0.54 (initial), 0.85 (development), 1.04 (mid-season), and 0.62 (late). Dual crop coefficients [Kcb (basal crop coefficient) + Ke (soil evaporation)] were 0.52, 0.83, 1.01, and 0.59, respectively. These findings underscore the lysimeter's effectiveness for calibrating ecohydrological crop evapotranspiration models and provide critical data for efficient irrigation planning in the temperate regions of Kashmir.