Sweet corn yield, evapotranspiration, production functions, basal crop coefficients, water productivity and soil-water extraction

Sweet corn (Zea mays convar. saccharata var. rugosa) is an important dietary commodity and is increasingly consumed in many applications. Despite its increased value worldwide, some of the fundamental sweet corn productivity variables are unknown. This research quantified and analyzed sweet corn ear yield, crop evapotranspiration [using FAO56 method (ET_c) and soil-water balance method (ET_{c_SWB})], water productivity (WP), transpiration (T_r), soil evaporation (E), ET_c-yield production function (ETYPF), soil-water extraction (SWE) and developed basal crop coefficients (K_cb) as a function of cumulative growing degree days (ΣGDD) for two growing seasons. In 2015, irrigated and rainfed yields were 9256 and 7943 kg/ha, respectively. In 2016, irrigated and rainfed yields were 8683 and 7342 kg/ha, respectively. Similar values of maximum K_cb occurred at different ΣGDD between the seasons. Seasonal ET_c were 462 mm in 2015 and 419 mm in 2016. Seasonal T_r was 316 mm in 2015 and 275 mm in 2016. Seasonal E was 143 mm in 2015 and 146 mm in 2016. The FAO56 ET_c and ET_{c_SWB} correlated strongly on a weekly time step [R²= 0.81, root mean squared difference (RMSD)= 6.3 mm/wk; slope= 0.99]. The irrigated WP values were 26.5 and 32.1 kg/m³ in 2015 and 2016, respectively. On a two-season average basis, rainfed sweet corn extracted 52, 33, 9, 8 and 5% of the seasonal total soil-water from the 0–030, 0.30–0.60, 0.60–0.90, 0.90–1.20 and 1.20–1.50 m soil layers, respectively; and irrigated sweet corn extracted 56, 29, 10, 7 and 3% of the seasonal total soil-water from the same soil layers, respectively.