Sunflower evapotranspiration and water use efficiency in response to plant density

ECHARTE, L.; ECHARTE, M.; CERRUDO, D.; GONZALEZ, V.H.; ALFONSO, C.; CAMBARERI, M.; HERNANDEZ, M.; NAGORE, L.; DELLA MAGGIORA, A.

CROP SCIENCE

CROP SCIENCE SOC AMER

Lugar: Baltimore; Año: 2020 p. 357 - 366

0011-183X

This study quantified sunflower (Helianthus annuus L.) water use efficiency forseed (WUEg) and for oil yield (WUEo) and their components (i.e. evapotranspiration,ET, seed and oil yields) in response to plant density increments; and studied, inparticular, the underlying processes relevant to the responses of crop ET to plantdensity (i.e. water uptake pattern, intercepted photosynthetically active radiation,iPAR and soil water depletion profile). Sunflower was grown at 3, 6 and 9 plants m-2in Season 1 and at 2, 3 and 6 plants m-2 in Season 2. Measurements included (i) soilwater content and iPAR during the whole growing season, and (ii) seed and oil yieldat physiological maturity. Crop ET was estimated by means of a water balance, andit was analyzed during three different periods (i.e. vegetative, critical period for seedset and seed filling period). Increasing sunflower plant density from 2 to 9 plants m-2did not modify seasonal ET but it changed the water uptake pattern through theseason; it increased ET during the vegetative period by depleting more water fromdeep soil layers (i.e. 41 to 140 cm) but it reduced ET during the seed filling period.Increments in plant density increased seed and oil yield in accordance withsignificant iPAR increments, whereas harvest index remained stable. SunflowerWUEg ranged from 4.8 to 9.4 kg ha-1 mm-1 and WUEo ranged from 1.8 to 4.5 kgoilha-1 mm-1 across plant densities; and they were positively and closely associatedwith seasonal iPAR.