Adequate supplemental irrigation amount during the critical period for yield in chia prevents reductions in radiation capture, radiation and water use efficiencies, and grain yield

Abstract

Chia is generally grown under rainfed conditions and is often under water de cit conditions during the critical period of owering and grain lling when yield is determined. Thus, the objective of this study was to determine how intercepted photosynthetically active radiation (iPAR), radiation use e ciency (RUE), water use e ciency (WUE), and grain yield were affected by different soil water availabilities during the critical period for yield in chia. Four levels of total available water (TAW) during the critical period were obtained using supplemental drip irrigation including: T90 (90% TAW), T65 (65% TAW), T45 (45% TAW), and T30 (30% TAW). No reductions in iPAR and RUE (total dry matter or yield per unit of intercepted radiation) were found between T65 and T90, which led to similar total dry matter and grain yield. In contrast, water availabilities equal to or lower than 45% of TAW decreased iPAR and RUE, and subsequently total dry matter and yield decreased. The decrease in RUE was associated with a reduction in WUE (total dry matter per mm of evapotranspiration) and crop conductance (gc; evapotranspiration per unit of iPAR). This occurred in part because moderate-to-severe water stress increased the proportion of crop evapotranspiration that evaporated from the soil and decreased the amount of water transpired per unit of intercepted radiation. The use of supplemental irrigation to ensure 65% of total available water in the soil during the critical period for yield would reduce the contribution of soil evaporation and increase crop transpiration by increasing crop ground cover and would lead to improved grain yields.

Polymer and photo‐selective covers on plant and fruit development: A review

“…Increased shade levels have been shown to reduce both RZT and evaporative water demand, leading to a decrease in both transpiration rates and soil water uptake by plants. Research has also shown how growers may make use of these phenomena to reduce incident solar radiation, wind speed, and water requirements for bell pepper ( Capsicum annuum ), chia ( Salvia hispanica ) and tomato ( Solanum lycopersicum ) production, leading to an increase in irrigation water use efficiency (Diez et al., 2023; Möller & Assouline, 2006). In a study of the effects of shade covers on heat stress in Herminio sweet pepper ( C. annuum ) during a winter–summer crop cycle, the temperature reduction caused by shading was found to improve both plant vegetative growth and leaf water status (López‐Marín et al., 2013).…”