Crop Water Stress Index and Canopy Temperature Changes of Triticale (X Triticosecale Wittmack) Cultivars under Irrigation Scheduling

Abstract

A field experiment was laid out to evaluate the crop water stress index (CWSI) and canopy temperature of triticale under drought stress in 2013 growing season. Three triticale cultivars including Sanabad, ET-83-3, and ET-84-5, were arranged in sub-plots and four levels of irrigation regimes including well watered, cutting off irrigation at flowering, milk development, and dough development stages as main plots of a split plot experiment with three replicates. Results showed that Sanabad and ET-83-3 cultivars with 6.31 and 6.89 °C had the higher canopy-air temperature differences, while in ET-84-5 this difference reached to 2.66 °C. In all cultivars and cutting off irrigation regimes, high amount of variation (0.18 to 0.91) was observed for monthly CWSI and increased by progressing drought from cutting off irrigation at flowering to milk development. Under cutting off irrigation at flowering, ET-83-3 with 0.67 had the highest mean seasonal CWSI, while in ET-84-5 reached to 0.50. Polynomial regression showed that with decreasing water applied, CWSI increased and the slope of regression from 353 to 429 mm water applied was more than that of well watered condition (R2=0.85). The highest grain yield (476.2 g/m2) was obtained in ET-84-5 under well watered and CWSI in these cultivars ranged from 0.18 to 0.33. By lowering water applied (from flowering to milk development) and increasing CWSI, grain yield decreased especially in Sanabad and ET-83-3. Overall, ET-84-5, with lower Tc-Ta, water applied, and mean CWSI had better performances when exposed to drought.