Canopy temperature and water stress quantificaiton in rainfed pigeonpea (Cajanus cajan (L.) Millsp.)

Field studies were conducted at Anand (22 degrees 35 'N, 72 degrees 55 'E), India, to investigate utility of remotely sensed canopy temperature to ass ess crop water status and to quantify terminal water stress in rainfed pige onpea (Cajanus cajan (L.) Millsp.) during the southwest monsoon seasons of 1993-1994 and 1994-1995, using different planting dates. Canopy-air tempera ture differential were measured by thermal IR thermometer. Differences in t emporal variation in canopy-air temperature differential clearly described the differential response of pigeonpea to soil water availability. The cano py-air temperature differential (T-c - T-a) was significantly (P less than or equal to 0.05) related to soil moisture, soil water content in the root zone and evapotranspiration. Significantly negative relationship was also n oticed for yield attributes with both T-c - T-a and stress degree days (SDD ) during reproductive ontogeny. Total water use during reproductive phase i n pigeonpea decreased with increasing SDD. A close relationship between see d yield per plant and SDD in flowering stage clearly showed the potential u tility of canopy temperature to describe water stress effects in rainfed pi geonpea. (C) 2001 Elsevier Science B.V. All rights reserved.