Pv. Kumar et al., Assessment of plant-extractable soil water in castor beans (Ricinus communis L.) using infrared thermometry, AGR WATER M, 39(1), 1999, pp. 69-83
Assessment of plant-extractable soil water from experimental plots using in
frared thermometer was carried out through a field experiment on rainfed ca
stor beans (Ricinus communis L.) conducted for 2 years (1992-1993) at Hyder
abad, India. The castor beans (cultivar: Aruna) were planted on three diffe
rent dates in both years. Attempts were made to normalize canopy temperatur
e and stress degree days (SDD) for environmental variability to accurately
assess the plant-extractable soil water (PESW) using an Infrared thermomete
r. Normalization of SDD for variability of temperature and saturation defic
it (division of SDD by air temperature and saturation deficit), greatly imp
roved the predictability of the soil water status (PESW), than that based o
n SDD. The coefficients of determination (R-2 values) of the relationship b
etween PESW and SDD after normalization were 0.65 and 0.61 in the years 199
2 and 1993, compared to 0.19 and 0.08 before normalization, in respective y
ears. This simple method of normalization of SDD (the division of SDD with
weather parameters), which seems to be a promising technique for assessing
the soil water status through remote sensing techniques in semi-arid tropic
s (SAT) needs to be further tested in other environmental conditions and al
so in other crops, for realising the long-felt objective of assessing soil
moisture status with the help of infrared thermometry. (C) 1999 Elsevier Sc
ience B.V. All rights reserved.