Selection for Drought Avoidance in Sorghum Using Aerial Infrared Photography¹

Abstract

In previous research, genetic variation in sorghum(Sorghum bicolor L. Moench) drought avoidance (maintenance of relatively high leaf water potential under conditions of soil moisture stress) was revealed. Practical screening for drought avoidance requires a fast field method. The response of near infrared reflectance from plant leaves to leaf water status stimulated the development of such a method, based on infrared photographic imagery of water‐stressed sorghum breeding nurseries. Aerial infrared photography was performed from several altitudes over water‐stressed and non‐stressed sorghum nurseries at Lubbock, Halfway, and Chillicothe, Texas. Noontime leaf water potentials, as a measure of drought avoidance, were determined in selected strains at each nursery. Total leaf chlorophyll content of the respective strains was determined at Lubbock and Chillicothe. Strain canopy color densities in the resulting infrared color transparencies were analyzed by three methods: l) Scanning densitometry; 2) measurement of integrated light transmittance by manual photometry; 3) visual rating of color density. Over all locations, the best correlations between canopy color density and leaf water potential across strains were obtained with the photometric method. The poorest correlations were obtained with scanning densitometry. For all methods of color density measurement, the correlations with leaf water potential across strains were the best at Halfway. At this location, plant canopies were dense, ground cover was almost complete, and film exposure and development were optimal. Leaf chloroFhyll content in the various strains was not correlated with canopy color density, although one strain presented a consistent exception. The method and some guidelines for its utilization are discussed.

Variation in morpho-physiological, biochemical and molecular responses of two Eucalyptus species under short-term water stress

“…It was reported that maintenance of lower leaf surface temperature in tolerant genotypes during stress conditions could lead to favourable water status, sustained transpiration and increased photosynthetic efficiency, resulting in improved yields (Kumar 2005). Using leaf temperature as drought index has been reported in potato (Gerhards et al 2016), maize (Carroll et al 2017), sorghum (Blume et al 1978), wheat (Fischer et al 1998, Talebi 2011, sugarcane (Silva et al 2007), rice (Hirayama et al 2006) and Firmiana platanifolia (Yu et al 2015). However, in woody perennials leaf surface temperature as water stress index is of limited use.…”

Estimation of Drought Tolerance Based on Leaf Temperature in Upland Rice Breeding

“…Blume et al (1978) observed a rise in the leaf temperature associated with the decrease of the transpiration rate, reflecting the degree of water stress in sorghum, and indicated the possibility of selecting for drought tolerance based on the leaf temperature. O'Toole et al (1984) also indicated the effectiveness of remote sensing of the canopy temperature using an infrared thermometer to estimate water stress in rice plants.…”

Leaf greenness measurements to evaluate water stressed genotypes in Vitis vinifera

“…Canopy temperatures were used as a selection index in wheat (Blum et al ., 1978) and in cotton (Hatfield et al ., 1987) ; visual indicators of water stress such as leaf movements and leaf rolling are currently used for breeding purpose in rice (O'Toole & Gruz, 1980) . Insufficient information exists on suitable parameters for a drought screening test in grapes ; the leaf color change is widely recognized as a useful indicator for irrigation scheduling in this crop .…”