Leaf greenness measurements to evaluate water stressed genotypes in Vitis vinifera

Abstract

The leaf greenness (measured by a portable chlorophyll meter SPAD-501) has been used to differentiate table grape genotypes (Vitis vinifera) in water stress condition . The SPAD and chlorophyll values are lower in the stressed treatment after 2 weeks from the onset of stress . Linear response model has been observed between the chlorophyll content and the SPAD readings . The leaf greenness (SPAD readings) of apical and expanded leaves seems an easy indicator, which might be used for screening grape genotypes (Vitis vinifera) for drougth tolerance .

White mulch and a south facing position favour strawberry growth and quality in high latitude tunnel cultivation

“…Reduced chlorophyll indicates stressful growth conditions (Fanizza et al 1991;Chaitanya et al 2001) suggesting that black mulch colour provided less favourable growth conditions to plants, most probably due heat stress, but in the early season only. In tunnel conditions, where vegetative growth is vigorous, this is logical because most of the mulch surface is covered by leaves once the canopy is fully grown.…”

Evaluación de un método no destructivo para estimar las concentraciones de clorofila en hojas de variedades de uva de mesa

“…La elección de las hojas al realizar las mediciones toma vital trascendencia, debido a que la lectura de los medidores portátiles varía notablemente entre hojas apicales de vid y hojas completamente extendidas, y entre plantas sometidas a estrés hídrico y plantas bajo riego (Fanizza et al, 1991), por lo tanto la estandarización de las hojas al realizar el muestreo resulta de gran importancia. Curvas similares a las encontradas en este estudio, pero en V. vinifera cv.…”

Relationship Between Aphid Infestation and Chlorophyll Content in Fabaceae Species

“…This instrument has a self-contained light source for uniform lighting over the sampled leaf surface, and two detectors, one sensitive to red light (645 nm) and the other sensitive to infrared radiation (790 nm). The sensors convert the light into electrical currents for calculation of the SPAD value: SPAD = A(log(I or /I r ) -log(I of /I f ) + B, where A and B are constant, and I r and I f are respectively the currents from red and infrared detectors with sample in place and with no sample in place (I or and I of ) (Fanizza et al, 1991). Five SPAD readings were averaged for each leaf to represent one observation.…”

“…Chlorophyll levels change during plant development (Costa et al, 2001), and can alter in response to a wide variety of stresses (Fanizza et al, 1991;Samdur et al, 2000;Lawson et al, 2001). Chlorophyll catabolism is equal to global chlorophyll synthesis, and can be reduced by insect feeding, nutritional deficiencies and pathogen infections (Ni et al, 2002).…”