Detecting different levels of drought stress in apple trees ( Malus domestica Borkh.) with selected biochemical and physiological parameters

• Published in: Scientia horticulturae Vol. 113; no. 4; pp. 362 - 369
• Main Authors: Šircelj, Helena, Tausz, Michael, Grill, Dieter, Batič, Franc
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 14.08.2007; Elsevier
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; Apple; apples; ascorbic acid; Biological and medical sciences; biomarkers; carbohydrate content; carbon dioxide; carotenoids; chlorophyll; Drought; drought tolerance; free amino acids; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; glutathione; Irrigation scheduling; Irrigation. Drainage; leaf water potential; Malus domestica; Marker; orchards; photosynthesis; relative humidity; sorbitol; stomatal conductance; Stress; tocopherols; transpiration; Tree; water stress; Tree; Apple; Marker; Irrigation scheduling; Drought; Stress; Physiological condition; Irrigation; Horticulture; Rosaceae; Biochemistry; Malus domestica; Water stress; Dicotyledones; Angiospermae; Spermatophyta; Fruit tree
• ISSN: 0304-4238; 1879-1018
• DOI: 10.1016/j.scienta.2007.04.012

Rational irrigation scheduling based on sensing drought stress directly in plants is becoming more important due to increasing worldwide scarcity of fresh water supplies. In order to evaluate a set of potential biochemical and physiological stress indicators and select the best drought stress markers in apple trees, two experiments with potted trees and an experiment with intensive orchard grown apple trees ‘Elstar’ and ‘Jonagold Wilmuta’ were conducted in early summer in tree following years. Biochemical parameters: ascorbic acid, glutathione, tocopherols, chlorophylls, carotenoids, free amino acids, soluble carbohydrates, and physiological parameters already known as stress indicators in apple trees: predawn and midday leaf water potential, net photosynthesis (Pn), stomatal conductance ( g s), transpiration (Tr) and intercellular CO 2 concentration (Ci) were measured in leaves of apple trees subjected to different intensities of slowly progressing drought or no drought. Our study pointed out zeaxanthin and glutathione as the best drought stress markers in apple trees. Ascorbate and sorbitol appeared to be reliable indicators of moderate drought only. Responses of other tested biochemical parameters were not consistent enough to prove their role as drought stress markers in apple trees. Relative air humidity should be taken in consideration when physiological parameters g s, Pn, Tr and Ci are used as drought stress markers in apple trees. Our study revealed that in situations where low relative air humidity affects g s and with g s connected physiological parameters, biochemical markers may be better tool for determination of drought stress intensities in apple trees.