Asian Journal of Research in Biosciences

Response of Durum Wheat (Triticum turgidum L. subsp. durum) to Root Exudate Autotoxicity and Osmotic Stress Depends on Variety Combination

Imen Bouhaouel *

National Agronomic Institute of Tunisia, Genetics and Cereal Breeding Laboratory, University of Carthage, LR14AGR01, 1082 Tunis, Tunisia. 2Higher Institute of Biotechnology of Béja, University of Jendouba, 9000 Béja, Tunisia.

Soumaya Nasraoui

Higher Institute of Biotechnology of Béja, University of Jendouba, 9000 Béja, Tunisia.

Khaoula Boudabbous

National Agronomic Institute of Tunisia, Genetics and Cereal Breeding Laboratory, University of Carthage, LR14AGR01, 1082 Tunis, Tunisia and National Agronomic Institute of Tunisia, Horticultural Sciences Laboratory, University of Carthage, LR13AGR01, 1082 Tunis, Tunisia.

Olfa Ayed-Slama

National Agronomic Institute of Tunisia, Genetics and Cereal Breeding Laboratory, University of Carthage, LR14AGR01, 1082 Tunis, Tunisia.

Hajer Slim Amara

National Agronomic Institute of Tunisia, Genetics and Cereal Breeding Laboratory, University of Carthage, LR14AGR01, 1082 Tunis, Tunisia.

*Author to whom correspondence should be addressed.

---

Abstract

The problem of autotoxicity is known in cereal crop residues, and is one of the major reasons for reduced growth/yield under continuous monoculture practice. However, investigation on the autotoxic effects of wheat root exudates is scarce. This is the first report on autoinhibition activity of durum wheat roots during seedling establishment stage. Nine variety combinations were tested according to two experimental protocols, ‘seed-to-seed’ and ‘seed-after-seed’, under water stress applied at different osmotic pressures (0, 50, 100, 150, and 200 g l^-1) using the polyethylene glycol ‘PEG₆₀₀₀’. Comparing the two protocols, our finding showed that durum wheat root exudates cause autotoxicity. Coleoptile growth seems to be more sensitive to high PEG₆₀₀₀ concentrations (100, 150, and 200 g l^-1) than that of radicle. The magnitude of the inhibitory action depended on the combination of donor and receiver plants, which may be of the same or different varieties. Notably, Nasr-Karim, Maali-Maali, and Maali-Khiar were the most affected combinations by root exudate autotoxicity and water stress effect, while combinations with the same variety, such as Sculpture-Sculpture, Khiar-Khiar, and Nasr-Nasr were the least affected.

Keywords: Durum wheat, autotoxicity, root exudates, variety combinations, water stress, PEG6000

---

---