Screening local and exotic varieties of tomato (lycopersicon esculentum) for tolerance to waterlogged soils
Three pot experiments were conducted to determine the effects of waterlogging on morphological and physiological traits, yields and the production of ethylene from leaves of local and exotic varieties of tomato. To study the morphological and physiological traits, the experiment investigated the development of adventitious roots, the reduction of primary roots and the reduction of plant shoots using thetr..dry weights, the reduction of plant heights, the abscission of leaves and leaf area and the increase of shoot: root ratio. Six varieties including "Accession 1", "Accession 2" of the local varieties, "Marglobe", "Kenturn FT', "Moneymaker" and "Cal J" were used with four replications in the first experiment, three replications in the second experiment and two replications in the last experiment. Waterlogging treatments included the control or normal irrigation where the soil was maintained at field capacity, seven days of waterlogging (7 D. W.) and fourteen days of waterlogging (14 D. W.). The interaction 'waterlogging x variety' was significant (p ~ 0.05) in adventitious root dry weight, primary root dry weight, total root dry weight, total number of leaves per plant, shoot dry weight, tomato yield (tons/ha) and ethylene production. However, waterlogging treatments significantly decreased leaf area and height of the different varieties of tomato included in this study Waterlogging and variety differently affected shoot: root ratio and the total number of fruits per plants. Varietal differences were noted in adventitious root development and ethylene production attributes. Varieties "Accession 1" and "Moneymaker" were more tolerant to waterlogging than all other varieties which was attributed to their ability to allocate the carbohydrates for the development of adventitious roots that replace the dying primary roots. The study demonstrated that adventitious root development is higher for the varieties with high production of ethylene. Following these findings, "Moneymaker" would be recommended for the areas with waterlogging problems while "Accession I" would be used in breeding programmes in order to produce varieties tolerant to waterlogging.