University of Khartoum

Responses of Different Tomato (Lycopersicon Esculentum Mill.) Genotypes to Heat Stress

Responses of Different Tomato (Lycopersicon Esculentum Mill.) Genotypes to Heat Stress

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Title: Responses of Different Tomato (Lycopersicon Esculentum Mill.) Genotypes to Heat Stress
Author: Abdelmageed, Adil Hassan Ahmed
Abstract: Five experiments were conducted in the glasshouse and growth chambers at the Humboldt University of Berlin, Germany during 2001-2004 and under field conditions in the Department of Horticulture Orchard, Faculty of Agriculture, University of Khartoum, Shambat, Sudan during summer for two successive seasons (2002/2003, 2003/2004). The objectives of these studies were to investigate the effects of heat stress on growth, flowering, fruit setting and photosynthetic rate of diverse tomato genotypes and to investigate if there are any positive effects of heat shock or grafting treatments on the heat tolerance of tomatoes. Different approaches namely; screening of different tomato genotypes under field, plant growth chamber and glasshouse conditions; grafting and heat shock technique were conducted to investigate if there are any positive effects of these approaches on tomatoes production under heat stress conditions. In the first and second experiment, eleven tomato genotypes of diverse origin were grown in the Department of Horticulture Orchard, Faculty of Agriculture, Shambat, University of Khartoum, Sudan, in a randomized block design with three replications for two successive seasons (2002/2003, 2003/2004) and in the glasshouse at the Humboldt University of Berlin, Germany during 2002. High temperatures under field conditions resulted in poor stand and stunted growth of tomato plants. Highly significant differences were encountered among the different genotypes for most of the characters. In the third experiment, eight tomato cultivars of different origin were evaluated for heat tolerance under plant growth chamber conditions at the Institute of Crop Sciences of the Humboldt University of Berlin. The transplants were divided into two sets, one set was transferred in a plant growth chamber at 37/22 °C (day/night) for 13/11 h. Another set was transferred in a second plant growth chamber at 37/27 °C (day/night) for 13/11 h. Photosynthetic photon flux density (PPFD) which was approximately 500 µ mol m-2 s-1 at the top of the canopy-using cool white fluorescent were provided on the day for each set and a relative humidity of 45/55% (day/night). These levels were chosen on the basis of previously published research results and actual summer temperatures in arid subtropical regions like Sudan (El-Ahmadi and Stevens, 1979a, b). The experiments were set up in a complete randomized design with five replicates. The reproductive processes in tomato were more sensitive to high temperatures than the vegetative ones. Number of pollen grains, number of fruits and fruits fresh weight produced by the heat tolerant cultivars were higher than those produced by the heat sensitive ones. Night temperature had an effect on the number of pollen grains produced and released and fruit set percentage. Heat tolerant cultivars showed higher photosynthetic rate under heat stress conditions at the different growth stages in comparison to the heat sensitive ones. The fourth experiment was conducted to investigate if there is any positive effect of grafting on the vegetative and reproductive development of tomato plants under heat stress conditions. The heat tolerant tomato cultivar ‘Summerset’ and the eggplant cultivar ‘Black Beauty’ as rootstock as well as the heat sensitive tomato cultivar ‘UC 82-B’as scion were selected. Plants were grown under two temperature regimes 26/20 ºC and 37/27 ºC (day/night) in plant growth chambers at the Department of Vegetable Crops, Institute for Horticultural Sciences, Faculty of Agriculture and Horticulture, Humboldt University of Berlin. The experiments were set up in a complete randomized design with five replicates. Significant differences (PX04; 0.05) were encountered between treatment ‘UC 82-B/Black Beauty’ and ‘UC 82-B’ under 37/27 °C for chlorophyll fluorescence, electrolyte leakage and other vegetative and reproductive parameters e.g. plant height, number of leaves per plant, stem fresh and dry weight, leaf fresh and dry weight, number of flowers per plant, number of pollen grains per flower, number of fruits per plant, fruit fresh weight and fruit set percentage. The result of this experiment showed that grafting has a positive effect on the vegetative growth of tomato plants under high temperature conditions. The fifth experiment was conducted to investigate the effect of high temperature on the growth and development of different cultivars under defined heat stress conditions (intensity and duration) as well as to investigate if there are any positive effects of heat shock treatments on tomatoes production. Plants were grown under two temperature regimes 26/20 ºC and 37/27 ºC (day/night) in plant growth chambers at the Department of Vegetable Crops, Institute for Horticultural Sciences, Faculty of Agriculture and Horticulture, Humboldt University of Berlin. The experiment was set up in a complete randomized design with five replicates. The reproductive processes in tomato were more sensitive to high temperatures than the vegetative ones. The numbers of pollen grains, number of fruits and fruits fresh weight produced by the heat tolerant cultivars were higher than those produced by the heat sensitive cultivar. Heat shock treatments have no positive effects on tomato growth and development.
Description: March 2006176 Pages
URI: http://khartoumspace.uofk.edu/handle/123456789/11090
Date: 2015-05-19


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