University of Khartoum

Improved Germination of Carrot at Stressful High Temperature by Seed Priming

Improved Germination of Carrot at Stressful High Temperature by Seed Priming

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Title: Improved Germination of Carrot at Stressful High Temperature by Seed Priming
Author: Mohamed Ali El Balla, Mustafa
Abstract: Three seed lots of carrot (Daucus carota l. cv. Orlando Gold) produced in the same year at three separate locations were used to study the effects of seed lot variability on seed priming and the effects of addition of growth regulators to the osmotic priming solution. Gibberellin, GA3 or GA4f7 at 100 ppm, alone or combined with 100 ppm Benzladenine (BA) or 500 ppm ethephon were incorporated in -10 bar polyethylene glycol (PEG) solution to formulate nine treatments. Seeds were primed for 7 or 14 days at 15C and seed germination was evaluated at 15, 25, and 35C. The effect of seed priming in PEG on total germination in all three lots was not improved by the addition of growth regulators. Seed priming was more effective in improving seed germination at 25C than 15C, and was highly effective at a constant high temperature of 35C. The effect of priming treatment was dependent on seed lot quality. Germination at 25 and 35C of lot 2, which was judged to be of good quality, was improved by all treatments regardless of prime duration, whereas that of lots 1 and 3 was only improved after 14 days of priming by some of the treatments. Although addition of GA3, ethephon, or GA3 + ethephon to PEG did not result in improvement in seed germination compared to the PEG treatment alone, their addition helped improve germination compared to the nontreated control, whenever PEG failed to do so. Thus, addition of hormones might improve the performance of some seed lots which do not respond to priming in PEG alone. The use of high quality seed for priming is recommended to obtain the best results from priming. The use of primed seed during the warm part of the growing season in Florida could result in improved carrot stand establishment. Failure to obtain uniform field stands is a major factor limiting optimum yields in the production of carrots. Poor stands occur when planting is done during extremely warm temperatures (such as Aug. or Sept. in California or Florida) or by planting in cold soil temperatures (early spring in most northern climates). Seed priming has been shown to be useful in promoting seed germination under unfavorable conditions, and enhanced germination even under ideal conditions (Ells, 1963; Guedes and Cantliffe, 1977; Heydecker et al., 1975; Heydecker and Coolbear, 1977; Koehler, 1967; Parera and Cantliffe, 1994; Sachs, 1977; Salter and Darby, 1976). The use of seed priming allows the seed to imbibe water slowly, permitting the early stages of germination to begin without radicle protrusion through the seed coat. Radicle protrusion may be regulated through priming under low temperature, short soak duration, or by the use of solutions of low osmotic potential (Ells, 1963; Heydecker and Cool bear, 1977).
URI: http://hdl.handle.net/123456789/6556
Date: 1994


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