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Sudan Journal of Agricultural Research

Effect of heat stress on subsequent germination and viability of Brachiaria eruciformis (Sm.), Dinebra retroflexa (Vahl) Panz. and Ocimum basilicum L. seeds

Azhari Abdelazim Hamada, Wener Koch, Abdallah Hamdoun, Joachim Sauerborn and Markus Knapp

Abstract

Exposing unimbibed weed species Brachiaria eruciformis, Dinebra retroflexa, and Ocimum basilicum seeds to 60 ⁰C for 24 hr had no adverse effect on their viability. Viability was, however, reduced under moist conditions in the incubator or water bath at 45-60 ⁰C. At these temperatures, it was found that, the higher the temperature and/or the longer the exposure period, the greater was the reduction in seed viability. Indiscriminately, 2 hr of heat stress at 60 ⁰C under moist condition killed all the seeds. Heat stress for 15 min exposure at 60 ⁰C in a water bath had no adverse effect on seed viability. In contrast, the reduction in viability amounted to 77% (Brachiaria eruciformis), 36% (Dinebra retroflexa) and 76% (Ocimum basilicum) following 7.5 min exposure period made daily for two consecutive days. Seeds, which were previously imbibed at 30 ⁰C, were susceptible to a 15 minutes exposure at 60 ⁰C in a water bath and their susceptibility increased with the imbibition period .The results were briefly discussed in relation to solarization.
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Sudan Journal of Agricultural Research Vol. 9 (2007) PP. 1-7