Effect of Three Threshing Methods on Kernel Fissuring, Seed Germination and Seedling Growth in Rice (Oryza sativa L.) cv. Hashemi

Effects of three threshing methods (T30 thresher, Tractor powered thresher and cereal combine) on kernel fissuring, seed germination and seedling growth of rice (Oryza sativa L. cv. Hashemi) were evaluated in an experiment conducted in 2008. At the first stage, number of fissured kernels and number of fissures on kernel were measured. Germination and seedling growth of intact and fissured seeds were measured at the second and third stages. Results showed that the cereal combine produced the maximum (13%) and Tractor powered thresher and T30 thresher had less negative effects on kernel fissuring (9.7% and 4.7%, respectively). Germination test showed that the intact seed of three threshing methods had the maximum germinability (98%), germination index (2.5), and germination energy (0.90). Seedling vigor test also showed that the intact seeds obtained from the three threshing methods had the maximum shoot height (24.8 cm), leaf area (5.2 cm2), shoot dry matter (11.8 mg), total root length (125.5 cm) and root area (2.7 cm2) that were significantly different as compared with fissured kernels. In conclusion, evaluation of threshing methods effect on kernel fissuring, germinability and seedling growth revealed that the unsuitable threshing method (cereal combine) may negatively affect germination and seedling vigor of the paddy that are going to be used as seed in the next cropping season.