Rapid seed germination will facilitate quick plant stand establishment in direct sown rice (Oryza sativa L.) culture. Sixty‐eight rice cultivars were grown in the field and in the phytotron, and the harvested seed evaluated for germination rate. Cultivars ‘Laxmi’, TNAU(AD)103, IR25924‐92‐1‐3, ‘IR50’, PND160‐2‐1, RNR1429, IR31779‐19‐3‐3‐2‐2, and B3981c‐Pn‐165‐2‐l produced seeds in the field and the phytotron that exhibited superior performance. Therefore, these could be useful donor parents for promoting rapid seed germination when breeding rice for direct‐sown culture. One hundred seed weight was negatively correlated with germination rate. Path analysis suggested that 100 seed weight acted through a high indirect effect of free amino acid content on germination rate. Oxygen uptake and dehydrogenase activity also contributed to germination rate variability. Cultivar differences were evident for germination rate following aging and under low temperature (20 and 15 °C) and moisture stress (−5̄ polyethylene glycol 8000). Hulls did not contribute to variability in germination rate.

Fumigation of seeds is one of the quarantine precautions directed against the international spread of pests. Seed treatment should ward off the pests without hampering seed germination and vigor. A study was conducted to evaluate the effect of fumigation with phosphine at different doses, exposure times, and seed moisture contents, and after the seed has been treated with fungicides on seed germination and seedling vigor in rice (Oryza sativa L.). The fumigated seed was evaluated for germination and vigor, initially and after 90 d of storage. At the normal recommended dose of 3 g m−3, fumigation did not affect germination or vigor. At 6 g m−3, vigor decreased. The effect became more perceptible after 90 d of storage. Long exposure time (6 d) showed deleterious effects. Entry differences were not significant under any of the treatments with respect to germination percentage, shoot length, root length, and seedling dry weight. However, such differences were evident in the degree of seed leaching as measured by the electrical conductivity of the leachates, and dehydrogenase activity, when seed was fumigated with a higher dose (6 g m−3) of phosphine and evaluated after 90 d of storage. There were no interaction effects between fungicidal treatment with Benlate [methyl l‐(butylcarbamoyl)‐2‐benzimi dazole carbamate] or Dithane M‐45 (zinc ion and manganese ethylene bisdithio carbamate) and fumigation on seed germination and vigor.

No abstract

No abstract

No abstract