Influência da salinidade dos substratos na germinação das sementes de fumo (Nicotiana tabacum)

The tobacco production (Nicotiana tabacum) is one crop of high importance in the Rio Grande do Sul. The major part of seedlings are gotten with seedbed, so it is important fast and uniform germination of the seeds. In this direction, choose of substrate more adequate for production of healthful and good seedlings for tobacco is fundamental factor. The objective of this paper was compared the use of substrates in relation to salinity, due to the Na+, for tobacco production. It was used one substrate with humus 0,11% of Na+, one substrate indicated for tobacco culture with 0,01% of de Na+ and sand seedbed, that after 15 days from sowing received nutritive solution without Na+. Germination test, emergency after 7, 16 and 21 days, speed of germination, fresh weight and dry weight of seedlings, seedlings length, chlorophyll a, b and total chlorophyll were evaluated. The results show that the better substrate for tobacco germination was sand with nutritive solution for 15 days, while in other two substrates with Na+ decrease seeds vigor, the seedlings had shorter development and decrease in content of chlorophyll b and total.