Dormência, germinação e vigor de sementes de Parkia pendula (Willd.) Benth. ex Walpers e Samanea tubulosa (Benth.) Barneley & Grimes

Abstract

The use of quality seeds that assure propagation, growth and establishment of vigorous seedlings is an important point in the reforestation programs and restoration of the forest ecosystem. Therefore, the objective of this work was to study the germination and initial growth of seedlings of two native forest species, Parkia pendula (Willd.) Benth. ex Walpers and Samanea tubulosa (Benth. ) Barneby & Grimes to establish methodology for germination and vigor tests to contribute for analysis and technology of native forest seeds. The obtained information are useful for researchers and technologists of forest seeds, once in the current Rules for testing of seeds the norms and patterns ideals are not prescribed for the germination of seeds of the species in study. For dormancy breaking of Parkia pendula seeds, besides the seeds without any treatment (control), were used the following pregerminative treatments: mechanical scarification in the part distal of the seed with sandpaper for mass nº80 without and with soak for 24 hours; chemical scarification with concentrated sulfuric acid (98%) for 30 seconds, 1 and 2 minutes; submission of seeds at 10ºC for 24 and 48 hours; stratification into vermiculite at 10ºC for 24 and 48 hours; immersion in water at 80º C until cooling. Already for Samanea tubulosa seeds the first three treatments above were used increased by the following treatments: soak of intact seeds for 24 hours; chemical scarification with concentrated sulfuric acid (98%) for 15, 30 and 60 seconds; stratification into vermiculite at 18ºC ± 2 for 24 hours; immersion in water at 80º C until cooling; submission of seeds in fast drying at 80ºC for 1 minute. For evaluation of the germinativeperformance seeds of both species were tested different substrates (into sand, sugarcane bagasse, coconut fiber, waste of sisal, vermiculite and paper towel) and different temperatures (25, 30, 35, 20-30, 25-35), for the two species was used continuous light. The following parameters were evaluated: germination (%), first germination count (%), germination speed index, length of the primary root and hypocotyl, dry weight matter of seedlings. Mechanical scarification with sandpaper for mass nº 80 in the part distal of Parkia pendula and Samanea tubulosa seeds, without soak, promoted the biggest and speedy germination. The constant temperature of 30ºC and the substrates into sand and paper towel favored the germination and vigor of Parkia pendula seedlings. Samanea tubulosa seeds germinated in larger percentage and speed in the temperatures alternate 20-30 and 25-35ºC and in the substrates paper towel, into vermiculite and sand; therefore, they are recommended for evaluation of the physiological quality of these seeds. In all substrates tested, the is null or drastically reduced at 35ºC.