Avaliação da qualidade fisiológica de sementes de azevém anual do banco de sementes do solo / Physiological quality evaluation of annual ryegrass seeds from the soil seed bank

AUTOR(ES)

Ana Laura Pereira Amato

DATA DE PUBLICAÇÃO

2006

RESUMO

The study evaluated the physiological quality evolution of annual ryegrass seeds (Lolium multiflorum Lam.) from the soil seed bank, in no tillage system with soybean. From an area of 336 m 2 , with 11 years of soybean annual ryegrass rotation, 21 soil samples with 10 cm of diameter were taken, 5 cm deep, four times (December, January, March and April), representing the four treatments. The samples were artificially dried and broken, to allow the separation of annual ryegrass seeds. Seeds were counted and weighed. The following tests were done with the portion of pure seed from 21 samples of each treatment: germination test, first counting, tetrazolium, germination velocity index, dry weight and seedling height. The tests were done two times, one just after sampling and the other in June. Seed quantity linearly decreases from December to April, with 20% of the initial number of seeds in the last one. One thousand seed weight did not show significant differences among sampling times. Seedlings from seeds that were in the soil for more time have a low seedling height. It is also possible to verify a lower performance in first counting and germination velocity index tests, after the seeds overcome dormancy, in March. The PMS did not show significant differences in any sampling time. When the physiological quality was evaluated in June, there was a reduction of viability and vigor in all tests of the seeds that stayed longer in soil, except in dry weight test. The number of seeds that are able to germinate increases until March. Dormancy regulates the germination flux of annual ryegrass seeds, which is concentrated in the end of Summer and beginning of Autumn, which is the best period to sown the pasture. The loss of quality seems to have less impact than the quantity of seeds, for the success of soybean-annual ryegrass rotation system.

ASSUNTO(S)

bss vigor agronomia germinação sementes ressemeadura natural germination vigor seeds lolium multiflorum

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