Germination, viability and longevity of horseweed em funcao da temperatura e periodos de avaliacao

• Published in: Ciência rural 2018-09, Vol.48 (9)
• Main Authors: Agostinetto, Dirceu, Vargas, Andres Antonio Monge, Ruchel, Queli, da Silva, Jessica Dias Gomes, Vargas, Leandro
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20170687

In Brazil, horseweed is one of the most important weeds because of the resistance to herbicides and high competitive for the crops. A large of losses were reported in major crops such as soybeans, wheat and corn, where the use a no-tillage system and the herbicide resistance promote better establishment. A correct understanding of the way temperature influences germination enables the prediction of the regions with the highest potential for colonization by this weed and thus facilitates its control. The objective of this study; therefore, was to discern the ways temperature affected the germination, viability and longevity of horseweed seeds. Testing was done at 10, 20 and 30[degrees]C, while evaluation occurred on days 0, 15, 30, 45 and 60. Seeds were packed in a nylon mesh bag (5x5 cm), with 10g of upland soil (Yellow Red Argissolo, sandy loam texture), placed in transparent plastic boxes at 0 to 0.5 cm soil depth, at the temperatures specified. Percentage of remaining seeds, first and second germination counts, abnormal seedlings, and dead, dormant, viable and non-viable seeds, were assessed. Horseweed seeds achieve secondary dormancy at 10, 20 and 30[degrees]C, while their quality and the longevity showed damage at 20 and 30[degrees]C temperatures. Key words: secondary dormancy, depth, management, seed quality. No Brasil, a buva (Conyza spp.) e uma das principais plantas daninhas devido a resistencia a herbicidas e alta competividade com as culturas. Esta e responsavel por perdas de produtividade em culturas como soja, milho, algodao e trigo cuja implementacao da semeadura direta e a resistencia aos herbicidas favorecem seu estabelecimento. O conhecimento do efeito da temperatura na germinacao permite prever as regioes com maior potencial de colonizacao e auxiliar no manejo. Assim, objetivou-se com este trabalho determinar o efeito da temperatura na germinacao, viabilidade e longevidade de sementes de buva em solo de terras altas. As temperaturas testadas foram 10, 20 e 30[degrees]C e os periodos de avaliacao 0, 15, 30, 45 e 60 dias. As sementes foram acondicionadas em saco de malha de nylon (5 x 5cm), distribuidas em 10g de solo de terras altas (Argissolo Vermelho Amarelo, de textura franco-arenosa), e, alocadas em caixas gerbox com solo a profundidade de 0 a 0,5 cm, nas temperaturas descritas. Avaliou-se em percentagem de sementes remanescentes, primeira e segunda contagem de germinacao, plantulas anormais, sementes mortas, dormentes, viaveis e nao v