Maturação e dormência em diásporos de carrapicho-de-carneiro (Acanthospermum hispidum DC. - Asteraceae)

Abstract

RESumo -objetivou-se acompanhar a maturação dos diásporos de carrapicho-de-carneiro (Acanthospermum hispidum DC.) e avaliar métodos de superação da dormência. Diásporos com 7, 14, 21, 28 e 35 dias após antese (DAA) obtidos em plantas ocorrentes na área experimental da universidade Federal do Recôncavo da Bahia, Cruz das Almas, BA, Brasil. Foram avaliadas as dimensões dos diásporos de cada estádio, seu teor de água e de massa seca. Fez-se um teste de emergência de plântulas, a 25 ºC, sob 16 horas de luz em areia lavada. Avaliou-se semanalmente a emissão da parte aérea, determinando o índice de velocidade de emergência (IVE) e a porcentagem de diásporos mortos e dormentes. Em outro experimento, utilizaram-se tratamentos para superação da dormência: escarificação com lixa; lavagem em água corrente por 24 horas; estratificação a 10 ºC por sete dias; GA 3 a 4000 mg L -1 ; sementes intactas. Ocorreram incrementos na largura e na massa da matéria seca até 21 DAA, o comprimento aumentou até 35 DAA. A máxima emergência de plântulas (45%) e o máximo IVE (3,4) ocorreram aos 21 DAA, quando ocorreu a maturidade fisiológica; nos estádios seguintes verificou-se aumento da dormência. A. hispidum dispersa sementes fisiologicamente dormentes e a dormência é superada com GA 3 .Termos para indexação: planta daninha, germinação, vigor, giberelina. maturation and dormancy in Acanthospermum hispidum DC. -Asteraceae diaspores ABSTRACT -The objective of the study was to evaluate the maturation of A. hispidum diaspores and methods for overcoming dormancy. Diaspores were obtained 7, 14, 21, 28 and 35 days after anthesis (DAA) from plants in the experimental area of the universidade Federal do Recôncavo Bahiano, Cruz das Almas, Bahia, Brazil. Diaspore dimensions, water content and dry weight were evaluated. Emergence was tested at 25°C with 16 hours of light in washed sand. Emergence was monitored weekly, counting the aerial part of the seedlings above the substrate, and determining the germination velocity emergence (GVE) and percentage of dead and dormant diaspores. In another experiment, the treatments for overcoming dormancy were: scarification with sandpaper; washing in running water for 24 h; stratification at 10 ºC for 7 days; GA 3 4000 mg L -1 ; and intact seeds. The dry weight increased until 21 days and the length increased until 35 DAA. The maximum emergence (45%) and GVE (3.4) of the diaspores was at 21 DAA when there was physiological maturity. Dormancy increased in the subsequent stages. A. hispidum disperses physiologically dormant seeds and dormancy can be overcome with GA 3 .

Maturation, processing and seed storage of Elephantopus mollis Kunth Maturação, processamento e armazenamento de sementes de Elaphantopus mollis Kunth.

“…Several species of the Asteraceae show similar behavior to that found in this study for E. mollis, with seed maturation close to 45 DAA (Bezerra et al, 2003;Duarte, Santos, Souza Peixoto, & Santos, 2012;Grzybowski et al, 2016;Guimarães, Oliveira, Mantovani-Alvarenga, & Grossi, 1998;Silveira, Villela, & Tillmann, 2002), with some species showing earlier maturation, such as Adenostemma brasilianum (Pers.) Cass.…”

Physiological analysis and heat-resistant protein (LEA) activity in squash hybrid seeds during development

“…Generally, the harvesting period depends on the seed physiological maturity, which, in most cases, coincides with the maximum accumulation of dry matter, and when the seeds reach this stage, usually their potential for germination and vigor increases (Duarte and Carneiro, 2009). The seed vigor modifications occur in parallel with the transfer progress of plant dry matter for the seeds, i.e., the proportion of vigorous seeds increases during maturation, reaching a maximum at a time that is very close to or coincident with the maximum accumulation of reserves (Marcos-Filho, 2005).…”

Seed dormancy in Asteraceae: a global vegetation zone and taxonomic/phylogenetic assessment

“…Rout et al, 2009;Aguado et al, 2011;Gandy et al, 2015). Also, treatment with GA 3 may promote germination by increasing the growth potential of the embryo (Afolayan et al, 1997;Dissanayake et al, 2010;Duarte et al, 2012;Aiello et al, 2017;Guo et al, 2021). Scarifiction followed by treatment with GA 3 of the perennials Helianthus angustifolia, H. glaucophyllus and H. pumilus promoted cypsela germination (Castillo-Lorenzo et al, 2019).…”