Effects of after‐harvest period and environmental factors on seed dormancy of Amaranthus species

Abstract

Summary The effects of seven constant temperatures (10–40°C at 5°C intervals) and seven after‐harvest periods (30–540 days after harvest) were evaluated on seed germination of nine Amaranthus species (A. albus, A. blitoides, A. cruentus, A. deflexus, A. graecizans, A. hybridus, A. lividus, A. retroflexus and A. viridis). Seeds of A. blitoides and A. viridis were also tested at alternating temperatures of 10/30°C (12/12 h thermoperiod) in continuous darkness and in an alternating 12/12 h dark/light photoperiod. With the exception of A. blitoides and A. viridis, germination increased as temperature increased from 20 to 35°C; the latter representing the optimum temperature (70–100% germination). At 10 and 15°C constant temperatures, no significant seed germination occurred in A. albus, A. deflexus, A. graecizans and A. lividus, while in A. cruentus, A. hybridus and A. retroflexus there was no germination at 10°C, but at 15°C more than 60% germination occurred. Germination was influenced strongly by after‐ripening period in A. cruentus, A. hybridus and A. retroflexus, partially in A. deflexus, and barely in A. graecizans and A. lividus. Seeds of A. blitoides and A. viridis required alternating temperatures and light to achieve high germination percentage (>90%). Primary dormancy in Amaranthus plays a fundamental role in extending germination over a longer period, so that the probability of seedling survival is maximised. The present study adds to the understanding of the environmental control and germination ecology of Amaranthus species and provides data that can contribute to predicting weed emergence dynamics.

Factors affecting Cyperus difformis seed germination and seedling emergence

“…Knowledge of the effect of constant and alternating temperatures on C. difformisgermination can help us understand its emergence pattern and its management in different cropping systems. Light is an important ecological determinate for germination; the absence of light acts as a soil-depth indicator that prevents many seeds from germinating (Crisraudo et al, 2007). Similarly, an ability to germinate under conditions of moisture stress or high salinity can enable a weed to take advantage of conditions that limit the growth of other species.…”

Allelopathic effects of Cynara cardunculus L. leaf aqueous extracts on seed germination of some Mediterranean weed species

“…Daily mean temperature during the year ranges from 8.5°C to 26°C: minimum temperature is around 0°C, while maximum can peak at over 35°C. Annual precipitation is about 500 mm (Cristaudo et al, 2007).…”

“…Petri dishes, hermetically sealed with parafilm to prevent evaporation of the solution, were stored in incubators at the optimal conditions of temperature and photoperiod for single weed species tested. Germination tests were performed in continuous darkness and at a constant temperature of 35°C for Amaranthus retroflexus L. (Cristaudo et al, 2007) and Portulaca oleracea L. (Singh, 1973), in continuous darkness and at a constant temperature of 20°C for C. cardunculus var. sylvestris (Lekić et al, 2011), while Diplotaxis erucoides (L.) DC.…”

Factors Affecting Tausch’s Goatgrass (Aegilops tauschii Coss.) Seed Germination and Seedling Emergence

“…There was no significant difference in other regimes. Response of germination to light varied from species to species (Crisraudo et al, 2007;Gallagher and Cardina 1998). Seeds of some species required light to stimulate their germination (Chauhan and Johnson 2009;Chauhan and Johnson 2008b;Chauhan et al, 2006), but others germinated equally well in light and dark (Chauhan and Johnson 2008a;Teuton et al, 2004).…”