Effects of environmental factors on germination and emergence ofAmaranthus retroflexus

Abstract

Detailed knowledge about the environmental conditions required for weed seed germination and establishment in soil is an important prerequisite for the development of integrated and biological weed control strategies. Germination and establishmentof Amaranthus retroflexuswere studied at different temperatures, planting depths, soil types, nitrogen supply, and water potentials. The minimum temperature for seed germination was > 5 C; maximum germination occurred between 35 and 40 C. At temperatures between 25 and 35 C, an additive effect on germination rate was observed when temperature and water availability were increased. For all soils tested, the percentage emergence of seeds placed on the soil surface and 4 cm deep was significantly lower than seeds placed between 0.5 and 3 cm. Emergence in the four sandy soils was generally greater than in the two heavier soils included in the study. There was a highly significant interaction between seed depth and soil type. Plant growth was also greatest in the lighter soils. Plant height, number of leaves, leaf area, fresh and dry weight, and nitrogen and carbon percentage in plant tissues ofA. retroflexusincreased significantly with increasing soil nitrogen supply.

Effects of Environmental Factors on Germination and Emergence of Swallowwort

“…They realized that although light can be a requirement in some seeds, this requirement can often be overcome by warmer germination temperatures and can vary with seasonal seed dormancy fluctuations. Results of this study were in agreement with those obtained by Siriwardana and Zimdahl (1984), Martinez et al (1992), and Ghorbani et al (1999). By sensing the most favorable environmental signals, natural factors (light, temperature, rainfall, etc.…”

Germination Response of Four Alien Congeneric Amaranthus Species to Environmental Factors

“…Some results of germination ecology and response to environmental factors were reported by weed scientists [26–32]. Amaranthus is also the genus with several naturalized weeds including the highly invasive A .…”

Weed Problems, Ecology, and Management Options in Conservation Agriculture: Issues and Perspectives

“…Buhler et al (1994) have noticed greater and more diverse populations of perennial weeds under RT systems in corn-soybean rotations. Buhler (1995) found that the densities of large-seeded dicot species often decreased under RT in corn-soybean rotation as minimizing soil disturbance affected the composition of weed communities (Zanin et al, 1997), e.g., small-seeded weeds, such as pigweeds, emerged only from shallow burial depths (0.5-2.5 cm) (Buhler et al, 1996;Ghorbani et al, 1999;Oryokot et al, 1997). Torresen et al (1999) found that due to survival of more weeds to the next growing season more seeds were produced as compared to autumn ploughing at Norway.…”