Responses of Abutilon theophrasti to agricultural management systems

Abstract

Summary Seeds of Abutilon theophrasti Medic., collected from plants growing in a continuous maize or soyabean field subjected to herbicide application, cultivation or no weed management for 10 years, differed significantly in their weight and germinability. The differences in mean weight and germinability of the progeny seeds were maintained when the parent plants were grown in a greenhouse under controlled conditions. The offspring of plants with or without previous exposure to atrazine responded similarly to the herbicide in all the measurements of the growth and development of the plants, except blooms. Significant differences between the two groups of plants were mainly observed in the weight and germinability of their seeds. Although plants with or without previous exposure to atrazine usually did not differ significantly in their response to the herbicide in terms of individual traits, they differed both in the amount and pattern of overall response across all traits. The difference in overall response between plants increased with increasing rate of atrazine. It is possible that previous exposure to the herbicide had caused minor variation in a group of inter‐correlated traits or in the strength or pattern of correlation among traits.

Demography of Corn Poppy (Papaver rhoeas) in Relation to Emergence Time and Crop Competition

“…Average seed weight did not differ among cohorts or years or by crop competition (data not shown), and therefore, this value was used to calculate seed production from total seed weight. For other species, differences in seed mass have been found among plants (Hubner et al 2003;Luzuriaga et al 2006;Mennan et al 2006;Zhang and Cavers 1994;Zhang and Hamill 1996). The plasticity in the reproductive fitness of corn poppy is not related to the weight or size of seeds but to the number of capsules per plant and the number of seeds per capsule.…”

Temporal and spatial distributions of velvetleaf seedlings after 1 year's seeding

“…was also observed in velvetleaf plants growing in the field (5. E. Weaver, personal communication) or greenhouse conditions with limited root growth (Zhang and Hamill 1996). The total seed production by the 10 plants within each patch (from south to north; Figure 1) was 800, 1,400, 2,040, and 1,600 seeds for the 1974 experiment and 3,120, 3,280, 3,440, and 3,640 seeds for the 1976 experiment, respectively.…”

Variation in Seed Characters of Terminalia Chebula Retz. From the Southern Western Ghats of Tamil Nadu

“…Hendrix (1984) reported that the increase or decrease in rate of germination with increase in seed size was dependent on the environmental conditions. Several studies have documented the variation in seed weight both within and between plant populations (Hawke and Maun, 1988;Michaels et al, 1998, Zhang andHamill, 1996;Cordazzo, 2002). Populations with different seed weights are expected to have evolved under different selection pressures (Westoby et al, 1990;1992).…”