Effects of 2,4-D and Dalapon on Weed Seed Production and Dormancy

Abstract

2,4-D [(2,4-dichlorophenoxy)acetie acid] and dalapon (2,2-dichloropropionic acid) were applied to a natural stand of annual weeds at a time near flowering to determine effects on seed production and the dormancy and viability of seeds produced. At rates of 0.6 and 1.1 kg/ha, 2,4-D reduced, respectively the seed production of common lambsquarters(Chenopodium albumL.) 99 and 99%, redroot pigweed(Amaranthus retroflexusL.) 77 and 84%, and jimsonweed(Datura stramoniumL.) 64 and 100%, while giant foxtail(Setaria faberiHerrm) seed production was increased to 307 and 381% of the control, respectively. Dalapon at rates of 2.2 and 4.5 kg/ha reduced respectively seed production of giant foxtail 100 and 100%, and jimsonweed 100 and 91%. Before and after overwinter burial in the soil, common lambsquarters seeds from plants treated with 4.5 kg/ha dalapon were less dormant than control seeds. After overwintering, redroot pigweed seeds from dalapon-treated plants were less dormant than controls, and more seeds survived the winter burial. Common lambsquarters and redroot pigweed seeds from plants treated with 1.1 kg/ha 2,4-D were more dormant than control seeds before overwintering,’ while giant foxtail seeds from 2,4-D treated plants were less dormant than controls after overwintering. Viability of seeds produced by herbicide-treated plants, as determined by germination in KCN, was not greatly different from control seeds. Treatment with 2,4-D or dalapon resulted in the production of common lambsquarters seeds which produced seedlings about half as vigorous as controls. Jimsonweed seedlings grown from seeds from 2,4-D-treated plants showed phenoxy herbicide injury symptoms.

Germination behaviour of seeds from herbicide treated plants of Chenopodium album L.

“…The results of this experiment seem to follow those of Fawcett and Slife (1978). They found that viability of C. album, Amaranthus retoflexux, Dtaura stramonium and Setaria feberi seeds produced by 2, 4-D and Dalapon treated Zollinger and Evans (1985).…”

“…ASIF TANVEER et al Fawcett and Slife (1978) found that viability of C. album, Amaranthus retoflexus L., Datura stramonium L. and Setaria feberi Herrum seeds produced by 2, 4-D and dalapon treated plants was not greatly different from control seeds. Reduced germination or viability due to herbicide application has also been reported by Singhal and Sen (1981), Doliner and Stewart (1992), Young et al (1984), Kasera and Sen (1986), Catizone and Viggaiani (1990) and Don et al (1990).…”

Cutleaf Groundcherry (Physalis angulata) Density, Biomass and Seed Production in Peanut (Arachis hypogaeaL.) Following Regrowth Due to Inadequate Control

“…Seed pod production under hand-pruning was not negatively affected in either year with 290,000 and 85,000 pods/ha in 2009 and 2011, respectively. Seed pod counts were similar to non-treated counts in each year with a slight elevation in seed pod production in 2009, which may indicate the potential for increased seed production in cutleaf groundcherry with sub-lethal herbicide applications, as has been observed in a limited number of other weed species (Fawcett and Slife 1978;Sikkema et al 2004). Seed pod production was highly related to cutleaf groundcherry plant biomass (Figure 1).…”

Efeitos de herbicidas aplicados no período reprodutivo sobre o crescimento inicial de plantas daninhas na geração seguinte

“…No entanto, Fawcet & Slife (1978) encontraram resultados distintos. Citam os autores que a redução na matéria seca das plântulas pode ser devido ao baixo acúmulo de A. Andres & N.G.…”