Effects of Pollen-Load Size and Number of Donors on Sporophyte Fitness in Wild Radish (Raphanus raphanistrum)

Abstract Wild radish is the most problematic broadleaf weed of Australian grain production. The propensity of wild radish to evolve resistance to herbicides has led to high frequencies of multiple herbicide resistant populations present in these grain production regions. The objective of this study was to evaluate the potential of mesotrione to selectively control wild radish in wheat. The initial dose response pot trials determined that at the highest mesotrione rate of 50 g ha−1, PRE application was 30% more effective than POST on wild radish. This same rate of mesotrione POST resulted in a 30% reduction in wheat biomass compared to 0% for the PRE application. Subsequent, mesotrione PRE dose response trials identified a wheat selective rate range of >100 and < 300 g ai ha−1 that provided greater than 85% wild radish control with less than 15% reduction in wheat growth. Field evaluations confirmed the efficacy of mesotrione at 100 to 150 g ai ha−1 in reducing wild radish populations by greater than 85% following PRE application and incorporation by wheat planting. Additionally, these field trials demonstrated the opportunity for season-long control of wild radish when mesotrione PRE was followed by bromoxynil POST. The sequential application of mesotrione, an HPPD-inhibiting herbicide, PRE followed by bromoxynil, a PS II-inhibiting herbicide POST has the potential to provide 100% wild radish control with no effect on wheat growth.

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Effects of Pollen Load Size and Maternal Plant on Pollen Performance and Seedling Vigor in Clarkia unguiculata (ONAGRACEAE)

International Journal of Botany ◽

10.3923/ijb.2006.83.92 ◽

2005 ◽

Vol 2 (1) ◽

pp. 83-92 ◽

Cited By ~ 3

Author(s):

M. Barbara Nemeth ◽

Nancy L. Smith-Huert .

Keyword(s):

Seedling Vigor ◽

Pollen Load ◽

Maternal Plant ◽

Pollen Performance ◽

Load Size ◽

Clarkia Unguiculata

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Early growth and development of wild radish (Raphanus raphanistrum L.) in relation to wheat

Australian Journal of Agricultural Research ◽

10.1071/ar00150 ◽

2001 ◽

Vol 52 (7) ◽

pp. 755 ◽

Cited By ~ 17

Author(s):

R. D. Cousens ◽

J. W. Warringa ◽

J. E. Cameron ◽

V. Hoy

Keyword(s):

Specific Leaf Area ◽

Growth And Development ◽

Early Growth ◽

Detectable Effect ◽

Wild Radish ◽

Raphanus Raphanistrum ◽

Short Delay ◽

Wheat Growth ◽

Competition Models ◽

Sowing Dates

Raphanus raphanistrum was grown in monoculture and as a range of cohorts of emergence in mixture with wheat. Growth and development were recorded at frequent intervals up to anthesis of the wheat.R. raphanistrum remained shorter than wheat, only over-topping the crop prior to anthesis for 2 of 7 sowing dates. When expressed in terms of photothermal time, growth in monocultures was similar for all sowing dates except those for wheat in mid-summer. Even a short delay in R. raphanistrumemergence in mixture decreased its growth considerably; R. raphanistrum emerging more than 4 weeks after the crop had no detectable effect on the wheat. However, even R. raphanistrum plants emerging 10 weeks after the crop produced some seeds. In mixture, R. raphanistrum had a higher specific leaf area (SLA), reduced leaf partitioning, and taller stems than in monoculture. A physiological growth model based on parameters from monocultures was unable to predict growth in mixtures; inclusion of changes in SLA and height in mixture improved predictions in some cases. It is concluded that competition models based on monoculture parameters, although previously successful for species with similar height and phasic development, are unlikely to work for species that differ in these attributes. Further work is required on the physiology of plants within mixtures.

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