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The relative response of poppy (Papaver somniferum L.) and eight crop and vegetable species to excess manganese was investigated in a glasshouse, solution culture experiment. Plant yields and manganese concentrations were measured after two and six weeks growth at five levels of manganese (10–800 μM). Poppies were highly sensitive to manganese toxicity in solution culture and reductions in shoot yield occurred at lower manganese levels in solution and at lower shoot manganese concentrations than that for the following sensitive species, ranked in order of increasing tolerance : brussels sprout, barley, green beans, lucerne and grean pea. In contrast lupins, oats and sugar beet were relatively tolerant producing about 80% or more of maximum shoot yield at the highest solution manganese level (800 μM Mn). In this study the sensitivity of poppy, and brussels sprout, to manganese excess was attributed to their low shoot manganese “toxicity threshold values”; and their capacity to partition a high pro...

Fifteen cultivars of subterranean clover (Trifolium subterraneum L.) and 1 cultivar of balansa clover (Trifolium balansae Boiss.) were screened for tolerance to 2,4-DB, MCPA-Na salt, MCPA amine, bromoxynil and combinations of these herbicides. The clovers were sprayed at the 3-4 trifoliate leaf stage and dry matter production assessed in the following spring. All herbicides reduced clover dry matter production (DM). The least damaging herbicides to subterranean clover were bromoxynil (0.3 kg a.i./ha) and MCPA-Na salt (0.313 kg a.i./ha) which reduced DM production by 23 and 39% respectively. The most damaging were 2,4-DB (0.8 kg a.i./ha) and MCPA amine (0.313 kg a.i./ha) plus bromoxynil (0.3 kg a.i./ha) which reduced DM production by 62 and 56% respectively. The damage caused by MCPA-Na salt (0.5 kg a.i./ha) plus bromoxynil (0.3 kg a.i./ha) was intermediate, reducing clover production by 44%. Second year seedling regeneration was reduced across all herbicide treatments by 32%. Of the currently recommended cultivars, Trikkala was the most tolerant to herbicides, with an average reduction in DM of 37%. Bromoxynil was the herbicide tolerated best by cvv. Enfield, Karridale, Larisa, Mt Barker and Woogenellup. The most effective weed killing treatments were 2,4-DB plus bromoxynil and MCPA-Na salt (0.5 kg a.i./ha) plus bromoxynil(0.3 kg a.i./ha).