Amaranthus germplasm is efficiently regenerated in plastic tents within greenhouses . This protocol involves the cultivation of 100-plant populations in 0.8 m2 x 1 m tall tents , and generally yields 40 000-120 000 seeds about 3 months after planting. Expsriments were performed to test the effectiveness of pollination control by isolating four monoecious Amaranthus species in these plastic tents . The estimated f requency of pollen contamination between tents was 0.01%. The estimated frequency of cross-pollination within tents was 3.9%.