1Department of Crop Physiology, CPMB, Tamil Nadu Agricultural University, Coimbatore, 641 003, India.
2Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore, 641 003, India.
Field investigation was carried out during rabi 2004–05 at Tamil Nadu agricultural University, Colmbatore to evaluate the threshold values of Trianthema portulacastrum in onion. The results indicated that the increase in densities of Trianthema portulacastrum increase the yield reduction linearly in onion crop. The maximum percentage of yield reduction was recorded with 64 weeds m−2 (54.8%) over the zero weeds m−2. The lowest yield reduction was with 4 weeds m−2 (8.8%) followed by 8, 16, 32 weeds m−2 (27.1, 38.61, 46.38% respectively). From this experiment, it is evident that a density of 4 weeds m−2 is the threshold value of Trianthema portulacastrum for onion crop to avoid significant yield reduction.
Threshold level, Trianthema portulacastrum, onion
