1985 Volume 30 Issue 3 Pages 231-236
Seedling growth of quackgrass was investigated twice in relation to mechanical stresses (treading and rubbing) and nitrogen levels (50 and 210oom) during May 23 to August 15 and during July 23 to October 15 in 1983. Germinated seeds were planted in plastic pots (20cm in diameter) containing river sand, and watered with nutrient solutions, prepared by standard or modified HOAGLAND'S prescription. Treading (0.5kg/cm2) with an oilpressured jack was conducted five times at ten day intervals and rubbing with the tip of a soft broom was conducted twenty time simultaneously in a day. These treatments were conducted for 45 days, and plants were sampled.
1) Mean daily temperature and photoperiod were 26.3°C and 14h 50′, respectively, in the 1st experiment, in comparison with 15.2°C and 12h 20′, respectively, in the 2nd experiment.
2) Plant heights were decreased by 72-96% in mechanically stressed plots, by 58-59% in the 2nd experiment, and by 81% in low nitrogen level, compared with control, the 1st experiment and high nitrogen level, respectively.
3) On the contrary, tiller number was increased by 133-221, 134-224 and 158-239%, respectively.
4) DM production per plant and nitrogen content of leaf, sheath and rhizome showed the similar tendency to those in plant heights and tiller number, respectively, whereas root was not sensitive to any treatment.
5) Nitrogen absorption per plant was mostly affected by nitrogen level, and least by other treatments.
6) These results suggest that treading stress for quackgrass caused the same morphogenetic response as rubbing stress, although the effects of mechanical stresses were less than those of nitrogen level or growing season, and had little interaction with those.
