Abstract: By using chemiluminescence technique, this paper studied the nitric oxide (NO) emission from Hordeum vulgare seedlings under high temperature, dro
ught, salt, and heavy metals (cadmium and copper) stresses. Shortterm high temperature stress induced the increase of H. vulgare seedlings NO emission, while longterm high temperature stress dropped the NO emission to the level of the control. Under shortterm drought stress, the NO emission from the seedling streated with high concentration polyethyleneglycol 6000 (25% and 30%) increased significantly, but under longterm drought, the NO emission decreased. Similarly, the NO emission increased under shortterm salt stress, but differed under longterm salt stress, depending on salt concentration, i.e., kept a lower level similar to the control at low salt concentration (≤400 mmol·L^-1) but maintained at a higher level at high salt concentration (≥600 mmol·L^-1). No significant change was observed in the NO emission under shortterm heavy metals (cadmium and copper) stress, but the emission increased significantly under longterm cadmium stress and low concentration copper stress. The results suggested that environmental strinduced the NO emission from H. vulgare seedlings, and the emission ratewas correlated with the stress strength and stress duration.

Key words: Sheep urine patches, Soil chemical properties, Carbon, Nitrogen, Phosphorus, Temporal change