1Ph.D. Graduate studentconducting thesis research jointly between Department of Horticultural Science and Engineering, University of Tehran, Iran, and University of Idaho, USA.
2Department of Horticultural Science and Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
3University of Idaho, Parma Research and Extension Center, 29603 U of I Lane, Parma, ID, USA
Water shortage worldwide mandates minimum use of irrigation water with maximum efficiency and productivity in all agricultural crops, landscape plants and turf. The objective in this experiment was to study the effect of two levels of evapotranspiration-based (ETc) drought in combination with two levels of nanosilicon dioxide (SiO2; NanSi1=1 mM and NanSi=2 mM), two levels of digoxin (Dig1=0.25 mg.l-1 and Dig2=0.5 mg.l-1) and Dig1 plus NanSi1 on mineral nutrient concentration, chlorophyll index, visual performance of perennial ryegrass (loliumperenne) under climatic conditions of the southwest Idaho in the Intermountain West Regions of the United States. Clippings with 50% ETc had higher percentage dry weight but lower chlorophyll index and visual rating than those with 75%. Clippings of 75% ETc treatment had significantly higher concentrations of nitrogen (N), potassium (K), zinc (Zn) and copper (Cu) but lower sodium (Na), than those of 50% ETc treatment. Considering all mineral nutrient values, chlorophyll indices and visual performance ratings, we conclude that application of 75% ET c is sufficient for maintaining a healthy lawn with satisfactory appearance while we can save 25% water as compared to application of water at 100%. Root growth was not affected by any of these treatments. Based on the results of this study, applications of NanSi1 or Dig1, either individually or simultaneously, can slow the process of quality decline in perennial ryegrass turf under extremely severe drought conditions.