Abstract:

We studied water consumption and water use characteristics of poplar under three different soil water regimes: adequate soil water, medium drought, and severe drought conditions, which were about 70%, 55% and 40% of field capacity. The results showed that water potential, water content, photosynthesis rate, water use efficiency of leaves, and plant growth rates decreased significantly with decreases in soil water content. At levels of adequate soil water content and medium drought, fast growth and biomass accumulation of poplar occurred during May and June, whereas this occurred during May only under severe drought conditions. Total water consumption and biomass growth were greatest under adequate soil water conditions, decreased under medium drought, and was lowest under severe drought conditions. Total water use efficiency was highest under medium drought conditions and lowest under severe drought. Patterns of water consumption on a daily rate, every 10 days, and monthly rates were different under the three soil water treatments. For all three treatments, the highest monthly water consumption occurred in July and then June. The highest water consumption over a ten-day period was in the second ten days of July, the first ten days of July, and the last ten days of June for the three treatments, respectively. The highest water consumption day of the medium and severe drought treatments occurred one or two months earlier than the adequate soil water treatment. The time of day when the greatest water consumption occurred changed throughout the life span of the poplar and under the differnt soil water treatments.From our results, we conclude that poplar does not have characteristics of drought resistance plants; hence, we do not recommend that this species is planted over a wider range in the loess plateau.