Effects of Drought and Nitrogen Treatments on Water Storage and Transportation in Lycium barbarum L.

In order to gain insights in the combined effects of drought and nitrogen fertilization on water storage and transportation in these plants, pot experiments were conducted. Two-year-old seedlings of 'Ningqi 1' variety of L. barbarum were subjected to three levels of drought combined with three levels of nitrogen fertilization (in the form of urea), plus controls of normal watering and no added nitrogen. Following these treatments, the water content, tissue water capacity, natural dehydration rate and hydraulic characteristics of the plant parts were determined. Under drought stress, the application of nitrogen increased the observed changes of water content in the plant's canopy was more significant than in their roots. The water capacity decreased under increasing drought stress, but when combined with nitrogen application this decrease could be slowed down. The natural dehydration rate of stems was the lowest, that of roots was higher and that of leaves was the highest. With increasing levels of nitrogen fertilization, the natural dehydration rate under drought stress was increased. The root system is the main part that affects water transport in the plants, and we show here that nitrogen application can temper the change of hydraulic conductance and reduce the xylem embolism vulnerability and water potential threshold under drought stress. The results suggest that under water-limiting conditions a proper nitrogen treatment can be beneficial to the water storage and transportation, reduce the vulnerability of xylem vessel embolism, and improve the ability of water retention in Lycium barbarum L.