The present study aimed to determine effects of drought stress on Lycium ruthenicum Murr. seedlings. Our results showed that mild drought stress was beneficial to growth of L. ruthenicum seedlings. Their height, basal diameter, crown, leaf number, stem dry mass, leaf and root dry mass increased gradually when the soil water content declined from 34.7 to 21.2%. However, with further decrease of the soil water content, the growth of L. ruthenicum seedlings was limited. After 28 d of treatment, the seedlings were apparently vulnerable to drought stress, which resulted in significant leaf shedding and slow growth. However, growth was restored after rehydration. Drought treatments led to a decrease in contents of chlorophyll (Chl) a, b, and Chl (a+b) and increase in the Chl a/b ratio. After rewatering, the Chl content recovered to the content of the control plants. Under drought stress, minimal fluorescence and nonphotochemical quenching coefficient increased, thereby indicating that L. ruthenicum seedlings could protect PSII reaction centres from damage. Maximum fluorescence, maximum quantum yield, actual quantum yield of PSII photochemistry, and photochemical quenching decreased, which suggested that drought stress impacted the openness of PSII reaction centres. A comparison of these responses might help identify the drought tolerance mechanisms of L. ruthenicum. This could be the reference for the planting location and irrigation arrangements during the growing period of L. ruthenicum., Y.-Y. Guo, H.-Y. Yu, D.-S. Kong, F. Yan, Y.-J. Zhang., and Obsahuje bibliografii
The absence of fungal or viral diseases of some invasive alien plants partially explains their success. However, for several species this issue has not been studied and no account of such infections are recorded for Impatiens glandulifera, a problematic weed in moist and half-open habitats of central and western Europe. We record for the first time viral infections in plants from different European regions grown in a common garden experiment. The infection was systemic and could be transferred to two species of Chenopodium and five species of Nicotiana, and resulted in the development of local necrotic spots within a week. The symptoms resembled Tobacco Rattle Virus, but this was not confirmed by an ELISA-test. In I. glandulifera the virus led to reduced above-ground biomass. Relative stem biomass and basal diameter were also lower in diseased plants, but therewas no significant differences in plant height and number of main branches. Also virus infection did not affect the following reproductive traits: time to flowering, pollen viability, fruit abortion, seed/ovule ratio, seed number per fruit and individual seed mass. This virus was not transmitted via seed. The potential effects of such viral infections on the population dynamics and biological control of this alien plant are discussed.