[ Objective] The aim was to provide strategies for development of rare earth and control of environmental pollution. [ Method] Responses of membrane lipid peroxidation and endogenous hormones of soybean seedlings to UV-B radiation and rare earth were studied through hydroponics in laboratory. [ Result] The results showed that under irradiation of UV-B（ T1-0.15 W/m^2 and T2-0.45 W/m^2）, chlorophyll and indole-3-acetic acid（IAA） contents firstly decreased during the stress phase （1 -5 d） and then increased during the restoration phase （6 -9 d） while contents of malonadialdehyde（MDA） and abscisic acid（ABA） gradually increased during the imposition of UV-B radiation （1 -5 d） and subsequently decreased during recovery from UV-B stress （6 -9 d） . With adding of La （III） with the concentration of 20 mg · L^-1 , the decline/dse trend of chlorophyll, IAA, MDA and ABA contents was slowed down during the stress period while the rise/decline speed was accelerated during the recovery period. [ Conclusion] It suggests that the regulation of La （ III ） on membrane lipid peroxidation and endogenous hormones could increase chlorophyll and IAA contents, improve the metabolism of reactive oxygen species （ ROS）, inhibit membrane lipid peroxidation, decrease the accumulation amount of ABA and alleviate injury of UV-B radiation to soybean seedlings. Further, the protective potential of La （ III ） was better under low UV-B radiation than under high one.
The seedling hydroponic culture experiment of kidney bean （ Phaseolus vulgaris ） and corn （ Zea mays ） was conducted to investigate the alleviation effect of lanthanum on Cd stress. It is found that growth is seriously inhibited and metabolism is maladjusted in the two crops under 30 and 300 μmol·L^-1 Cd^2＋ stress. Plant height, taproot length, leaf area, and fresh or dry weight of root, stem, and leaf are all obviously decreased. Further, chlorophyll content decreases, membrane permeability, malonydialdehyde （MDA） content, activities of catalase （CAT） and peroxidase （POD） increases under Cd stress, as compared with the control. The damage to these two crops becomes more conspicuous with the prolongation of Cd stress. It is suggested that lanthanum might help kidney bean and corn seedlings alleviate Cd stress by improving the photosynthetic capacity, reducing membrane permeability and MDA content, and maintaining the activities of CAT and POD of these two crops.
Objective The aim of this study was to explore the method and standard for rapidly screening low temperature-resistant pepper germplasm resources and provide a theoretical basis for the breeding of low temperature-resistant pepper. [ Method ] With 110 pigment pepper seeds as the materials, their germination vigor under optimum temperature and suboptimal temperature were determined by means of roll rapid germination, and seeds with different genetic types were evaluated from aspects of germination vigor and its interval division. [ Result ] 37 pepper seeds with stronger low temperature resistance were screened. [ Conclusion]This study provides an important basis for screening low temperature-resistant pepper germplasm resources.
Effect of cerium （Ce^3＋） on growth and photosynthesis in rape seedlings exposed to two levels of ultraviolet-B radiation （UV-B, 280 - 320 nm） was studied with hydroponics under laboratory conditions. The growth of rape seedlings exposed to two levels of UV-B irradiation （0.15 and 0.35 W· m^-2/T2） was both heavily restrained. The aboveground growth indices including stem （plant） height, leaf number, leaf area, leaf fresh/dry weight and stem fresh/dry weight were obviously decreased by 13.2% - 44.1% （T1） and 21 .4% - 49.3% （T2）. Compared to CK, and except active absorption area of roots, the belowground indices main root length, root volume and fresh/dry weight by 14.1% -35.6% （T1） and 20.3% - 42.6% （T2）, respectively. For Ce ＋ UV-B treatments, the aboveground and belowground growth indices were decreased by 4.1% - 23.6%, 5.2% -23.3% （Ce＋T1） and 10.8% -28.4%, 7.0% -27.8% （Ce ＋T2）, lower than those of UV-B treatments mentioned above. These results show that Ce has protective effect on plant against injury of UV-B radiation. Furthermore, the protective effect of Ce on seedlings exposed to T1 level of UV-B radiation is superior to T2 level. Chlorophyll content, net photosynthesis rate, transpiration rate, stomatal conductance and water use efficiency in UV-B treatments decrease dramatically, whereas intercellular CO2 concentration increases. Although these indices in Ce ＋ UV-B treatments decrease compared with those of CK, the decrease in Ce ＋ UV-B treatments are lower than those in UV-B treatment. This phenomenon indicates that the ecophysiological protective effect of Ce is based on improving photosynthesis in plants. The dynamic curves of photosynthesis indices show that the course of light-repair is shortened and the injury to rape seedlings by UV-B radiation stress is alleviated by Ce.
