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Vitex trifolia Linn. var. simplicifolia Cham is a medicinal aromatic plant and perennial halophyte growing in the coastal areas around the Bohai Sea in China. The aim of this study was to investigate the salt tolerance mechanisms of V. trifolia when subjected to different concentrations of NaCl (0, 90, 180, 270, 360 and 450 mM) by measuring growth parameters, ion contents, proline, soluble sugar, soluble protein, malondialdehyde (MDA), photosynthetic pigment contents, chlorophyll fluorescence parameters and antioxidant enzyme activities. The plants died when the NaCl concentration reached 450 mM 20 days after salt stress. Biomass and shoot growth were inhibited by increasing salinity, while root growth was promoted at a NaCl concentration ranging from 90 to 270 mM. Na+ and Cl– accumulation was markedly promoted in both leaves and roots with increasing salinity, while no significant changes were observed in the K+ concentration and K+/Na+ ratio in the leaves. Proline, soluble sugar and soluble protein contents increased significantly with increasing salinity. In order to eliminate the reactive oxygen species (ROS) produced by salt-induced oxidative stress, the activities of peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were enhanced. Photosynthetic pigment contents and PSII activity did not significantly decrease under salt stress. The results indicate that the mechanism of salt tolerance in V. trifolia are by ion homeostasis, osmotic balance, antioxidant enzyme induction and photosynthesis adjustment.

Limonium bicolor, Vitex trifolia Linn. var. simplicifolia Cham and Apocynaceae venetum are halophyte species with ecological restoration function of saline soil that are widely distributed in coastal areas around Bohai Sea in China. The mechanism of response to salt stress is different between them. The salt-tolerance mechanism, especially for ion homeostasis, of these halophytes varies and is not properly understood. The purpose of the work was to reveal the effect of salinity on ion homeostasis in these three halophyte species. Plant growth, leaf succulence, Na+, K+ and Cl− concentrations, as well as ion flux were examined at various concentrations (0–100%) of artificial sea water after 10 days. The results showed as follows: the growth of L. bicolor was obviously stimulated under salt stress, while V. trifolia Linn. var. simplicifolia Cham and A. venetum was strongly inhibited. The contents of Na+ and Cl− increased with salinity in the three halophyte species, in both the leaves and roots. The accumulation of K+ in roots was promoted by salinity except in L. bicolor subjected to 100% artificial sea water concentration. L. bicolor roots showed a lower net Na+ efflux compared with the control. By contrast, V. trifolia Linn. var. simplicifolia Cham and A. venetum roots retained a greater capacity for net Na+ efflux compared with the control. L. bicolor and V. trifolia Linn. var. simplicifolia Cham roots exhibited a lower and higher net Cl− influx, respectively, than the control, but the differences were not significant. By contrast, A. venetum roots exhibited a Cl− efflux compared with the control. L. bicolor and V. trifolia Linn. var. simplicifolia Cham roots reduced net K+ efflux, and L. bicolor even appeared to exhibit a K+ influx at certain points in time, whereas A. venetum strongly increased net K+ efflux compared with the control. The accumulation and partitioning of ions differed between the three halophyte species, and the salt-tolerance ranking from high to low was L. bicolor, V. trifolia Linn. var. simplicifolia Cham, and A. venetum.

To take full advantage of the natural hazel resources and improve its yield and quality in Great Xing’an Ridge region, we carried out an initial investigation. The result showed that: there are two species in this area: Corylus heterophlla and Corylus mandshurica. They mainly distribute from south of XinLin town, HuMa county, Heilongjiang province to south boundary of Great Xing’ an Ridge in mountain and hilly areas. Most of hazel in this area was under the state of natural growth with no scientific man-management. Soil where Corylus heterophlla grew was about 40 cm to 50 cm and Corylus mandshurica was 30 cm to 45 cm. The main plant disease was powdery mildew and insect pest were Curculio dieckmani, Zeuzera sp. and Faust Cockchafer. 100-seed weight of Corylus heterophylla was more than twice of Corylus mandshuria. However, Corylus mandshuria was plumper, had much more kernel and much less empty shell than Corylus heterophylla, and what’s more, shell sickness of it turned to be significantly thinner than Corylus heterophylla, all of which showed great cultivation value and economic commodity value.