Seasonal Dynamics of Metabolites in Needles of Taxus wallichiana var. mairei.

Seasonal variations of the phytochemicals contents in needles of var. due to the effects of growth meteorological parameters were investigated in this study. The needles of var.

Effects of climate warming on plant autotoxicity in forest evolution: a case simulation analysis for Picea schrenkiana regeneration.

In order to explore how plant autotoxicity changes with climate warming, the autotoxicity of P. schrenkiana needles' water extract, organic extract fractions, and key allelochemical DHAP was systemically investigated at the temperature rising 2 and 4°C based on the data-monitored soil temperature during the last decade in the stage of Schrenk spruce regeneration (seed germination and seedling growth). The results showed that the criterion day and night temperatures were 12°C and 4°C for seed germination, and 14°C and 6°C for seedling growth, respectively.

[Spectral characteristic parameters estimation models for potassium content of Juglans regia 'Wen185' leaves.].

According to the field trials with quantitative fertilization, the spectral characteristic parameters which were highly significantly correlated with foliar potassium (K) content were screened out using Pearson correlation analysis, and the foliar K content estimation models of Juglans regia 'Wen185' in different phenological periods of fruit development were built up with these parameters as independent variables using regression analysis. The results showed that there were one or more spectral characteristic parameters which were highly significantly correlated with the foliar K contents of 'Wen185' walnut in the different phonological periods of fruit development (P＜0.01).

Enantioselective Separation of 4,8-DHT and Phytotoxicity of the Enantiomers on Various Plant Species.

As a candidate for bioherbicide, 4,8-dihydroxy-1-tetralone (4,8-DHT) was isolated from Caryospora callicarpa epicarp and its two enantiomers, S-(+)-isosclerone and R-(-)-regiolone, were separated by chiral high-performance liquid chromatography (HPLC) on a Chiralcel OD column with chiral stationary phase (CSP)-coated cellulose-tris(3,5-dimethylphenylcarbamate). Then, the phytotoxicity of 4,8-DHT and its enantiomers toward the seeds germination and seedling growth of the five tested plant species, including lettuce (Latuca sativa), radish (Raphanus sativus), cucumber (Cucumis sativus), onion (Allium cepa), and wheat (Triticum aestivum), were investigated and the results indicated a hormesis at low concentration of 4,8-DHT and its enantiomers, but a retardant effect at high concentration. Between the two enantiomers of 4,8-DHT, the S-(+)-isosclerone was more toxic to seeds germination and seedling growth of the five tested plant species than the R-(-)-regiolone, and also the phytotoxicity of S-(+)-isosclerone varied with different plants.

[Models for estimating foliar Fe and Mn Concentration of Armeniaca vulgaris cv. Luntaibaixing using spectral reflectance].

Aimed at providing technology for a rapid nutrition diagnosis system of micronutrients in Armeniaca vulgaris cv. Luntaibaixing, we established an element concentration estimation model for its foliar ferrum (Fe) and manganese (Mn) concentration based on spectrum analysis. The foliar spectrum reflectance at various phenological periods of fruit development under different soil fertility conditions was measured by Unispec-SC spectrometer.

[Root system spatial distribution of different aged Armeniaca vulgaris cv. Luntaibaixing in arid oasis under irrigation].

By the methods of layered digging and image scanning analysis, this paper studied the root system spatial distribution of different aged Armeniaca vulgaris cv. Luntaibaixing in arid oasis under irrigation. The root system of A.

Autotoxicity and allelopathy of 3,4-dihydroxyacetophenone isolated from Picea schrenkiana needles.

Bioassay-guided fractionation of the diethyl ether fraction of a water extract of Picea schrenkiana needles led to the isolation of the phenolic compound 3,4-dihydroxy- acetophenone (DHAP). The allelopathic effects of DHAP were evaluated under laboratory conditions on P. schrenkiana, rice (Oryza sativa L.

Phenolics and plant allelopathy.

Phenolic compounds arise from the shikimic and acetic acid (polyketide) metabolic pathways in plants. They are but one category of the many secondary metabolites implicated in plant allelopathy. Phenolic allelochemicals have been observed in both natural and managed ecosystems, where they cause a number of ecological and economic problems, such as declines in crop yield due to soil sickness, regeneration failure of natural forests, and replanting problems in orchards.