Studies On Biological Characteristics And Cultivation Techniques Of Urtica Dioica L.

As a perennial herbaceous vegetation , Urtica dioica L. has the greatest value in development among Urtica, not only for medicine use, but also for consumption as wild vegetable. This experiment focused on the biological characteristics and cultivatation measures of Urtica dioica L. in different provenance by potted planting methods. The main results are as follows::①The whole growth period of Urtica dioica L. can be divided into 5 stages according to the different characteristics shown in each stage. The growth rate of individual Urtica dioica L. varies at each reproduction stages and shows a S-curve through its whole growth period, which can be simulated by Logistic equation.②Most roots of Urtica dioica L. are less than 1mm in diameter, while their links and length about account for 80%.And the root sueface area ismainly contributed by big diameter roots. The roots consistes mainly of 1 order root, which also play a key role in absorbing nutrient.③During the growth period, the photosynthesis rate of Urtica dioica L. first increases, then decreases after it reaches the highest point. The curve, which illustrates the daily changes of photosynthesis rate, varies at different seasons. In summer, it is an asymmetrical double-apex curve; the phenomenon of"noon nap"is obvious, resulted from the"non-pore factor". In autumn, it is a mono-apex curve; the net photosynthesis rate usually reaches its maximum at 1:00 pm each day.④When the light intensity growes, the net photosynthesis rate of the leaves first increases and then decreases. When the CO2 concentration rise, the net photosynthesis rate increases. They can be simulated by Farquhar model.⑤By comparing the photosynthesis characteristics and growth states of 3 provenances of Urtica dioica L., Urtica dioica L. of Tiantai county obviously exceeds to other 2 provenances.⑥The influence of pruning intensity on biomass of shoot and root is significant. The relationship between shoot biomass and pruning intensity is as: 3/4 height>peaking>control>1/2 height>1/4 height; The relationship between root biomass and pruning intensity is as: control>3/4 height>peaking>1/2 height>1/4 height.⑦Planting density is the important factor influencing yield, the best maize planting density is 740000～775000 plant·hm^-2. Different densities have influence on individual Urtica dioica L. and colony Urtica dioica L.. Take the colony as example, the total shoot biomass is decrease with the following densities: 767263 plant·hm^-2>575448 plant·hm^-2>959079 plant·hm^-2>383632 plant·hm^-2>191816 plant·hm^-2; the total root biomass is decrease with the following densities: 767263 plant·hm^-2>959079 plant·hm^-2>575448 plant·hm^-2>383632 plant·hm^-2>191816 plant·hm^-2.