Morphological and ecophysiological study of Ephedra equisetina grown under different light, substrate and water conditions

概要

Irrigated agriculture has made a significant contribution to world food security. However, water resources for agriculture are often overused and misused. The result has been large-scale salinization and reducing productivity of irrigated lands globally. Efficient water use in agriculture and optimizing land use strategies in the arid and semi-arid regions are the greatest challenges for Uzbekistan. Cultivation of medicinal plant species that native to dry regions with effective water use could contribute to sustainable agriculture practices in Uzbekistan. Therefore, the present study was conducted to investigate plant vegetative characteristics of Ephedra equisetina (E. equisetina) focusing on its potential as an alternative crop with compelling medicinal value.

The effects of different light emitting diode (LED) factors were examined considering their possible influence on the seed germination, plant morphology, the quality and potential of biomass accumulation, which may promote the functional metabolites in generating of alkaloids in E.equisetina. Furthermore, the capability of polymer hydrogel in releasing retained water for the plant need in order to achieve water using efficiency under controlled conditions were studied. All experiments under the study were provided at the Advanced Plant Factory of the Tokyo University of Agriculture and Technology.

Firstly, the influence of different wavelengths of LED lights on the seed germination characteristics of E. equisetina was studied. The results showed that the germination of E. equisetina increased significantly under the red LED light compared to control and slightly decreased under the blue LED light. Results confirmed that adjusting light conditions with LED lights is an innovative and promising technology that has positive effect on the germination rate of E. equisetina and can improve the shoot length and seminal root length during the germination of E. equisetina.

Moreover, possible responses of plant morphology on the influence of different environmental media including soil components were studied. The results revealed that plants could maximize their growth in habitats with mixed peat moss and Kanuma soils comparing to coconut fiber medium. Mixed peat moss and Kanuma soils encouraged the accumulation of biomass and dry masses of shoots and roots of seedlings were higher in this media. On the other hand, the highest shoot length was recorded under the artificial medium Pafcal (a special soilless sponge-like material, held together by a thin layer of polyurethane binder) among other combination of soil components, but also with the lowest total dry matter.

This was followed by an investigation on possible direct or indirect effects of various intensities of LED lights on morphological and anatomical features of E. equisetina. The results demonstrated positive influence on dry matter, where E. equisetina seedlings grown under 600 μmol m-2 s-1 treatment had greater total biomass weight at 64% than those grown in control treatments under florescence light. However, the increased intensity of blue LED lights extensively inhibited the growth of shoots.

The analysis clearly indicated that different spectrum of LED lights are an effective and reliable source of lighting where discrete wavelengths can manipulate morphology, biomass accumulation and total yield of E. equisetina for its production of high quality seedlings. In addition, the study revealed that LED light treatments could promote the functional metabolites in accumulation of valuable alkaloids (ephedrine and pseudoephedrine) in the seedlings of E. equisetina. In the experiment, alkaloids were also detected in young (one-year) seedlings of E.equisetina. The highest content of total alkaloids with full ratio was recorded under mix LED light, where interestingly, alkaloid consisting of only pseudoephedrine was found to be accumulated under all LED lights treatments but not under control. A new system for accumulating alkaloids in a shorter timeline through the introduction the LED light treatments in a controlled environment was identified under this experiment.

Finally, in the experiment with polymer hydrogel, it was observed that its application to soil medium demonstrated a positive affect for preserving of productive moisture in the upper layers of sandy soils. Our findings indicated that the application of polymer hydrogel was also beneficial for the germination rate of E. equisetina and could significantly increase the survival rate of E. equisetina seedlings subjected to drought conditions. The most important finding was that the polymer hydrogel showed its remarkably high ability in releasing its retained water, which can contribute in achieving water use efficiency under controlled conditions.

The study confirmed that each of the LED light has a specific influence on the morphology, seed germination, biomass accumulation, and accumulation of alkaloids in E. equisetina. Including the different soil components and polymer hydrogel amendments, which play a key role to grow the seedling of E. equisetina with desirable quality characteristics under controlled environments. However, since the research was provided in controlled environments and limited pot size, it should be noted that the outcomes of the above-mentioned experiments might be considerably different under actual field conditions.

Therefore, further experiments are recommended to explore the effects of different LED lights on morphogenesis and production of functional metabolites in E. equisetina plant under arid and semi-arid areas of Uzbekistan.