The red alga Chondria crassicaulis has a wide‐ranging bioactive chemical composition and is used as a local foodstuff, representing a potentially new cultivar in Korea. The cultivation techniques were developed by examining the monthly changes in frond weight in a field population of C. crassicaulis from November 2016 to October 2017. For seedling production, temperature and irradiance effects on the attachment and growth of vegetative propagules of C. crassicaulis were evaluated. In addition, effects of day length and salinity on the propagule growth were examined. C. crassicaulis is a year‐round species with a maximum frond wet weight of 817 mg observed in July 2017, as seawater temperature increases to 20°C. The attachment of vegetative propagules was significantly affected by temperature and irradiance, with maximal values detected at 20–25°C and 60 µmol photons m?2 s?1. The relative growth rates of vegetative propagules of C. crassicaulis were the highest at 20–25°C, 60 µmol photons m?2 s?1, and a salinity of 25 psu. In conclusion, due to its tremendous tolerance under variable environmental conditions, the vegetative propagules of C. crassicaulis can be used as seedlings for mass cultivation. 相似文献
Biological soil crusts (biocrusts) are ubiquitous in arid and semi-arid regions and play many critical roles in soil stabilization and erosion prevention, greatly decreasing soil loss. Although sediments may be completely controlled by well-developed biocrusts, runoff loss is observed. Consequently, it is important to study how biocrusts resist runoff erosion in different developmental stages to evaluate and manage water erosion.
Materials and methods
In the Loess Plateau Region, we sampled 32 biocrust plots representing eight stages of biocrust development and 5 slope cropland soil plots as bare soil control plots. We then used a rectangular open channel hydraulic flume to test the effects of biocrust development on runoff erosion.
Results and discussion
As expected, the establishment of biocrusts enhanced soil stability, and accordingly, soil anti-scourability significantly increased with biocrust development. Biocrusts exhibiting more than 36% or 1.22 g dm?2 of moss coverage or biomass fully protected the soil from runoff erosion. Moreover, soil properties, such as soil organic matter, soil cohesion and soil bulk density, were also important in reducing erosion. The findings indicated that biocrusts inhibited runoff erosion through direct physical protection related to biocrust cover and biomass and through the indirect modification of soil properties. In the early biocrust development stage (when moss cover was less than 36%), cyanobacterial biocrust played a primary role in providing resistance to runoff erosion, with resistance being positively related to cyanobacterial biomass (chlorophyll a) and influenced by soil properties.
Conclusions
The relationship between soil anti-scourability and moss coverage or biomass can be divided into two stages based on a moss cover or biomass threshold. The capacity of biocrusts to resist runoff erosion was limited when moss cover was below the threshold value. Therefore, the stage corresponding to this level of moss cover should be of concern when estimating, predicting and managing water erosion.