Joint interactions of carbon and nitrogen metabolism dominated by bicarbonate and nitrogen in Orychophragmus violaceus and Brassica napus under simulated karst habitats

Karst habitats are uniquely characterized by high bicarbonate, high nitrate, and low ammonium, which are in-conducive to their growth and biodiversity. The occurrence of inorganic carbon and nitrogen in karst soil profoundly affects the carbon/nitrogen metabolism and adaptability of plants. However, there has been no final conclusion to the joint interactions of carbon and nitrogen metabolism in plants under karst habitats. In this study, we selected a karst-adaptable plant Orychophragmus violaceus (Ov), and a non-karst-adaptable plant Brassica napus (Bn) as experimental plants, and compared their joint effects of carbon and nitrogen metabolism under simulated karst habitats. It was found that the two species had different joint effects of carbon and nitrogen metabolisms. Bicarbonate and nitrate joint promoted photosynthetic activity and glucose metabolism, facilitating the carbon/nitrogen metabolism and growth of Ov, but their impacts on the carbon and nitrogen metabolism were insignificant in Bn. Bicarbonate and ammonium joint inhibited the photosynthesis and nitrogen metabolism, but promoted water use efficiency in Ov, leading to its enhance of growth reduction, ammonium toxicity alleviation, and drought resistance, while they inhibited the water use efficiency of Bn. In general, bicarbonate and nitrate/ammonium more significantly joint affected the carbon and nitrogen metabolism in Ov than Bn, which is vital for Ov to adapt to karst habitats.

Automated summary

Karst habitats have negative effects on the growth and biodiversity of plants. This study compared the joint effects of carbon and nitrogen metabolism in karst-adaptable Orychophragmus violaceus and non-karst-adaptable Brassica napus under simulated karst habitats. The results showed that factors such as bicarbonate and nitrate had a significant impact on the carbon and nitrogen metabolism and growth of Orychophragmus violaceus, while their effects on Brassica napus were insignificant. The carbon and nitrogen metabolism in Orychophragmus violaceus played a vital role in its adaptation to karst habitats.