The reduction of tea quality caused by irrational phosphate application is associated with anthocyanin metabolism

Phosphorus(P)is the second most limiting nutrient for plant growth.Previous studies suggested that P substantially affects the yield and quality of tea by affecting root growth,the decomposition and metabolism of minerals and metabolites in plants.Thus,the environmental pollution and degradation of crop quality caused by irrational fertilization is of increasing interest for researchers worldwide.To understand the effects of P fertilization on tea quality and metabolism of key quality components,three P fertilization levels(excessive,appropriate,and deficient application)were applied to tea plants using pot experiments.Content of P,potassium,polyphenols,amino acids and anthocyanins in the leaves or soil were quantified.The sensory quality of tea infusion was reduced under irrational(excessive or deficient)P fertilization.Under P deficiency,the total content of polyphenols and anthocyanins in the leaves were strongly increased compared with those of the control.A high soil P content(excessive)inhibited polyphenol accumulation,but induced the accumulation of certain anthocyanins,such as peonidin-3-Osambubioside-5-O-glucoside and peonidin-3-O-5-O-(6-O-p-coumaryl)-diglucoside.These results suggest that the reduction of tea quality caused by irrational P application is associated with anthocyanin metabolism,which provides a scientific basis for improving P fertilization strategies in tea plantations.

Insight into the sorption and desorption pattern of pyrrolizidine alkaloids and their N-oxides in acidic tea(Camellia sinensis)plantation soils

Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are crucial due to the horizontal transfer of these natural products from PA-producing plants to soil and subsequently absorbed by plant roots.This study firstly investigated the sorption/desorption behaviors of PAs/PANOs in tea plantation soils with distinct characteristics.Sorption amounts for seneciphylline(Sp)and seneciphylline-N-oxide(SpNO)in three acidic soils ranged from 2.9 to 5.9μg/g and 1.7 to 2.8μg/g,respectively.Desorption percentages for Sp and SpNO were from 22.2%to 30.5%and 36.1%to 43.9%.In the mixed PAs/PANOs systems,stronger sorption of PAs over PANOs was occurred in tested soils.Additionally,the Freundlich models more precisely described the sorption/desorption isotherms.Cation exchange capacity,sand content and total nitrogen were identified as major influencing factors by linear regression models.Overall,the soils exhibiting higher sorption capacities for compounds with greater hydrophobicity.PANOs were more likely to migrate within soils and be absorbed by tea plants.It contributes to the understanding of environmental fate of PAs/PANOs in tea plantations and provides basic data and clues for the development of PAs/PANOs reduction technology.