Foliar N Application on Tea Plant at Its Dormancy Stage Increases the N Concentration of Mature Leaves and Improves the Quality and Yield of Spring Tea

Abstract

Over 30% of the Chinese tea plantation is supplied with excess fertilizer, especially nitrogen (N) fertilizer. Whether or not foliar N application on tea plants at the dormancy stage could improve the quality of spring tea and be a complementary strategy to reduce soil fertilization level remains unclear. In this study, the effects of foliar N application on tea plants were investigated by testing the types of fertilizers and their application times, and by applying foliar N under a reduced soil fertilization level using field and 15N-labeling pot experiments. Results showed that the foliar N application of amino acid liquid fertilizer two times at the winter dormancy stage was enough to significantly increase the N concentration of the mature leaves and improved the quality of spring tea. The foliar application of 2% urea or liquid amino acid fertilizer two times at the winter dormancy stage and two times at the spring dormancy stage showed the best performance in tea plants among the other foliar N fertilization methods, as it reduced the soil fertilization levels in tea plantations without decreasing the total N concentration of the mature leaves or deteriorating the quality of spring tea. Therefore, foliar N application on tea plants at its dormancy stage increases the N concentration of the mature leaves, improves the quality and yield of spring tea, and could be a complementary strategy to reduce soil fertilization levels.

Application of Multi-Perspectives in Tea Breeding and the Main Directions

“…The decline of tea quality might relate to the soil environment, long-term application of organic fertilizer can improve the acid soil and the yield, quality and performance, while continuous application of chemical fertilizer will further worsen the soil and aggravate the acidity, which will hinder the growth of tea plants [ 176 ]. Research on tea plants has often focused attention towards the growing period, while foliar nitrogen application during the winter dormancy of tea plants improves the nitrogen content of mature leaves with the quality and yield of spring tea, while fertilizer dosage can be reduced [ 177 ]. The interaction between hormones and metabolites within the tea plants also influenced quality, as the expression of CsJAZ6 in tea plants inhibited the JA pathway, which regulated most secondary metabolites, notably catechins, and the interaction between CsJAZ6 and catechin biosynthesis regulators negatively regulated catechin accumulation [ 178 ].…”

Synergistic effects of nitrogen metabolites on auxin regulating plant growth and development

“…This leads to a theory that plant cells needed an availability sensor for . Local availability regulates the expression of nitrate assimilation genes ( Krapp et al., 2014 ), breaks seed dormancy ( Alboresi et al., 2005 ; Liu et al., 2021 ), controls leaf morphogenesis ( Yang et al., 2022 ), stimulates the formation and extension of lateral roots ( Forde and Walch-Liu, 2009 ; Chen et al., 2018 ; Contreras-López et al., 2022 ) and postpones flowering ( Yuan et al., 2016 ; Sanagi et al., 2021 ; Ye et al., 2021 ; Zhang S. et al., 2021 ). Lack of nitrate also affects tomato fruit yield and quality ( Belfry et al., 2017 ) and maize stem internodes development ( Peng et al., 2013 ).…”

Inorganic Nitrogen-Containing Aerosol Deposition Caused “Excessive Photosynthesis” of Herbs, Resulting in Increased Nitrogen Demand

“…However, these results usually came from experiments spraying or smearing the nitrogenous solution on the leaves of fruit trees or other crops, while the spraying of nitrogen fertilizer on leaves, known as foliar fertilization, is an important management method in agriculture [33], in which the effect of nitrogen application is more through infiltration than through penetration into the sub-pores [34]. The nitrogen concentration in PM 2.5 is usually represented by the unit µg/m 3 [35,36] (such as 13.9-14.7 µg m −3 in 2004-2005 from Hangzhou City, China) [37], which is much less than the application concentration in foliar fertilization that usually uses the unit g N [38,39] (such as leaves spraying 0.5-1 g N plant −1 week −1 in a foliar fertilization experiment) [40]. In addition, the amount of nitrogen penetrating through stomata and participating in the process of metabolism and circulation in plants is also much less than the amount of nitrogen applied for fertilization.…”