Effects of carbon, nitrogen, phosphorus, and potassium on flowering and Fruiting of Glycyrrhiza uralensis

Carbon (C), nitrogen (N), phosphorus (P), and potassium (K) play an important role in flower bud differentiation and seed-filling; however, the effects of these elements on the flowering and fruiting of Glycyrrhiza uralensis Fisch. are not known. In this study, we evaluated the differences in the C, N, P, and K levels between the fruiting and nonfruiting plants of G. uralensis at different growth stages. The correlations between the elements C, N, P, and K and the flower and fruit falling rates, rate of empty seeds, rate of shrunken grains, and thousand kernel weight (TKW) were also determined. The results show that the P and K levels and C:N, P:N, and K:N ratios of flowering plants are significantly higher than those of nonflowering plants; N level of flowering plants is significantly lower than that of nonflowering plants at the flower bud differentiation stage. The number of inflorescences was positively correlated with C and K levels and C:N and K:N ratios. A low level of C, P, and K and high level of N in flowering and pod setting stage may lead to the flower and fruit drop of G. uralensis. The K level is significantly negatively correlated with the rates of empty and shrunken seeds. The N level is significantly positively correlated with TKW. Thus, high levels of C, P, and K might be beneficial to flower bud differentiation, while higher levels of N is not beneficial to the flower bud formation of G. uralensis. Higher levels of N and K at the filling stage were beneficial to the seed setting and seed-filling of G. uralensis.HighlightHigh levels of C, P, and K might be beneficial to flower bud differentiation, while higher levels of N is not beneficial to the flower bud formation of G. uralensis. Higher levels of N and K at the filling stage were beneficial to the seed setting and seed-filling of G. uralensis.