Dynamic changes of nutrition in litchi foliar and effects of potassium–nitrogen fertilization ratio

Abstract

Field experiments were conducted to determine the annual dynamic changes of element contents in litchi leaves and the effects of the potassium and nitrogen ratio (K 2 O/N ratios: 0.6, 0.8, 1.0, 1.2, and 1.4) on the yield and planting benefits of litchi. The cultivar ‘Feizixiao’ litchi planted in a typical acidic upland orchard was used as a subject. The following results were obtained. (1) The elemental contents of litchi leaves significantly varied during the different developmental stages. Throughout the developmental period, the elemental contents in litchi leaves were in the descending order of N > K > Ca > Mg > P > S > B > Zn > Mo. The K content showed a highly significant negative correlation with the Ca and Mg contents and significant negative correlation with the Zn content. The Ca, Mg, and Zn contents exhibited significantly positive correlation with each other. The N content was significantly negatively correlated with the S and B contents in leaves, and the S and B contents showed significant positive correlation with each other. The P content exhibited significant negative correlation with Ca and Si, whereas Ca and Si were significantly positively correlated with each other. (2) Under the same N application conditions, the yield and planting benefits of litchi initially increased and then subsequently decreased with increasing K 2 O/N ratio. litchi had the highest yield and plant benefit when the ratio of K 2 O to N ranged from 1.0 to 1.2. Thus, this ratio is recommended for the main litchi production areas in China.