Interactions between Superabsorbent Polymers and Nitrogen on Growth and Water Use of Arabica Coffee
The production arabica coffee is frequently restricted by seasonal drought and soil undernutrition. The objectives of this study was to explore the optimal mode of water-saving, drought resistance and efficient use of water and fertilizer of arabica coffee. Using 3 levels of superabsorbent polymers(SAP) and 3 levels of nitrogen, the complete design experiments were conducted and effects of SAP and nitrogen nutrition on growth and water use of arabica coffee seedling were studied. Results showed that the growth(plant height, stem diameter and leaf area) and dry mass accumulation of arabica coffee seedling was the largest under low level of SAP and nitrogen. Compared to control(no nitrogen treatment), low level of nitrogen increased dry mass accumulation by 24.10%, while high level of nitrogen reduced it by 11.95%. In contrast to no SAP treatment, middle level of SAP increased dry mass accumulation by 11.53%, while high level of SAP reduced it by 8.65%. In addition, application of nitrogen and SAP reduced daily evapotranspiration but increased water use efficiency. Nitrogen and SAP increased water use efficiency by 2.72%-35.37% and 8.48%-20.24%, respectively. Arabica coffee nitrogen accumulation first increased and then decreased with the increase of nitrogen rate. Inhibitory effects of excessive application of nitrogen and SAP was obvious, and higher dry mass accumulation and water use efficiency could be obtained by combination of low level of nitrogen and SAP simultaneously.