Optimizing drip fertigation at different periods to improve yield, volatile compounds and cup quality of Arabica coffee

How to improve and regulate coffee bean yield and quality through split fertilization in the whole life cycle of coffee is still unclear and deserves further study. A field experiment of 5-year-old Arabica coffee trees was conducted for 2 consecutive years from 2020 to 2022. The fertilizer (750 kg ha(-1) year(-1), N-P(2)O(5)-K(2)O:20%-20%-20%) was split in three times at early flowering (FL), the berry expansion (BE), and the berry ripening (BR). Taking equal fertilization throughout the growth cycle (FL(250)BE(250)BR(250)) as the control check, variable fertilizations including FL(150)BE(250)BR(350), FL(150)BE(350)BR(250), FL(250)BE(150)BR(350), FL(250)BE(350)BR(150), FL(350)BE(150)BR(250), and FL(350)BE(250)BR(150). Leaf net photosynthetic rate (A (net)), stomatal conductance (g (s)), transpiration rate (T (r)), leaf water use efficiency (LWUE), carboxylation efficiency (CE), partial factor productivity of fertilizer (PFP), bean yield, crop water use efficiency (WUE), bean nutrients, volatile compounds and cup quality, and the correlation of nutrients with volatile compounds and cup quality was evaluated. FL(350)BE(250)BR(150) had the maximum A (net) and g (s), followed by FL(250)BE(350)BR(150). The highest dry bean yield and WUE were obtained from FL(250)BE(350)BR(150), which increased by 8.86% and 8.47% compared with FL(250)BE(250)BR(250) in two-year average. The ash, total sugar, fat, protein, caffeine and chlorogenic acid in FL(250)BE(350)BR(150) were 6.47%, 9.48%, 3.60%, 14.02%, 4.85% and 15.42% higher than FL(250)BE(250)BR(250). Cluster analysis indicated FL(150)BE(350)BR(250), FL(250)BE(350)BR(150), FL(350)BE(150)BR(250) and FL(350)BE(250)BR(150) under medium roasted degree increased pyrazines, esters, ketones and furans, FL(150)BE(350)BR(250) and FL(250)BE(350)BR(150) under dark roasted degree increased ketones and furans. The aroma, flavor, acidity and overall score of medium roasted coffee were higher than dark roasted coffee, while the body score of dark roasted coffee was higher than medium roasted coffee. The nutrient contents were correlated with the volatile compounds and cup quality. TOPSIS indicated that FL(250)BE(350)BR(150) was the optimal fertilization mode in the xerothermic regions. The obtained optimum fertilization mode can provide a scientific basis for coffee fertilization optimization and management.