Abstract:The object was to explore precise management mode of water and nitrogen to tropical economic crop of young arabica coffee tree, using four levels of irrigation, WS (75%~85% field capacity), WH (65%~75% field capacity), WM (55%~65% field capacity) and WL (45%~55% field capacity), and four levels of nitrogen, NH (0.60g/kg), NM (0.40g/kg), NL(0.20g/kg) and NZ (0g/kg). The effect of irrigation and nitrogen on biochemical index and water and nitrogen use of arabica coffee young tree was studied. The result showed that, compared with WL, increasing irrigation amount reduced chlorophyll, carotenoid, malondialdehyde, proline and soluble sugar by 5.8%~15.5%, 6.0%~14.4%, 14.2%~30.3%, 27.6%~60.0% and 22.6%~57.5% respectively, and increased root activity and water use efficiency by 15.8%~63.8% and 21.6%~29.6%, and reduced the average value of soil NO-3-N by 21.5%~36.2%. Compared with NZ, increasing nitrogen rate reduced malondialdehyde by 23.8%~49.8%, while increased chlorophyll, carotenoid, proline, soluble sugar, root activity and water use efficiency by 49.0%~88.4%, 21.9%~60.9%, 509%~703%, 20.7%~52.3%, 23.5%~41.8% and 21.6%~53.9% respectively, and increased the average value of soil NO-3-N by 2.73~14.44 times. Total N uptake was positively correlated with irrigation amount under NZ and NL treatment, and water use efficiency and total N uptake increased at first and then decreased with irrigation amount under NM and NH treatment. Water use efficiency and total N uptake were quadratic curve relation with nitrogen rate under deferent irrigation treatment. Water use efficiency of NM/WH treatment was the largest, and N apparent recovery fraction and N uptake efficiency were the largest under NM and NH treatment. Thus combination of NM/WH was the efficient use of water and nitrogen of young arabica coffee tree.
