Effects of N fertilization levels on ammonia volatilization from rice shoot at later growth stages.
施氮水平对水稻生育后期地上部氨挥发的影响

With simulated pot culture in greenhouse, the ammonia volatilization from rice shoot and its affecting factors after flowering was studied under different N fertilization levels. The results showed that the daily and total amount of volatilized ammonia increased with increasing N application rate, with a certain variance among different N levels observed. At flowering and maturing stages; the ammonia volatilization from rice shoot (y) had significant negative correlations with functional leaf GS activity (x1) and positive correlations with functional leaf apoplastic NH4+ concentration (x2), with y = -0.37846x1 + 0.41821x2 + 0.04925 (R2 = 0.9471, n = 16), and negative correlations with N harvest index (x1) and physiological N use efficiency (x2), following y = -0.02117x1 + 0.75186 (R2 = 0.842, n = 8) and y = -1.10386x2 + 35.52676 (R2 = 0.8489, n = 8), respectively. It was suggested that the increasing ammonia volatilization from rice shoot under high N fertilization level was correlated with the decrease of N use efficiency by rice.