| To explore the use of peanut leaf SPAD value to estimate nitrogen status of peanuts in real-time and non-destructive diagnosis for guiding nitrogen fertilization of peanut, we preset the third leaf SPAD value after peanut emergence at 30, 45, 60, 75 d, and 90 d，and designed SPAD corresponding N fertilization for days of 30~33, 38~41, 42~45, 44~47 d, and 43~46 d. There was 3 designs as SN-1, SN-2, and SN-3. We also studied the effect of different nitrogen management programs on peanut nitrogen fixation, nitrogen use efficiency, and its yield. The results showed that, SN-3 threshold was set too high so it was not conducive to the peanut growth. The SN-1 and SN-2 were more optimal and promoted peanut N-fixation nodule growth, improved N efficiency and peanut yield. Comparing with the conventional fertilization, the SPAD threshold for SN-1 design was the best and resulted in 17.65% and 4.35% increases in single nodule volume and weight of peanut root, respectively and 19.36% and 3.99% increase in N use efficiency and N agronomic use efficiency, 12.95% increase in peanut yield. Therefore, the preset SPAD value for SN-1 can be used as N management guidance at each growth stage of peanut production in the region. |