EFFECT OF ENHANCED PANICLE FERTILIZATION ON NITROGEN USE EFFICIENCY TRAITS OF RICE (ORYZA SATIVA) WITH DIFFERENT PLANTING PATTERNS

To evaluate the nitrogen (N) use efficiency of rice plants applied with enhanced panicle N fertilization (PN) on different planting patterns, field experiments were carried out with 5 nitrogen managements (two PN levels combined with two total N levels, and check, CK) under transplanting (TP) and direct seeded (DS). Our result showed that nitrogen use efficiency traits of physiological efficiency (PE), nitrogen use efficiency for grain (NUEg), and recovery efficiency (RE) of DS rice were decreased compared with TP rice, and total nitrogen accumulation (TN+N) were kept consistent between TP and DS. However, PN x PT interaction effect was significant in partial factor productive of applied N (PEP), agronomic efficiency (AE), nitrogen harvest index (NHI) and nitrogen translocation rate (NTR). High PN improved the AE value in DS system, but showed little effect in TP system. Oppositely, high PN decreased the PEP in TP system, while showed little effect in DS rice. The results indicated that improved PN applied in the TP system might affect the farmer's benefits without improving plant nitrogen utilization. For DS rice, though PEP was not significantly improved, but the N utilization efficiency of fertilizer uptake was enhanced. Furthermore, PE, AE, PEP, and NUEg, which were related to the performance of yield production, were significantly correlated with each other with P value <0.01. RE was correlated with all traits but NTR and NUEg with P value <0.01. NTR was correlated with NHI and NUEg with P < 0.01. Results showed that NUEg was significantly correlated with PE, AE, PEP, and NTR. Considering most of the agronomic practice was carried out without zero N control, NUEg might be a practical option for farmers to evaluate the plant N fertilizer physiological use efficiency when soil texture is similar.