Comparison of SPAD-502 Plus and at LEAF+chlorophyll meters as diagnostic tools for nitrogen fertilizer management in irrigated lowland rice
2016
Ramos, M.A. | Tallada, J.G.
The SPAD-502 Plus (Soil Plant Analysis Development) and atLEAF+ are handheld portable electronic meters that measure the chlorophyll content of the leaves and hence, can guide in situ nitrogen (N) fertilizer management. The study was conducted in 2015 Wet Season to compare the atLEAF+ with SPAD-502 Plus values to determine the N rate requirement based on chlorophyll readings at critical growth stages. PSB Rc82 was used with six N treatments (TI-zero N fertilizer); T2-60 kg N/ha; T3-90 kg N/ha; T4-120 kg N/ha; T5- SPAD-502 Plus-based and T6- atLEAF+-based N requirement). The SPAD-502 Plus uses transmittance at 650 nm and 940 nm with flexible measuring head, while atLEAF+ uses 660 nm and 940 nm with fixed measuring head. Chlorophyll meter readings were gathered at weekly interval starting at early tillering until early flowering stage. Zero N treatment had the lowest SPAD-502 Plus and atLEAF+ readings while in other treatment SPAD-502 Plus and atLEAF+ responded to N applied. There was high correlation (r) between SPAD-502 Plus and atLEAF+ readings, with an r=0.917 at early tillering stage, r=0.993 at active tillering, r=0.998 at panicle initiation, r=0.999 at booting-heading stage. The pooled data across growth stages also showed high correlation (0.997). This indicates that atLEAF+ meter can be a good substitute for SPAD-502 Plus at a lesser cost. It can perform substantially well compared to SPAD-502 Plus. Thus, the atLEAF+ meter can be used as alternative chlorophyll meter in managing the N fertilizer of their rice crop.
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