"Wheat yield prediction by using an active sensor

1

• "Wheat yield prediction by using an active sensor
  
• in the Northern Argentinean Pampas."

Ricardo Melchiori1, Octavio Caviglia1, Agustín
Bianchini2, Nelson Faccendini3, Susana
Albarenque3 and William Raun4 1INTA EEA Paraná,
Argentina 2AAPRESID, 3FCA-Univ. Nac. de ER,
4Oklahoma State University. rmelchiori_at_parana.in
ta.gov.ar
Objectives

• To correlate NDVI readings with spring wheat
  grain yield .
• To evaluate cultivar and water availability
  effects on NDVI and grain yield .

Materials and methods
Results

• Three experiments (E) were conducted during 2005
  in Paraná, Argentina. (31.5ºS).
• E1 included three N levels (0 88 and 166 kg N
  ha-1) applied early in the season (at three
  leaves, Zadocks 13) and an additional treatment
  was set to test the SBNRC at visible first node
  (Zadocks 31) on the plots where 88 kg N ha-1 was
  applied.
• E2 was conducted to evaluate the SBNRC at Zadocks
  31 with no N applied at planting.
• E3 included two N levels (0 and 120 kg N ha-1)
  three water availability levels (full irrigation,
  irrigation during vegetative period only, and
  irrigation during grain filling only) and three
  short season and three full season wheat
  cultivars.
• Normalized difference vegetative index (NDVI)
  measurements were taken using a Green Seeker
  Sensor (NTech Industries, Inc., CA, USA) during
  de season. At maturity, grain yield, and N
  concentration in grain were recorded. Nitrogen
  use efficiency (NUE) of N applied was calculated
  as grain yield / N applied.

Green Seeker NDVI readings at Zadocks 31 were a
good tool to predict wheat yield (r2gt0,80). In E1
a great biomass and yield variability was
detected and sensor based variable rate N
management (SBNRC) improved NUE. NDVI response
index and grain yield response index were
significantly (plt0.05) correlated (r2 0,46). In
E2, the SBNRC was useful to predict crop yield N
needs and grain yield response. Wheat yields
obtained with the SBNRC, irrespective of N rate
at planting, were similar to crop yield of the
reference plots (166 kg N ha-1). In E3, the
effect of water availability was more important
on NDVI than on grain yield. Different NDVI and
grain yield relationships were obtained for short
and full season spring wheat cultivars. Results
showed that sensor-based N prescription tools are
promissory to improve NUE. Additional extensive
on-farm studies will be conducted in the future.
Figure 2. Relationship between NDVI (Green
Seeker) at first visible node (GS 31) and wheat
yield in short and full season wheat cultivars
Figure 1. Relationship between NDVI (Green
Seeker) at first visible node (GS 31) and wheat
yield
Conclusions Sensor based diagnostic tool, can
help to predict wheat yield, calculate N
fertilization rates and to improve nitrogen use
efficiency.
Figure 3. Water availability effects on NDVI vs
yield relationships.
Acknowledgments This work was possible by the
financial support from PASA FERTILIZANTES