Estimation of Sugarcane Yield Potential Using Normalized Difference Vegetative Index.

Estimating crop yield using remote sensing techniques has proven to be successful in many crops.  However, sugarcane possesses unique characteristics; such as, a multi-year cropping cycle and plant height-limiting for midseason fertilizer application timing.  This more dynamic estimation of yield could help producers develop more robust N management scheme for in-season fertilization.  The objective of this study was to determine if sugarcane yield potential could be estimated using early season normalized difference vegetative index.  The experiment was conducted over five site years from 2008 to 2010 in southern Louisiana.  The study was evaluated on trials that received various amounts of fertilizer N over four different varieties, HoCP 96-540, LCP 85-384, L01-283, and L99-226.  Sensor readings were taken using the GreenSeeker® handheld sensor for each trial.  In-season estimates of yield (INSEY) values were calculated by dividing NDVI by growing degree days (GDD), where 64.4°F was used at baseline temperature.  Optimum time for predicting sugarcane yield using an INSEY value was obtained between 650-750 GDD.  Both prior to and after this range resulted in weaker relationships.  Generally, INSEY value had a positive exponential relationship with yield; however, predictability of sugarcane across all varieties was low (r² values 0.23 and 0.18 for cane yield and sugar yield, respectively).  An increase in the ability of INSEY to predict sugarcane yield was obtained when varieties were grouped based on canopy structure (r² values 0.31 and 0.23 for cane yield and sugar yield, respectively).  Using an INSEY value for predicting sugarcane yield shows potential of being a valuable management tool for sugarcane producers in Louisiana.