Using ndvi from a modified digital camera to estimate potato crop cover under different conditions of nitrogen fertilization

Abstract

The fraction of the ground covered by a crop (CC) determines both interception of solar radiation and the size of the transpiration apparatus. Besides, the availability of nitrogen (N) in the potato crop (Solanum tuberosum L.) affects the yield and the quality of tubers. Digital procedures for estimating CC in potato from conventional and modified cameras to calculate Normalized Difference Vegetation Index (NDVI) were developed and evaluated under different conditions of nitrogen fertilization in potato commercial fields during the late growing season of 2012 and 2013. In 2012, the CC and the yield of a sector that received no fertilizer at planting were compared to the commercial treatment, while in 2013 four treatments with different doses of N were considered. Both cameras, as well as the procedures for estimating CC, rendered appropriate results to indicate significant differences in CC related to fertilization status in 2012. While the lower fertilization in 2012 produced an early decrease of CC at the end of the growing season reducing both productivity and commercial quality of tubers, in 2013 the CC and yield differences between treatments were less significant.