Estimating the conditions of sunflower crop using NDVI and Vegetation Coverage Temperature (VCT) in the Semiarid Region of La Pampa in Argentina

 The factors that determine the success of the crop is water content in the soil profile explored by the roots, where soil and management condition affect the storage and availability. Because of the sites defined by the altimetry and crops predecessors affect the behavior of water content stored in the soil available for plants.  The aim of this work was to analyze the relationship between different vegetation parameters such as growth rate estimated from Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI)) and the vegetation coverage temperature (VCT) in sites delimited by altimetry and different crops predecessors. As a hypothesis, the rate of crop growth estimated from NDVI is related to the differences between sites by water useful and altimetry.  The experience was carried out during the agricultural season 2010-2011 in a field with sunflower crop located just east of La Pampa. The crops predecessors were soybeans and corn crop (half of lot). During the planting and flowering was measured water useful up to a depth of 3.2 m. We analyzed the rate of growth of the crop, with this purpose was used information of NDVI obtained from satellite imagery LANDSAT TM and was detected water stress through measurements of VCT using a portable sensor that measured in the thermal portion.  The results showed a high rate of growth of the crop in sites where the predecessor was corn crop, due to a higher water content in the soil 233 mm for sites of low height in the field and 216 mm for sites with high altimetry in the field. In sites where the predecessor is a soybean crop growth rates were lower than the observed, coinciding with a lower content of water of soil (164 and 127 mm for sites high and low respectively). The water content in the soil in flowering will be significantly reduced to values situated between 10 and 60 mm for of low height and high altimetry in the field. This weaknesses in the water status of the soil was corroborated with measurements of VCT where an inverse relationship was found with the LAI (0.56) and with the water content (0.62), suggesting that this variable is an indicator of the water deficit of the crop.  In the conclusions, there is evidence that the use of technologies, such as offers satellite image and VCT provide information about the condition of the crop, which is viable for determinations of water stress.  In regions where water is the main limiting factor, the use and knowledge of the environments determined by altimetry and managements conditions allows be efficient in the production of sunflowers. Key word: Satellite imageNDVIVegetation Coverage Temperature Sunflower