Comparing efficiency of different sampling schemes to estimate yield and quality parameters in fruit orchards

Different sampling schemes were tested to estimate yield (kg/tree), fruit firmness (kg) and the refractometric index (oBaumé) in a peach orchard. In contrast to simple random sampling (SRS), the use of auxiliary information (NDVI and apparent electrical conductivity, ECa) allowed sampling points to be stratified according to two or three classes (strata) within the plot. Sampling schemes were compared in terms of accuracy and efficiency. Stratification of samples improved efficiency compared to SRS. However, yield and quality parameters may require different sampling strategies. While yield was better estimated using stratified samples based on the ECa, fruit quality (firmness and oBaumé) showed better results when stratifying by NDVI.