Scientific Study

Background: Difference strategies are needed to mitigate the negative impact or to increment fruit quality. The effect of spraying Kaolin (K), Ascophyllum nodosum (An) and Salicylic acid (SA), in trees with and without irrigation, on quality and sensorial attributes of hazelnut (Grada de Viseu cultivar) was investigated during two consecutive years (2016 and 2017) in a commercial orchard located in Moimenta da Beira, Portugal. Results: The treatments affected positively the biometric parameters, nut and kernel, weight, length, width, thickness and volume as well as the vitamin E level, antioxidant activity and some individual phenolic content, such as protocatechuic acid, gallocatechin, catechin and epicatechin. The levels of amino acids in hazelnut kernels decreased in all the assayed treatments, while the kernel colour and sensorial attributes were not affected by the treatments. Hazelnut physical properties (nut and kernels), chemical and phytochemical composition and antioxidant activities were positively related. Conclusion: The application of K, An and SA improve the hazelnut tree response to the climate change, without compromising the hazelnut chemical and sensorial quality. Furthermore, due to the similar observations on the same treatments with and without irrigation, it can be stated that K, An and SA can be effective and cost-effective tools to mitigate summer stress in rainfed orchards.