Kaolin,Ascophyllum nodosumand salicylic acid mitigate effects of summer stress improving hazelnut quality

BACKGROUND Various strategies are needed to mitigate the negative impact on or to increase 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 content of some individual phenolics, 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. CONCLUSIONS The application of K, An and SA improved the hazelnut tree response to climate change, without compromising the hazelnut chemical and sensorial quality. Furthermore, due to the similar observations for the same treatments with and without irrigation, it can be stated that K, An and SA can be efficient and cost-effective tools to mitigate summer stress in rain-fed orchards. (c) 2020 Society of Chemical Industry

Automated summary

The study in a commercial orchard in Portugal examined the effects of spraying kaolin, Ascophyllum nodosum, and salicylic acid on hazelnut quality and sensorial attributes, finding positive impacts on biometric parameters, vitamin E level, antioxidant activity, and various phenolics content. Hazelnut physical properties, chemical and phytochemical composition, and antioxidant activities were all positively correlated. The application of these substances improved hazelnut tree response to climate change, and could be cost-effective tools to mitigate summer stress in rain-fed orchards.