Evaluation of ‘Esterhazy II’ Persian walnut (Juglans regia L.) genotypes from Hungary, Austria, and Switzerland

Abstract The historic Persian walnut genotype, known as ‘Esterhazy II’ and derived from Hungary, is well-known in the German-speaking countries; however, there are only a few specimens showing significant variability in traits in its native country. In this current study, the aim was to evaluate our genotype, labelled ‘Esterhazy II’, which is planted in the ex-situ gene bank of the Hungarian University of Agriculture and Life Sciences, and compare it to other true-to-type ones. During the examination, the SSR analysis confirmed that the Hungarian ‘Esterhazy II’ is exactly identical to the true-to-type Austrian and Swiss varieties. The Austrian and the Swiss ‘Esterhazy II’ differed significantly in nut height from the control ‘Chandler’. There was no further significant difference in the nut parameters. All Esterhazy genotypes, except ‘Esterhazy II’ from Hungary, as well as ‘Milotai 10’, ‘Chandler’, were significantly different from ‘Alsószentiváni 117’ and ‘Tiszacsécsi 83’ in shell thickness. The Hungarian ‘Esterhazy II’ reached the heaviest dried nut weight; there wasn’t any significant difference in this parameter among the study's varieties. The Swiss ‘Esterhazy II’ and ‘Esterhazy kesei’ had the heaviest kernel weight. Kernel weight of the Austrian ‘Esterhazy II’ differed from the Swiss ‘Esterhazy II’ and ‘Esterhazy kesei’. The Austrian ‘Esterhazy II’ had a significantly smaller cracking rate compared to Swiss ‘Esterhazy II’, ‘Alsószentiváni 117’, and ‘Tiszacsécsi 83’ and a higher rate of halves compared to ‘Esterhazy kesei’ and ‘Alsószentiváni 117’.