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Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a catastrophic disease that threatens the global kiwifruit industry. As yet, no cure has been developed. Planting resistant cultivars is considered as one of the most effective ways to control Psa. However, most existing cultivars lack Psa‐resistance genes. Wild Actinidia resources contain rich genetic diversity and may have powerful disease‐resistance genes under long‐term natural selection, but lack of knowledge about the resistance to Psa for most Actinidia species results in some excellent wild resistant genotypes being underutilized. In this study, the response to Psa of 104 wild genotypes of 30 Actinidia species (including 37 taxa) was tested with an in vitro bioassay, and a considerable number of individuals from different species with tolerance or high resistance to Psa were identified. The results showed high consistency between years. This is the first large‐scale evaluation of diverse Actinidia species with resistance to Psa through an in vitro bioassay. The resistant genotypes of A. chinensis identified could be used in future kiwifruit improvement programmes. The findings should help provide an understanding of the resistance to Psa. [ABSTRACT FROM AUTHOR]

[Objective]Photosynthetic characteristic comparison of 'Hongyang' kiwifruit grafted with four different rootstocks was conducted to provide references for selecting suitable rootstock for 'Hongyang' kiwifruit. [Method] The light response curve and diurnal variation of photosynthetic physiological parameters of two-year-old 'Hongyang' kiwifruit grafted with four different rootstocks (Actinidia latifolia, A. guilinensis, A. longicarpa and A. chinensis) were measured by using Li-6400 portable photosynthesis system. The non-rectangular hyperbolic model was adopted to fit the light response curve. [Result] The results of light response curve measurement indicated that the photosynthetic characteristics of 'Hongyang' kiwifruit grafted with four rootstocks showed obvious variations. The variations of maximum net photosynthetic rate (Pmax), apparent photosynthetic quantum yield (AQY), light saturation point (LSP) and light compensation point (LCP) were 17.6853-24.8340 μmol/m2 ·s, 0.0465-0.0538 μmol/m2 ·s, 433.60-494.79 μmol/m2 · s and 33.19-61.79 (μmol/m2 ·s, respectively. The Pmax, AQY and LSP in 'Hongyang' kiwifruit grated with rootstock of Actinidia longicarpa were all the highest. The results of diurnal variation of photosynthesis measurement showed that the diurnal variation of net photosynthetic rate (Pn) in 'Hongyang' kiwifruit was a double-peak model. and the first photosynthetic peaked at about 9:30 a.m. The midday depression of photosynthesis appeared at 13:00-14: 00, and it was because of the stomatal closure caused by high temperature and the decrease of air humidity. The Pn, water use efficiency (WIE), light use efficiency (LLE) and carboxylation efficiency (CE) in 'Hongyang' kiwifruit grafted with rootstock of A. longicarpa were all the highest compared with those grafted with other three root-stocks. [Conclusion] Based on the performances of photosynthetic characteristics, A. longicarpa may be the best for 'Hongyang' kiwifruit among the four rootstocks tested. [ABSTRACT FROM AUTHOR]