Resumen de Comparison of cold hardiness in the leaves of various grape cultivars based on photochemical reflectance index

Lulong Sun, Wei Song, QIingwei Geng, Yuanpeng Du, Heng Zhai, Weishuai Qin

• We compared cold hardiness with the leaves of 12 grape cultivars, including two of wild species, two of Vitis vinifera × Vitis labrusca, three INCs (interspecific crosses) and five Vitis vinifera L. cultivars using PRI-T curves and analysis of variance (ANOVA). The photochemical reflectance index (PRI) of most grape leaves decreased linearly when frozen progressively in darkness. The PRI of diploid cultivars and blanc cultivars at the standard temperature (PRI 4 °C) remained relatively steady during exposure to successively lower temperatures (0, -2, -4 and -6 °C) compared with the polyploid and the red cvs. representing a boundary dividing grape cultivars into tolerant and vulnerable. According to this principle, the cold hardiness of the four species was ranked Vitis vinifera L. > INCs = wild species > Vitis vinifera × Vitis labrusca. RPRI((PRI-PRIcontrol)/PRIcontrol) was introduced to divided the cold hardiness of 12 cultivars into three classes. Resistant: RPRI > 0; Tolerant: RPRI trended to 0; Vulnerable: RPRI < 0. We also observed seasonal differences in the cold hardiness of the cultivars; grape leaves were more vulnerable to cold in fall than in spring.