The anatomical structure character of raspberry stems is a key factor affecting its cold resistance

Red raspberries (Rubus idaeus L.) are economically important fruits, being highly valued for their taste and medicinal properties. However, low temperature is one of the important limiting factors for crop growth, raspberries must be kept in the soil from coldness to ensure their survival during overwintering in most areas of China. To explore the difference of cold resistance among different species, 2 wild red raspberry species and 3 cultivated species were used as the test materials in this experiment, the anatomical structure and physiological indices were analyzed comprehensively. Stem issues were dyed by Safranine and Fast Green and made in paraffin section. The experiment showed that all cold resistance physiological indices of wild raspberry species was significantly better than that of the cultivars. In terms of anatomical structure, wild varieties have higher phloem ratio, phloem fiber layers, larger diameter vessels, lower pith ratio and pith cell damage rate compared to cultivated species. According to the comprehensive analysis of the membership function, the cold resistance of the wild species is better than that of the cultivated species. Synthesizing the correlation among the anatomical structure indices, the phloem ratio in the anatomical structure of the 1-year-old stem of raspberry has a significant correlation with almost indicators, which can be used as a crucial anatomical factor that affects the cold resistance of the stem of red raspberry.