Studies On The Relationship Between Anatomic Structure And Cold Resistance Of Different Pear Cultivars In Yanbian Area

Anatomical studies of the four different pear cultivars including'Pingguoli','Nanguoli'and'Xiaoxiangshui'and Pyrus ussuriensis Maxim in Yanbian area was carried out to discuss the relationship between the structures and cold resistance by beans of paraffin method, free hand section, wood maceration, epidermis maceration, coupled with microscopic photography.It has been found that there are some differences between the anatomic structures of the different cold resistance cultivars. The structures of the'Pingguoli'and'Nanguoli'which are less cold resistance are as follows: the size of the leaf stomata is larger, while the thickness of the upper epidermal cell is smaller, and the pattern of the anticlinal wall of the lower epidermal cell is straight, light sinuate. The main vein of leaf has larger diameter. There exist fewer fibers and loosely arranged radial pore chains, fewer tangential multiple pores and pore clusters in petiole with lower pore density and even diameter. The vessel of the main vein and the early wood is larger in diameter, with larger pits on the walls. The least cold resistance cultivar'Pingguoli'also shows some characters: the leaf has the largest spongy tissue thickness, lowest CTR (cell tense ratio of the leaves), highest SR (spongy ratio of leaves).The vessel in late wood has smaller diameter, and the length and width of the ray is smallest.'Xiaoxiangshui'and Pyrus ussuriensis Maxim which are high cold resistance generally show the contrary characters: the size of the stomata is smaller and the thickness of the upper epidermal cell is larger, and the style of the lower epidermal cell wall is deep sinuate, light sinuate. The main vein of leaf has smaller diameter. There are well-developed fibers outside of the vascular bundle and closely arranged radial pore chains and more tangential multiple pores and pore clusters in petioles, with higher pore density and uneven diameter. The vessels of the main vein and the early wood are relatively smaller in diameter, with smaller pits on the walls. In addition, Pyrus ussuriensis Maxim also shows some characters: the thinnest spongy tissue, the smallest vessel diameter in the petiole and late wood.Experimental results and statistics show that pear cultivars with higher cold resistance possess smaller diameter of the pore and smaller pits, closer arrangement, higher density and more radial pore chains, tangential multiple pores, pore clusters.Pear cultivars with less cold resistance have vessels with larger diameter and the larger pits on the vessel walls, lower density, loosely arranged radial pore chains and less tangential multiple pores and the pore clusters .The depth of anticlinal wall of the lower epidermal cell increases as the cold resistance increasing, while size of the stomata and the spongy tissue and generally are negatively correlated with the cold resistance of the cultivars. As cold resistance increasing, fibers in petiole tend to be well-developed, with main vein tending to be"smaller".This study is aimed to help identify cold-resistance characteristics of pear cultivars and to select the cold-resistance cultivars, provide the structural basis for the identification, and provide the necessary anatomical reference for the cold-resistance mechanism of fruit trees.