Studies on the leaf epidermal structure of columnar apple and dwarf pear seedlings in vitro
LIANG Mei-xia1,2,GE Hong-juan2,DAI Hong-yi2 (1College of Horticulture and Landscape,Hunan Agricultural University,Changsha,Hunan 410128 China; 2College of Landscape and Horticulture,Qingdao Agricultural University,Qingdao,Shandong 266109 China)
Plantlets generated in vitro from 3 apple cultivars with columnar tree type including Telamon,Lujia No. 5 and Lujia No. 6 and 3 cultivars with standard tree type including Fuji,Lujia No. 2 and Lujia No.3 and dwarfing and vigorous hybrid pear seedlings were used for studying their leaf epidermal structure characteristics using scanning electronic microscope (SEM). The results showed that the upper leaf epidermal cells of both apple and pear plantlets were usually irregular polygons and were arrayed in different directions. There were no stomata on their upper epidermis. The densities of upper epidermal cells of columnar apple and dwarf pear plantlets were obviously higher than those of standard type respectively. The average densities of upper epidermal cells were 2 986·mm-2 and 2 087·mm-2 for columnar and standard apple plantlets respectively and 2 633·mm-2 and 1 635·mm-2 for dwarf and standard pear plantlets respectively. There were lots of stomata distributed on the leaf lower epidermis of apple and pear. The type of stomata was mainly anomocytic. The average length and width of stomata of columnar and standard apples plantlets were 23.21 μm×19.58 μm and 24.17 μm×22.96 μm respectively. The average densities of stomata of columnar and standard apple plantlets were 401.17·mm-2 and 262.50·mm-2 respectively. The average length and width of stomata of dwarfing and standard pear plantlets were 29.57 μm×20.30 μm and 26.93 μm×24.51 μm re-spectively. The average densities of stomata of dwarfing and standard pear plantlets were 265.67·mm-2 and158.00·mm-2 re-spectively. There was no obvious difference at the length of stomata between two kinds of apple and pear plantlets. But the width of stomata of columnar apple and dwarf pear plantlets were obviously shorter than those of standard types. The stomata densities of columnar apple and dwarf pear plantlets were obviously higher than those of standard types.