Partitioning patterns of photosynthates from different shoot types in 'Nijisseiki' pear (Pyrus pyrifolia Nakai)

• Published in: The journal of horticultural science & biotechnology Vol. 77; no. 6; pp. 758 - 765
• Main Authors: Teng, Yuanwen, Tamura, Fumio, Tamura, Kenji, Nakai, Teruo
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 2002
• ISSN: 1462-0316; 2380-4084
• DOI: 10.1080/14620316.2002.11511569

Partitioning patterns of photosynthates from different shoot types on 16 year old 'Nijisseiki' pears were investigated 1, 2, 4, 7 and 13 weeks after anthesis (WAA). When leaves were at 45% of final expansion at 1 WAA, net leaf photosynthetic rate reached about two-thirds of its maximum value. One WAA, unfolded leaves could export photosynthates, although most photosynthates remained in source leaves, regardless of shoot type. The proportion of fruiting-spur-leaf-derived photosynthates entering fruit increased from 13±14% at 1 WAA to 50-65% at 13 WAA. In contrast, bourse leaves contributed only 1.1-1.8% of photosynthates to fruitlets 1 WAA. By 13 WAA this value increased to more than 21%. Nonfruiting spurs could export photosynthates to fruit on an adjacent spur as early as 1 WAA; this was accelerated by removing the fruiting spur leaves. From 2 WAA, nonfruiting spurs showed an apparent export of photosynthates out of the spur complex. The fruiting-spur-leaf-derived photosynthates were exported out of the spur complex after 4 WAA. No export of bourse-derived photosynthates out of the spur complex was found from 1 to 7 WAA, except some export at 2 WAA. By 13 WAA, both spur and bourse leaves exported photosynthates out of the spur complex. The extension-shoot-derived photosynthates might play a complementary role in the growth of fruit on spurs with few leaf numbers. Competition for current photosynthates between bourse shoots and fruit during the early developmental stage of fruit was not recognized.