Regulation of photosynthesis through source: sink imbalance in citrus is mediated by carbohydrate content in leaves

• DOI: 10.1034/j.1399-3054.2002.1160416.x
• Publication Date: 2003-03-12T18:33:36Z
• Authors: Domingo J. Iglesias; Ignacio Lliso; Francisco R. Tadeo; Manuel Talon
• Keywords: Girdling; Sink (geography); Limiting

In citrus, the occurrence of a sink effect on photosynthesis (A) is controversial. Leaf carbohydrates and photosynthetic rates in field‐grown trees Satsuma mandarin ( Citrus unshiu [Mak.] Marc.) cv. Okitsu, were measured to elucidate whether or not demand for photoassimilates regulates A. The data indicated that source‐sink imbalances induced by different treatments altered both soluble (sucrose, glucose fructose) insoluble leaves, as well rates. general, girdling defruiting increased starch reduced photosynthesis, whereas source‐limiting conditions imposed through partial defoliations had opposite effect. These results are compatible with assumption lack activity leads carbohydrate accumulation feedback inhibition A, vice versa. Further evidence supporting A was provided measurements dry matter:leaf area ratio, since defoliations, example, this ratio. vivo sucrose supplementation plants source:sink ratios (control, defoliated, girdled defruited plants) photosynthesis. This suggests sugars may have, per se, potential repress intact active sinks. Based these we propose sugar citrus leaves causes