PT  - JOURNAL ARTICLE
AU  - S. Poni
AU  - C. Intrieri
AU  - O. Silvestroni
TI  - Interactions of Leaf Age, Fruiting, and Exogenous Cytokinins in Sangiovese Grapevines Under Non-Irrigated Conditions. I. Gas Exchange
AID  - 10.5344/ajev.1994.45.1.71
DP  - 1994 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 71--78
VI  - 45
IP  - 1
4099  - http://www.ajevonline.org/content/45/1/71.short
4100  - http://www.ajevonline.org/content/45/1/71.full
SO  - Am J Enol Vitic.1994 Jan 01; 45
AB  - The interactions of leaf age and gas exchange, together with modifications induced by fruiting and exogenous kinetin treatments, were investigated in field-grown Sangiovese (Vitis vinifera L.) grapevines. Analyses carried out both on a seasonal basis and within each sampling date as a function of the natural gradient of age along the shoot showed that maximum Pn occurred at 30 to 35 days of age. A progressive decline started at about 50 days and four-month-old leaves retained 45% of maximum Pn. Very young, rapidly expanding leaves (< 15 days) also showed a consistently lower Pn and water use efficiency (WUE) than recently fully expanded leaves. Differential rates of leaf senescence due to fruiting or kinetin were not observed. These data form a basis for improving the physiological understanding of widely used vineyard management operations (shoot topping, leaf removal) which normally induce variations in canopy leaf age.