Photosynthesis and breeding of the vine

Photosynthesis of a plant is the process that allows a plant to absorb the nutrients necessary for its growth.
The leaves, where the process takes place, receive sunlight. Through the stomata in the lower part of the leaf, store carbon dioxide; From the stem crude sap with water. In the reaction of these factors combine to give sap with nutrients (sugars, including sucrose) and oxygen.

Greater efficiency in photosynthesis is had for the leaves in the apex zone, in the upper part where there is more sunlight intercepted. In the lower part, the foliage is wider, and this only partially offsets the reduced brightness that affects the leaves.

Intervenes in determining the efficiency, the duration of the presence of light and shadow on the upper and lower surface of the leaves; It affects the wind between the foliage and the position of the leaves in the foliage: in fact the layer of outer leaves intercept 70-80% of photosynthesis.

The temperature promotes photosynthesis in principle. At temperatures of between 15-30 ° C there is a positive linear correlation between temperature and photosynthesis, between 30-45 ° C on the contrary it has negative correlation. Optimum temperature for photosynthesis between 22-27 ° C. Recent studies The critical temperature is 47 ° C photosynthesis stops, and show how free and hybrid species are more resistant to temperature than the cultivars.

Influence on the photosynthetic capacity is also in relation to the disposal of the foliage in the east-west direction. The part of the crown facing east presents substantial differences in photosynthetic performance than westward.

About photosynthesis in grapevine breeding and you need to balance the growth of the crown, with the special conditions of the terroir, such as orientation of the rows, row spacing and between the vines, type of farming, soil type, temperature conditions. It 'important to set up immediately a proper system for breeding, which takes account of all these features, to make the most out of the vineyard.

Practice is essential for a good breeding is the beginning of 'fruit set, proceed to the hairstyle, which is to place the sprouts accurately; between fruit set and veraison, when the foliage is dense, they perform thinning leaves, to create a microclimate within the plant well balanced between light and shade and air movement that promotes photosynthesis, plant development and the maturation of the grapes.

(1) Low temperature effects on photosynthesis and growth of grapevine, l. hendrickson, m. c. ball, j. t. wood, w. s. chow and r. t. Furbank,
(2) Improving Photosynthesis, John R. Evans,
(3) Sugars and Organic Acids of Vitis vinifera - W. Mark Kliewer, 1966
(4) Comparison of investigation methods of heat injury in grapevine (Vitis) and assessment to heat tolerance in different cultivars and species Hongguo Xu, Liu Guojie, Guotian Liu, Bofang Yan, Wei Duan, Wang Lijun and Li Shaohua