Pilar Baeza

Vegetative Development: Total Leaf Area and Surface Area Indexes

Canopy management determines canopy shape and spatial leaf area distribution which in turn determines vineyard productivity. There are two indexes evaluating vineyard productivity which involve leaf development: total leaf area – LAI – and external leaf area – SA –. The first one refers to total leaf area developed per m2 of soil while SA refers to the external leaves, assuming that most of photosynthesis – 90% – is carried out by those leaves. This chapter aims to provide a feasible methodology to calculate both LAI and SA under different training systems and cultivars in order to predict vineyard productivity or/and to make decisions along the season. Relations between main leaf nerve length (cm) and leaf surface area (cm2) are given for Airen, Albarino, Barbera, Cabernet franc, Cabernet sauvignon, Chardonnay, Godello, Garnacha, Graciano, Mencia, Merlot, Petit verdot, Pinot noir, Semillon, Syrah, Tempranillo, Treixadura, Verdejo and Viognier.

Radiation Balance in Vineyards

Light intercepted by grapevines is linearly related to vineyard productivity. Radiation intercepted is also linked to vegetative development and in turn with water consume by plants. Thus, potential yield and crop coefficient – kc – for irrigation management can indirectly be predicted based on canopy light interception and vegetative development. The radiation balance of a crop can be calculated as absorbed radiation (Ra) or intercepted radiation (Rit). Ra is the balance between the input of radiation in the vine-soil group (incident radiation –Ri- and reflected radiation by the soil –Rrs-) and the output of radiation from the vine-soil (transmitted radiation –Rt- and reflected by soil and plant together –Rrsp-). In crops in rows, the soil between rows must be taken into account especially in those periods when the canopy does not cover it completely, representing a drain of energy. But once the development of the canopy is complete, Rit can be used as a simplification of Ra. Rit is the difference between Ri and Rt, without considering the reflected radiation because its value is very small.