Permanent vs temporary cover crops in a Sangiovese vineyard: preliminary results on vine physiology and productive traits

Abstract

Cover crops in vineyards have been extensively studied, as the choice of grass species and their management significantly influence soil properties and vine performance. However, the anomalous distribution and intensity of rainfall events driven by climate change have renewed interest in soil management, highlighting the need to update our knowledge.

Considering the importance of this issue, this study aimed to evaluate the effects of different permanent and temporary cover crop management strategies on vine physiology and productive traits.

The trial was conducted in a Sangiovese vineyard in the Senio Valley (Emilia-Romagna, Italy) and vines, clone VCR4 grafted onto SO4 rootstock, were trained to free cordon. In November 2023, two specific cover crop mixes were sown in the interrow following a randomized block experimental design: a) mix of Lolium perenne, Festuca Rubra, Poa pratense and Trifolium repens to establish a permanent sward that was mown twice in the following spring/summer (P+M); b) mix of Hordeum vulgare, Brassica napus, Avena strigosa, Phacelia tanacetifolia and Trifolium incarnatum to establish a temporary cover crop that in May 2024 was mowed with a trimmer and incorporated to the soil by tillage, realizing a green manure (T+GM) or mowed and laid down in the interrow as organic mulching (T+OM).

Midday stem water potential measurements of July and August 2024 showed lower potentials of P+M vines compared to those of the other treatments, in two of the five days they were performed, but no difference of net assimilation between treatments was noted in the three days in which gas exchange measurements were conducted. At harvest, cluster and berry weight of P+M grapes resulted lower than the other treatments, leading to a slight and not significant lower yield. Quite surprisingly, total soluble solids concentration resulted higher in T+GM than in P+M, while T+OM showed an intermediate value. No difference in pH and titratable acidity was found. These results appear related to the competition of the permanent cover crops in terms of nutrients and water uptake, which may have reduced the development of main and lateral shoots, resulting in a lower leaf area compared to T+GM vines. This hypothesis will soon be tested by assessing vegetative growth through the measurement of pruning weight.

The preliminary results of this trial bring to light some interesting insights on soil management which need to be evaluated in the coming years.