Under-vine management effects on grapevine vegetative growth, gas exchange and rhizosphere microbial diversity

The use of cover crops under the vines might be an alternative to the use of herbicides or tillage, improving grapevine quality and soil characteristics. The aim of this research was to study the implications of different management strategies of the soil under the vines (herbicide, cultivation or cover crops) on grapevine growth, water and nutritional status, gas exchange parameters and belowground microbial communities.

The experimental design consisted in 4 treatments applied on 35L-potted Tempranillo vegetative grapevines with 10 replicates each grown in an open-top greenhouse in 2022 and 2023. Treatments included two cover crop species (Trifolium fragiferum and Bromus repens), herbicide (glyphosate al 36%) and an untreated control. Vines were irrigated weekly to fulfil water requirements without fertilization. Gas exchange parameters were measured with portable gas exchange photosynthesis system (Li-Cor 6400, Lincoln, NE, USA) and water status was monitored by measuring the stem water potential with a Scholander pressure chamber (Precis 2000, Gradignan, France). Sown cover crops were mowed during the growing season, and at the end of summer, control and cover crop treatments were sowed. According to our results, T. fragiferum was the cover crop under the vine that reached the highest biomass. Despite the increased vegetative development of T. fragiferum, preliminary results did not show differences on grapevine performance and growth compared to other treatments. Conversely, the use of cover crops under the vine affected soil microbial communities. In general, the cover crops increased heterotrophic microbial diversity estimated with Biolog Ecoplates^TM and mycorrhizal colonization of grapevine roots in comparison with the use of herbicide, T. fragiferum being the one that had the greatest effect on the biological quality of the soil. The scarce effect of the cover crops under the vines on the grapevine performance might indicate a relative weak competition between the grapevine and the studied cover crops. Therefore, the use of these under-vine covers could be an alternative to the use of herbicides to control the adventitious vegetation growth. Also, the improvement of soil biological quality of the soil would affect positively grapevines performance.

Acknowledgements: This work was funded by Navarra Government (project PC044-045_CUALVID). N. Torres is beneficiary of a Ramón y Cajal Grant RYC2021-034586-I funded by MCIN/AEI/ 10.13039/501100011033 and by “European Union NextGenerationEU/PRTR”.