Implications of herbicide, cultivation or cover crop under-vine soil management on the belowground microbiote

Abstract

Context and purpose of the study. Soil management through cover crops in the lines of the vineyards is a common practice in viticulture, since it improves the characteristics of the soil. It has been shown that the cover crops can influence the cycle of nutrients, promote infiltration, decrease erosion, and enhance the soil microbiota biodiversity improving the grapevines. However, the area under the vines tends to be left bare by applying herbicides or tillage to avoid competition with the crop in hot climates. The use of cover crops under the vines might be a plausible alternative to the use of herbicides or cultivation, improving grapevine quality and soil characteristics. The aim of this research was to study the implications of different management of the soil under the vines (herbicide, cultivation or cover crops) on grapevine growth, water and nutritional status and belowground microbial communities.

Material and methods: Experimental design consisted in 4 treatments applied on potted Tempranillo grapevines with 10 repetitions each grown in an open-top greenhouse in 2022. Treatments consisted in two species of cover crops (Trifolium fragiferum and Bromus repens), herbicide (glyphosate al 36%) and an untreated control. The total biomass of covers and the vine growth were measured throughout the season.  Water status was monitored by measuring the stem water potential. In Autumn, three plants per treatment were collected to record fresh and dry masses of the different organs (roots and shoots) and water content was estimated as the relationship between the fresh and dry masses. Soil microbial diversity and physiological profiles were measured using the plates Biolog EcoplatesTM from soil samples collected at 25 cm.

Results. According to our results, T. Fragiferum was the cover crop under the vine that obtained the highest biomass. In spite of the enhanced vegetative development of T. fragiferum, preliminary results did not show differences on grapevine performance and growth compared to other treatments. However, the use of cover crops under the vine affected soil microbial communities enhancing their diversity and their activity. In general, the cover crops obtained better results, 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 lack of effect on cover crops under the vines on the grapevine performance might indicate a minimum competition between the grapevine and the studied cover crops. Therefore, the use of these covers under-vine could be an alternative to the use of herbicides to control the growth of adventitious vegetation. In addition, the improvement of the biological quality of the soil would also affect positively the performance of grapevines.