Screening of Cover Crop Species for Sustainable Vineyard Floor Management

Increasing use of cover crops (CC) is a necessity in sustainable viticulture although it might clash against possible excessive competition towards vines. Especially under a global warming scenario, the latter feature should be minimised while maintaining ecosystem services. Aiming at identifying low-maintenance CC for vineyard floor management, the trial characterized several species depending on their evapotranspiration (ET) rates and root growth patterns. The study was performed in 2020 in Piacenza (northern Italy) on CC grown in 15-L pots kept outdoor. The behaviour of 15 CC species classified as follows: grasses (GR), legumes (LE) and creeping (CR), was compared to bare soil (control) as part of a complete randomized block design. On DOY (day of the year) 183 irrigation was stopped and ET rates assessed through a gravimetric method. Above-ground dry biomass, root length density (RLD) and root dry weight (RDW) within 0-20 cm depth were measured. Daily ET was the highest in LE (18.6 mm d(-1)) and the lowest in CR (8.1 mm d(-1)), the latter being even lower than the control (8.5 mm d(-1)). Mean daily ET was 10.6 mm d(-1) in GR, with F. arundinacea (FA) and F. ovina (FO) showing the highest (13.4 mm d(-1)) and the lowest (7.5 mm d(-1)) ET, respectively. The highest RLD was for GR, varying from 15.4 (FO) to 34.4 (FA) cm cm(-3). L. corniculatus (LC) had the highest above-ground biomass (2.12 kg m(-2)) than any other CC, ranging between 0.28 and 1.09 kg m(-2). RDW was the highest in FA (6.30 mg cm(-3)) and LC (6.77 mg cm(-3)). Under-vine grassing using creeping species has an unexplored potential for assuring rapid soil coverage and lowest ET rates. Conversely, FO stands out among GR as the one with the lowest RDW, RDL and ET values.