Evaluation of the establishment of lowland and upland switchgrass (Panicumvirgatum L.) varieties under different tillage and seedbed conditions in northern Italy

Information is needed on potential biomass crops for marginal lands in sout hern Europe. The objective of this study was to investigate switchgrass est ablishment in four seedbed preparation treatments (sowing, rolling before s owing, rolling before and after sowing and no till) for two varieties (smal l and large seed types). A 4 x 2 split-plot factorial design with four bloc ks was adopted over a 2 years period. Trials were conducted in Bologna (lat itude 44 degrees 33'N, longitude 11 degrees 21'E, 32 m a.s.l.), in a silt l oam soil (Udic Ustochreps fine silty, mixed, mesic). In general, emergence was lower in the autumn trials than in the spring one. Emergence on rolled soil (single and double) was statistically higher than tilled unrolled soil . Cumulative analysis of the two autumn trials including no till showed a s ignificant (P less than or equal to 0.05) interaction between treatment and varieties: the large seed variety had a better performance only with no ti ll, particularly in the first year. Overall, if no till was not considered, no significant interactions between variety and tillage treatments were fo und for final seedling numbers. The statistical analysis on both varieties was therefore combined. Although the double rolled tillage treatment consis tently showed a slightly higher average seedling emergence than the single rolled treatment, the final number of emerged seedlings was never significa ntly different. In all cases, the rolled treatments (single and double) had significantly higher final emergence rates than the treatment with no soil compaction. The average emergence index of unrolled plots was 20% lower th an rolled plots. A function was calculated to predict the seedling numbers at the end of emergence based on the seedling numbers at the beginning of e mergence. Generally rolling was needed to obtain best switchgrass performan ces. In northern Italy both varieties had a good emergence when soil condit ions were appropriated. (C) 2001 Elsevier Science B.V. All rights reserved.