Wheat yield and grain quality as affected by tillage, sowing time and nitrogen fertilization under rainfed Mediterranean conditions

The research was carried out in 9 sites (5 in 1999-00 and 4 in 2000-01) of inner area of Sicily different for soil type, slope, exposure and preceding crop. The following treatments were studied: (i) conventional tillage and sowing at conventional time (CT); (ii) no tillage and sowing at conventional time (NTc); and (iii) no tillage and early sowing (NTe). In 2000-01 the effect of three nitrogen fertilization treatment (single application at planting, P, and split dressing at two different rates, S and S+) were also evaluated. No tillage systems (NTc and NTe) significantly increased grain yield compared to CT treatment; no differences were observed between the two sowing dates. The productive benefits of no tillage were associated with a decrease of grain protein content that was heavier with early sowing. Regarding N fertilization treatments, S compared with P allowed a significant yield increase; no interaction with tillage technique was found. At the lowest fertilizer rates, split fertilization allowed a significant increase of grain protein content only in NTe.