The long-term effects of conventional and organic cropping systems,tillage managements and weather conditions on yield and grainquality of durum wheat (Triticum durum Desf.) in the Mediterraneanenvironment of Central Italy

Cropping system, tillage management and weather conditions can greatly affect durum wheat (Triticumdurum Desf.) determining its grain yield and quality. The aims of this study were to evaluate the effectsof cropping system (conventional vs. organic), tillage management (plowed at a depth of 30 cm vs.subsoiled at a depth of 20 cm), and the interaction between cropping system and weather conditionson yield and grain quality of durum wheat. The study was part of a long-term experiment carriedout in a rainfed Mediterranean environment of Central Italy where a 3-year crop rotation (durumwheat–tomato–chickpea) was compared in organic and conventional cropping systems. The study periodlasted from 2005 to 2011. The combined effect of cropping system and weather conditions determinedstrong differences in durum grain yield and quality parameters. The durum grain yield was on average15% lower in organic compared to conventional, although the yield gap between the cropping systemsvaried from −5 to −32% across the years. The air temperature influenced the grain yield more in organicthan in conventional, while high rainfall during the grain filling stage produced a higher grain yield inconventional than organic due to a different weed infestation. A severe water stress period starting fromstem elongation determined a poor grain yield and low protein concentration, while high temperaturesand water stress throughout the grain filling period resulted in a poor yield, yet high protein content inboth cropping systems. Conventional wheat generally showed a higher level of vitreousness and glutenquality, while protein and gluten content were higher in conventional compared to organic when a regular rainfall distribution occurred throughout the wheat reproductive period. These results are probablydue to a lower nitrogen supply in organic compared to conventional wheat. Yield and grain quality ofdurum wheat under different tillage managements such as plowed and subsoiled soil were comparable.Considering subsoiling as an important mode of conservation tillage, the results highlight that it is advis-able to use a subsoiler for durum wheat production. Weed control and nitrogen supply appear to be themain factors, which hinder yield production and grain quality especially when an excess of rainfall andlow temperatures occur throughout the crop reproductive period in organic durum wheat production.