Effetti della forma azotata e delle modalità di distribuzione sulla produzione e la qualità di lattuga

Lettuce has a primary importance among vegetable crops in Italy. Despite the limited duration of crop cycle, lettuce needs high doses of N due to limited growth and low roots N absorption efficiency. Doses and distribution tecniques of nitrogen may affect growth and nitrate accumulation in plant tissues. In order to evaluate the productive and qualitative response of lettuce to different forms of nitrogen and distribution tecniques, a field trial was carried out in Palermo (Sicily) from November 2007 to February 2008. Two forms of nitrogen (ammonium or nitrate) and two distribution tecniques (50% pre-planting+50% post-planting; 25% pre-planting+50% post-planting+25% post planting) were compared in a split plot design. The use of ammonium nitrogen results in a higher yield and average weigth, while the tecnique of distribution influences significantly the nitrate content of plants, with lower values with two post-planting fertilizations.