Effect of various nitrogen fertilisation and foliar nutrition regimes on carrot (Daucus carota L.) yield

This research was aimed at determining the influence of various forms, diverse doses, and dates of application, of nitrogen fertilisation and foliar nutrition on the amount and structure of carrot yield. Two field experiments [Experiment I (2003 - 2005) and Experiment II (2004 - 2005)] with carrot 'Kazan F-1' were conducted at Trzciana (50 degrees 06' N; 21 degrees 85'E) in Poland. Both Experiments were set up as split-plots in a randomised design. Two sub-blocks were identified in both Experiments: (A) without foliar nutrition; and (B) sub-blocks with foliar nutrition in which plants were sprayed three-times with 2% (w/v) urea, then a 1 % (v/v) solution of multi-component 'Supervit R' fertiliser; and again with 2% (w/v) urea. Plots with various nitrogen fertilisation were distinguished within both sub-blocks in both Experiments. The treatments in Experiment I consisted of: (i) control; (ii) 70 kg N ha(-1) as Ca(NO3)(2); (iii) 70+70 kg N ha(-1), as Ca(NO3)(2); (iv) 70 kg N ha(-1) as (NH4)(2)SO4; and (v) 70+70 kg N ha(-1) as (NH4)(2)SO4, where the 70 kg N ha(-1) was applied before sowing, and the 70+70 kg N ha(-1) was applied before sowing and as a top dressing, respectively. The treatments in Experiment II consisted of: (i) control; (ii) 35+35 kg N ha(-1) as ENTEC-26 [solid fertiliser containing 26% (w/w) N (7.5% N-NO3, Plus 18.5% N-NH4),13% (w/w) S, and the nitrification inhibitor, 3,4-dimethylpyrazol phosphate (DMPP)]; (iii) 70+70 kg N ha(-1) as ENTEC-26; (iv) 105+105 kg N ha(-1) as ENTEC-26; (v) 35+35 kg N ha(-1) as NH4NO3; (vi) 70+70 kg N ha(-1) as NH4NO3; and (vii) 105+105 kg N ha(-1) as NH4NO3, where the 35+35, 70+70, and 105+105 kg N ha(-1) treatments were applied before sowing and as a top dressing, respectively. In Experiment I, nitrogen fertilisation was found to have no effect on carrot yield, irrespective of foliar nutrition. Foliar nutrition caused a rise in carrot storage root yield. In Experiment II, the highest marketable yield and total yield of carrot, as well as biological yield (leaves + storage roots), were produced using of 35+35 kg N ha(-1) as ENTEC-26. Foliar nutrition. decreased the marketable yield of carrot to 4.2 t ha(-1). Neither Experiment showed any statistically significant interaction between foliar nutrition and fertilisation on leaf yield, marketable or total yields of carrot storage roots, biological yield, or on the proportion of marketable yield in the total yield of storage roots.