TY - JOUR AU - PIETOLA, L. AU - TANNI, R. AU - ELONEN, P. PY - 1999/01/04 Y2 - 2024/03/28 TI - Responses of yield and N use of spring sown crops to N fertilization, with special reference to the use of plant growth regulators JF - Agricultural and Food Science JA - AFSci VL - 8 IS - 4-5 SE - Articles DO - 10.23986/afsci.5639 UR - https://journal.fi/afs/article/view/5639 SP - 423-440 AB - The role of plant growth regulators (PGR) in nitrogen (N) fertilization of spring wheat and oats (CCC), fodder barley (etephon/mepiquat) and oilseed rape (etephone) in crop rotation was studied in 1993–1996 on loamy clay soil. Carry over effect of the N fertilization rates (0–180 kg ha-1 ) was evaluated in 1997. N fertilization rate for the best grain/seed yield (120–150 kg ha-1 ) was not affected by PGRs. The seed and N yields of oilseed rape were improved most frequently by recommended use of PGR. The yields of oats were increased in 1995–96. Even though PGR effectively shortened the plant height of spring wheat, the grain yield increased only in 1995. N yield of wheat grains was not increased. Response of fodder barley to PGR was insignificant or even negative in 1995. The data suggest that PGRs may decrease some N leaching at high N rates by improving N uptake by grain/seeds, if the yield is improved. The carryover study showed that in soils with no N fertilization, as well as in soils of high N rates, N uptake was higher than in soils with moderate N fertilization (60–90 kg ha-1 ), independent of PGRs. According to soil mineral N contents, N leaching risk is significant (15–35 kg ha-1 ) only after dry and warm late seasons. After a favourable season of high yields, the N rates did not significantly affect soil mineral N contents. ; ER -