The influence of nitrogen and potassium fertilizers on the growth and yield of raspberries cv. ‘Polana’
¹Lithuanian Institute of Horticulture, LT–-54333 Babtai, Kaunas distr., Lithuania; e-mail:email@example.com
²Lithuanian Institute of Horticulture, LT–-54333 Babtai, Kaunas distr., Lithuania; e-mail:firstname.lastname@example.org
The experiment was carried out from 1998–2001 at the Lithuanian Institute of Horticulture, according to the scheme: N60 (control); N60K90; N90; N90K130; N120; N120K180; N150;N150K240. The soil was Epicalcari – Endohypogleic cambisol, clay loam, containing 7.2% oforganic matter, 140 mg kg-1 P2O5, 125 mg kg-1 K2O, 11900 mg kg-1 CaO, 3040 mg kg-1 MgO,pHKCl –7.3.Primocane raspberries cv. ‘Polana’ fertilized with the largest amount of nitrogen fertilizers(N150) produced 20% more primocanes in comparison with the control (N60). Potassiumfertilizers increased the diameter of raspberry stems – fertilizing them with N120K180 stemdiameter resulted in an increase of 5.3%, with N90K130 and by 4.2% with N150K240 incomparison with the control.Primocane raspberries cv. ‘Polana’ fertilized with N120K180 gave the highest yieldincrement – 2.5 t ha-1, and, with N60K90 – 2.4 t ha-1 – in comparison with those fertilized onlywith nitrogen fertilizers (N60).When the rate of nitrogen fertilizers was increased from 60 to 90–150 kg ha-1, the nitrogencontent in the soil increased by approximately 25%. When the rate of potassium fertilizers was increased from 90 to 240 kg ha-1, potassium content in the soil increased to 33%. The content of potassium in raspberry cv. ‘Polana’ leaves significantly increased when fertilizing only with the highest rates of potassium fertilizers (N120K180 – N150K240) – by 12.1–19.7% – in comparisonwith control (N60).