Studies on the Effect of Npk Fertilization on Frost Tolerance in the Hacihalilodlu Apricot (Prunus Armenica L.) Cultivar

Abstract

This study was conducted to determine the effect of NPK fertilization on the frost tolerance in the HacyhaliloSlu apricot cultivar in the years 1996-1997. The fertilizer treatments comprised all factorial combinations of 4 levels of N (No=0.0, N1=0.2, N2=0.4 and N3=0.6 kg of N per tree per year), 3 levels of P (P,=0.2 P2=0..4 and P3=0.6 kg of P2O5 and 3 levels of K (Ki=0.4, K2=0.8 and K3= 1.6 kg K2O). These treatments were applied to the trees between 1994-1997. Samples of two twigs were collected and exposed to artificial freezing tests, periodically between December and March. The artificial freezing was made at -10C° for a duration of 7 hours. Statistically significant differences were found between the frost tolerance of NPK-treated flower buds of the HacyhaliloQlu cv. The frost tolerance abilities, at the investigated NPK doses, were found to be higher in January and lower in December and March. Potassium and phosphorus fertilizers had significant effects on the frost tolerance of flower buds. Potassium fertilizer played the most important role on frost tolerance, compared with nitrogen or phosphorus fertilizers. The results indicated that, the frost tolerance of flower buds following K2O applications was higher than that of buds treated with other NPK doses. Lower survival percentages of buds were found with nitrogen applications. The frost tolerance ability was found to be lower following fertilization at the higher doses of nitrogen. In all the investigated NPK doses, the level of K and Fe increased from January to February, in parallel with the frost tolerance ability of the flower buds, but decreased in November and March.