A. I. Kuzin, A. A. Shmakova, A. A. Karpukhina
Michurin Federal Scientific Center, ul. Michurina, 30, Michurinsk, Tambovskaya obl., 393774, Russian Federation
Abstract. The study was conducted in the Tambov region in 2016 and 2017. The purpose was to determine the optimal level of potassium content in apple leaves, depending on the crop load and the rate of potassium fertilizer when forming a fertigation program. The experiments were conducted in plantations of two apple-tree varieties (Lobo and Zhigulevskoe) engrafted on the stock 62-396. In one group of options, the rates of fertigation with potassium fertilizers were unchanged (N20P15K25, N20P15K35, and N20P15K45); in the other group they changed annually depending on the crop load (N20P15K20, N20P15K25, and N20P15K35 in 2016 and N20P15K35, N20P15K45, N20P15K55 in 2017); in the control, we did not use potassium fertilizers (N20P15). The application of potassium fertilizers increased the yield of the apple-tree variety Zhigulevskoye up to 38.8 t/ha (in the control, this indicator was 31.3 t/ha); the yield of the apple-tree variety Lobo increased up to 31.8 t/ha (in the control this indicator was 24.1 t/ha). A close positive correlation between potassium content in leaves and apple yield (r = 0.43–0.76) was noted at the end of May. The optimal potassium content in leaves at the beginning of active shoot growth was 1.7–2.3% per dry matter. A close negative relationship between these values was observed at the end of August for the Zhigulevskoye variety (from -0.65 to -0.75) and in September for the Lobo variety (from -0.37 to -0.63). The different crop loads determined the unequal need of apple plants in potassium nutrition. In 2016, a decrease in the potassium application rate at a relatively low crop load did not have a significant effect on the apple yield of the Zhigulevskoye variety: 27.8 t/ha for N20P15K20 and 28.8 t/ha for N20P15K45. In 2017, with a higher crop load, an increase in the fertilizing rate to N20P15K55 ensured an increase in the yield of the Lobo variety to 40.3 t/ha versus 38.9 t/ha at the recommended regional rate (N20P15K35), that is, the efficiency of potassium fertilization increased.
Keywords: apple tree (Malus domestica Borkh); fertigation; potassium fertilizer; exchangeable potassium content in soil; potassium content in leaves; yield.
Author Details: A. I. Kuzin, D. Sc. (Agr.), head of division (e-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.); A. A. Shmakova, junior research fellow; A. A. Karpukhina, post graduate student.
For citation: Kuzin AI, Shmakova AA, Karpukhina AA [Precision potassium fertilization by apple tree fertigation]. Dostizheniya nauki i tekhniki APK. 2021; 35 (7):50-7.Russian. doi: 10.53859/02352451_2021_35_7_50.